+
+\end_layout
+
+\begin_layout Standard
+This is the
+\series bold
+default
+\series default
+ storage class for the Small Memory model (
+\emph on
+data
+\emph default
+ and
+\emph on
+near
+\emph default
+ or the more ANSI-C compliant forms
+\emph on
+__data
+\emph default
+ and
+\emph on
+__near
+\emph default
+ can be used synonymously).
+ Variables declared with this storage class will be allocated in the directly
+ addressable portion of the internal RAM of a 8051, e.g.:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+__data unsigned char test_data;
+\end_layout
+
+\begin_layout Standard
+Writing 0x01 to this variable generates the assembly code:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+75*00 01\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov\InsetSpace ~
+\InsetSpace ~
+_test_data,#0x01
+\end_layout
+
+\begin_layout Subsubsection
+xdata
+\begin_inset LatexCommand \index{xdata (mcs51, ds390 storage class)}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_xdata (mcs51, ds390 storage class)}
+
+\end_inset
+
+ / far
+\begin_inset LatexCommand \index{far (storage class)}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_far (storage class)}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+Variables declared with this storage class will be placed in the external
+ RAM.
+ This is the
+\series bold
+default
+\series default
+ storage class for the Large Memory model, e.g.:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+__xdata unsigned char test_xdata;
+\end_layout
+
+\begin_layout Standard
+Writing 0x01 to this variable generates the assembly code:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+90s00r00\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov\InsetSpace ~
+\InsetSpace ~
+dptr,#_test_xdata
+\newline
+74\InsetSpace ~
+01\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov\InsetSpace ~
+\InsetSpace ~
+a,#0x01
+\newline
+F0\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+movx\InsetSpace ~
+@dptr,a
+\end_layout
+
+\begin_layout Subsubsection
+idata
+\begin_inset LatexCommand \index{idata (mcs51, ds390 storage class)}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_idata (mcs51, ds390 storage class)}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+Variables declared with this storage class will be allocated into the indirectly
+ addressable portion of the internal ram of a 8051, e.g.:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+__idata unsigned char test_idata;
+\end_layout
+
+\begin_layout Standard
+Writing 0x01 to this variable generates the assembly code:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+78r00\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov\InsetSpace ~
+\InsetSpace ~
+r0,#_test_idata
+\newline
+76\InsetSpace ~
+01\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov\InsetSpace ~
+\InsetSpace ~
+@r0,#0x01
+\end_layout
+
+\begin_layout Standard
+Please note, the first 128 byte of idata physically access the same RAM
+ as the data memory.
+ The original 8051 had 128 byte idata memory, nowadays most devices have
+ 256 byte idata memory.
+ The stack
+\begin_inset LatexCommand \index{stack}
+
+\end_inset
+
+ is located in idata memory.
+\end_layout
+
+\begin_layout Subsubsection
+pdata
+\begin_inset LatexCommand \index{pdata (mcs51, ds390 storage class)}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_pdata (mcs51, ds390 storage class)}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+Paged xdata access is just as straightforward as using the other addressing
+ modes of a 8051.
+ It is typically located at the start of xdata and has a maximum size of
+ 256 bytes.
+ The following example writes 0x01 to the pdata variable.
+ Please note, pdata access physically accesses xdata memory.
+ The high byte of the address is determined by port P2
+\begin_inset LatexCommand \index{P2 (mcs51 sfr)}
+
+\end_inset
+
+(or in case of some 8051 variants by a separate Special Function Register,
+ see section
+\begin_inset LatexCommand \ref{sub:MCS51-variants}
+
+\end_inset
+
+).
+ This is the
+\series bold
+default
+\series default
+ storage class for the Medium Memory model, e.g.:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+__pdata unsigned char test_pdata;
+\end_layout
+
+\begin_layout Standard
+Writing 0x01 to this variable generates the assembly code:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+78r00\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov r0,#_test_pdata
+\newline
+74 01\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov a,#0x01
+\newline
+F2\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+movx @r0,a
+\end_layout
+
+\begin_layout Standard
+If the -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-xstack
+\begin_inset LatexCommand \index{-\/-xstack}
+
+\end_inset
+
+ option is used the pdata memory area is followed by the xstack memory area
+ and the sum of their sizes is limited to 256 bytes.
+\end_layout
+
+\begin_layout Subsubsection
+code
+\begin_inset LatexCommand \index{code}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_code}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+'Variables' declared with this storage class will be placed in the code
+ memory:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+__code unsigned char test_code;
+\end_layout
+
+\begin_layout Standard
+Read access to this variable generates the assembly code:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+90s00r6F\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov dptr,#_test_code
+\newline
+E4\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+clr a
+\newline
+93\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+movc a,@a+dptr
+\end_layout
+
+\begin_layout Standard
+
+\family typewriter
+char
+\family default
+ indexed arrays of characters in code memory can be accessed efficiently:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+__code char test_array[] = {'c','h','e','a','p'};
+\end_layout
+
+\begin_layout Standard
+Read access to this array using an 8-bit unsigned index generates the assembly
+ code:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+E5*00\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov a,_index
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+90s00r41\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov dptr,#_test_array
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+93\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+movc a,@a+dptr
+\end_layout
+
+\begin_layout Subsubsection
+bit
+\begin_inset LatexCommand \index{bit}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_bit}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+This is a data-type and a storage class specifier.
+ When a variable is declared as a bit, it is allocated into the bit addressable
+ memory of 8051, e.g.:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+__bit test_bit;
+\end_layout
+
+\begin_layout Standard
+Writing 1 to this variable generates the assembly code:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+D2*00\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+setb\InsetSpace ~
+_test_bit
+\end_layout
+
+\begin_layout Standard
+The bit addressable memory consists of 128 bits which are located from 0x20
+ to 0x2f in data memory.
+
+\newline
+Apart from this 8051 specific storage class most architectures support
+ ANSI-C bitfields
+\begin_inset LatexCommand \index{bitfields}
+
+\end_inset
+
+
+\begin_inset Foot
+status open
+
+\begin_layout Standard
+Not really meant as examples, but nevertheless showing what bitfields are
+ about: device/include/mc68hc908qy.h and support/regression/tests/bitfields.c
+\end_layout
+
+\end_inset
+
+.
+ In accordance with ISO/IEC 9899 bits and bitfields without an explicit
+ signed modifier are implemented as unsigned.
+\end_layout
+
+\begin_layout Subsubsection
+sfr
+\begin_inset LatexCommand \index{sfr}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_sfr}
+
+\end_inset
+
+ / sfr16
+\begin_inset LatexCommand \index{sfr16}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_sfr16}
+
+\end_inset
+
+ / sfr32
+\begin_inset LatexCommand \index{sfr32}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_sfr32}
+
+\end_inset
+
+ / sbit
+\begin_inset LatexCommand \index{\_\_sbit}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{sbit}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+Like the bit keyword,
+\emph on
+sfr / sfr16 / sfr32 / sbit
+\emph default
+signify both a data-type and storage class, they are used to describe the
+
+\emph on
+s
+\emph default
+pecial
+\emph on
+f
+\emph default
+unction
+\emph on
+r
+\emph default
+egisters and
+\emph on
+s
+\emph default
+pecial
+\emph on
+bit
+\emph default
+ variables of a 8051, eg:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+__sfr __at
+\begin_inset LatexCommand \index{at}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_at}
+
+\end_inset
+
+ (0x80) P0;\InsetSpace ~
+ /* special function register P0 at location 0x80 */
+\newline
+
+\newline
+/* 16 bit
+ special function register combination for timer 0
+\newline
+\InsetSpace ~
+\InsetSpace ~
+ with the high byte at
+ location 0x8C and the low byte at location 0x8A */
+\newline
+__sfr16 __at (0x8C8A)
+ TMR0;
+\newline
+
+\newline
+__sbit __at
+\begin_inset LatexCommand \index{at}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_at}
+
+\end_inset
+
+ (0xd7) CY;\InsetSpace ~
+ /* CY (Carry Flag
+\begin_inset LatexCommand \index{Flags}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{Carry flag}
+
+\end_inset
+
+) */
+\end_layout
+
+\begin_layout Standard
+Special function registers which are located on an address dividable by
+ 8 are bit-addressable, an
+\emph on
+ sbit
+\emph default
+ addresses a specific bit within these sfr.
+\newline
+16 Bit and 32 bit special function
+ register combinations which require a certain access order are better not
+ declared using
+\emph on
+sfr16
+\emph default
+ or
+\emph on
+sfr32.
+
+\emph default
+ Allthough SDCC usually accesses them Least Significant Byte (LSB) first,
+ this is not guaranteed.
+\newline
+
+\end_layout
+
+\begin_layout Standard
+Please note, if you use a header file which was written for another compiler
+ then the sfr / sfr16 / sfr32 / sbit Storage Class extensions will most
+ likely be
+\emph on
+not
+\emph default
+compatible.
+ Specifically the syntax
+\family typewriter
+\InsetSpace ~
+sfr P0 = 0x80;\InsetSpace ~
+
+\family default
+ is compiled
+\emph on
+without warning
+\emph default
+ by SDCC to an assignment of 0x80 to a variable called P0
+\family typewriter
+
+\begin_inset Marginal
+status collapsed
+
+\begin_layout Standard
+
+\series bold
+\InsetSpace ~
+!
+\end_layout
+
+\end_inset
+
+.
+
+\family default
+Nevertheless it is possible to write header files
+\begin_inset LatexCommand \index{Header files}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{Include files}
+
+\end_inset
+
+ which can be shared among different compilers (see section
+\begin_inset LatexCommand \ref{sec:Porting-code-to-other-compilers}
+
+\end_inset
+
+).
+
+\end_layout
+
+\begin_layout Subsubsection
+Pointers
+\begin_inset LatexCommand \index{Pointer}
+
+\end_inset
+
+ to MCS51/DS390 specific memory spaces
+\end_layout
+
+\begin_layout Standard
+SDCC allows (via language extensions) pointers to explicitly point to any
+ of the memory spaces
+\begin_inset LatexCommand \index{Memory model}
+
+\end_inset
+
+ of the 8051.
+ In addition to the explicit pointers, the compiler uses (by default) generic
+ pointers which can be used to point to any of the memory spaces.
+\newline
+
+\newline
+Pointer
+ declaration examples:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+/* pointer physically in internal ram pointing to object in external ram
+ */
+\newline
+__xdata unsigned char * __data p;
+\newline
+
+\newline
+/* pointer physically in external ram
+ pointing to object in internal ram */
+\newline
+__data unsigned char * __xdata p;
+\newline
+
+\newline
+/*
+ pointer physically in code rom pointing to data in xdata space */
+\newline
+__xdata
+ unsigned char * __code p;
+\newline
+
+\newline
+/* pointer physically in code space pointing to
+ data in code space */
+\newline
+__code unsigned char * __code p;
+\newline
+
+\newline
+/* generic pointer
+ physically located in xdata space */
+\newline
+unsigned char * __xdata p;
+\newline
+
+\newline
+/* generic
+ pointer physically located in default memory space */
+\newline
+unsigned char * p;
+\newline
+
+\newline
+/*
+ the following is a function pointer
+\begin_inset LatexCommand \index{function pointer}
+
+\end_inset
+
+ physically located in data space */
+\newline
+char (* __data fp)(void);
+\end_layout
+
+\begin_layout Standard
+Well you get the idea.
+
+\newline
+
+\newline
+All unqualified pointers are treated as 3-byte (4-byte for the ds390)
+\emph on
+generic
+\emph default
+ pointers.
+
+\size small
+
+\newline
+
+\newline
+
+\size default
+The highest order byte of the
+\emph on
+generic
+\emph default
+ pointers contains the data space information.
+ Assembler support routines are called whenever data is stored or retrieved
+ using
+\emph on
+generic
+\emph default
+ pointers.
+ These are useful for developing reusable library
+\begin_inset LatexCommand \index{Libraries}
+
+\end_inset
+
+ routines.
+ Explicitly specifying the pointer
+\begin_inset LatexCommand \index{pointer}
+
+\end_inset
+
+ type will generate the most efficient code.
+\end_layout
+
+\begin_layout Subsubsection
+Notes on MCS51 memory
+\begin_inset LatexCommand \index{MCS51 memory}
+
+\end_inset
+
+ layout
+\end_layout
+
+\begin_layout Standard
+The 8051 family of microcontrollers have a minimum of 128 bytes of internal
+ RAM memory which is structured as follows:
+\newline
+
+\newline
+- Bytes 00-1F - 32 bytes to hold
+ up to 4 banks of the registers R0 to R7,
+\newline
+- Bytes 20-2F - 16 bytes to hold
+ 128 bit
+\begin_inset LatexCommand \index{bit}
+
+\end_inset
+
+ variables and,
+\newline
+- Bytes 30-7F - 80 bytes for general purpose use.
+\newline
+
+\end_layout
+
+\begin_layout Standard
+Additionally some members of the MCS51 family may have up to 128 bytes of
+ additional, indirectly addressable, internal RAM memory (
+\emph on
+idata
+\emph default
+
+\begin_inset LatexCommand \index{idata (mcs51, ds390 storage class)}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_idata (mcs51, ds390 storage class)}
+
+\end_inset
+
+).
+ Furthermore, some chips may have some built in external memory (
+\emph on
+xdata
+\emph default
+
+\begin_inset LatexCommand \index{xdata (mcs51, ds390 storage class)}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_xdata (mcs51, ds390 storage class)}
+
+\end_inset
+
+) which should not be confused with the internal, directly addressable RAM
+ memory (
+\emph on
+data
+\emph default
+
+\begin_inset LatexCommand \index{data (mcs51, ds390 storage class)}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_data (mcs51, ds390 storage class)}
+
+\end_inset
+
+).
+ Sometimes this built in
+\emph on
+xdata
+\emph default
+ memory has to be activated before using it (you can probably find this
+ information on the datasheet of the microcontroller your are using, see
+ also section
+\begin_inset LatexCommand \ref{sub:Startup-Code}
+
+\end_inset
+
+\InsetSpace ~
+Startup-Code).
+\end_layout
+
+\begin_layout Standard
+Normally SDCC will only use the first bank
+\begin_inset LatexCommand \index{register bank (mcs51, ds390)}
+
+\end_inset
+
+ of registers (register bank 0), but it is possible to specify that other
+ banks of registers (keyword
+\emph on
+using
+\emph default
+
+\emph on
+
+\begin_inset LatexCommand \index{using (mcs51, ds390 register bank)}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_using (mcs51, ds390 register bank)}
+
+\end_inset
+
+
+\emph default
+) should be used for example in interrupt
+\begin_inset LatexCommand \index{interrupt}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_interrupt}
+
+\end_inset
+
+ routines.
+ By default, the compiler will place the stack after the last byte of allocated
+ memory for variables.
+ For example, if the first 2 banks of registers are used, and only four
+ bytes are used for
+\emph on
+data
+\emph default
+ variables, it will position the base of the internal stack at address 20
+ (0x14).
+ This implies that as the stack
+\begin_inset LatexCommand \index{stack}
+
+\end_inset
+
+ grows, it will use up the remaining register banks, and the 16 bytes used
+ by the 128 bit variables, and 80 bytes for general purpose use.
+ If any bit variables are used, the data variables will be placed in unused
+ register banks and after the byte holding the last bit variable.
+ For example, if register banks 0 and 1 are used, and there are 9 bit variables
+ (two bytes used),
+\emph on
+data
+\emph default
+ variables will be placed starting from address 0x10 to 0x20 and continue
+ at address 0x22.
+ You can also use -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-data-loc
+\begin_inset LatexCommand \index{-\/-data-loc <Value>}
+
+\end_inset
+
+ to specify the start address of the
+\emph on
+data
+\emph default
+ and -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-iram-size
+\begin_inset LatexCommand \index{-\/-iram-size <Value>}
+
+\end_inset
+
+ to specify the size of the total internal RAM (
+\emph on
+data
+\emph default
++
+\emph on
+idata
+\emph default
+).
+
+\newline
+
+\end_layout
+
+\begin_layout Standard
+By default the 8051 linker will place the stack after the last byte of (i)data
+ variables.
+ Option -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-stack-loc
+\begin_inset LatexCommand \index{-\/-stack-loc <Value>}
+
+\end_inset
+
+ allows you to specify the start of the stack, i.e.
+ you could start it after any data in the general purpose area.
+ If your microcontroller has additional indirectly addressable internal
+ RAM (
+\emph on
+idata
+\emph default
+) you can place the stack on it.
+ You may also need to use -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-xdata-loc
+\begin_inset LatexCommand \index{-\/-xdata-loc<Value>}
+
+\end_inset
+
+ to set the start address of the external RAM (
+\emph on
+xdata
+\emph default
+) and -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-xram-size
+\begin_inset LatexCommand \index{-\/-xram-size <Value>}
+
+\end_inset
+
+ to specify its size.
+ Same goes for the code memory, using -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-code-loc
+\begin_inset LatexCommand \index{-\/-code-loc <Value>}
+
+\end_inset
+
+ and -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-code-size
+\begin_inset LatexCommand \index{-\/-code-size <Value>}
+
+\end_inset
+
+.
+ If in doubt, don't specify any options and see if the resulting memory
+ layout is appropriate, then you can adjust it.
+\end_layout
+
+\begin_layout Standard
+The linker generates two files with memory allocation information.
+ The first, with extension .map
+\begin_inset LatexCommand \index{<file>.map}
+
+\end_inset
+
+ shows all the variables and segments.
+ The second with extension .mem
+\begin_inset LatexCommand \index{<file>.mem}
+
+\end_inset
+
+ shows the final memory layout.
+ The linker will complain either if memory segments overlap, there is not
+ enough memory, or there is not enough space for stack.
+ If you get any linking warnings and/or errors related to stack or segments
+ allocation, take a look at either the .map or .mem files to find out what
+ the problem is.
+ The .mem file may even suggest a solution to the problem.
+\begin_inset VSpace bigskip
+\end_inset
+
+
+\end_layout
+
+\begin_layout Subsection
+Z80/Z180 Storage Class
+\begin_inset LatexCommand \index{Z80!Storage class}
+
+\end_inset
+
+ Language Extensions
+\end_layout
+
+\begin_layout Subsubsection
+sfr
+\begin_inset LatexCommand \index{sfr}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_sfr}
+
+\end_inset
+
+ (in/out to 8-bit addresses)
+\end_layout
+
+\begin_layout Standard
+The Z80
+\begin_inset LatexCommand \index{Z80}
+
+\end_inset
+
+ family has separate address spaces for memory and
+\emph on
+i
+\emph default
+nput/
+\emph on
+o
+\emph default
+utput memory.
+ I/O memory
+\begin_inset LatexCommand \index{I/O memory (Z80, Z180)}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{Z80!I/O memory}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{Z180!I/O memory}
+
+\end_inset
+
+ is accessed with special instructions, e.g.:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+sfr at 0x78 IoPort;\InsetSpace ~
+\InsetSpace ~
+/* define a var in I/O space at 78h called IoPort */
+
+\end_layout
+
+\begin_layout Standard
+Writing 0x01 to this variable generates the assembly code:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+3E 01\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+ld a,#0x01
+\newline
+D3 78\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+out (_IoPort),a
+\end_layout
+
+\begin_layout Subsubsection
+banked sfr
+\begin_inset LatexCommand \index{sfr}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_sfr}
+
+\end_inset
+
+ (in/out to 16-bit addresses)
+\end_layout
+
+\begin_layout Standard
+The keyword
+\emph on
+banked
+\emph default
+ is used to support 16 bit addresses in I/O memory e.g.:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+sfr banked at
+\begin_inset LatexCommand \index{at}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_at}
+
+\end_inset
+
+ 0x123 IoPort;
+\end_layout
+
+\begin_layout Standard
+Writing 0x01 to this variable generates the assembly code:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+01 23 01\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+ld bc,#_IoPort
+\newline
+3E 01\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+ld a,#0x01
+\newline
+ED 79\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+out (c),a
+\end_layout
+
+\begin_layout Subsubsection
+sfr
+\begin_inset LatexCommand \index{sfr}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_sfr}
+
+\end_inset
+
+ (in0/out0 to 8 bit addresses on Z180
+\begin_inset LatexCommand \index{Z180}
+
+\end_inset
+
+/HD64180
+\begin_inset LatexCommand \index{HD64180 (see Z180)}
+
+\end_inset
+
+)
+\end_layout
+
+\begin_layout Standard
+The compiler option -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-portmode
+\begin_inset LatexCommand \index{Z180!Options!-\/-portmode}
+
+\end_inset
+
+=180 (80) and a compiler #pragma\InsetSpace ~
+portmode
+\begin_inset LatexCommand \index{Z180!Pragmas!\#pragma portmode}
+
+\end_inset
+
+ z180 (z80) is used to turn on (off) the Z180/HD64180 port addressing instructio
+ns
+\family typewriter
+in0/out0
+\family default
+ instead of
+\family typewriter
+in/out
+\family default
+.
+ If you include the file z180.h this will be set automatically.
+\begin_inset VSpace bigskip
+\end_inset
+
+
+\end_layout
+
+\begin_layout Subsection
+HC08 Storage Class
+\begin_inset LatexCommand \index{HC08!Storage class}
+
+\end_inset
+
+ Language Extensions
+\end_layout
+
+\begin_layout Subsubsection
+data
+\begin_inset LatexCommand \index{data (hc08 storage class)}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_data (hc08 storage class)}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+The data storage class declares a variable that resides in the first 256
+ bytes of memory (the direct page).
+ The HC08
+\begin_inset LatexCommand \index{HC08}
+
+\end_inset
+
+ is most efficient at accessing variables (especially pointers) stored here.
+\end_layout
+
+\begin_layout Subsubsection
+xdata
+\begin_inset LatexCommand \index{xdata (hc08 storage class)}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_xdata (hc08 storage class)}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+The xdata storage class declares a variable that can reside anywhere in
+ memory.
+ This is the default if no storage class is specified.
+
+\begin_inset VSpace bigskip
+\end_inset
+
+
+\end_layout
+
+\begin_layout Section
+Absolute Addressing
+\begin_inset LatexCommand \index{Absolute addressing}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+Data items can be assigned an absolute address with the
+\emph on
+at
+\begin_inset LatexCommand \index{at}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_at}
+
+\end_inset
+
+ <address>
+\emph default
+ keyword, in addition to a storage class, e.g.:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+xdata
+\begin_inset LatexCommand \index{xdata (mcs51, ds390 storage class)}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_xdata (mcs51, ds390 storage class)}
+
+\end_inset
+
+ at
+\begin_inset LatexCommand \index{at}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_at}
+
+\end_inset
+
+ 0x7ffe unsigned int chksum;
+\end_layout
+
+\begin_layout Standard
+or, better conforming to ISO/IEC 9899 C:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+__xdata __at (0x7ffe) unsigned int chksum;
+\end_layout
+
+\begin_layout Standard
+In the above example the variable chksum will be located at 0x7ffe and 0x7fff
+ of the external ram.
+ The compiler does
+\emph on
+not
+\emph default
+ reserve any space for variables declared in this way
+\begin_inset Marginal
+status collapsed
+
+\begin_layout Standard
+
+\series bold
+\InsetSpace ~
+!
+\end_layout
+
+\end_inset
+
+ (they are implemented with an equate in the assembler).
+ Thus it is left to the programmer to make sure there are no overlaps with
+ other variables that are declared without the absolute address.
+ The assembler listing file (.lst
+\begin_inset LatexCommand \index{<file>.lst}
+
+\end_inset
+
+) and the linker output files (.rst
+\begin_inset LatexCommand \index{<file>.rst}
+
+\end_inset
+
+) and (.map
+\begin_inset LatexCommand \index{<file>.map}
+
+\end_inset
+
+) are good places to look for such overlaps.
+ Variables with an absolute address are
+\emph on
+not
+\begin_inset Marginal
+status collapsed
+
+\begin_layout Standard
+
+\series bold
+\InsetSpace ~
+!
+\end_layout
+
+\end_inset
+
+
+\emph default
+ initialized
+\begin_inset LatexCommand \index{Variable initialization}
+
+\end_inset
+
+.
+\end_layout
+
+\begin_layout Standard
+In case of memory mapped I/O devices the keyword
+\emph on
+volatile
+\emph default
+ has to be used to tell the compiler that accesses might not be removed:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+volatile
+\begin_inset LatexCommand \index{volatile}
+
+\end_inset
+
+ __xdata
+\begin_inset LatexCommand \index{xdata (mcs51, ds390 storage class)}
+
+\end_inset
+
+ __at
+\begin_inset LatexCommand \index{at}
+
+\end_inset
+
+ (0x8000) unsigned char PORTA_8255;
+\end_layout
+
+\begin_layout Standard
+For some architectures (mcs51) array accesses are more efficient if an (xdata/fa
+r) array
+\family typewriter
+\size footnotesize
+
+\begin_inset LatexCommand \index{Aligned array}
+
+\end_inset
+
+
+\family default
+\size default
+ starts at a block (256 byte) boundary
+\begin_inset LatexCommand \index{block boundary}
+
+\end_inset
+
+ (section
+\begin_inset LatexCommand \ref{sub:A-Step-by Assembler Introduction}
+
+\end_inset
+
+ has an example).
+\newline
+Absolute addresses can be specified for variables in all
+ storage classes, e.g.:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+__bit
+\begin_inset LatexCommand \index{bit}
+
+\end_inset
+
+ __at
+\begin_inset LatexCommand \index{at}
+
+\end_inset
+
+ (0x02) bvar;
+\end_layout
+
+\begin_layout Standard
+The above example will allocate the variable at offset 0x02 in the bit-addressab
+le space.
+ There is no real advantage to assigning absolute addresses to variables
+ in this manner, unless you want strict control over all the variables allocated.
+ One possible use would be to write hardware portable code.
+ For example, if you have a routine that uses one or more of the microcontroller
+ I/O pins, and such pins are different for two different hardwares, you
+ can declare the I/O pins in your routine using:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+extern volatile
+\begin_inset LatexCommand \index{volatile}
+
+\end_inset
+
+ __bit MOSI;\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+/* master out, slave in */
+\newline
+extern volatile __bit MISO;\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+/* master
+ in, slave out */
+\newline
+extern volatile __bit MCLK;\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+/* master clock */
+\newline
+
+\newline
+/* Input and
+ Output of a byte on a 3-wire serial bus.
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+If needed adapt polarity of clock,
+ polarity of data and bit order
+\newline
+\InsetSpace ~
+*/
+\newline
+unsigned char spi_io(unsigned char out_byte)
+
+\newline
+{
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+unsigned char i=8;
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+do {
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+MOSI = out_byte & 0x80;
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+out_byte <<= 1;
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+MCLK =
+ 1;
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+/* _asm nop _endasm; */\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+/* for slow peripherals */
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+if(MISO)
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+out_byte +=
+ 1;
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+MCLK = 0;
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+} while(--i);
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+return out_byte;
+\newline
+}
+\end_layout
+
+\begin_layout Standard
+Then, someplace in the code for the first hardware you would use
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+__bit __at
+\begin_inset LatexCommand \index{at}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_at}
+
+\end_inset
+
+ (0x80) MOSI;\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+/* I/O port 0, bit 0 */
+\newline
+__bit __at (0x81) MISO;\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+/* I/O port 0,
+ bit 1 */
+\newline
+__bit __at (0x82) MCLK;\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+/* I/O port 0, bit 2 */
+\end_layout
+
+\begin_layout Standard
+Similarly, for the second hardware you would use
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+__bit __at (0x83) MOSI;\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+/* I/O port 0, bit 3 */
+\newline
+__bit __at (0x91) MISO;\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+/*
+ I/O port 1, bit 1 */
+\newline
+__bit
+\begin_inset LatexCommand \index{bit}
+
+\end_inset
+
+ __at (0x92) MCLK;\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+/* I/O port 1, bit 2 */
+\end_layout
+
+\begin_layout Standard
+and you can use the same hardware dependent routine without changes, as
+ for example in a library.
+ This is somehow similar to sbit, but only one absolute address has to be
+ specified in the whole project.
+\begin_inset VSpace bigskip
+\end_inset
+
+
+\end_layout
+
+\begin_layout Section
+Parameters
+\begin_inset LatexCommand \index{Parameters}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{function parameter}
+
+\end_inset
+
+ & Local Variables
+\begin_inset LatexCommand \index{local variables}
+
+\end_inset
+
+
+\begin_inset LatexCommand \label{sec:Parameters-and-Local-Variables}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+Automatic (local) variables and parameters to functions can either be placed
+ on the stack or in data-space.
+ The default action of the compiler is to place these variables in the internal
+ RAM (for small model) or external RAM (for large model).
+ This in fact makes them similar to
+\emph on
+static
+\begin_inset LatexCommand \index{static}
+
+\end_inset
+
+
+\emph default
+ so by default functions are non-reentrant
+\begin_inset LatexCommand \index{reentrant}
+
+\end_inset
+
+.
+
+\newline
+
+\newline
+They can be placed on the stack
+\begin_inset LatexCommand \index{stack}
+
+\end_inset
+
+ by using the
+\emph on
+ -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-stack-auto
+\begin_inset LatexCommand \index{-\/-stack-auto}
+
+\end_inset
+
+
+\emph default
+ option, by using
+\emph on
+#pragma\InsetSpace ~
+stackauto
+\emph default
+
+\begin_inset LatexCommand \index{\#pragma stackauto}
+
+\end_inset
+
+ or by using the
+\emph on
+reentrant
+\begin_inset LatexCommand \index{reentrant}
+
+\end_inset
+
+
+\emph default
+ keyword in the function declaration, e.g.:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+unsigned char foo(char i) __reentrant
+\newline
+{
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+...
+
+\newline
+}
+\end_layout
+
+\begin_layout Standard
+Since stack space on 8051 is limited, the
+\emph on
+reentrant
+\emph default
+keyword or the
+\emph on
+ -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-stack-auto
+\emph default
+ option should be used sparingly.
+ Note that the reentrant keyword just means that the parameters & local
+ variables will be allocated to the stack, it
+\emph on
+does not
+\emph default
+ mean that the function is register bank
+\begin_inset LatexCommand \index{register bank (mcs51, ds390)}
+
+\end_inset
+
+ independent.
+\newline
+
+\newline
+Local variables
+\begin_inset LatexCommand \index{local variables}
+
+\end_inset
+
+ can be assigned storage classes and absolute
+\begin_inset LatexCommand \index{Absolute addressing}
+
+\end_inset
+
+ addresses, e.g.:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+unsigned char foo()
+\newline
+{
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+__xdata unsigned char i;
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+__bit bvar;
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+__data __at
+\begin_inset LatexCommand \index{at}
+
+\end_inset
+
+ (0x31) unsigned char j;
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+...
+
+\newline
+}
+\end_layout
+
+\begin_layout Standard
+In the above example the variable
+\emph on
+i
+\emph default
+ will be allocated in the external ram,
+\emph on
+bvar
+\emph default
+ in bit addressable space and
+\emph on
+ j
+\emph default
+ in internal ram.
+ When compiled with
+\emph on
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-stack-auto
+\emph default
+ or when a function is declared as
+\emph on
+reentrant
+\emph default
+ this should only be done for static variables.
+\end_layout
+
+\begin_layout Standard
+Parameters
+\begin_inset LatexCommand \index{function parameter}
+
+\end_inset
+
+ however are not allowed any storage class
+\begin_inset LatexCommand \index{Storage class}
+
+\end_inset
+
+, (storage classes for parameters will be ignored), their allocation is
+ governed by the memory model in use, and the reentrancy options.
+\end_layout
+
+\begin_layout Standard
+It is however allowed to use bit parameters in reentrant functions and also
+ non-static local bit variables are supported.
+ Efficient use is limited to 8 semi-bitregisters in bit space.
+ They are pushed and popped to stack
+\begin_inset LatexCommand \index{stack}
+
+\end_inset
+
+ as a single byte just like the normal registers.
+\end_layout
+
+\begin_layout Section
+Overlaying
+\begin_inset LatexCommand \label{sub:Overlaying}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{Overlaying}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+For non-reentrant
+\begin_inset LatexCommand \index{reentrant}
+
+\end_inset
+
+ functions SDCC will try to reduce internal ram space usage by overlaying
+ parameters and local variables of a function (if possible).
+ Parameters and local variables
+\begin_inset LatexCommand \index{local variables}
+
+\end_inset
+
+ of a function will be allocated to an overlayable segment if the function
+ has
+\emph on
+no other function calls and the function is non-reentrant and the memory
+ model
+\begin_inset LatexCommand \index{Memory model}
+
+\end_inset
+
+ is small.
+
+\emph default
+ If an explicit storage class
+\begin_inset LatexCommand \index{Storage class}
+
+\end_inset
+
+ is specified for a local variable, it will NOT be overlayed.
+\end_layout
+
+\begin_layout Standard
+Note that the compiler (not the linkage editor) makes the decision for overlayin
+g the data items.
+ Functions that are called from an interrupt service routine
+\begin_inset Marginal
+status collapsed
+
+\begin_layout Standard
+
+\series bold
+!
+\end_layout
+
+\end_inset
+
+ should be preceded by a #pragma\InsetSpace ~
+nooverlay
+\begin_inset LatexCommand \index{\#pragma nooverlay}
+
+\end_inset
+
+ if they are not reentrant.
+\end_layout
+
+\begin_layout Standard
+Also note that the compiler does not do any processing of inline assembler
+ code, so the compiler might incorrectly assign local variables and parameters
+ of a function into the overlay segment if the inline assembler code calls
+ other c-functions that might use the overlay.
+ In that case the #pragma\InsetSpace ~
+nooverlay should be used.
+\end_layout
+
+\begin_layout Standard
+Parameters and local variables of functions that contain 16 or 32 bit multiplica
+tion
+\begin_inset LatexCommand \index{Multiplication}
+
+\end_inset
+
+ or division
+\begin_inset LatexCommand \index{Division}
+
+\end_inset
+
+ will NOT be overlayed since these are implemented using external functions,
+ e.g.:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+#pragma save
+\newline
+#pragma nooverlay
+\begin_inset LatexCommand \index{\#pragma nooverlay}
+
+\end_inset
+
+
+\newline
+void set_error(unsigned char errcd)
+\newline
+{
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+P3 = errcd;
+\newline
+}
+\newline
+#pragma restore
+\newline
+
+\newline
+void
+ some_isr () __interrupt
+\begin_inset LatexCommand \index{interrupt}
+
+\end_inset
+
+ (2)
+\newline
+{
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+...
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+set_error(10);
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+...
+
+\newline
+}
+\end_layout
+
+\begin_layout Standard
+In the above example the parameter
+\emph on
+errcd
+\emph default
+ for the function
+\emph on
+set_error
+\emph default
+ would be assigned to the overlayable segment if the #pragma\InsetSpace ~
+nooverlay was
+ not present, this could cause unpredictable runtime behavior when called
+ from an interrupt service routine.
+ The #pragma\InsetSpace ~
+nooverlay ensures that the parameters and local variables for
+ the function are NOT overlayed.
+\begin_inset VSpace bigskip
+\end_inset
+
+
+\end_layout
+
+\begin_layout Section
+Interrupt Service Routines
+\begin_inset LatexCommand \label{sub:Interrupt-Service-Routines}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Subsection
+General Information
+\end_layout
+
+\begin_layout Standard
+SDCC allows
+\emph on
+i
+\emph default
+nterrupt
+\emph on
+s
+\emph default
+ervice
+\emph on
+r
+\emph default
+outines to be coded in C, with some extended keywords.
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+void timer_isr (void) __interrupt (1) __using (1)
+\newline
+{
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+...
+
+\newline
+}
+\end_layout
+
+\begin_layout Standard
+The optional number following the
+\emph on
+interrupt
+\begin_inset LatexCommand \index{interrupt}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_interrupt}
+
+\end_inset
+
+
+\emph default
+ keyword is the interrupt number this routine will service.
+ When present, the compiler will insert a call to this routine in the interrupt
+ vector table
+\begin_inset LatexCommand \index{interrupt vector table}
+
+\end_inset
+
+ for the interrupt number specified.
+ If you have multiple source files in your project, interrupt service routines
+ can be present in any of them, but a prototype of the isr MUST be present
+ or included in the file that contains the function
+\emph on
+main
+\emph default
+.
+ The optional (8051 specific) keyword
+\emph on
+using
+\begin_inset LatexCommand \index{using (mcs51, ds390 register bank)}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_using (mcs51, ds390 register bank)}
+
+\end_inset
+
+
+\emph default
+ can be used to tell the compiler to use the specified register bank when
+ generating code for this function.
+
+\newline
+Interrupt service routines open the door for some very interesting bugs:
+\end_layout
+
+\begin_layout Subsubsection
+\begin_inset LatexCommand \label{sub:Common-interrupt-pitfall-volatile}
+
+\end_inset
+
+Common interrupt pitfall: variable not declared
+\emph on
+volatile
+\end_layout
+
+\begin_layout Standard
+If an interrupt service routine changes variables which are accessed by
+ other functions these variables have to be declared
+\emph on
+volatile
+\emph default
+
+\begin_inset LatexCommand \index{volatile}
+
+\end_inset
+
+.
+ See
+\begin_inset LatexCommand \url{http://en.wikipedia.org/wiki/Volatile_variable}
+
+\end_inset
+
+ .
+\end_layout
+
+\begin_layout Subsubsection
+\begin_inset LatexCommand \label{sub:Common-interrupt-pitfall-non-atomic}
+
+\end_inset
+
+Common interrupt pitfall:
+\emph on
+non-atomic access
+\end_layout
+
+\begin_layout Standard
+If the access to these variables is not
+\emph on
+atomic
+\begin_inset LatexCommand \index{atomic}
+
+\end_inset
+
+
+\emph default
+ (i.e.
+ the processor needs more than one instruction for the access and could
+ be interrupted while accessing the variable) the interrupt must be disabled
+ during the access to avoid inconsistent data.
+
+\newline
+Access to 16 or 32 bit variables is obviously not atomic on 8 bit CPUs
+ and should be protected by disabling interrupts.
+ You're not automatically on the safe side if you use 8 bit variables though.
+ We need an example here: f.e.
+ on the 8051 the harmless looking
+\begin_inset Quotes srd
+\end_inset
+
+
+\family typewriter
+flags\InsetSpace ~
+|=\InsetSpace ~
+0x80;
+\family default
+
+\begin_inset Quotes sld
+\end_inset
+
+ is not atomic if
+\family typewriter
+flags
+\family default
+ resides in xdata.
+ Setting
+\begin_inset Quotes srd
+\end_inset
+
+
+\family typewriter
+flags\InsetSpace ~
+|=\InsetSpace ~
+0x40;
+\family default
+
+\begin_inset Quotes sld
+\end_inset
+
+ from within an interrupt routine might get lost if the interrupt occurs
+ at the wrong time.
+
+\begin_inset Quotes sld
+\end_inset
+
+
+\family typewriter
+counter\InsetSpace ~
++=\InsetSpace ~
+8;
+\family default
+
+\begin_inset Quotes srd
+\end_inset
+
+ is not atomic on the 8051 even if
+\family typewriter
+counter
+\family default
+ is located in data memory.
+\newline
+Bugs like these are hard to reproduce and can
+ cause a lot of trouble.
+
+\end_layout
+
+\begin_layout Subsubsection
+\begin_inset LatexCommand \label{sub:Common-interrupt-pitfall-stack-overflow}
+
+\end_inset
+
+Common interrupt pitfall:
+\emph on
+stack overflow
+\end_layout
+
+\begin_layout Standard
+The return address and the registers used in the interrupt service routine
+ are saved on the stack
+\begin_inset LatexCommand \index{stack}
+
+\end_inset
+
+ so there must be sufficient stack space.
+ If there isn't variables or registers (or even the return address itself)
+ will be corrupted.
+ This
+\emph on
+stack overflow
+\emph default
+
+\begin_inset LatexCommand \index{stack overflow}
+
+\end_inset
+
+ is most likely to happen if the interrupt occurs during the
+\begin_inset Quotes sld
+\end_inset
+
+deepest
+\begin_inset Quotes srd
+\end_inset
+
+ subroutine when the stack is already in use for f.e.
+ many return addresses.
+\end_layout
+
+\begin_layout Subsubsection
+\begin_inset LatexCommand \label{sub:Common-interrupt-pitfall-non-reentrant}
+
+\end_inset
+
+Common interrupt pitfall:
+\emph on
+use of non-reentrant functions
+\end_layout
+
+\begin_layout Standard
+A special note here, int (16 bit) and long (32 bit) integer division
+\begin_inset LatexCommand \index{Division}
+
+\end_inset
+
+, multiplication
+\begin_inset LatexCommand \index{Multiplication}
+
+\end_inset
+
+ & modulus
+\begin_inset LatexCommand \index{Modulus}
+
+\end_inset
+
+ and floating-point
+\begin_inset LatexCommand \index{Floating point support}
+
+\end_inset
+
+ operations are implemented using external support routines.
+ If an interrupt service routine needs to do any of these operations then
+ the support routines (as mentioned in a following section) will have to
+ be recompiled using the
+\emph on
+ -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-stack-auto
+\begin_inset LatexCommand \index{-\/-stack-auto}
+
+\end_inset
+
+
+\emph default
+ option and the source file will need to be compiled using the
+\emph on
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-int-long-reent
+\emph default
+
+\begin_inset LatexCommand \index{-\/-int-long-reent}
+
+\end_inset
+
+ compiler option.
+
+\newline
+Note, the type promotion
+\begin_inset LatexCommand \index{type promotion}
+
+\end_inset
+
+ required by ANSI C can cause 16 bit routines to be used
+\begin_inset Marginal
+status collapsed
+
+\begin_layout Standard
+
+\series bold
+\InsetSpace ~
+!
+\end_layout
+
+\end_inset
+
+ without the programmer being aware of it.
+ See f.e.
+ the cast
+\family typewriter
+(unsigned char)(tail-1)
+\family default
+ within the if clause in section
+\begin_inset LatexCommand \ref{sub:A-Step-by Assembler Introduction}
+
+\end_inset
+
+.
+\end_layout
+
+\begin_layout Standard
+Calling other functions from an interrupt service routine is not recommended,
+ avoid it if possible.
+ Note that when some function is called from an interrupt service routine
+ it should be preceded by a #pragma\InsetSpace ~
+nooverlay
+\begin_inset LatexCommand \index{\#pragma nooverlay}
+
+\end_inset
+
+ if it is not reentrant.
+ Furthermore nonreentrant functions should not be called from the main program
+ while the interrupt service routine might be active.
+ They also must not be called from low priority interrupt service routines
+ while a high priority interrupt service routine might be active.
+ You could use semaphores or make the function
+\emph on
+ critical
+\emph default
+ if all parameters are passed in registers.
+\newline
+ Also see section
+\begin_inset LatexCommand \ref{sub:Overlaying}
+
+\end_inset
+
+\InsetSpace ~
+about Overlaying and section
+\begin_inset LatexCommand \ref{sub:Functions-using-private-banks}
+
+\end_inset
+
+\InsetSpace ~
+about Functions using private register banks.
+\begin_inset VSpace bigskip
+\end_inset
+
+
+\end_layout
+
+\begin_layout Subsection
+MCS51/DS390 Interrupt Service Routines
+\end_layout
+
+\begin_layout Standard
+Interrupt
+\begin_inset LatexCommand \index{interrupt}
+
+\end_inset
+
+ numbers and the corresponding address & descriptions for the Standard 8051/8052
+ are listed below.
+ SDCC will automatically adjust the
+\begin_inset LatexCommand \index{interrupt vector table}
+
+\end_inset
+
+ to the maximum interrupt number specified.
+\newline
+
+\end_layout
+
+\begin_layout Standard
+\align center
+\begin_inset Tabular
+<lyxtabular version="3" rows="9" columns="3">
+<features>
+<column alignment="center" valignment="top" leftline="true" width="0in">
+<column alignment="left" valignment="top" leftline="true" width="0in">
+<column alignment="left" valignment="top" leftline="true" rightline="true" width="0in">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Interrupt #
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Description
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Vector Address
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+0
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+External 0
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+0x0003
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+1
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Timer 0
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+0x000b
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+2
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+External 1
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+0x0013
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+3
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Timer 1
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+0x001b
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+4
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Serial
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+0x0023
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell multicolumn="1" alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+5
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Timer 2 (8052)
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+0x002b
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+...
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+...
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+n
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+0x0003 + 8*n
+\end_layout
+
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
+\newline
+
+\end_layout
+
+\begin_layout Standard
+If the interrupt service routine is defined without
+\emph on
+using
+\begin_inset LatexCommand \index{using (mcs51, ds390 register bank)}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_using (mcs51, ds390 register bank)}
+
+\end_inset
+
+
+\emph default
+ a register bank or with register bank 0 (
+\emph on
+using
+\emph default
+ 0), the compiler will save the registers used by itself on the stack upon
+ entry and restore them at exit, however if such an interrupt service routine
+ calls another function then the entire register bank will be saved on the
+ stack.
+ This scheme may be advantageous for small interrupt service routines which
+ have low register usage.
+\end_layout
+
+\begin_layout Standard
+If the interrupt service routine is defined to be using a specific register
+ bank then only
+\emph on
+a, b, dptr
+\emph default
+ & psw are saved and restored, if such an interrupt service routine calls
+ another function (using another register bank) then the entire register
+ bank of the called function will be saved on the stack
+\begin_inset LatexCommand \index{stack}
+
+\end_inset
+
+.
+ This scheme is recommended for larger interrupt service routines.
+\begin_inset VSpace bigskip
+\end_inset
+
+
+\end_layout
+
+\begin_layout Subsection
+HC08
+\begin_inset LatexCommand \index{HC08}
+
+\end_inset
+
+ Interrupt Service Routines
+\end_layout
+
+\begin_layout Standard
+Since the number of interrupts
+\begin_inset LatexCommand \index{HC08!interrupt}
+
+\end_inset
+
+ available is chip specific and the interrupt vector table always ends at
+ the last byte of memory, the interrupt numbers corresponds to the interrupt
+ vectors in reverse order of address.
+ For example, interrupt 1 will use the interrupt vector at 0xfffc, interrupt
+ 2 will use the interrupt vector at 0xfffa, and so on.
+ However, interrupt 0 (the reset vector at 0xfffe) is not redefinable in
+ this way; instead see section
+\begin_inset LatexCommand \ref{sub:Startup-Code}
+
+\end_inset
+
+ for details on customizing startup.
+\begin_inset VSpace bigskip
+\end_inset
+
+
+\end_layout
+
+\begin_layout Subsection
+Z80 Interrupt Service Routines
+\end_layout
+
+\begin_layout Standard
+The Z80
+\begin_inset LatexCommand \index{Z80}
+
+\end_inset
+
+ uses several different methods for determining the correct interrupt
+\begin_inset LatexCommand \index{Z80!interrupt}
+
+\end_inset
+
+ vector depending on the hardware implementation.
+ Therefore, SDCC ignores the optional interrupt number and does not attempt
+ to generate an interrupt vector table.
+\end_layout
+
+\begin_layout Standard
+By default, SDCC generates code for a maskable interrupt, which uses a RETI
+ instruction to return from the interrupt.
+ To write an interrupt handler for the non-maskable interrupt, which needs
+ a RETN instruction instead, add the
+\emph on
+critical
+\emph default
+ keyword:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+void nmi_isr (void) critical interrupt
+\newline
+{
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+...
+
+\newline
+}
+\end_layout
+
+\begin_layout Standard
+However if you need to create a non-interruptable interrupt service routine
+ you would also require the
+\emph on
+critical
+\emph default
+ keyword.
+ To distinguish between this and an nmi_isr you must provide an interrupt
+ number.
+\begin_inset VSpace bigskip
+\end_inset
+
+
+\end_layout
+
+\begin_layout Section
+Enabling and Disabling Interrupts
+\end_layout
+
+\begin_layout Subsection
+Critical Functions and Critical Statements
+\end_layout
+
+\begin_layout Standard
+A special keyword may be associated with a block or a function declaring
+ it as
+\emph on
+critical
+\emph default
+.
+ SDCC will generate code to disable all interrupts
+\begin_inset LatexCommand \index{interrupt}
+
+\end_inset
+
+ upon entry to a critical function and restore the interrupt enable to the
+ previous state before returning.
+ Nesting critical functions will need one additional byte on the stack
+\begin_inset LatexCommand \index{stack}
+
+\end_inset
+
+ for each call.
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+int foo () __critical
+\begin_inset LatexCommand \index{critical}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_critical}
+
+\end_inset
+
+
+\newline
+{
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+...
+
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+...
+
+\newline
+}
+\end_layout
+
+\begin_layout Standard
+The critical attribute maybe used with other attributes like
+\emph on
+reentrant.
+\emph default
+
+\newline
+The keyword
+\emph on
+critical
+\emph default
+ may also be used to disable interrupts more locally:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+__critical{ i++; }
+\end_layout
+
+\begin_layout Standard
+More than one statement could have been included in the block.
+\end_layout
+
+\begin_layout Subsection
+Enabling and Disabling Interrupts directly
+\end_layout
+
+\begin_layout Standard
+Interrupts
+\begin_inset LatexCommand \index{interrupt}
+
+\end_inset
+
+ can also be disabled and enabled directly (8051):
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+EA = 0;\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+or:\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+EA_SAVE = EA;
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+...\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+EA = 0;
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+EA = 1;\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+...
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+EA = EA_SAVE;
+\end_layout
+
+\begin_layout Standard
+On other architectures which have seperate opcodes for enabling and disabling
+ interrupts you might want to make use of defines with inline assembly
+\begin_inset LatexCommand \index{Assembler routines}
+
+\end_inset
+
+ (HC08
+\begin_inset LatexCommand \index{HC08!interrupt}
+
+\end_inset
+
+):
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+#define CLI _asm
+\begin_inset LatexCommand \index{\_asm}
+
+\end_inset
+
+\InsetSpace ~
+\InsetSpace ~
+cli\InsetSpace ~
+\InsetSpace ~
+_endasm
+\begin_inset LatexCommand \index{\_endasm}
+
+\end_inset
+
+;
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+#define SEI _asm\InsetSpace ~
+\InsetSpace ~
+sei\InsetSpace ~
+\InsetSpace ~
+_endasm;
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+...
+\end_layout
+
+\begin_layout Standard
+Note: it is sometimes sufficient to disable only a specific interrupt source
+ like f.e.
+ a timer or serial interrupt by manipulating an
+\emph on
+interrupt mask
+\begin_inset LatexCommand \index{interrupt mask}
+
+\end_inset
+
+
+\emph default
+ register.
+
+\end_layout
+
+\begin_layout Standard
+Usually the time during which interrupts are disabled should be kept as
+ short as possible.
+ This minimizes both
+\emph on
+interrupt latency
+\emph default
+
+\begin_inset LatexCommand \index{interrupt latency}
+
+\end_inset
+
+ (the time between the occurrence of the interrupt and the execution of
+ the first code in the interrupt routine) and
+\emph on
+interrupt jitter
+\emph default
+
+\begin_inset LatexCommand \index{interrupt jitter}
+
+\end_inset
+
+ (the difference between the shortest and the longest interrupt latency).
+ These really are something different, f.e.
+ a serial interrupt has to be served before its buffer overruns so it cares
+ for the maximum interrupt latency, whereas it does not care about jitter.
+ On a loudspeaker driven via a digital to analog converter which is fed
+ by an interrupt a latency of a few milliseconds might be tolerable, whereas
+ a much smaller jitter will be very audible.
+\end_layout
+
+\begin_layout Standard
+You can reenable interrupts within an interrupt routine and on some architecture
+s you can make use of two (or more) levels of
+\emph on
+interrupt priorities
+\emph default
+
+\begin_inset LatexCommand \index{interrupt priority}
+
+\end_inset
+
+.
+ On some architectures which don't support interrupt priorities these can
+ be implemented by manipulating the interrupt mask and reenabling interrupts
+ within the interrupt routine.
+ Check there is sufficient space on the stack
+\begin_inset LatexCommand \index{stack}
+
+\end_inset
+
+ and don't add complexity unless you have to.
+
+\end_layout
+
+\begin_layout Subsection
+Semaphore
+\begin_inset LatexCommand \index{semaphore}
+
+\end_inset
+
+ locking (mcs51/ds390)
+\end_layout
+
+\begin_layout Standard
+Some architectures (mcs51/ds390) have an atomic
+\begin_inset LatexCommand \index{atomic}
+
+\end_inset
+
+ bit test and
+\emph on
+
+\emph default
+clear
+\emph on
+
+\emph default
+instruction.
+ These type of instructions are typically used in preemptive multitasking
+ systems, where a routine f.e.
+ claims the use of a data structure ('acquires a lock
+\begin_inset LatexCommand \index{lock}
+
+\end_inset
+
+ on it'), makes some modifications and then releases the lock when the data
+ structure is consistent again.
+ The instruction may also be used if interrupt and non-interrupt code have
+ to compete for a resource.
+ With the atomic bit test and clear instruction interrupts
+\begin_inset LatexCommand \index{interrupt}
+
+\end_inset
+
+ don't have to be disabled for the locking operation.
+
+\end_layout
+
+\begin_layout Standard
+SDCC generates this instruction if the source follows this pattern:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+volatile
+\begin_inset LatexCommand \index{volatile}
+
+\end_inset
+
+ bit resource_is_free;
+\newline
+
+\newline
+if (resource_is_free)
+\newline
+\InsetSpace ~
+\InsetSpace ~
+{
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+resource_is_free=0;
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+...
+
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+resource_is_free=1;
+\newline
+\InsetSpace ~
+\InsetSpace ~
+}
+\end_layout
+
+\begin_layout Standard
+Note, mcs51 and ds390 support only an atomic
+\begin_inset LatexCommand \index{atomic}
+
+\end_inset
+
+ bit test and
+\emph on
+clear
+\emph default
+ instruction (as opposed to atomic bit test and
+\emph on
+set).
+\end_layout
+
+\begin_layout Section
+Functions using private register banks
+\begin_inset LatexCommand \label{sub:Functions-using-private-banks}
+
+\end_inset
+
+ (mcs51/ds390)
+\end_layout
+
+\begin_layout Standard
+Some architectures have support for quickly changing register sets.
+ SDCC supports this feature with the
+\emph on
+using
+\begin_inset LatexCommand \index{using (mcs51, ds390 register bank)}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_using (mcs51, ds390 register bank)}
+
+\end_inset
+
+
+\emph default
+ attribute (which tells the compiler to use a register bank
+\begin_inset LatexCommand \index{register bank (mcs51, ds390)}
+
+\end_inset
+
+ other than the default bank zero).
+ It should only be applied to
+\emph on
+interrupt
+\begin_inset LatexCommand \index{interrupt}
+
+\end_inset
+
+
+\emph default
+ functions (see footnote below).
+ This will in most circumstances make the generated ISR code more efficient
+ since it will not have to save registers on the stack.
+\end_layout
+
+\begin_layout Standard
+The
+\emph on
+using
+\emph default
+ attribute will have no effect on the generated code for a
+\emph on
+non-interrupt
+\emph default
+ function (but may occasionally be useful anyway
+\begin_inset Foot
+status open
+
+\begin_layout Standard
+possible exception: if a function is called ONLY from 'interrupt' functions
+ using a particular bank, it can be declared with the same 'using' attribute
+ as the calling 'interrupt' functions.
+ For instance, if you have several ISRs using bank one, and all of them
+ call memcpy(), it might make sense to create a specialized version of memcpy()
+ 'using 1', since this would prevent the ISR from having to save bank zero
+ to the stack on entry and switch to bank zero before calling the function
+\end_layout
+
+\end_inset
+
+).
+\newline
+
+\emph on
+(pending: Note, nowadays the
+\emph default
+using
+\emph on
+ attribute has an effect on
+\emph default
+
+\emph on
+the generated code for a
+\emph default
+non-interrupt
+\emph on
+ function
+\emph default
+.
+\emph on
+)
+\end_layout
+
+\begin_layout Standard
+An
+\emph on
+interrupt
+\emph default
+ function using a non-zero bank will assume that it can trash that register
+ bank, and will not save it.
+ Since high-priority interrupts
+\begin_inset LatexCommand \index{interrupts}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{interrupt priority}
+
+\end_inset
+
+ can interrupt low-priority ones on the 8051 and friends, this means that
+ if a high-priority ISR
+\emph on
+using
+\emph default
+ a particular bank occurs while processing a low-priority ISR
+\emph on
+using
+\emph default
+ the same bank, terrible and bad things can happen.
+ To prevent this, no single register bank should be
+\emph on
+used
+\emph default
+ by both a high priority and a low priority ISR.
+ This is probably most easily done by having all high priority ISRs use
+ one bank and all low priority ISRs use another.
+ If you have an ISR which can change priority at runtime, you're on your
+ own: I suggest using the default bank zero and taking the small performance
+ hit.
+\end_layout
+
+\begin_layout Standard
+It is most efficient if your ISR calls no other functions.
+ If your ISR must call other functions, it is most efficient if those functions
+ use the same bank as the ISR (see note 1 below); the next best is if the
+ called functions use bank zero.
+ It is very inefficient to call a function using a different, non-zero bank
+ from an ISR.
+
+\begin_inset VSpace bigskip
+\end_inset
+
+
+\end_layout
+
+\begin_layout Section
+Startup Code
+\begin_inset LatexCommand \label{sub:Startup-Code}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{Startup code}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Subsection
+MCS51/DS390 Startup Code
+\end_layout
+
+\begin_layout Standard
+The compiler triggers the linker to link certain initialization modules
+ from the runtime library
+\begin_inset LatexCommand \index{Runtime library}
+
+\end_inset
+
+ called crt<something>.
+ Only the necessary ones are linked, for instance crtxstack.asm (GSINIT1,
+ GSINIT5) is not linked unless the --xstack option is used.
+ These modules are highly entangled by the use of special segments/areas,
+ but a common layout is shown below:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+\series bold
+\size footnotesize
+(main.asm)
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+\size footnotesize
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+.area HOME (CODE)
+\newline
+__interrupt_vect:
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+ljmp __sdcc_gsinit_startup
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+\series bold
+\size footnotesize
+(crtstart.asm)
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+\size footnotesize
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+.area GSINIT0 (CODE)
+\newline
+__sdcc_gsinit_startup::
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov sp,#__start__stack - 1
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+\series bold
+\size footnotesize
+(crtxstack.asm)
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+\size footnotesize
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+.area GSINIT1 (CODE)
+\newline
+__sdcc_init_xstack::
+\newline
+; Need to initialize in GSINIT1 in
+ case the user's __sdcc_external_startup uses the xstack.
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov __XPAGE,#(__start__x
+stack >> 8)
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov _spx,#__start__xstack
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+\series bold
+\size footnotesize
+(crtstart.asm)
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+\size footnotesize
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+.area GSINIT2 (CODE)
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+lcall __sdcc_external_startup
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov a,dpl
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+jz __sdcc_init_data
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+ljmp
+ __sdcc_program_startup
+\newline
+__sdcc_init_data:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+\series bold
+\size footnotesize
+(crtxinit.asm)
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+\size footnotesize
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+.area GSINIT3 (CODE)
+\newline
+__mcs51_genXINIT::
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov r1,#l_XINIT
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov a,r1
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+orl a,#(l_XINIT
+ >> 8)
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+jz 00003$
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov r2,#((l_XINIT+255) >> 8)
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov dptr,#s_XINIT
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov r0,#s_XISEG
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov
+ __XPAGE,#(s_XISEG >> 8)
+\newline
+00001$:\InsetSpace ~
+clr a
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+movc a,@a+dptr
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+movx @r0,a
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+inc dptr
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+inc
+ r0
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+cjne r0,#0,00002$
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+inc __XPAGE
+\newline
+00002$:\InsetSpace ~
+djnz r1,00001$
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+djnz r2,00001$
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov __XPAGE,#0
+xFF
+\newline
+00003$:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+\series bold
+\size footnotesize
+(crtclear.asm)
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+\size footnotesize
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+.area GSINIT4 (CODE)
+\newline
+__mcs51_genRAMCLEAR::
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+clr a
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov r0,#(l_IRAM-1)
+\newline
+00004$:\InsetSpace ~
+mov
+ @r0,a
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+djnz r0,00004$
+\newline
+; _mcs51_genRAMCLEAR() end
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+\series bold
+\size footnotesize
+(crtxclear.asm)
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+\size footnotesize
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+.area GSINIT4 (CODE)
+\newline
+__mcs51_genXRAMCLEAR::
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov r0,#l_PSEG
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov a,r0
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+jz 00006$
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov
+ r1,#s_PSEG
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov __XPAGE,#(s_PSEG >> 8)
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+clr a
+\newline
+00005$:\InsetSpace ~
+movx @r1,a
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+inc r1
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+djnz r0,00005$
+\newline
+0
+0006$:
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov r0,#l_XSEG
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov a,r0
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+orl a,#(l_XSEG >> 8)
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+jz 00008$
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov r1,#((l_XSEG
+ + 255) >> 8)
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov dptr,#s_XSEG
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+clr a
+\newline
+00007$:\InsetSpace ~
+movx @dptr,a
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+inc dptr
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+djnz r0,00007$
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+djnz
+ r1,00007$
+\newline
+00008$:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+\series bold
+\size footnotesize
+(crtxstack.asm)
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+\size footnotesize
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+.area GSINIT5 (CODE)
+\newline
+; Need to initialize in GSINIT5 because __mcs51_genXINIT
+ modifies __XPAGE
+\newline
+; and __mcs51_genRAMCLEAR modifies _spx.
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov __XPAGE,#(__start__x
+stack >> 8)
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov _spx,#__start__xstack
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+\series bold
+\size footnotesize
+(application modules)
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+\size footnotesize
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+.area GSINIT (CODE)
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+\series bold
+\size footnotesize
+(main.asm)
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+\size footnotesize
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+.area GSFINAL (CODE)
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+ljmp __sdcc_program_startup
+\newline
+;---------------------------------
+-----------------------
+\newline
+; Home
+\newline
+;--------------------------------------------------
+------
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+.area HOME (CODE)
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+.area CSEG (CODE)
+\newline
+__sdcc_program_startup:
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+lcall _main
+\newline
+;
+ return from main will lock up
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+sjmp .
+\end_layout
+
+\begin_layout Standard
+One of these modules (crtstart.asm) contains a call to the C routine
+\emph on
+_sdcc_external_startup()
+\begin_inset LatexCommand \index{\_sdcc\_external\_startup()}
+
+\end_inset
+
+
+\series bold
+\emph default
+
+\series default
+at the start of the CODE area.
+ This routine is also in the runtime library
+\begin_inset LatexCommand \index{Runtime library}
+
+\end_inset
+
+ and returns 0 by default.
+ If this routine returns a non-zero value, the static & global variable
+ initialization will be skipped and the function main will be invoked.
+ Otherwise static & global variables will be initialized before the function
+ main is invoked.
+ You could add an
+\emph on
+_sdcc_external_startup()
+\emph default
+ routine to your program to override the default if you need to setup hardware
+ or perform some other critical operation prior to static & global variable
+ initialization
+\begin_inset LatexCommand \index{Variable initialization}
+
+\end_inset
+
+.
+ On some mcs51 variants xdata
+\begin_inset LatexCommand \index{xdata (mcs51, ds390 storage class)}
+
+\end_inset
+
+ memory has to be explicitly enabled before it can be accessed or if the
+ watchdog
+\begin_inset LatexCommand \index{watchdog}
+
+\end_inset
+
+ needs to be disabled, this is the place to do it.
+ The startup code clears all internal data memory, 256 bytes by default,
+ but from 0 to n-1 if
+\emph on
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-iram-size
+\begin_inset LatexCommand \index{-\/-iram-size <Value>}
+
+\end_inset
+
+n
+\emph default
+ is used.
+ (recommended for Chipcon CC1010).
+\end_layout
+
+\begin_layout Standard
+See also the compiler options
+\emph on
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-no-xinit
+\emph default
+-
+\emph on
+opt
+\emph default
+
+\begin_inset LatexCommand \index{-\/-no-xinit-opt}
+
+\end_inset
+
+,
+\emph on
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-main-return
+\emph default
+
+\begin_inset LatexCommand \index{-\/-main-return}
+
+\end_inset
+
+ and section
+\begin_inset LatexCommand \ref{sub:MCS51-variants}
+
+\end_inset
+
+ about MCS51-variants.
+\begin_inset VSpace bigskip
+\end_inset
+
+
+\end_layout
+
+\begin_layout Subsection
+HC08 Startup Code
+\end_layout
+
+\begin_layout Standard
+The HC08
+\begin_inset LatexCommand \index{HC08}
+
+\end_inset
+
+ startup code follows the same scheme as the MCS51 startup code.
+\begin_inset VSpace bigskip
+\end_inset
+
+
+\end_layout
+
+\begin_layout Subsection
+Z80 Startup Code
+\end_layout
+
+\begin_layout Standard
+On the Z80
+\begin_inset LatexCommand \index{Z80}
+
+\end_inset
+
+ the startup code is inserted by linking with crt0.o which is generated from
+ sdcc/device/lib/z80/crt0.s.
+ If you need a different startup code you can use the compiler option
+\emph on
+-
+\series bold
+\emph default
+
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+
+\series default
+\emph on
+-no-std-crt0
+\emph default
+
+\begin_inset LatexCommand \index{-\/-no-std-crt0}
+
+\end_inset
+
+ and provide your own crt0.o.
+
+\begin_inset VSpace bigskip
+\end_inset
+
+
+\end_layout
+
+\begin_layout Section
+Inline Assembler Code
+\begin_inset LatexCommand \index{Assembler routines}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Subsection
+A Step by Step Introduction
+\begin_inset LatexCommand \label{sub:A-Step-by Assembler Introduction}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+Starting from a small snippet of c-code this example shows for the MCS51
+ how to use inline assembly, access variables, a function parameter and
+ an array in xdata memory.
+ The example uses an MCS51 here but is easily adapted for other architectures.
+ This is a buffer routine which should be optimized:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+\size footnotesize
+unsigned char __far
+\begin_inset LatexCommand \index{far (storage class)}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_far (storage class)}
+
+\end_inset
+
+ __at
+\begin_inset LatexCommand \index{at}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_at}
+
+\end_inset
+
+(0x7f00) buf[0x100];
+\begin_inset LatexCommand \index{Aligned array}
+
+\end_inset
+
+
+\newline
+unsigned char head, tail;\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+/* if interrupts
+\begin_inset LatexCommand \index{interrupt}
+
+\end_inset
+
+ are involved see
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+section
+\begin_inset LatexCommand \ref{sub:Common-interrupt-pitfall-volatile}
+
+\end_inset
+
+ about
+\series bold
+ volatile
+\series default
+ */
+\newline
+
+\newline
+void to_buffer( unsigned char c )
+\newline
+{
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+if( head != (unsigned char)(tail-1)
+ )\InsetSpace ~
+/* cast
+\series bold
+needed
+\series default
+ to avoid promotion
+\begin_inset LatexCommand \index{promotion to signed int}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{type promotion}
+
+\end_inset
+
+ to integer */
+\begin_inset Marginal
+status collapsed
+
+\begin_layout Standard
+
+\series bold
+\InsetSpace ~
+!
+\end_layout
+
+\end_inset
+
+
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+buf[ head++ ] = c;\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+/* access to a 256 byte aligned array */
+\newline
+}
+\end_layout
+
+\begin_layout Standard
+If the code snippet (assume it is saved in buffer.c) is compiled with SDCC
+ then a corresponding buffer.asm file is generated.
+ We define a new function
+\family typewriter
+to_buffer_asm()
+\family default
+ in file buffer.c in which we cut and paste the generated code, removing
+ unwanted comments and some ':'.
+ Then add
+\begin_inset Quotes sld
+\end_inset
+
+
+\series bold
+_asm
+\series default
+
+\begin_inset Quotes srd
+\end_inset
+
+ and
+\begin_inset Quotes sld
+\end_inset
+
+
+\series bold
+_endasm;
+\series default
+
+\begin_inset Quotes srd
+\end_inset
+
+
+\begin_inset Foot
+status open
+
+\begin_layout Standard
+Note, that the single underscore form (_asm and _endasm) are not C99-compatible,
+ and for C-99 compatibility, the double-underscore form (__asm and __endasm)
+ has to be used.
+ The latter is also used in the library functions.
+\end_layout
+
+\end_inset
+
+ to the beginning and the end of the function body:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+\size footnotesize
+/* With a cut and paste from the .asm file, we have something to start with.
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+The
+ function is not yet OK! (registers aren't saved) */
+\newline
+void to_buffer_asm(
+ unsigned char c )
+\newline
+{
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+_asm
+\begin_inset LatexCommand \index{\_asm}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_asm}
+
+\end_inset
+
+
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov\InsetSpace ~
+\InsetSpace ~
+r2,dpl
+\newline
+;buffer.c if( head != (unsigned char)(tail-1) ) \InsetSpace ~
+/* cast
+\series bold
+needed
+\series default
+ to avoid promotion
+\begin_inset LatexCommand \index{promotion to signed int}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{type promotion}
+
+\end_inset
+
+ to integer */
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov\InsetSpace ~
+\InsetSpace ~
+a,_tail
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+dec\InsetSpace ~
+\InsetSpace ~
+a
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov\InsetSpace ~
+\InsetSpace ~
+r3,a
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov\InsetSpace ~
+\InsetSpace ~
+a,_head
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+cjne a,ar3,00106$
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+ret
+\newline
+00106$:
+
+\newline
+;buffer.c buf[ head++ ] = c; /* access to a 256 byte aligned array */
+\begin_inset LatexCommand \index{Aligned array}
+
+\end_inset
+
+
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov\InsetSpace ~
+\InsetSpace ~
+r3,_head
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+inc\InsetSpace ~
+\InsetSpace ~
+_head
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov\InsetSpace ~
+\InsetSpace ~
+dpl,r3
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov\InsetSpace ~
+\InsetSpace ~
+dph,#(_buf >> 8)
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov\InsetSpace ~
+\InsetSpace ~
+a,r2
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+movx @dptr,a
+
+\newline
+00103$:
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+ret
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+_endasm
+\begin_inset LatexCommand \index{\_endasm}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_endasm}
+
+\end_inset
+
+;
+\newline
+}
+\end_layout
+
+\begin_layout Standard
+The new file buffer.c should compile with only one warning about the unreferenced
+ function argument 'c'.
+ Now we hand-optimize the assembly code and insert an #define USE_ASSEMBLY
+ (1) and finally have:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+\size footnotesize
+unsigned char __far __at(0x7f00) buf[0x100];
+\newline
+unsigned char head, tail;
+\newline
+#define
+ USE_ASSEMBLY (1)
+\newline
+
+\newline
+#if !USE_ASSEMBLY
+\newline
+
+\newline
+void to_buffer( unsigned char c )
+\newline
+{
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+if(
+ head != (unsigned char)(tail-1) )
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+buf[ head++ ] = c;
+\newline
+}
+\newline
+
+\newline
+#else
+\newline
+
+\newline
+void to_buffer(
+ unsigned char c )
+\newline
+{
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+c; // to avoid warning: unreferenced function argument
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+_asm
+\begin_inset LatexCommand \index{\_asm}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_asm}
+
+\end_inset
+
+
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+; save used registers here.
+
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+; If we were still using r2,r3 we would have to push them here.
+
+\newline
+; if( head != (unsigned char)(tail-1) )
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov\InsetSpace ~
+ a,_tail
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+dec\InsetSpace ~
+ a
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+xrl\InsetSpace ~
+ a,_head
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+; we
+ could do an ANL a,#0x0f here to use a smaller buffer (see below)
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+jz\InsetSpace ~
+\InsetSpace ~
+ t_b_end$
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+;
+\newline
+;
+ buf[ head++ ] = c;
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov\InsetSpace ~
+ a,dpl \InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+; dpl holds lower byte of function argument
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov\InsetSpace ~
+
+ dpl,_head \InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+; buf is 0x100 byte aligned so head can be used directly
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov\InsetSpace ~
+ dph,#(_bu
+f>>8)
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+movx @dptr,a
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+inc \InsetSpace ~
+_head
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+; we could do an ANL _head,#0x0f here to use a
+ smaller buffer (see above)
+\newline
+t_b_end$:
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+; restore used registers here
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+_endasm
+\begin_inset LatexCommand \index{\_endasm}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_endasm}
+
+\end_inset
+
+;
+\newline
+}
+\newline
+#endif
+\end_layout
+
+\begin_layout Standard
+The inline assembler code can contain any valid code understood by the assembler
+, this includes any assembler directives and comment lines.
+ The assembler does not like some characters like ':' or ''' in comments.
+ You'll find an 100+ pages assembler manual in sdcc/as/doc/asxhtm.html
+\begin_inset LatexCommand \index{asXXXX (as-gbz80, as-hc08, asx8051, as-z80)}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{Assembler documentation}
+
+\end_inset
+
+ or online at
+\begin_inset LatexCommand \url{http://sdcc.svn.sourceforge.net/viewvc/*checkout*/sdcc/trunk/sdcc/as/doc/asxhtm.html}
+
+\end_inset
+
+\InsetSpace ~
+.
+\end_layout
+
+\begin_layout Standard
+The compiler does not do any validation of the code within the
+\family typewriter
+_asm
+\begin_inset LatexCommand \index{\_asm}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_asm}
+
+\end_inset
+
+ ...
+ _endasm
+\size footnotesize
+
+\begin_inset LatexCommand \index{\_endasm}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_endasm}
+
+\end_inset
+
+
+\size default
+;
+\family default
+ keyword pair.
+ Specifically it will not know which registers are used and thus register
+ pushing/popping
+\begin_inset LatexCommand \index{push/pop}
+
+\end_inset
+
+ has to be done manually.
+
+\end_layout
+
+\begin_layout Standard
+It is recommended that each assembly instruction (including labels) be placed
+ in a separate line (as the example shows).
+ When the -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-
+\emph on
+peep-asm
+\begin_inset LatexCommand \index{-\/-peep-asm}
+
+\end_inset
+
+
+\emph default
+ command line option is used, the inline assembler code will be passed through
+ the peephole optimizer
+\begin_inset LatexCommand \index{Peephole optimizer}
+
+\end_inset
+
+.
+ There are only a few (if any) cases where this option makes sense, it might
+ cause some unexpected changes in the inline assembler code.
+ Please go through the peephole optimizer rules defined in file
+\emph on
+SDCCpeeph.def
+\emph default
+ before using this option.
+\end_layout
+
+\begin_layout Subsection
+Naked Functions
+\begin_inset LatexCommand \label{sub:Naked-Functions}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{Naked functions}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+A special keyword may be associated with a function declaring it as
+\emph on
+_naked
+\begin_inset LatexCommand \index{\_naked}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_naked}
+
+\end_inset
+
+.
+
+\emph default
+The
+\emph on
+_naked
+\emph default
+ function modifier attribute prevents the compiler from generating prologue
+\begin_inset LatexCommand \index{function prologue}
+
+\end_inset
+
+ and epilogue
+\begin_inset LatexCommand \index{function epilogue}
+
+\end_inset
+
+ code for that function.
+ This means that the user is entirely responsible for such things as saving
+ any registers that may need to be preserved, selecting the proper register
+ bank, generating the
+\emph on
+return
+\emph default
+ instruction at the end, etc.
+ Practically, this means that the contents of the function must be written
+ in inline assembler.
+ This is particularly useful for interrupt functions, which can have a large
+ (and often unnecessary) prologue/epilogue.
+ For example, compare the code generated by these two functions:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+volatile
+\begin_inset LatexCommand \index{volatile}
+
+\end_inset
+
+ data unsigned char counter;
+\newline
+
+\newline
+void simpleInterrupt(void) __interrupt
+\begin_inset LatexCommand \index{interrupt}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_interrupt}
+
+\end_inset
+
+ (1)
+\newline
+{
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+counter++;
+\newline
+}
+\newline
+
+\newline
+void nakedInterrupt(void) __interrupt (2) __naked
+\newline
+{
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+_asm
+\begin_inset LatexCommand \index{\_asm}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_asm}
+
+\end_inset
+
+
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+inc\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+_counter ; does not change flags, no need to save psw
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+reti\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+; MUST explicitly
+ include ret or reti in _naked function.
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+_endasm
+\begin_inset LatexCommand \index{\_endasm}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_endasm}
+
+\end_inset
+
+;
+\newline
+}
+\end_layout
+
+\begin_layout Standard
+For an 8051 target, the generated simpleInterrupt looks like:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+Note, this is an
+\emph on
+outdated
+\emph default
+ example, recent versions of SDCC generate
+\newline
+the
+\emph on
+same
+\emph default
+ code for simpleInterrupt() and nakedInterrupt()!
+\newline
+
+\newline
+_simpleInterrupt:
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+push\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+acc
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+push\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+b
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+pu
+sh\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+dpl
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+push\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+dph
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+push\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+psw
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+psw,#0x00
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+inc\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+_counter
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+pop\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+psw
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+pop\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+dph
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+pop\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+dpl
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+pop\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+b
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+pop\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+acc
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+reti
+\end_layout
+
+\begin_layout Standard
+whereas nakedInterrupt looks like:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+_nakedInterrupt:
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+inc\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+_counter ; does not change flags, no need to save psw
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+reti\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+;
+ MUST explicitly include ret or reti in _naked function
+\end_layout
+
+\begin_layout Standard
+The related directive #pragma exclude
+\begin_inset LatexCommand \index{\#pragma exclude}
+
+\end_inset
+
+ allows a more fine grained control over pushing & popping
+\begin_inset LatexCommand \index{push/pop}
+
+\end_inset
+
+ the registers.
+\end_layout
+
+\begin_layout Standard
+While there is nothing preventing you from writing C code inside a
+\family typewriter
+_naked
+\family default
+ function, there are many ways to shoot yourself in the foot doing this,
+ and it is recommended that you stick to inline assembler.
+\end_layout
+
+\begin_layout Subsection
+Use of Labels within Inline Assembler
+\end_layout
+
+\begin_layout Standard
+SDCC allows the use of in-line assembler with a few restrictions regarding
+ labels.
+ All labels defined within inline assembler code have to be of the form
+
+\emph on
+nnnnn$
+\emph default
+ where nnnnn is a number less than 100 (which implies a limit of utmost
+ 100 inline assembler labels
+\emph on
+per function
+\emph default
+\noun on
+)
+\noun default
+.
+\begin_inset Foot
+status open
+
+\begin_layout Standard
+This is a slightly more stringent rule than absolutely necessary, but stays
+ always on the safe side.
+ Labels in the form of nnnnn$ are local labels in the assembler, locality
+ of which is confined within two labels of the standard form.
+ The compiler uses the same form for labels within a function (but starting
+ from nnnnn=00100); and places always a standard label at the beginning
+ of a function, thus limiting the locality of labels within the scope of
+ the function.
+ So, if the inline assembler part would be embedded into C-code, an improperly
+ placed non-local label in the assembler would break up the reference space
+ for labels created by the compiler for the C-code, leading to an assembling
+ error.
+\end_layout
+
+\begin_layout Standard
+The numeric part of local labels does not need to have 5 digits (although
+ this is the form of labels output by the compiler), any valid integer will
+ do.
+ Please refer to the assemblers documentation for further details.
+\end_layout
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+_asm
+\begin_inset LatexCommand \index{\_asm}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_asm}
+
+\end_inset
+
+
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+b,#10
+\newline
+00001$:
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+djnz\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+b,00001$
+\newline
+_endasm
+\begin_inset LatexCommand \index{\_endasm}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_endasm}
+
+\end_inset
+
+ ;
+\end_layout
+
+\begin_layout Standard
+Inline assembler code cannot reference any C-labels, however it can reference
+ labels
+\begin_inset LatexCommand \index{Labels}
+
+\end_inset
+
+ defined by the inline assembler, e.g.:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+foo() {
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+/* some c code */
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+_asm
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+; some assembler code
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+ljmp 0003$
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+_endasm;
+
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+/* some more c code */
+\newline
+clabel:\InsetSpace ~
+\InsetSpace ~
+/* inline assembler cannot reference this
+ label */
+\begin_inset Foot
+status open
+
+\begin_layout Standard
+Here, the C-label
+\family typewriter
+clabel
+\family default
+ is translated by the compiler into a local label, so the locality of labels
+ within the function is not broken.
+\end_layout
+
+\end_inset
+
+
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+_asm
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+0003$: ;label (can be referenced by inline assembler only)
+
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+_endasm
+\begin_inset LatexCommand \index{\_endasm}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_endasm}
+
+\end_inset
+
+ ;
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+/* some more c code */
+\newline
+}
+\end_layout
+
+\begin_layout Standard
+In other words inline assembly code can access labels defined in inline
+ assembly within the scope of the function.
+ The same goes the other way, i.e.
+ labels defines in inline assembly can not be accessed by C statements.
+\end_layout
+
+\begin_layout Section
+Interfacing with Assembler Code
+\begin_inset LatexCommand \index{Assembler routines}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Subsection
+Global Registers used for Parameter Passing
+\begin_inset LatexCommand \index{Parameter passing}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+The compiler always uses the global registers
+\emph on
+DPL, DPH
+\begin_inset LatexCommand \index{DPTR, DPH, DPL}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{DPTR}
+
+\end_inset
+
+, B
+\begin_inset LatexCommand \index{B (mcs51, ds390 register)}
+
+\end_inset
+
+
+\emph default
+and
+\emph on
+ ACC
+\begin_inset LatexCommand \index{ACC (mcs51, ds390 register)}
+
+\end_inset
+
+
+\emph default
+ to pass the first parameter to a function, and also to pass the return
+ value
+\begin_inset LatexCommand \index{return value}
+
+\end_inset
+
+of function; according to the following scheme: one byte return value in
+
+\emph on
+DPL
+\emph default
+, two byte value in
+\emph on
+DPL
+\emph default
+ (LSB) and
+\emph on
+DPH
+\emph default
+ (MSB).
+ three byte values (generic pointers) in
+\emph on
+DPH
+\emph default
+,
+\emph on
+DPL
+\emph default
+ and
+\emph on
+B
+\emph default
+, and four byte values in
+\emph on
+DPH
+\emph default
+,
+\emph on
+DPL
+\emph default
+,
+\emph on
+ B
+\emph default
+ and
+\emph on
+ACC
+\emph default
+.
+ Generic pointers
+\begin_inset LatexCommand \index{generic pointer}
+
+\end_inset
+
+ contain type of accessed memory in
+\emph on
+B
+\emph default
+:
+\series bold
+0x00
+\series default
+ -- xdata/far,
+\series bold
+0x40
+\series default
+ -- idata/near -- ,
+\series bold
+0x60
+\series default
+ -- pdata,
+\series bold
+0x80
+\series default
+ -- code
+\begin_inset Note Note
+status collapsed
+
+\begin_layout Standard
+This might not be the case of certain memory models (medium???)
+\end_layout
+
+\end_inset
+
+.
+\end_layout
+
+\begin_layout Standard
+The second parameter onwards is either allocated on the stack (for reentrant
+ routines or if -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-stack-auto is used) or in data/xdata memory (depending on the memory model).
+
+\end_layout
+
+\begin_layout Subsection
+Registers usage
+\end_layout
+
+\begin_layout Standard
+Unless the called function is declared as
+\family typewriter
+_naked
+\family default
+
+\begin_inset LatexCommand \index{naked}
+
+\end_inset
+
+, or the -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-callee-saves
+\begin_inset LatexCommand \index{-\/-callee-saves}
+
+\end_inset
+
+/-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-all-callee-saves command line option or the corresponding callee_saves
+ pragma are used, the caller will save the registers (
+\emph on
+R0-R7
+\emph default
+) around the call, so the called function can destroy they content freely.
+\end_layout
+
+\begin_layout Standard
+If the called function is not declared as
+\family typewriter
+_naked
+\family default
+, the caller will swap register banks around the call, if caller and callee
+ use different register banks (having them defined by the
+\family typewriter
+_using
+\family default
+ modifier).
+
+\end_layout
+
+\begin_layout Standard
+The called function can also use
+\emph on
+DPL
+\emph default
+,
+\emph on
+DPH
+\emph default
+,
+\emph on
+B
+\emph default
+ and
+\emph on
+ACC
+\emph default
+ observing that they are used for parameter/return value passing.
+\end_layout
+
+\begin_layout Subsection
+Assembler Routine (non-reentrant)
+\end_layout
+
+\begin_layout Standard
+In the following example
+\begin_inset LatexCommand \index{reentrant}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{Assembler routines (non-reentrant)}
+
+\end_inset
+
+ the function c_func calls an assembler routine asm_func, which takes two
+ parameters
+\begin_inset LatexCommand \index{function parameter}
+
+\end_inset
+
+.
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+extern int asm_func(unsigned char, unsigned char);
+\newline
+
+\newline
+int c_func (unsigned char
+ i, unsigned char j)
+\newline
+{
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+return asm_func(i,j);
+\newline
+}
+\newline
+
+\newline
+int main()
+\newline
+{
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+return c_func(10,9);
+\newline
+}
+\end_layout
+
+\begin_layout Standard
+The corresponding assembler function is:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+.globl _asm_func_PARM_2
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+.globl _asm_func
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+.area OSEG
+\newline
+_asm_func_PARM_2:
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+.ds
+ 1
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+.area CSEG
+\newline
+_asm_func:
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+a,dpl
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+add\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+a,_asm_func_PARM_2
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+dpl,a
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+dph
+\begin_inset LatexCommand \index{DPTR, DPH, DPL}
+
+\end_inset
+
+,#0x00
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+ret
+\end_layout
+
+\begin_layout Standard
+The parameter naming convention is _<function_name>_PARM_<n>, where n is
+ the parameter number starting from 1, and counting from the left.
+ The first parameter is passed in
+\emph on
+DPH
+\emph default
+,
+\emph on
+DPL
+\emph default
+,
+\emph on
+B
+\emph default
+ and
+\emph on
+ACC
+\emph default
+ according to the description above.
+ The variable name for the second parameter will be _<function_name>_PARM_2.
+\newline
+
+\newline
+Assem
+ble the assembler routine with the following command:
+\newline
+
+\newline
+
+\family sans
+\series bold
+asx8051 -losg asmfunc.asm
+\newline
+
+\newline
+
+\family default
+\series default
+Then compile and link the assembler routine to the C source file with the
+ following command:
+\newline
+
+\newline
+
+\family sans
+\series bold
+sdcc cfunc.c asmfunc.rel
+\end_layout
+
+\begin_layout Subsection
+Assembler Routine (reentrant)
+\end_layout
+
+\begin_layout Standard
+In this case
+\begin_inset LatexCommand \index{reentrant}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{Assembler routines (reentrant)}
+
+\end_inset
+
+ the second parameter
+\begin_inset LatexCommand \index{function parameter}
+
+\end_inset
+
+ onwards will be passed on the stack, the parameters are pushed from right
+ to left i.e.
+ before the call the second leftmost parameter will be on the top of the
+ stack (the leftmost parameter is passed in registers).
+ Here is an example:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+extern int asm_func(unsigned char, unsigned char, unsigned char) reentrant;
+\newline
+
+\newline
+int
+ c_func (unsigned char i, unsigned char j, unsigned char k) reentrant
+\newline
+{
+
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+return asm_func(i,j,k);
+\newline
+}
+\newline
+
+\newline
+int main()
+\newline
+{
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+return c_func(10,9,8);
+\newline
+}
+\end_layout
+
+\begin_layout Standard
+The corresponding (unoptimized) assembler routine is:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+.globl _asm_func
+\newline
+_asm_func:
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+push\InsetSpace ~
+_bp
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov\InsetSpace ~
+\InsetSpace ~
+_bp,sp\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+;stack contains: _bp, return
+ address, second parameter, third parameter
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov\InsetSpace ~
+\InsetSpace ~
+r2,dpl
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov\InsetSpace ~
+\InsetSpace ~
+a,_bp
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+add\InsetSpace ~
+\InsetSpace ~
+a,#0xfd\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+;calculate
+ pointer to the second parameter
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov\InsetSpace ~
+\InsetSpace ~
+r0,a
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov\InsetSpace ~
+\InsetSpace ~
+a,_bp
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+add\InsetSpace ~
+\InsetSpace ~
+a,#0xfc\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+;calculate pointer
+ to the rightmost parameter
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov\InsetSpace ~
+\InsetSpace ~
+r1,a
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov\InsetSpace ~
+\InsetSpace ~
+a,@r0
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+add\InsetSpace ~
+\InsetSpace ~
+a,@r1
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+add\InsetSpace ~
+\InsetSpace ~
+a,r2\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+;calculate the
+ result (= sum of all three parameters)
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov\InsetSpace ~
+\InsetSpace ~
+dpl,a\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+;return value goes into dptr
+ (cast into int)
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov\InsetSpace ~
+\InsetSpace ~
+dph,#0x00
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov\InsetSpace ~
+\InsetSpace ~
+sp,_bp
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+pop\InsetSpace ~
+\InsetSpace ~
+_bp
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+ret
+\end_layout
+
+\begin_layout Standard
+The compiling and linking procedure remains the same, however note the extra
+ entry & exit linkage required for the assembler code, _bp is the stack
+ frame pointer and is used to compute the offset into the stack for parameters
+ and local variables.
+\begin_inset VSpace bigskip
+\end_inset
+
+
+\end_layout
+
+\begin_layout Section
+int (16 bit)
+\begin_inset LatexCommand \index{int (16 bit)}
+
+\end_inset
+
+ and long (32 bit)
+\begin_inset LatexCommand \index{long (32 bit)}
+
+\end_inset
+
+ Support
+\end_layout
+
+\begin_layout Standard
+For signed & unsigned int (16 bit) and long (32 bit) variables, division,
+ multiplication and modulus operations are implemented by support routines.
+ These support routines are all developed in ANSI-C to facilitate porting
+ to other MCUs, although some model specific assembler optimizations are
+ used.
+ The following files contain the described routines, all of them can be
+ found in <installdir>/share/sdcc/lib.
+\newline
+
+\end_layout
+
+\begin_layout Standard
+\align center
+\begin_inset Tabular
+<lyxtabular version="3" rows="11" columns="2">
+<features>
+<column alignment="left" valignment="top" leftline="true" width="0">
+<column alignment="left" valignment="top" leftline="true" rightline="true" width="0">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\series bold
+Function
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\series bold
+Description
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+_mulint.c
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+16 bit multiplication
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+_divsint.c
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+ signed 16 bit division (calls _divuint)
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+_divuint.c
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+ unsigned 16 bit division
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+_modsint.c
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+signed 16 bit modulus (calls _moduint)
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+_moduint.c
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+unsigned 16 bit modulus
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+_mullong.c
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+32 bit multiplication
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+_divslong.c
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+ signed 32 division (calls _divulong)
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+_divulong.c
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+unsigned 32 division
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+_modslong.c
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+ signed 32 bit modulus (calls _modulong)
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+_modulong.c
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+unsigned 32 bit modulus
+\end_layout
+
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
+\newline
+
+\end_layout
+
+\begin_layout Standard
+Since they are compiled as
+\emph on
+non-reentrant
+\emph default
+
+\begin_inset LatexCommand \index{reentrant}
+
+\end_inset
+
+, interrupt
+\begin_inset LatexCommand \index{interrupt}
+
+\end_inset
+
+ service routines should not do any of the above operations.
+ If this is unavoidable then the above routines will need to be compiled
+ with the
+\emph on
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-stack-auto
+\begin_inset LatexCommand \index{-\/-stack-auto}
+
+\end_inset
+
+
+\emph default
+ option, after which the source program will have to be compiled with
+\emph on
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-int-long-reent
+\begin_inset LatexCommand \index{-\/-int-long-reent}
+
+\end_inset
+
+
+\emph default
+ option.
+ Notice that you don't have to call these routines directly.
+ The compiler will use them automatically every time an integer operation
+ is required.
+\end_layout
+
+\begin_layout Section
+Floating Point Support
+\begin_inset LatexCommand \index{Floating point support}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+SDCC supports IEEE (single precision 4 bytes) floating point numbers.
+ The floating point support routines are derived from gcc's floatlib.c and
+ consist of the following routines:
+\newline
+
+\end_layout
+
+\begin_layout Standard
+\align center
+
+\size footnotesize
+\begin_inset Tabular
+<lyxtabular version="3" rows="17" columns="2">
+<features>
+<column alignment="left" valignment="top" leftline="true" width="0">
+<column alignment="left" valignment="top" leftline="true" rightline="true" width="0">
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+\begin_inset Text
+
+\begin_layout Standard
+
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+\bar no
+\noun off
+\color none
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+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Description
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
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+\end_layout
+
+\end_inset
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+
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+
+\end_inset
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+</row>
+<row topline="true">
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+
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+
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+\end_layout
+
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+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
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+
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+
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+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
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+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
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+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\family roman
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+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\family roman
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+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
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+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
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+\color none
+convert floating point to unsigned char
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\family roman
+\series medium
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+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
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+
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+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
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+\end_layout
+
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+
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+
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+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\family roman
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+\family default
+\series default
+\shape default
+\size default
+\emph default
+\bar default
+\noun default
+c
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\family roman
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+\noun off
+\color none
+convert floating point to unsigned long
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
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+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
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+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
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+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\family roman
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+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
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+\color none
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+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\family roman
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+\shape up
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+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
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+
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+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
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+
+\begin_layout Standard
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+
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+</cell>
+</row>
+<row topline="true">
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+
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+
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+
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+\end_layout
+
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
+\newline
+
+\end_layout
+
+\begin_layout Standard
+These support routines are developed in ANSI-C so there is room for space
+ and speed improvement
+\begin_inset Foot
+status open
+
+\begin_layout Standard
+These floating point routines (
+\emph on
+not
+\emph default
+ sinf(), cosf(), ...) for the mcs51 are implemented in assembler.
+
+\end_layout
+
+\end_inset
+
+.
+ Note if all these routines are used simultaneously the data space might
+ overflow.
+ For serious floating point usage the large model might be needed.
+ Also notice that you don't have to call this routines directly.
+ The compiler will use them automatically every time a floating point operation
+ is required.
+\begin_inset VSpace bigskip
+\end_inset
+
+
+\end_layout
+
+\begin_layout Section
+Library Routines
+\begin_inset LatexCommand \index{Libraries}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+
+\emph on
+<pending: this is messy and incomplete - a little more information is in
+ sdcc/doc/libdoc.txt
+\emph default
+ >
+\end_layout
+
+\begin_layout Subsection
+Compiler support routines (_gptrget, _mulint etc.)
+\end_layout
+
+\begin_layout Subsection
+Stdclib functions (puts, printf, strcat etc.)
+\end_layout
+
+\begin_layout Subsubsection
+<stdio.h>
+\end_layout
+
+\begin_layout Paragraph
+getchar(), putchar()
+\end_layout
+
+\begin_layout Standard
+\begin_inset LatexCommand \index{<stdio.h>}
+
+\end_inset
+
+As usual on embedded systems you have to provide your own
+\family typewriter
+getchar()
+\begin_inset LatexCommand \index{getchar()}
+
+\end_inset
+
+
+\family default
+and
+\family typewriter
+putchar()
+\begin_inset LatexCommand \index{putchar()}
+
+\end_inset
+
+
+\family default
+ routines.
+ SDCC does not know whether the system connects to a serial line with or
+ without handshake, LCD, keyboard or other device.
+ And whether a
+\family typewriter
+lf
+\family default
+ to
+\family typewriter
+crlf
+\family default
+ conversion within
+\family typewriter
+putchar()
+\family default
+ is intended.
+ You'll find examples for serial routines f.e.
+ in sdcc/device/lib.
+ For the mcs51 this minimalistic polling
+\family typewriter
+putchar()
+\family default
+ routine might be a start:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+void putchar (char c) {
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+while (!TI)\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+ /* assumes UART is initialized */
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+;
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+TI
+ = 0;
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+SBUF = c;
+\newline
+}
+\end_layout
+
+\begin_layout Paragraph
+printf()
+\end_layout
+
+\begin_layout Standard
+The default
+\family typewriter
+ printf()
+\begin_inset LatexCommand \index{printf()}
+
+\end_inset
+
+
+\family default
+ implementation in
+\family typewriter
+ printf_large.c
+\family default
+ does not support float (except on ds390).
+ To enable this recompile it with the option
+\emph on
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+DUSE_FLOATS=1
+\begin_inset LatexCommand \index{USE\_FLOATS}
+
+\end_inset
+
+
+\emph default
+ on the command line.
+ Use
+\emph on
+ -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-model-large
+\begin_inset LatexCommand \index{-\/-model-large}
+
+\end_inset
+
+
+\emph default
+ for the mcs51 port, since this uses a lot of memory.
+\end_layout
+
+\begin_layout Standard
+If you're short on code memory you might want to use
+\family typewriter
+printf_small()
+\begin_inset LatexCommand \index{printf\_small()}
+
+\end_inset
+
+
+\family default
+
+\emph on
+instead
+\emph default
+ of
+\family typewriter
+ printf().
+
+\family default
+ For the mcs51 there additionally are assembly versions
+\family typewriter
+printf_tiny()
+\begin_inset LatexCommand \index{printf\_tiny() (mcs51)}
+
+\end_inset
+
+
+\family default
+ (subset of printf using less than 270 bytes) and
+\family typewriter
+printf_fast()
+\begin_inset LatexCommand \index{printf\_fast() (mcs51)}
+
+\end_inset
+
+
+\family default
+and
+\family typewriter
+ printf_fast_f()
+\begin_inset LatexCommand \index{printf\_fast\_f() (mcs51)}
+
+\end_inset
+
+
+\family default
+ (floating-point aware version of printf_fast) which should fit the requirements
+ of many embedded systems (printf_fast() can be customized by unsetting
+ #defines to
+\emph on
+not
+\emph default
+ support long variables and field widths).
+ Be sure to use only one of these printf options within a project.
+\newline
+
+\end_layout
+
+\begin_layout Standard
+Feature matrix of different
+\emph on
+printf
+\emph default
+ options on mcs51.
+\end_layout
+
+\begin_layout Standard
+\begin_inset Tabular
+<lyxtabular version="3" rows="14" columns="7">
+<features islongtable="true">
+<column alignment="left" valignment="middle" leftline="true" width="14col%">
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" width="12col%">
+<column alignment="center" valignment="top" leftline="true" width="10col%">
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="12col%">
+<column alignment="center" valignment="top" rightline="true" width="0">
+<row topline="true" bottomline="true" endhead="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\series bold
+\size large
+mcs51
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+printf
+\begin_inset LatexCommand \index{printf}
+
+\end_inset
+
+
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+printf
+\size scriptsize
+USE_FLOATS=1
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+printf_small
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+printf_fast
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+printf_fast_f
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+printf_tiny
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true" endhead="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+filename
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\size scriptsize
+printf_large.c
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\size scriptsize
+printf_large.c
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\size scriptsize
+printfl.c
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\size scriptsize
+printf_fast.c
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\size scriptsize
+printf_fast_f.c
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\size scriptsize
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+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true" endhead="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+\begin_inset Quotes sld
+\end_inset
+
+Hello World
+\begin_inset Quotes srd
+\end_inset
+
+ size
+\end_layout
+
+\begin_layout Standard
+small / large
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+1.7k / 2.4k
+\end_layout
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+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
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+\begin_layout Standard
+4.3k / 5.6k
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+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
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+\begin_inset Text
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+\end_inset
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+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+cdi
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+o
+\emph default
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+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
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+\family default
+\series default
+\shape default
+\size default
+\emph default
+\bar default
+\noun default
+f
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+i
+\family default
+\series default
+\shape default
+\size default
+\emph on
+\bar default
+\noun default
+o
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+psux
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+c
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+d
+\family default
+\series default
+\shape default
+\size default
+\emph on
+\bar default
+\noun default
+o
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+s
+\family default
+\series default
+\shape default
+\size default
+\emph default
+\bar default
+\noun default
+x
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+cdsux
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+cdfsux
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
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+
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+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+long (32 bit) support
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
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+\end_layout
+
+\end_inset
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+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
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+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
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+
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+
+\end_inset
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+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
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+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\family roman
+\series medium
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+\noun off
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+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
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+
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+\end_layout
+
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+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
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+
+\begin_layout Standard
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+
+\end_inset
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+
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+
+\end_inset
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+
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+
+\begin_layout Standard
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+\end_layout
+
+\end_inset
+
+
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+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+x
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+x
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+-
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+string speed
+\begin_inset Foot
+status collapsed
+
+\begin_layout Standard
+Execution time of printf("%s%c%s%c%c%c", "Hello", ' ', "World", '!', '
+\backslash
+r', '
+\backslash
+n'); standard 8051 @ 22.1184 MHz, empty putchar()
+\end_layout
+
+\end_inset
+
+,
+\end_layout
+
+\begin_layout Standard
+small / large
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+1.52 / 2.59 ms
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+1.53 / 2.62 ms
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+0.92 / 0.93 ms
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+0.45 / 0.45 ms
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+0.46 / 0.46 ms
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+0.45 / 0.45 ms
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+int speed
+\begin_inset Foot
+status collapsed
+
+\begin_layout Standard
+Execution time of printf("%d", -12345); standard 8051 @ 22.1184 MHz, empty
+ putchar()
+\end_layout
+
+\end_inset
+
+,
+\end_layout
+
+\begin_layout Standard
+small / large
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+3.01 / 3.61 ms
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+3.01 / 3.61 ms
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+3.51 / 18.13 ms
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+0.22 / 0.22 ms
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+0.23 / 0.23 ms
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+0.25 / 0.25 ms
+\begin_inset Foot
+status collapsed
+
+\begin_layout Standard
+printf_tiny integer speed is data dependent, worst case is 0.33 ms
+\end_layout
+
+\end_inset
+
+
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+long speed
+\begin_inset Foot
+status collapsed
+
+\begin_layout Standard
+Execution time of printf("%ld", -123456789); standard 8051 @ 22.1184 MHz,
+ empty putchar()
+\end_layout
+
+\end_inset
+
+,
+\end_layout
+
+\begin_layout Standard
+small / large
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+5.37 / 6.31 ms
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+5.37 / 6.31 ms
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+8.71 / 40.65 ms
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+0.40 / 0.40 ms
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+0.40 / 0.40 ms
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+-
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+float speed
+\begin_inset Foot
+status collapsed
+
+\begin_layout Standard
+Execution time of printf("%.3f", -12345.678); standard 8051 @ 22.1184 MHz,
+ empty putchar()
+\end_layout
+
+\end_inset
+
+,
+\end_layout
+
+\begin_layout Standard
+small / large
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+-
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+7.49 / 22.47 ms
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+-
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+-
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+1.04 / 1.04 ms
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+-
+\end_layout
+
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Subsubsection
+<malloc.h>
+\begin_inset LatexCommand \index{malloc.h}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+As of SDCC 2.6.2 you no longer need to call an initialization routine before
+ using dynamic memory allocation
+\begin_inset LatexCommand \index{dynamic memory allocation (malloc)}
+
+\end_inset
+
+ and a default heap
+\begin_inset LatexCommand \index{heap (malloc)}
+
+\end_inset
+
+ space of 1024 bytes is provided for malloc to allocate memory from.
+ If you need a different heap size you need to recompile _heap.c with the
+ required size defined in HEAP_SIZE.
+ It is recommended to make a copy of this file into your project directory
+ and compile it there with:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+sdcc -c _heap.c -D HEAD_SIZE=2048
+\end_layout
+
+\begin_layout Standard
+And then link it with:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+sdcc main.rel _heap.rel
+\end_layout
+
+\begin_layout Subsection
+Math functions (sinf, powf, sqrtf etc.)
+\end_layout
+
+\begin_layout Subsubsection
+<math.h>
+\end_layout
+
+\begin_layout Standard
+See definitions in file <math.h>.
+\end_layout
+
+\begin_layout Subsection
+Other libraries
+\end_layout
+
+\begin_layout Standard
+Libraries
+\begin_inset LatexCommand \index{Libraries}
+
+\end_inset
+
+ included in SDCC should have a license at least as liberal as the GNU Lesser
+ General Public License
+\begin_inset LatexCommand \index{GNU Lesser General Public License, LGPL}
+
+\end_inset
+
+
+\emph on
+LGPL
+\emph default
+.
+\end_layout
+
+\begin_layout Standard
+\begin_inset Note Note
+status collapsed
+
+\begin_layout Standard
+license statements for the libraries are missing.
+ sdcc/device/lib/ser_ir.c
+\end_layout
+
+\begin_layout Standard
+or _decdptr f.e.
+ come with a GPL (as opposed to LGPL) License - this will not be liberal
+ enough for many embedded programmers.
+\end_layout
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+If you have ported some library or want to share experience about some code
+ which f.e.
+ falls into any of these categories Busses (I
+\begin_inset Formula $^{\textrm{2}}$
+\end_inset
+
+C, CAN, Ethernet, Profibus, Modbus, USB, SPI, JTAG ...), Media (IDE, Memory
+ cards, eeprom, flash...), En-/Decryption, Remote debugging, Realtime kernel,
+ Keyboard, LCD, RTC, FPGA, PID then the sdcc-user mailing list
+\begin_inset LatexCommand \url{http://sourceforge.net/mail/?group_id=599}
+
+\end_inset
+
+\InsetSpace ~
+would certainly like to hear about it.
+\end_layout
+
+\begin_layout Standard
+Programmers coding for embedded systems are not especially famous for being
+ enthusiastic, so don't expect a big hurray but as the mailing list is searchabl
+e these references are very valuable.
+ Let's help to create a climate where information is shared.
+\begin_inset VSpace bigskip
+\end_inset
+
+
+\end_layout
+
+\begin_layout Section
+Memory Models
+\end_layout
+
+\begin_layout Subsection
+MCS51 Memory Models
+\begin_inset LatexCommand \index{Memory model}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{MCS51 memory model}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Subsubsection
+Small, Medium and Large
+\end_layout
+
+\begin_layout Standard
+SDCC allows three memory models for MCS51 code,
+\shape slanted
+small, medium
+\shape default
+ and
+\shape slanted
+large
+\shape default
+.
+ Modules compiled with different memory models should
+\emph on
+never
+\emph default
+ be combined together or the results would be unpredictable.
+ The library routines supplied with the compiler are compiled as small,
+ medium and large.
+ The compiled library modules are contained in separate directories as small,
+ medium and large so that you can link to the appropriate set.
+\end_layout
+
+\begin_layout Standard
+When the medium or large model is used all variables declared without a
+ storage class will be allocated into the external ram, this includes all
+ parameters and local variables (for non-reentrant
+\begin_inset LatexCommand \index{reentrant}
+
+\end_inset
+
+ functions).
+ When the small model is used variables without storage class are allocated
+ in the internal ram.
+\end_layout
+
+\begin_layout Standard
+Judicious usage of the processor specific storage classes
+\begin_inset LatexCommand \index{Storage class}
+
+\end_inset
+
+ and the 'reentrant' function type will yield much more efficient code,
+ than using the large model.
+ Several optimizations are disabled when the program is compiled using the
+ large model, it is therefore recommended that the small model be used unless
+ absolutely required.
+\end_layout
+
+\begin_layout Subsubsection
+External Stack
+\begin_inset LatexCommand \label{sub:External-Stack}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{stack}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{External stack (mcs51)}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+The external stack (-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-xstack option
+\begin_inset LatexCommand \index{-\/-xstack}
+
+\end_inset
+
+) is located in pdata
+\begin_inset LatexCommand \index{pdata (mcs51, ds390 storage class)}
+
+\end_inset
+
+ memory (usually at the start of the external ram segment) and uses all
+ unused space in pdata (max.
+ 256 bytes).
+ When -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-xstack option is used to compile the program, the parameters and local
+ variables
+\begin_inset LatexCommand \index{local variables}
+
+\end_inset
+
+ of all reentrant functions are allocated in this area.
+ This option is provided for programs with large stack space requirements.
+ When used with the -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-stack-auto
+\begin_inset LatexCommand \index{-\/-stack-auto}
+
+\end_inset
+
+ option, all parameters and local variables are allocated on the external
+ stack (note: support libraries will need to be recompiled with the same
+ options.
+ There is a predefined target in the library makefile).
+\end_layout
+
+\begin_layout Standard
+The compiler outputs the higher order address byte of the external ram segment
+ into port P2
+\begin_inset LatexCommand \index{P2 (mcs51 sfr)}
+
+\end_inset
+
+ (see also section
+\begin_inset LatexCommand \ref{sub:MCS51-variants}
+
+\end_inset
+
+), therefore when using the External Stack option, this port
+\emph on
+may not
+\emph default
+ be used by the application program.
+\end_layout
+
+\begin_layout Subsection
+DS390 Memory Model
+\begin_inset LatexCommand \index{Memory model}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{DS390 memory model}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+The only model supported is Flat 24
+\begin_inset LatexCommand \index{Flat 24 (DS390 memory model)}
+
+\end_inset
+
+.
+ This generates code for the 24 bit contiguous addressing mode of the Dallas
+ DS80C390 part.
+ In this mode, up to four meg of external RAM or code space can be directly
+ addressed.
+ See the data sheets at www.dalsemi.com for further information on this part.
+\newline
+
+\newline
+Note
+ that the compiler does not generate any code to place the processor into
+ 24 bitmode (although
+\emph on
+tinibios
+\emph default
+ in the ds390 libraries will do that for you).
+ If you don't use
+\emph on
+tinibios
+\emph default
+
+\begin_inset LatexCommand \index{Tinibios (DS390)}
+
+\end_inset
+
+, the boot loader or similar code must ensure that the processor is in 24
+ bit contiguous addressing mode before calling the SDCC startup code.
+\newline
+
+\newline
+Like
+ the
+\emph on
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-model-large
+\emph default
+ option, variables will by default be placed into the XDATA segment.
+
+\newline
+
+\newline
+Segments may be placed anywhere in the 4 meg address space using the usual
+ -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-*-loc options.
+ Note that if any segments are located above 64K, the -r flag must be passed
+ to the linker to generate the proper segment relocations, and the Intel
+ HEX output format must be used.
+ The -r flag can be passed to the linker by using the option
+\emph on
+-Wl-r
+\emph default
+ on the SDCC command line.
+ However, currently the linker can not handle code segments > 64k.
+\end_layout
+
+\begin_layout Section
+Pragmas
+\begin_inset LatexCommand \label{sec:Pragmas}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{Pragmas}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+Pragmas are used to turn on and/or off certain compiler options.
+ Some of them are closely related to corresponding command-line options
+ (see section
+\begin_inset LatexCommand \vref{sec:Command-Line-Options}
+
+\end_inset
+
+).
+\newline
+Pragmas should be placed before and/or after a function, placing pragmas
+ inside a function body could have unpredictable results.
+\newline
+
+\newline
+SDCC supports the
+ following #pragma directives:
+\end_layout
+
+\begin_layout Itemize
+
+\series bold
+save
+\series default
+
+\begin_inset LatexCommand \index{\#pragma save}
+
+\end_inset
+
+ - this will save most current options to the save/restore stack.
+ See #pragma\InsetSpace ~
+restore.
+\end_layout
+
+\begin_layout Itemize
+
+\series bold
+restore
+\series default
+
+\begin_inset LatexCommand \index{\#pragma restore}
+
+\end_inset
+
+ - will restore saved options from the last save.
+ saves & restores can be nested.
+ SDCC uses a save/restore stack: save pushes current options to the stack,
+ restore pulls current options from the stack.
+ See #pragma\InsetSpace ~
+save.
+\newline
+
+\end_layout
+
+\begin_layout Itemize
+
+\series bold
+callee_saves
+\series default
+
+\begin_inset LatexCommand \index{\#pragma callee\_saves}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{function prologue}
+
+\end_inset
+
+ function1[,function2[,function3...]]
+\begin_inset LatexCommand \label{ite:callee_saves-function1[,function2[,function3...]]--}
+
+\end_inset
+
+- The compiler by default uses a caller saves convention for register saving
+ across function calls, however this can cause unnecessary register pushing
+ and popping
+\begin_inset LatexCommand \index{push/pop}
+
+\end_inset
+
+ when calling small functions from larger functions.
+ This option can be used to switch off the register saving convention for
+ the function names specified.
+ The compiler will not save registers when calling these functions, extra
+ code need to be manually inserted at the entry and exit for these functions
+ to save and restore the registers used by these functions, this can SUBSTANTIAL
+LY reduce code and improve run time performance of the generated code.
+ In the future the compiler (with inter procedural analysis) may be able
+ to determine the appropriate scheme to use for each function call.
+ If -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-callee-saves command line option is used (see page
+\begin_inset LatexCommand \vpageref{lyx:--callee-saves-function1[,function2][,function3]...}
+
+\end_inset
+
+), the function names specified in #pragma\InsetSpace ~
+callee_saves
+\begin_inset LatexCommand \index{\#pragma callee\_saves}
+
+\end_inset
+
+ is appended to the list of functions specified in the command line.
+\end_layout
+
+\begin_layout Itemize
+
+\series bold
+exclude
+\series default
+
+\begin_inset LatexCommand \index{\#pragma exclude}
+
+\end_inset
+
+ none | {acc[,b[,dpl[,dph]]] - The exclude pragma disables the generation
+ of pairs of push/pop
+\begin_inset LatexCommand \index{push/pop}
+
+\end_inset
+
+ instructions in
+\emph on
+I
+\emph default
+nterrupt
+\begin_inset LatexCommand \index{interrupt}
+
+\end_inset
+
+
+\emph on
+S
+\emph default
+ervice
+\emph on
+R
+\emph default
+outines.
+ The directive should be placed immediately before the ISR function definition
+ and it affects ALL ISR functions following it.
+ To enable the normal register saving for ISR functions use #pragma\InsetSpace ~
+exclude\InsetSpace ~
+none
+\begin_inset LatexCommand \index{\#pragma exclude}
+
+\end_inset
+
+.
+ See also the related keyword _naked
+\begin_inset LatexCommand \index{\_naked}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_naked}
+
+\end_inset
+
+.
+\end_layout
+
+\begin_layout Itemize
+
+\series bold
+less_pedantic
+\series default
+
+\begin_inset LatexCommand \index{pedantic}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\#pragma less\_pedantic}
+
+\end_inset
+
+
+\begin_inset LatexCommand \label{ite:less_pedantic}
+
+\end_inset
+
+- the compiler will not warn you anymore for obvious mistakes, you'r on
+ your own now ;-( .
+ See also the command line option -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-less-pedantic
+\begin_inset LatexCommand \vpageref{lyx:--less-pedantic}
+
+\end_inset
+
+.
+
+\newline
+More specifically, the following warnings will be disabled:
+\shape italic
+comparison is always [true/false] due to limited range of data type
+\shape default
+ (94);
+\shape italic
+overflow in implicit constant conversion
+\shape default
+ (158); [the (in)famous]
+\shape italic
+conditional flow changed by optimizer: so said EVELYN the modified DOG
+\shape default
+ (110);
+\shape italic
+function '[function name]' must return value
+\shape default
+ (59).
+
+\newline
+Furthermore, warnings of less importance (of PEDANTIC and INFO warning
+ level) are disabled, too, namely:
+\shape italic
+constant value '[
+\begin_inset Note Note
+status collapsed
+
+\begin_layout Standard
+dunno what comes here - this warning appears to be unused altogether
+\end_layout
+
+\end_inset
+
+]', out of range
+\shape default
+ (81);
+\shape italic
+[left/right] shifting more than size of object changed to zero
+\shape default
+ (116);
+\shape italic
+unreachable code
+\shape default
+ (126);
+\shape italic
+integer overflow in expression
+\shape default
+ (165);
+\shape italic
+unmatched #pragma save and #pragma restore
+\shape default
+ (170);
+\shape italic
+comparison of 'signed char' with 'unsigned char' requires promotion to int
+\shape default
+ (185);
+\shape italic
+ISO C90 does not support flexible array members
+\shape default
+ (187);
+\shape italic
+extended stack by [number] bytes for compiler temp(s) :in function '[function\InsetSpace ~
+nam
+e]':\InsetSpace ~
+[
+\begin_inset Note Note
+status collapsed
+
+\begin_layout Standard
+appears to be always blank - what was supposed to be here?
+\end_layout
+
+\end_inset
+
+]
+\shape default
+ (114);
+\shape italic
+function '[function name]', # edges [number] , # nodes [number] , cyclomatic
+ complexity [number]
+\shape default
+ (121).
+\end_layout
+
+\begin_layout Itemize
+
+\series bold
+disable_warning
+\series default
+ <nnnn>
+\begin_inset LatexCommand \index{\#pragma disable\_warning}
+
+\end_inset
+
+ - the compiler will not warn you anymore about warning number <nnnn>.
+\end_layout
+
+\begin_layout Itemize
+
+\series bold
+nogcse
+\series default
+
+\begin_inset LatexCommand \index{\#pragma nogcse}
+
+\end_inset
+
+ - will stop global common subexpression elimination.
+\end_layout
+
+\begin_layout Itemize
+
+\series bold
+noinduction
+\series default
+
+\begin_inset LatexCommand \index{\#pragma noinduction}
+
+\end_inset
+
+ - will stop loop induction optimizations.
+\end_layout
+
+\begin_layout Itemize
+
+\series bold
+noinvariant
+\series default
+
+\begin_inset LatexCommand \index{\#pragma noinvariant}
+
+\end_inset
+
+ - will not do loop invariant optimizations.
+ For more details see Loop Invariants in section
+\begin_inset LatexCommand \ref{sub:Loop-Optimizations}
+
+\end_inset
+
+.
+\end_layout
+
+\begin_layout Itemize
+
+\series bold
+noiv
+\series default
+
+\begin_inset LatexCommand \index{\#pragma noiv}
+
+\end_inset
+
+ - Do not generate interrupt
+\begin_inset LatexCommand \index{interrupt}
+
+\end_inset
+
+ vector table
+\begin_inset LatexCommand \index{interrupt vector table}
+
+\end_inset
+
+ entries for all ISR functions defined after the pragma.
+ This is useful in cases where the interrupt vector table must be defined
+ manually, or when there is a secondary, manually defined interrupt vector
+ table (e.g.
+ for the autovector feature of the Cypress EZ-USB FX2).
+ More elegantly this can be achieved by obmitting the optional interrupt
+ number after the interrupt keyword, see section
+\begin_inset LatexCommand \ref{sub:Interrupt-Service-Routines}
+
+\end_inset
+
+\InsetSpace ~
+about interrupts.
+\end_layout
+
+\begin_layout Itemize
+
+\series bold
+nojtbound
+\series default
+
+\begin_inset LatexCommand \index{\#pragma nojtbound}
+
+\end_inset
+
+ - will not generate code for boundary value checking, when switch statements
+ are turned into jump-tables (dangerous).
+ For more details see section
+\begin_inset LatexCommand \ref{sub:'switch'-Statements}
+
+\end_inset
+
+.
+\end_layout
+
+\begin_layout Itemize
+
+\series bold
+noloopreverse
+\series default
+
+\begin_inset LatexCommand \index{\#pragma noloopreverse}
+
+\end_inset
+
+ - Will not do loop reversal optimization
+\end_layout
+
+\begin_layout Itemize
+
+\series bold
+nooverlay
+\series default
+
+\begin_inset LatexCommand \index{\#pragma nooverlay}
+
+\end_inset
+
+ - the compiler will not overlay the parameters and local variables of a
+ function.
+\end_layout
+
+\begin_layout Itemize
+
+\series bold
+stackauto
+\series default
+
+\begin_inset LatexCommand \index{\#pragma stackauto}
+
+\end_inset
+
+- See option -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-stack-auto
+\begin_inset LatexCommand \index{-\/-stack-auto}
+
+\end_inset
+
+ and section
+\begin_inset LatexCommand \ref{sec:Parameters-and-Local-Variables}
+
+\end_inset
+
+ Parameters and Local Variables.
+\end_layout
+
+\begin_layout Itemize
+
+\series bold
+opt_code_speed
+\series default
+
+\begin_inset LatexCommand \index{\#pragma opt\_code\_speed}
+
+\end_inset
+
+- The compiler will optimize code generation towards fast code, possibly
+ at the expense of code size.
+ Currently this has little effect.
+\end_layout
+
+\begin_layout Itemize
+
+\series bold
+opt_code_size
+\series default
+
+\begin_inset LatexCommand \index{\#pragma opt\_code\_size}
+
+\end_inset
+
+- The compiler will optimize code generation towards compact code, possibly
+ at the expense of code speed.
+ Currently this has little effect.
+\end_layout
+
+\begin_layout Itemize
+
+\series bold
+opt_code_balanced
+\series default
+
+\begin_inset LatexCommand \index{\#pragma opt\_code\_balanced}
+
+\end_inset
+
+- The compiler will attempt to generate code that is both compact and fast,
+ as long as meeting one goal is not a detriment to the other (this is the
+ default).
+
+\end_layout
+
+\begin_layout Itemize
+
+\series bold
+std_sdcc89
+\series default
+
+\begin_inset LatexCommand \index{\#pragma std\_sdcc89}
+
+\end_inset
+
+- Generally follow the C89 standard, but allow SDCC features that conflict
+ with the standard (default).
+\end_layout
+
+\begin_layout Itemize
+
+\series bold
+std_c89
+\series default
+
+\begin_inset LatexCommand \index{\#pragma std\_c89}
+
+\end_inset
+
+- Follow the C89 standard and disable SDCC features that conflict with the
+ standard.
+\end_layout
+
+\begin_layout Itemize
+
+\series bold
+std_sdcc99
+\series default
+
+\begin_inset LatexCommand \index{\#pragma std\_sdcc99}
+
+\end_inset
+
+- Generally follow the C99 standard, but allow SDCC features that conflict
+ with the standard (incomplete support).
+\end_layout
+
+\begin_layout Itemize
+
+\series bold
+std_c99
+\series default
+
+\begin_inset LatexCommand \index{\#pragma std\_c99}
+
+\end_inset
+
+- Follow the C99 standard and disable SDCC features that conflict with the
+ standard (incomplete support).
+\end_layout
+
+\begin_layout Itemize
+
+\series bold
+codeseg
+\series default
+ <name>
+\begin_inset LatexCommand \index{\#pragma codeseg}
+
+\end_inset
+
+- Use this name (max.
+ 8 characters) for the code segment.
+ See option -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-codeseg.
+\end_layout
+
+\begin_layout Itemize
+
+\series bold
+constseg
+\series default
+ <name>
+\begin_inset LatexCommand \index{\#pragma constseg}
+
+\end_inset
+
+- Use this name (max.
+ 8 characters) for the const segment.
+ See option -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-constseg.
+\end_layout
+
+\begin_layout Standard
+The preprocessor SDCPP
+\begin_inset LatexCommand \index{sdcpp (preprocessor)}
+
+\end_inset
+
+ supports the following #pragma directives:
+\end_layout
+
+\begin_layout Itemize
+
+\series bold
+pedantic_parse_number
+\series default
+
+\begin_inset LatexCommand \index{pedantic}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\#pragma pedantic\_parse\_number}
+
+\end_inset
+
+ (+ | -)
+\begin_inset LatexCommand \label{ite:pedantic_parse_number}
+
+\end_inset
+
+- Pedantic parse numbers so that situations like 0xfe-LO_B(3) are parsed
+ properly and the macro LO_B(3) gets expanded.
+ Default is off.
+ See also the -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-pedantic-parse-number command line option
+\begin_inset LatexCommand \vpageref{lyx:-pedantic-parse-number}
+
+\end_inset
+
+.
+
+\newline
+Below is an example on how to use this pragma.
+
+\emph on
+ Note: this functionality is not in conformance with standard!
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+#pragma pedantic_parse_number +
+\begin_inset LatexCommand \index{\#pragma pedantic\_parse\_number}
+
+\end_inset
+
+
+\newline
+
+\newline
+#define LO_B(x) ((x) & 0xff)
+\newline
+
+\newline
+unsigned char foo(void)
+\newline
+{
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+unsigned char c=0xfe-LO_B(3)
+;
+\newline
+
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+return c;
+\newline
+}
+\newline
+
+\end_layout
+
+\begin_layout Itemize
+
+\series bold
+preproc_asm
+\series default
+
+\begin_inset LatexCommand \index{\#pragma preproc\_asm}
+
+\end_inset
+
+ (+ | -) - switch _asm _endasm block preprocessing on / off.
+ Default is on.
+ You use this prama to define multilines of assembly code.
+ This will prevent the preprocessor from changing the formating required
+ by assembly code.
+ Below is an example on how to use this pragma.
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+#pragma preproc_asm -
+\begin_inset LatexCommand \index{\#pragma preproc\_asm}
+
+\end_inset
+
+
+\newline
+#define MYDELAY _asm
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+nop ;my assembly comment...
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+nop
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+nop
+\newline
+_endasm
+\newline
+#pragma preproc_asm
+ +
+\newline
+
+\newline
+void foo (void)
+\newline
+{
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+ ...
+
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+ MYDELAY;
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+ ...
+
+\newline
+}
+\newline
+
+\end_layout
+
+\begin_layout Itemize
+
+\series bold
+sdcc_hash
+\series default
+
+\begin_inset LatexCommand \index{\#pragma sdcc\_hash}
+
+\end_inset
+
+ (+ | -) - Allow "naked" hash in macro definition, for example:
+\newline
+
+\family typewriter
+#define DIR_LO(x) #(x & 0xff)
+\family default
+
+\newline
+Default is off.
+ Below is an example on how to use this pragma.
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+#pragma preproc_asm +
+\newline
+#pragma sdcc_hash +
+\begin_inset LatexCommand \index{\#pragma sdcc\_hash}
+
+\end_inset
+
+
+\newline
+
+\newline
+#define ROMCALL(x)
+\backslash
+
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov R6_B3, #(x & 0xff)
+\backslash
+
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mov R7_B3, #((x >> 8) & 0xff)
+\backslash
+
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+lcall __romcall
+\newline
+
+\newline
+...
+\newline
+_asm
+\newline
+ROMCALL(72)
+\newline
+_endasm;
+\newline
+...
+\newline
+
+\end_layout
+
+\begin_layout Standard
+Some of the pragmas are intended to be used to turn-on or off certain optimizati
+ons which might cause the compiler to generate extra stack and/or data space
+ to store compiler generated temporary variables.
+ This usually happens in large functions.
+ Pragma directives should be used as shown in the following example, they
+ are used to control options and optimizations for a given function.
+
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+#pragma save
+\begin_inset LatexCommand \index{\#pragma save}
+
+\end_inset
+
+ \InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+/* save the current settings */
+\newline
+#pragma nogcse
+\begin_inset LatexCommand \index{\#pragma nogcse}
+
+\end_inset
+
+ \InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+/* turnoff global subexpression elimination */
+\newline
+#pragma noinduction
+\begin_inset LatexCommand \index{\#pragma noinduction}
+
+\end_inset
+
+ /* turn off induction optimizations */
+\newline
+int foo ()
+\newline
+{
+\newline
+\InsetSpace ~
+ \InsetSpace ~
+ ...
+
+\newline
+\InsetSpace ~
+ \InsetSpace ~
+ /* large code */
+\newline
+\InsetSpace ~
+ \InsetSpace ~
+ ...
+
+\newline
+}
+\newline
+#pragma restore
+\begin_inset LatexCommand \index{\#pragma restore}
+
+\end_inset
+
+ /* turn the optimizations back on */
+\end_layout
+
+\begin_layout Standard
+The compiler will generate a warning message when extra space is allocated.
+ It is strongly recommended that the save and restore pragma's be used when
+ changing options for a function.
+\newline
+
+\newline
+
+\newline
+
+\end_layout
+
+\begin_layout Section
+Defines Created by the Compiler
+\end_layout
+
+\begin_layout Standard
+The compiler creates the following #defines
+\begin_inset LatexCommand \index{\#defines}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{Defines created by the compiler}
+
+\end_inset
+
+:
+\newline
+
+\end_layout
+
+\begin_layout Standard
+\begin_inset Tabular
+<lyxtabular version="3" rows="11" columns="2">
+<features>
+<column alignment="left" valignment="top" leftline="true" width="3in">
+<column alignment="left" valignment="top" leftline="true" rightline="true" width="3in">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\series bold
+#define
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\series bold
+Description
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+SDCC
+\begin_inset LatexCommand \index{SDCC}
+
+\end_inset
+
+
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Always defined.
+ Since version 2.5.6 the version number as an int (ex.
+ 256)
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+SDCC_mcs51
+\begin_inset LatexCommand \index{SDCC\_mcs51}
+
+\end_inset
+
+ or SDCC_ds390
+\begin_inset LatexCommand \index{SDCC\_ds390}
+
+\end_inset
+
+ or SDCC_z80
+\begin_inset LatexCommand \index{SDCC\_z80}
+
+\end_inset
+
+, etc.
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+depending on the model used (e.g.: -mds390)
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+__mcs51
+\begin_inset LatexCommand \index{\_\_mcs51}
+
+\end_inset
+
+, __ds390
+\begin_inset LatexCommand \index{\_\_ds390}
+
+\end_inset
+
+, __hc08
+\begin_inset LatexCommand \index{\_\_hc08}
+
+\end_inset
+
+, __z80
+\begin_inset LatexCommand \index{\_\_z80}
+
+\end_inset
+
+, etc
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+depending on the model used (e.g.
+ -mz80)
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+SDCC_STACK_AUTO
+\begin_inset LatexCommand \index{SDCC\_STACK\_AUTO}
+
+\end_inset
+
+
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+when
+\emph on
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-stack-auto
+\emph default
+ option is used
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+SDCC_MODEL_SMALL
+\begin_inset LatexCommand \index{SDCC\_MODEL\_SMALL}
+
+\end_inset
+
+
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+when
+\emph on
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-model-small
+\emph default
+ is used
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+SDCC_MODEL_MEDIUM
+\begin_inset LatexCommand \index{SDCC\_MODEL\_MEDIUM}
+
+\end_inset
+
+
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+when
+\emph on
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-model-medium
+\emph default
+ is used
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+SDCC_MODEL_LARGE
+\begin_inset LatexCommand \index{SDCC\_MODEL\_LARGE}
+
+\end_inset
+
+
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+when
+\emph on
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-model-large
+\emph default
+ is used
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+SDCC_USE_XSTACK
+\begin_inset LatexCommand \index{SDCC\_USE\_XSTACK}
+
+\end_inset
+
+
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+when
+\emph on
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-xstack
+\emph default
+ option is used
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+SDCC_STACK_TENBIT
+\begin_inset LatexCommand \index{SDCC\_STACK\_TENBIT}
+
+\end_inset
+
+
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+when
+\emph on
+-mds390
+\emph default
+ is used
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+SDCC_MODEL_FLAT24
+\begin_inset LatexCommand \index{SDCC\_MODEL\_FLAT24}
+
+\end_inset
+
+
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+when
+\emph on
+-mds390
+\emph default
+ is used
+\end_layout
+
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Chapter
+Notes on supported Processors
+\end_layout
+
+\begin_layout Section
+MCS51 variants
+\begin_inset LatexCommand \label{sub:MCS51-variants}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{MCS51 variants}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+MCS51 processors are available from many vendors and come in many different
+ flavours.
+ While they might differ considerably in respect to Special Function Registers
+ the core MCS51 is usually not modified or is kept compatible.
+
+\end_layout
+
+\begin_layout Subsection
+pdata access by SFR
+\end_layout
+
+\begin_layout Standard
+With the upcome of devices with internal xdata and flash memory devices
+ using port P2
+\begin_inset LatexCommand \index{P2 (mcs51 sfr)}
+
+\end_inset
+
+ as dedicated I/O port is becoming more popular.
+ Switching the high byte for pdata
+\begin_inset LatexCommand \index{pdata (mcs51, ds390 storage class)}
+
+\end_inset
+
+ access which was formerly done by port P2 is then achieved by a Special
+ Function Register
+\begin_inset LatexCommand \index{sfr}
+
+\end_inset
+
+.
+ In well-established MCS51 tradition the address of this
+\emph on
+sfr
+\emph default
+ is where the chip designers decided to put it.
+ Needless to say that they didn't agree on a common name either.
+ So that the startup code can correctly initialize xdata variables, you
+ should define an sfr with the name _XPAGE
+\family typewriter
+
+\begin_inset LatexCommand \index{\_XPAGE (mcs51)}
+
+\end_inset
+
+
+\family default
+ at the appropriate location if the default, port P2, is not used for this.
+ Some examples are:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+__sfr __at (0x85) _XPAGE; /* Ramtron VRS51 family a.k.a.
+ MPAGE */
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+__sfr __at (0x92) _XPAGE; /* Cypress EZ-USB family, Texas Instruments (Chipcon)
+ a.k.a.
+ MPAGE */
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+__sfr __at (0x91) _XPAGE; /* Infineon (Siemens) C500 family a.k.a.
+ XPAGE */
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+__sfr __at (0xaf) _XPAGE; /* some Silicon Labs (Cygnal) chips a.k.a.
+ EMI0CN */
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+__sfr __at (0xaa) _XPAGE; /* some Silicon Labs (Cygnal) chips a.k.a.
+ EMI0CN */
+\end_layout
+
+\begin_layout Standard
+For more exotic implementations further customizations may be needed.
+ See section
+\begin_inset LatexCommand \ref{sub:Startup-Code}
+
+\end_inset
+
+ for other possibilities.
+\end_layout
+
+\begin_layout Subsection
+Other Features available by SFR
+\end_layout
+
+\begin_layout Standard
+Some MCS51 variants offer features like Double DPTR
+\begin_inset LatexCommand \index{DPTR}
+
+\end_inset
+
+, multiple DPTR, decrementing DPTR, 16x16 Multiply.
+ These are currently not used for the MCS51 port.
+ If you absolutely need them you can fall back to inline assembly or submit
+ a patch to SDCC.
+\begin_inset VSpace bigskip
+\end_inset
+
+
+\end_layout
+
+\begin_layout Section
+DS400 port
+\end_layout
+
+\begin_layout Standard
+The DS80C400
+\begin_inset LatexCommand \index{DS80C400}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{DS400}
+
+\end_inset
+
+ microcontroller has a rich set of peripherals.
+ In its built-in ROM library it includes functions to access some of the
+ features, among them is a TCP stack with IP4 and IP6 support.
+ Library headers (currently in beta status) and other files are provided
+ at
+\size footnotesize
+
+\begin_inset LatexCommand \url{ftp://ftp.dalsemi.com/pub/tini/ds80c400/c_libraries/sdcc/index.html}
+
+\end_inset
+
+.
+
+\begin_inset VSpace bigskip
+\end_inset
+
+
+\end_layout
+
+\begin_layout Section
+The Z80 and gbz80 port
+\end_layout
+
+\begin_layout Standard
+SDCC can target both the Zilog Z80
+\begin_inset LatexCommand \index{Z80}
+
+\end_inset
+
+ and the Nintendo Gameboy's Z80-like gbz80
+\begin_inset LatexCommand \index{gbz80 (GameBoy Z80)}
+
+\end_inset
+
+.
+ The Z80 port is passed through the same
+\emph on
+regressions tests
+\begin_inset LatexCommand \index{Regression test}
+
+\end_inset
+
+
+\emph default
+ (see section
+\begin_inset LatexCommand \ref{sec:Quality-control}
+
+\end_inset
+
+) as the MCS51 and DS390 ports, so floating point support, support for long
+ variables and bitfield support is fine.
+ See mailing lists and forums about interrupt routines.
+\end_layout
+
+\begin_layout Standard
+As always, the code is the authoritative reference - see z80/ralloc.c and
+ z80/gen.c.
+ The stack
+\begin_inset LatexCommand \index{Z80!stack}
+
+\end_inset
+
+ frame is similar to that generated by the IAR Z80 compiler.
+ IX is used as the base pointer, HL and IY are used as a temporary registers,
+ and BC and DE are available for holding variables.
+ Return values
+\begin_inset LatexCommand \index{Z80!return value}
+
+\end_inset
+
+ for the Z80 port are stored in L (one byte), HL (two bytes), or DEHL (four
+ bytes).
+ The gbz80 port use the same set of registers for the return values, but
+ in a different order of significance: E (one byte), DE (two bytes), or
+ HLDE (four bytes).
+\begin_inset VSpace bigskip
+\end_inset
+
+
+\end_layout
+
+\begin_layout Section
+The HC08 port
+\end_layout
+
+\begin_layout Standard
+The port to the Freescale/Motorola HC08
+\begin_inset LatexCommand \index{HC08}
+
+\end_inset
+
+ family has been added in October 2003, and is still undergoing some basic
+ development.
+ The code generator is complete, but the register allocation is still quite
+ unoptimized.
+ Some of the SDCC's standard C library functions have embedded non-HC08
+ inline assembly and so are not yet usable.
+\end_layout
+
+\begin_layout Standard
+The HC08 port passes the regression test suite (see section
+\begin_inset LatexCommand \ref{sec:Quality-control}
+
+\end_inset
+
+).
+\begin_inset VSpace bigskip
+\end_inset
+
+
+\newpage
+
+\end_layout
+
+\begin_layout Section
+The PIC14 port
+\end_layout
+
+\begin_layout Standard
+The PIC14 port adds support for Microchip(TM)'s 14
+\begin_inset ERT
+status open
+
+\begin_layout Standard
+
+
+\backslash
+,
+\end_layout
+
+\end_inset
+
+bit PIC
+\begin_inset LatexCommand \index{PIC14}
+
+\end_inset
+
+ MCUs.
+ This port is not yet mature and still lacks many features.
+ However, it can work for simple code.
+\end_layout
+
+\begin_layout Standard
+Currently supported devices include:
+\end_layout
+
+\begin_layout Standard
+12F: 629, 635, 675, 683
+\end_layout
+
+\begin_layout Standard
+16C: 432, 433
+\end_layout
+
+\begin_layout Standard
+16C: 554, 557, 558
+\end_layout
+
+\begin_layout Standard
+16C: 62, 620, 620a, 621, 621a, 622, 622a, 63a, 65b
+\end_layout
+
+\begin_layout Standard
+16C: 71, 710, 711, 715, 717, 72, 73b, 745, 74b, 765, 770, 771, 773, 774,
+ 781, 782
+\end_layout
+
+\begin_layout Standard
+16C: 925, 926
+\end_layout
+
+\begin_layout Standard
+16F: 627, 627a, 628, 628a, 630, 636, 639, 648a, 676, 684, 685, 687, 688,
+ 689, 690
+\end_layout
+
+\begin_layout Standard
+16F: 716, 72, 73, 737, 74, 76, 767, 77, 777, 785
+\end_layout
+
+\begin_layout Standard
+16F: 818, 819, 84, 84a, 87, 870, 871, 872, 873, 873a, 874, 874a, 876, 876a,
+ 877, 877a, 88
+\end_layout
+
+\begin_layout Standard
+16F: 913, 914, 916, 917
+\end_layout
+
+\begin_layout Standard
+An up-to-date list of currently supported devices can be obtained via
+\family typewriter
+sdcc -mpic14 -phelp foo.c
+\family default
+ (foo.c must exist...).
+\end_layout
+
+\begin_layout Subsection
+PIC Code Pages
+\begin_inset LatexCommand \index{code page (pic14)}
+
+\end_inset
+
+ and Memory Banks
+\begin_inset LatexCommand \index{Memory bank (pic14)}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+The linker organizes allocation for the code page and RAM banks.
+ It does not have intimate knowledge of the code flow.
+ It will put all the code section of a single .asm file into a single code
+ page.
+ In order to make use of multiple code pages, separate asm files must be
+ used.
+ The compiler assigns all
+\emph on
+static
+\emph default
+ functions of a single .c file into the same code page.
+\newline
+
+\newline
+To get the best results,
+ follow these guidelines:
+\end_layout
+
+\begin_layout Enumerate
+Make local functions static, as non static functions require code page selection
+ overhead.
+\newline
+Due to the way sdcc handles functions, place called functions prior
+ to calling functions in the file wherever possible: Otherwise sdcc will
+ insert unneccessary pagesel directives around the call, believing that
+ the called function is externally defined.
+\end_layout
+
+\begin_layout Enumerate
+For devices that have multiple code pages it is more efficient to use the
+ same number of files as pages: Use up to 4 separate .c files for the 16F877,
+ but only 2 files for the 16F874.
+ This way the linker can put the code for each file into different code
+ pages and there will be less page selection overhead.
+\end_layout
+
+\begin_layout Enumerate
+And as for any 8 bit micro (especially for PIC14 as they have a very simple
+ instruction set), use 'unsigned char' wherever possible instead of 'int'.
+\end_layout
+
+\begin_layout Subsection
+Adding New Devices to the Port
+\end_layout
+
+\begin_layout Standard
+Adding support for a new 14
+\begin_inset ERT
+status open
+
+\begin_layout Standard
+
+
+\backslash
+,
+\end_layout
+
+\end_inset
+
+bit PIC MCU requires the following steps:
+\end_layout
+
+\begin_layout Enumerate
+Create a new device description.
+\newline
+Each device is described in two files: pic16f*.h
+ and pic16f*.c.
+ These files primarily define SFRs, structs to access their bits, and symbolic
+ configuration options.
+ Both files can be generated from gputils' .inc files using the perl script
+
+\family typewriter
+support/scripts/inc2h.pl
+\family default
+.
+ This file also contains further instructions on how to proceed.
+\end_layout
+
+\begin_layout Enumerate
+Copy the .h file into SDCC's include path and either add the .c file to your
+ project or copy it to
+\family typewriter
+device/lib/pic/libdev
+\family default
+.
+ Afterwards, rebuild and install the libraries.
+\end_layout
+
+\begin_layout Enumerate
+Edit pic14devices.txt in SDCC's include path (
+\family typewriter
+device/include/pic/
+\family default
+ in the source tree or
+\family typewriter
+/usr/local/share/sdcc/include/pic
+\family default
+ after installation).
+\newline
+You need to add a device specification here to make
+ the memory layout (code banks, RAM, aliased memory regions, ...) known to
+ the compiler.
+ Probably you can copy and modify an existing entry.
+ The file format is documented at the top of the file.
+\end_layout
+
+\begin_layout Subsection
+Interrupt Code
+\end_layout
+
+\begin_layout Standard
+For the interrupt function, use the keyword '__interrupt'
+\begin_inset LatexCommand \index{PIC14!interrupt}
+
+\end_inset
+
+ with level number of 0 (PIC14 only has 1 interrupt so this number is only
+ there to avoid a syntax error - it ought to be fixed).
+ E.g.:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+void Intr(void) __interrupt 0
+\newline
+{
+\newline
+\InsetSpace ~
+\InsetSpace ~
+T0IF = 0; /* Clear timer interrupt */
+\newline
+}
+\end_layout
+
+\begin_layout Subsection
+Linking and Assembling
+\end_layout
+
+\begin_layout Standard
+For assembling you can use either GPUTILS'
+\begin_inset LatexCommand \index{gputils (pic tools)}
+
+\end_inset
+
+ gpasm.exe or MPLAB's mpasmwin.exe.
+ GPUTILS are available from
+\begin_inset LatexCommand \url{http://sourceforge.net/projects/gputils}
+
+\end_inset
+
+.
+ For linking you can use either GPUTILS' gplink or MPLAB's mplink.exe.
+ If you use MPLAB and an interrupt function then the linker script file
+ vectors section will need to be enlarged to link with mplink.
+\newline
+
+\newline
+Here is a
+\family typewriter
+Makefile
+\family default
+ using GPUTILS:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+.c.o:
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+sdcc -V -mpic14 -p16f877 -c $<
+\newline
+
+\newline
+$(PRJ).hex: $(OBJS)
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+gplink -m -s $(PRJ).lkr
+ -o $(PRJ).hex $(OBJS) libsdcc.lib
+\end_layout
+
+\begin_layout Standard
+Here is a
+\family typewriter
+Makefile
+\family default
+ using MPLAB:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+.c.o:
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+sdcc -S -V -mpic14 -p16f877 $<
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mpasmwin /q /o $*.asm
+\newline
+
+\newline
+$(PRJ).hex: $(OBJS)
+
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+mplink /v $(PRJ).lkr /m $(PRJ).map /o $(PRJ).hex $(OBJS) libsdcc.lib
+\end_layout
+
+\begin_layout Standard
+Please note that indentations within a
+\family typewriter
+ Makefile
+\family default
+ have to be done with a tabulator character.
+\end_layout
+
+\begin_layout Subsection
+Command-Line Options
+\end_layout
+
+\begin_layout Standard
+Besides the switches common to all SDCC backends, the PIC14 port accepts
+ the following options (for an updated list see sdcc -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-help):
+\end_layout
+
+\begin_layout Description
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-debug-xtra
+\begin_inset LatexCommand \index{PIC14!Options!-\/-debug-extra}
+
+\end_inset
+
+ emit debug info in assembly output
+\end_layout
+
+\begin_layout Description
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-no-pcode-opt
+\begin_inset LatexCommand \index{PIC14!Options!-\/-no-pcode-opt}
+
+\end_inset
+
+ disable (slightly faulty) optimization on pCode
+\end_layout
+
+\begin_layout Description
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-stack-loc
+\begin_inset LatexCommand \index{PIC14!Options!-\/-stack-loc}
+
+\end_inset
+
+ sets the lowest address of the argument passing stack (defaults to a suitably
+ large shared databank to reduce BANKSEL overhead)
+\end_layout
+
+\begin_layout Description
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-stack-size
+\begin_inset LatexCommand \index{PIC14!Options!-\/-stack-size}
+
+\end_inset
+
+ sets the size if the argument passing stack (default: 16, minimum: 4)
+\end_layout
+
+\begin_layout Subsection
+Environment Variables
+\end_layout
+
+\begin_layout Standard
+The PIC14 port recognizes the following environment variables:
+\end_layout
+
+\begin_layout Description
+SDCC_PIC14_SPLIT_LOCALS If set and not empty, sdcc will allocate each temporary
+ register (the ones called r0xNNNN) in a section of its own.
+ By default (if this variable is unset), sdcc tries to cluster registers
+ in sections in order to reduce the BANKSEL overhead when accessing them.
+\end_layout
+
+\begin_layout Subsection
+The Library
+\end_layout
+
+\begin_layout Standard
+The PIC14 library currently only contains support routines required by the
+ compiler to implement multiplication, division, and floating point support.
+ No libc-like replacement is available at the moment, though many of the
+ common sdcc library sources (in
+\family typewriter
+device/lib
+\family default
+) should also compile with the PIC14 port.
+\end_layout
+
+\begin_layout Subsubsection
+error: missing definition for symbol
+\begin_inset Quotes sld
+\end_inset
+
+__gptrget1
+\begin_inset Quotes srd
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+The PIC14 port uses library routines to provide more complex operations
+ like multiplication, division/modulus and (generic) pointer dereferencing.
+ In order to add these routines to your project, you must link with PIC14's
+
+\family typewriter
+libsdcc.lib
+\family default
+.
+ For single source file projects this is done automatically, more complex
+ projects must add
+\family typewriter
+libsdcc.lib
+\family default
+ to the linker's arguments.
+ Make sure you also add an include path for the library (using the -I switch
+ to the linker)!
+\end_layout
+
+\begin_layout Subsubsection
+Processor mismatch in file
+\begin_inset Quotes sld
+\end_inset
+
+XXX
+\begin_inset Quotes srd
+\end_inset
+
+.
+\end_layout
+
+\begin_layout Standard
+This warning can usually be ignored due to the very good compatibility amongst
+ 14
+\begin_inset ERT
+status open
+
+\begin_layout Standard
+
+
+\backslash
+,
+\end_layout
+
+\end_inset
+
+bit PIC
+\begin_inset LatexCommand \index{PIC14}
+
+\end_inset
+
+ devices.
+\end_layout
+
+\begin_layout Standard
+You might also consider recompiling the library for your specific device
+ by changing the ARCH=p16f877 (default target) entry in
+\family typewriter
+device/lib/pic/Makefile.in
+\family default
+ and
+\family typewriter
+device/lib/pic/Makefile
+\family default
+ to reflect your device.
+ This might even improve performance for smaller devices as unneccesary
+ BANKSELs might be removed.
+\end_layout
+
+\begin_layout Subsection
+Known Bugs
+\end_layout
+
+\begin_layout Subsubsection
+Function arguments
+\end_layout
+
+\begin_layout Standard
+Functions with variable argument lists (like printf) are not yet supported.
+ Similarly, taking the argument of the first argument passed into a function
+ does not work: It is currently passed in WREG and has no address...
+\end_layout
+
+\begin_layout Subsubsection
+Regression tests fail
+\end_layout
+
+\begin_layout Standard
+Though the small subset of regression tests in src/regression passes, SDCC
+ regression test suite does not, indicating that there are still major bugs
+ in the port.
+ However, many smaller projects have successfully used SDCC in the past...
+\end_layout
+
+\begin_layout Standard
+
+\size footnotesize
+
+\newpage
+
+\end_layout
+
+\begin_layout Section
+The PIC16
+\begin_inset LatexCommand \index{PIC16}
+
+\end_inset
+
+ port
+\end_layout
+
+\begin_layout Standard
+The PIC16
+\begin_inset LatexCommand \index{PIC16}
+
+\end_inset
+
+ port is the portion of SDCC that is responsible to produce code for the
+ Microchip
+\begin_inset LatexCommand \index{Microchip}
+
+\end_inset
+
+(TM) microcontrollers with 16 bit core.
+ Currently this family of microcontrollers contains the PIC18Fxxx and PIC18Fxxxx.
+ Currently supported devices are:
+\end_layout
+
+\begin_layout Standard
+18F: 242, 248, 252, 258, 442, 448, 452, 458
+\end_layout
+
+\begin_layout Standard
+18F: 1220, 1320
+\end_layout
+
+\begin_layout Standard
+18F: 2220, 2221, 2320, 2321, 2331, 2431, 2455, 2525, 2550, 2620
+\end_layout
+
+\begin_layout Standard
+18F: 4220, 4221, 4320, 4321, 4331, 4431, 4455, 4520, 4525, 4550, 4620
+\end_layout
+
+\begin_layout Standard
+18F: 6520, 6620, 6680, 6720
+\end_layout
+
+\begin_layout Standard
+18F: 8520, 8620, 8680, 8720
+\end_layout
+
+\begin_layout Subsection
+Global Options
+\end_layout
+
+\begin_layout Standard
+PIC16 port supports the standard command line arguments as supposed, with
+ the exception of certain cases that will be mentioned in the following
+ list:
+\end_layout
+
+\begin_layout Description
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-callee-saves
+\begin_inset LatexCommand \index{PIC16!Options!-\/-callee-saves}
+
+\end_inset
+
+ See -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-all-callee-saves
+\end_layout
+
+\begin_layout Description
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-fommit-frame-pointer
+\begin_inset LatexCommand \index{PIC16!Options!-\/-fommit-frame-pointer}
+
+\end_inset
+
+ Frame pointer will be omitted when the function uses no local variables.
+\end_layout
+
+\begin_layout Subsection
+Port Specific Options
+\begin_inset LatexCommand \index{Options PIC16}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+The port specific options appear after the global options in the sdcc -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-help output.
+\end_layout
+
+\begin_layout Subsubsection
+Code Generation Options
+\end_layout
+
+\begin_layout Standard
+These options influence the generated assembler code.
+\end_layout
+
+\begin_layout Description
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-pstack-model=[model] Used in conjuction with the command above.
+ Defines the stack model to be used, valid stack models are:
+\end_layout
+
+\begin_deeper
+\begin_layout List
+\labelwidthstring 00.00.0000
+
+\emph on
+small
+\emph default
+ Selects small stack model.
+ 8 bit stack and frame pointers.
+ Supports 256 bytes stack size.
+\end_layout
+
+\begin_layout List
+\labelwidthstring 00.00.0000
+
+\emph on
+large
+\emph default
+ Selects large stack model.
+ 16 bit stack and frame pointers.
+ Supports 65536 bytes stack size.
+\end_layout
+
+\end_deeper
+\begin_layout Description
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-pno-banksel Do not generate BANKSEL assembler directives.
+\end_layout
+
+\begin_layout Description
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-extended Enable extended instruction set/literal offset addressing mode.
+ Use with care!
+\end_layout
+
+\begin_layout Subsubsection
+Optimization Options
+\end_layout
+
+\begin_layout Description
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-obanksel=n Set optimization level for inserting BANKSELs.
+\newline
+
+\end_layout
+
+\begin_deeper
+\begin_layout List
+\labelwidthstring 00.00.0000
+0 no optimization
+\end_layout
+
+\begin_layout List
+\labelwidthstring 00.00.0000
+1 checks previous used register and if it is the same then does not emit
+ BANKSEL, accounts only for labels.
+\end_layout
+
+\begin_layout List
+\labelwidthstring 00.00.0000
+2 tries to check the location of (even different) symbols and removes BANKSELs
+ if they are in the same bank.
+
+\newline
+
+\emph on
+Important: There might be problems if the linker script has data sections
+ across bank borders!
+\end_layout
+
+\end_deeper
+\begin_layout Description
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-denable-peeps Force the usage of peepholes.
+ Use with care.
+\end_layout
+
+\begin_layout Description
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-optimize-goto Try to use (conditional) BRA instead of GOTO.
+\end_layout
+
+\begin_layout Description
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-optimize-cmp Try to optimize some compares.
+\end_layout
+
+\begin_layout Description
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-optimize-df Analyze the dataflow of the generated code and improve it.
+\end_layout
+
+\begin_layout Subsubsection
+Assembling Options
+\end_layout
+
+\begin_layout Description
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-asm= Sets the full path and name of an external assembler to call.
+\end_layout
+
+\begin_layout Description
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-mplab-comp MPLAB
+\begin_inset LatexCommand \index{PIC16!MPLAB}
+
+\end_inset
+
+ compatibility option.
+ Currently only suppresses special gpasm directives.
+\end_layout
+
+\begin_layout Subsubsection
+Linking Options
+\end_layout
+
+\begin_layout Description
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-link= Sets the full path and name of an external linker to call.
+\end_layout
+
+\begin_layout Description
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-preplace-udata-with=[kword] Replaces the default udata keyword for allocating
+ unitialized data variables with [kword].
+ Valid keywords are: "udata_acs", "udata_shr", "udata_ovr".
+\end_layout
+
+\begin_layout Description
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-ivt-loc=n Place the interrupt vector table at address
+\emph on
+n
+\emph default
+.
+ Useful for bootloaders.
+\end_layout
+
+\begin_layout Description
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-nodefaultlibs Do not link default libraries when linking.
+\end_layout
+
+\begin_layout Description
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-use-crt= Use a custom run-time module instead of the defaults.
+\end_layout
+
+\begin_layout Description
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-no-crt Don't link the default run-time modules
+\end_layout
+
+\begin_layout Subsubsection
+Debugging Options
+\end_layout
+
+\begin_layout Standard
+Debugging options enable extra debugging information in the output files.
+\end_layout
+
+\begin_layout Description
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-debug-xtra Similar to -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-debug
+\begin_inset LatexCommand \index{-\/-debug}
+
+\end_inset
+
+, but dumps more information.
+\end_layout
+
+\begin_layout Description
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-debug-ralloc Force register allocator to dump <source>.d file with debugging
+ information.
+ <source> is the name of the file being compiled.
+\end_layout
+
+\begin_layout Description
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-pcode-verbose Enable pcode debugging information in translation.
+\end_layout
+
+\begin_layout Description
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-calltree Dump call tree in .calltree file.
+\end_layout
+
+\begin_layout Description
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-gstack Trace push/pops for stack pointer overflow.
+\end_layout
+
+\begin_layout Subsection
+Enviroment Variables
+\end_layout
+
+\begin_layout Standard
+There is a number of enviromental variables that can be used when running
+ SDCC to enable certain optimizations or force a specific program behaviour.
+ these variables are primarily for debugging purposes so they can be enabled/dis
+abled at will.
+\end_layout
+
+\begin_layout Standard
+Currently there is only two such variables available:
+\end_layout
+
+\begin_layout Description
+OPTIMIZE_BITFIELD_POINTER_GET When this variable exists, reading of structure
+ bitfields is optimized by directly loading FSR0 with the address of the
+ bitfield structure.
+ Normally SDCC will cast the bitfield structure to a bitfield pointer and
+ then load FSR0.
+ This step saves data ram and code space for functions that make heavy use
+ of bitfields.
+ (i.e., 80 bytes of code space are saved when compiling malloc.c with this
+ option).
+
+\end_layout
+
+\begin_layout Description
+NO_REG_OPT Do not perform pCode registers optimization.
+ This should be used for debugging purposes.
+ If bugs in the pcode optimizer are found, users can benefit from temporarily
+ disabling the optimizer until the bug is fixed.
+\end_layout
+
+\begin_layout Subsection
+Preprocessor Macros
+\end_layout
+
+\begin_layout Standard
+PIC16
+\begin_inset LatexCommand \index{PIC16}
+
+\end_inset
+
+ port defines the following preprocessor macros while translating a source.
+\end_layout
+
+\begin_layout Standard
+\align center
+\begin_inset Tabular
+<lyxtabular version="3" rows="6" columns="2">
+<features>
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Macro
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Description
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+SDCC_pic16
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Port identification
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+_
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+_pic16
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Port identification (same as above)
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+pic18fxxxx
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+MCU Identification.
+
+\emph on
+xxxx
+\emph default
+ is the microcontrol identification number, i.e.
+ 452, 6620, etc
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+_
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+_18Fxxxx
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+MCU Identification (same as above)
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+STACK_MODEL_nnn
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+nnn = SMALL or LARGE respectively according to the stack model used
+\end_layout
+
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+In addition the following macros are defined when calling assembler:
+\end_layout
+
+\begin_layout Standard
+\align center
+\begin_inset Tabular
+<lyxtabular version="3" rows="4" columns="2">
+<features>
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Macro
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Description
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+__18Fxxxx
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+MCU Identification.
+
+\emph on
+xxxx
+\emph default
+ is the microcontrol identification number, i.e.
+ 452, 6620, etc
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+SDCC_MODEL_nnn
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+nnn = SMALL or LARGE respectively according to the memory model used for
+ SDCC
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+STACK_MODEL_nnn
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+nnn = SMALL or LARGE respectively according to the stack model used
+\end_layout
+
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Subsection
+Directories
+\end_layout
+
+\begin_layout Standard
+PIC16
+\begin_inset LatexCommand \index{PIC16}
+
+\end_inset
+
+ port uses the following directories for searching header files and libraries.
+\end_layout
+
+\begin_layout Standard
+\align center
+\begin_inset Tabular
+<lyxtabular version="3" rows="3" columns="4">
+<features>
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<column alignment="center" valignment="top" width="0">
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Directory
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Description
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Target
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Command prefix
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+PREFIX/sdcc/include/pic16
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+PIC16 specific headers
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Compiler
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+-I
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+PREFIX/sdcc/lib/pic16
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+PIC16 specific libraries
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Linker
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+-L
+\end_layout
+
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Subsection
+Pragmas
+\begin_inset LatexCommand \label{sub:PIC16_Pragmas}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+The PIC16
+\begin_inset LatexCommand \index{PIC16}
+
+\end_inset
+
+ port currently supports the following pragmas:
+\end_layout
+
+\begin_layout Description
+stack
+\begin_inset LatexCommand \index{PIC16!Pragmas!\#pragma stack}
+
+\end_inset
+
+ This forces the code generator to initialize the stack & frame pointers
+ at a specific address.
+ This is an ad hoc solution for cases where no STACK directive is available
+ in the linker script or gplink is not instructed to create a stack section.
+\newline
+The
+ stack pragma should be used only once in a project.
+ Multiple pragmas may result in indeterminate behaviour of the program.
+\begin_inset Foot
+status open
+
+\begin_layout Standard
+The old format (ie.
+ #pragma stack 0x5ff) is deprecated and will cause the stack pointer to
+ cross page boundaries (or even exceed the available data RAM) and crash
+ the program.
+ Make sure that stack does not cross page boundaries when using the SMALL
+ stack model.
+\end_layout
+
+\end_inset
+
+
+\newline
+The format is as follows:
+\newline
+
+\end_layout
+
+\begin_layout LyX-Code
+#pragma stack bottom_address [stack_size]
+\newline
+
+\end_layout
+
+\begin_layout Standard
+
+\emph on
+bottom_address
+\emph default
+ is the lower bound of the stack section.
+ The stack pointer initially will point at address (bottom_address+stack_size-1).
+\end_layout
+
+\begin_layout LyX-Code
+Example:
+\end_layout
+
+\begin_layout LyX-Code
+
+\end_layout
+
+\begin_layout LyX-Code
+/* initializes stack of 100 bytes at RAM address 0x200 */
+\end_layout
+
+\begin_layout LyX-Code
+#pragma stack 0x200 100
+\end_layout
+
+\begin_layout Standard
+If the stack_size field is omitted then a stack is created with the default
+ size of 64.
+ This size might be enough for most programs, but its not enough for operations
+ with deep function nesting or excessive stack usage.
+\end_layout
+
+\begin_layout Description
+code
+\begin_inset LatexCommand \index{PIC16!Pragmas!\#pragma code}
+
+\end_inset
+
+ Force a function to a static FLASH address.
+\end_layout
+
+\begin_layout LyX-Code
+Example:
+\end_layout
+
+\begin_layout LyX-Code
+
+\end_layout
+
+\begin_layout LyX-Code
+/* place function test_func at 0x4000 */
+\end_layout
+
+\begin_layout LyX-Code
+#pragma code test_func 0x4000
+\end_layout
+
+\begin_layout LyX-Code
+
+\end_layout
+
+\begin_layout Description
+library instructs the linker to use a library module.
+\newline
+Usage:
+\end_layout
+
+\begin_layout LyX-Code
+#pragma library module_name
+\end_layout
+
+\begin_layout Standard
+
+\emph on
+module_name
+\emph default
+ can be any library or object file (including its path).
+ Note that there are four reserved keywords which have special meaning.
+ These are:
+\end_layout
+
+\begin_layout Standard
+\align center
+\begin_inset Tabular
+<lyxtabular version="3" rows="6" columns="3">
+<features>
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="block" valignment="top" leftline="true" width="20page%">
+<column alignment="left" valignment="top" leftline="true" rightline="true" width="0">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Keyword
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Description
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Module to link
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\series bold
+ignore
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+ignore all library pragmas
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\emph on
+(none)
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\series bold
+c
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+link the C library
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\emph on
+libc18f
+\emph default
+.lib
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\series bold
+math
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+link the Math libarary
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\emph on
+libm18f
+\emph default
+.lib
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\series bold
+io
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+link the I/O library
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\emph on
+libio18f*
+\emph default
+.lib
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\series bold
+debug
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+link the debug library
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\emph on
+libdebug
+\emph default
+.lib
+\end_layout
+
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
+\newline
+* is the device number, i.e.
+ 452 for PIC18F452 MCU.
+\end_layout
+
+\begin_layout Standard
+This feature allows for linking with specific libraries withoug having to
+ explicit name them in the command line.
+ Note that the
+\noun on
+ignore
+\noun default
+ keyword will reject all modules specified by the library pragma.
+\end_layout
+
+\begin_layout Description
+udata The pragma udata instructs the compiler to emit code so that linker
+ will place a variable at a specific memory bank.
+\end_layout
+
+\begin_layout LyX-Code
+Example:
+\end_layout
+
+\begin_layout LyX-Code
+
+\end_layout
+
+\begin_layout LyX-Code
+/* places variable foo at bank2 */
+\end_layout
+
+\begin_layout LyX-Code
+#pragma udata bank2 foo
+\end_layout
+
+\begin_layout LyX-Code
+char foo;
+\end_layout
+
+\begin_layout Standard
+In order for this pragma to work extra SECTION directives should be added
+ in the .lkr script.
+ In the following example a sample .lkr file is shown:
+\end_layout
+
+\begin_layout LyX-Code
+
+\end_layout
+
+\begin_layout LyX-Code
+// Sample linker script for the PIC18F452 processor
+\end_layout
+
+\begin_layout LyX-Code
+LIBPATH .
+\end_layout
+
+\begin_layout LyX-Code
+CODEPAGE NAME=vectors START=0x0 END=0x29 PROTECTED
+\end_layout
+
+\begin_layout LyX-Code
+CODEPAGE NAME=page START=0x2A END=0x7FFF
+\end_layout
+
+\begin_layout LyX-Code
+CODEPAGE NAME=idlocs START=0x200000 END=0x200007 PROTECTED
+\end_layout
+
+\begin_layout LyX-Code
+CODEPAGE NAME=config START=0x300000 END=0x30000D PROTECTED
+\end_layout
+
+\begin_layout LyX-Code
+CODEPAGE NAME=devid START=0x3FFFFE END=0x3FFFFF PROTECTED
+\end_layout
+
+\begin_layout LyX-Code
+CODEPAGE NAME=eedata START=0xF00000 END=0xF000FF PROTECTED
+\end_layout
+
+\begin_layout LyX-Code
+ACCESSBANK NAME=accessram START=0x0 END=0x7F
+\end_layout
+
+\begin_layout LyX-Code
+
+\end_layout
+
+\begin_layout LyX-Code
+DATABANK NAME=gpr0 START=0x80 END=0xFF
+\end_layout
+
+\begin_layout LyX-Code
+DATABANK NAME=gpr1 START=0x100 END=0x1FF
+\end_layout
+
+\begin_layout LyX-Code
+DATABANK NAME=gpr2 START=0x200 END=0x2FF
+\end_layout
+
+\begin_layout LyX-Code
+DATABANK NAME=gpr3 START=0x300 END=0x3FF
+\end_layout
+
+\begin_layout LyX-Code
+DATABANK NAME=gpr4 START=0x400 END=0x4FF
+\end_layout
+
+\begin_layout LyX-Code
+DATABANK NAME=gpr5 START=0x500 END=0x5FF
+\end_layout
+
+\begin_layout LyX-Code
+ACCESSBANK NAME=accesssfr START=0xF80 END=0xFFF PROTECTED
+\end_layout
+
+\begin_layout LyX-Code
+
+\end_layout
+
+\begin_layout LyX-Code
+SECTION NAME=CONFIG ROM=config
+\end_layout
+
+\begin_layout LyX-Code
+
+\end_layout
+
+\begin_layout LyX-Code
+SECTION NAME=bank0 RAM=gpr0 # these SECTION directives
+\end_layout
+
+\begin_layout LyX-Code
+SECTION NAME=bank1 RAM=gpr1 # should be added to link
+\end_layout
+
+\begin_layout LyX-Code
+SECTION NAME=bank2 RAM=gpr2 # section name 'bank?' with
+\end_layout
+
+\begin_layout LyX-Code
+SECTION NAME=bank3 RAM=gpr3 # a specific DATABANK name
+\end_layout
+
+\begin_layout LyX-Code
+SECTION NAME=bank4 RAM=gpr4
+\end_layout
+
+\begin_layout LyX-Code
+SECTION NAME=bank5 RAM=gpr5
+\end_layout
+
+\begin_layout Standard
+The linker will recognise the section name set in the pragma statement and
+ will position the variable at the memory bank set with the RAM field at
+ the SECTION line in the linker script file.
+\end_layout
+
+\begin_layout Subsection
+Header Files
+\begin_inset LatexCommand \label{sub:PIC16_Header-Files}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+There is one main header file
+\begin_inset LatexCommand \index{PIC16!Header files}
+
+\end_inset
+
+ that can be included to the source files using the pic16
+\begin_inset LatexCommand \index{PIC16}
+
+\end_inset
+
+ port.
+ That file is the
+\series bold
+pic18fregs.h
+\series default
+.
+ This header file contains the definitions for the processor special registers,
+ so it is necessary if the source accesses them.
+ It can be included by adding the following line in the beginning of the
+ file:
+\end_layout
+
+\begin_layout LyX-Code
+#include <pic18fregs.h>
+\end_layout
+
+\begin_layout Standard
+The specific microcontroller is selected within the pic18fregs.h automatically,
+ so the same source can be used with a variety of devices.
+\end_layout
+
+\begin_layout Subsection
+Libraries
+\end_layout
+
+\begin_layout Standard
+The libraries
+\begin_inset LatexCommand \index{PIC16!Libraries}
+
+\end_inset
+
+ that PIC16
+\begin_inset LatexCommand \index{PIC16}
+
+\end_inset
+
+ port depends on are the microcontroller device libraries which contain
+ the symbol definitions for the microcontroller special function registers.
+ These libraries have the format pic18fxxxx.lib, where
+\emph on
+xxxx
+\emph default
+ is the microcontroller identification number.
+ The specific library is selected automatically by the compiler at link
+ stage according to the selected device.
+\end_layout
+
+\begin_layout Standard
+Libraries are created with gplib which is part of the gputils package
+\begin_inset LatexCommand \url{http://sourceforge.net/projects/gputils}
+
+\end_inset
+
+.
+\end_layout
+
+\begin_layout Subsubsection*
+Building the libraries
+\end_layout
+
+\begin_layout Standard
+Before using SDCC/pic16 there are some libraries that need to be compiled.
+ This process is not done automatically by SDCC since not all users use
+ SDCC for pic16 projects.
+ So each user should compile the libraries separately.
+\end_layout
+
+\begin_layout Standard
+The steps to compile the pic16 libraries under Linux and Mac OS X are:
+\end_layout
+
+\begin_layout LyX-Code
+cd device/lib/pic16
+\end_layout
+
+\begin_layout LyX-Code
+./configure
+\end_layout
+
+\begin_layout LyX-Code
+make
+\end_layout
+
+\begin_layout LyX-Code
+cd ..
+\end_layout
+
+\begin_layout LyX-Code
+make model-pic16
+\end_layout
+
+\begin_layout LyX-Code
+su -c 'make install' # install the libraries, you need the root password
+\end_layout
+
+\begin_layout Standard
+If you need to install the headers too, do:
+\end_layout
+
+\begin_layout LyX-Code
+cd device/include
+\end_layout
+
+\begin_layout LyX-Code
+su -c 'make install' # install the headers, you need the root password
+\end_layout
+
+\begin_layout Standard
+There exist a special target to build the I/O libraries.
+ This target is not automatically build because it will build the I/O library
+ for
+\emph on
+every
+\emph default
+ supported device.
+ This way building will take quite a lot of time.
+ Users are advised to edit the
+\series bold
+device/lib/pic16/pics.build
+\series default
+ file and then execute:
+\end_layout
+
+\begin_layout LyX-Code
+make lib-io
+\end_layout
+
+\begin_layout Subsection
+Adding New Devices to the Port
+\end_layout
+
+\begin_layout Standard
+Adding support for a new 16
+\begin_inset ERT
+status open
+
+\begin_layout Standard
+
+
+\backslash
+,
+\end_layout
+
+\end_inset
+
+bit PIC MCU requires the following steps:
+\end_layout
+
+\begin_layout Enumerate
+Create picDEVICE.c and picDEVICE.h from pDEVICE.inc using
+\newline
+
+\family typewriter
+perl /path/to/sdcc/support/scripts/inc2h-pic16.pl /path/to/gputils/header/pDEVICE.
+inc
+\end_layout
+
+\begin_layout Enumerate
+
+\family typewriter
+mv picDEVICE.h /path/to/sdcc/device/include/pic16
+\end_layout
+
+\begin_layout Enumerate
+
+\family typewriter
+mv picDEVICE.c /path/to/sdcc/device/lib/pic16/libdev
+\end_layout
+
+\begin_layout Enumerate
+Add DEVICE to
+\family typewriter
+/path/to/sdcc/device/lib/pics.all
+\family default
+ (and
+\family typewriter
+.build
+\family default
+).
+\newline
+Note: No 18f prefix here!
+\end_layout
+
+\begin_layout Enumerate
+Adjust
+\family typewriter
+/path/to/sdcc/device/lib/pic16/libio/*.ignore
+\family default
+
+\newline
+Add your DEVICE if it does not compile in
+\family typewriter
+adc
+\family default
+,
+\family typewriter
+i2c
+\family default
+, or
+\family typewriter
+usart
+\family default
+.
+\end_layout
+
+\begin_layout Enumerate
+Edit
+\family typewriter
+/path/to/sdcc/device/include/pic16/pic18fregs.h
+\family default
+.
+ The file format is self-explanatory, just add
+\newline
+
+\family typewriter
+#elif defined(picDEVICE)
+\newline
+# include <picDEVICE.h>
+\family default
+
+\newline
+at the right place (keep it sorted).
+\end_layout
+
+\begin_layout Enumerate
+Edit
+\family typewriter
+/path/to/sdcc/src/pic16/devices.inc
+\family default
+.
+ Copy and modify an existing entry and insert it at the correct place (keep
+ the file sorted).
+ The file is hardly documented, look at the entries for the 18f2221...
+\end_layout
+
+\begin_layout Enumerate
+Recompile SDCC, including the pic16 libraries.
+\end_layout
+
+\begin_layout Subsection
+Memory Models
+\end_layout
+
+\begin_layout Standard
+The following memory models are supported by the PIC16 port:
+\end_layout
+
+\begin_layout Itemize
+small model
+\end_layout
+
+\begin_layout Itemize
+large model
+\end_layout
+
+\begin_layout Standard
+Memory model affects the default size of pointers within the source.
+ The sizes are shown in the next table:
+\end_layout
+
+\begin_layout Standard
+\align center
+\begin_inset Tabular
+<lyxtabular version="3" rows="3" columns="3">
+<features>
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Pointer sizes according to memory model
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+small model
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+large model
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+code pointers
+\end_layout
+
+\end_inset
+</cell>
+<cell multicolumn="1" alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+16-bits
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+24-bits
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+data pointers
+\end_layout
+
+\end_inset
+</cell>
+<cell multicolumn="1" alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+16-bits
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+16-bits
+\end_layout
+
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+It is advisable that all sources within a project are compiled with the
+ same memory model.
+ If one wants to override the default memory model, this can be done by
+ declaring a pointer as
+\series bold
+far
+\series default
+ or
+\series bold
+near
+\series default
+.
+ Far selects large memory model's pointers, while near selects small memory
+ model's pointers.
+\end_layout
+
+\begin_layout Standard
+The standard device libraries (see
+\begin_inset LatexCommand \ref{sub:PIC16_Header-Files}
+
+\end_inset
+
+) contain no reference to pointers, so they can be used with both memory
+ models.
+\end_layout
+
+\begin_layout Subsection
+Stack
+\end_layout
+
+\begin_layout Standard
+The stack
+\begin_inset LatexCommand \index{PIC16!stack}
+
+\end_inset
+
+ implementation for the PIC16 port uses two indirect registers, FSR1 and
+ FSR2.
+\end_layout
+
+\begin_layout Description
+FSR1 is assigned as stack pointer
+\end_layout
+
+\begin_layout Description
+FSR2 is assigned as frame pointer
+\end_layout
+
+\begin_layout Standard
+The following stack models are supported by the PIC16 port
+\end_layout
+
+\begin_layout Itemize
+
+\noun on
+small
+\noun default
+ model
+\end_layout
+
+\begin_layout Itemize
+
+\noun on
+large
+\noun default
+ model
+\end_layout
+
+\begin_layout Standard
+
+\noun on
+Small
+\noun default
+ model means that only the FSRxL byte is used to access stack and frame,
+ while
+\emph on
+\noun on
+large
+\emph default
+\noun default
+ uses both FSRxL and FSRxH registers.
+ The following table shows the stack/frame pointers sizes according to stack
+ model and the maximum space they can address:
+\end_layout
+
+\begin_layout Standard
+\align center
+\begin_inset Tabular
+<lyxtabular version="3" rows="3" columns="3">
+<features>
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Stack & Frame pointer sizes according to stack model
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+small
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+large
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Stack pointer FSR1
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+8-bits
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+16-bits
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Frame pointer FSR2
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+8-bits
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+16-bits
+\end_layout
+
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+
+\noun on
+Large
+\noun default
+stack model is currently not working properly throughout the code generator.
+ So its use is not advised.
+ Also there are some other points that need special care:
+\newline
+
+\end_layout
+
+\begin_layout Enumerate
+Do not create stack sections with size more than one physical bank (that
+ is 256 bytes)
+\end_layout
+
+\begin_layout Enumerate
+Stack sections should no cross physical bank limits (i.e.
+ #pragma stack 0x50 0x100)
+\end_layout
+
+\begin_layout Standard
+These limitations are caused by the fact that only FSRxL is modified when
+ using SMALL stack model, so no more than 256 bytes of stack can be used.
+ This problem will disappear after LARGE model is fully implemented.
+\end_layout
+
+\begin_layout Subsection
+Functions
+\end_layout
+
+\begin_layout Standard
+In addition to the standard SDCC function keywords, PIC16
+\begin_inset LatexCommand \index{PIC16}
+
+\end_inset
+
+ port makes available two more:
+\end_layout
+
+\begin_layout Description
+wparam
+\begin_inset LatexCommand \index{PIC16!wparam}
+
+\end_inset
+
+ Use the WREG to pass one byte of the first function argument.
+ This improves speed but you may not use this for functions with arguments
+ that are called via function pointers, otherwise the first byte of the
+ first parameter will get lost.
+ Usage:
+\end_layout
+
+\begin_layout LyX-Code
+void func_wparam(int a) wparam
+\end_layout
+
+\begin_layout LyX-Code
+{
+\end_layout
+
+\begin_layout LyX-Code
+ /* WREG hold the lower part of a */
+\end_layout
+
+\begin_layout LyX-Code
+ /* the high part of a is stored in FSR2+2 (or +3 for large stack model)
+ */
+\end_layout
+
+\begin_layout LyX-Code
+...
+\end_layout
+
+\begin_layout LyX-Code
+}
+\end_layout
+
+\begin_layout Description
+shadowregs
+\begin_inset LatexCommand \index{PIC16!shadowregs}
+
+\end_inset
+
+ When entering/exiting an ISR, it is possible to take advantage of the PIC18F
+ hardware shadow registers which hold the values of WREG, STATUS and BSR
+ registers.
+ This can be done by adding the keyword
+\emph on
+shadowregs
+\emph default
+ before the
+\emph on
+interrupt
+\emph default
+ keyword in the function's header.
+\end_layout
+
+\begin_layout LyX-Code
+void isr_shadow(void) shadowregs interrupt 1
+\end_layout
+
+\begin_layout LyX-Code
+{
+\end_layout
+
+\begin_layout LyX-Code
+...
+\end_layout
+
+\begin_layout LyX-Code
+}
+\end_layout
+
+\begin_layout Standard
+
+\emph on
+shadowregs
+\emph default
+ instructs the code generator not to store/restore WREG, STATUS, BSR when
+ entering/exiting the ISR.
+\end_layout
+
+\begin_layout Subsection
+Function return values
+\end_layout
+
+\begin_layout Standard
+Return values from functions are placed to the appropriate registers following
+ a modified Microchip policy optimized for SDCC.
+ The following table shows these registers:
+\end_layout
+
+\begin_layout Standard
+\align center
+\begin_inset Tabular
+<lyxtabular version="3" rows="6" columns="2">
+<features>
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+size
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+destination register
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+8 bits
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+WREG
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+16 bits
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+PRODL:WREG
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+24 bits
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+PRODH:PRODL:WREG
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+32 bits
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+FSR0L:PRODH:PRODL:WREG
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+>32 bits
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+on stack, FSR0 points to the beginning
+\end_layout
+
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Subsection
+Interrupts
+\end_layout
+
+\begin_layout Standard
+An interrupt
+\begin_inset LatexCommand \index{PIC16!interrupt}
+
+\end_inset
+
+ service routine (ISR) is declared using the
+\emph on
+interrupt
+\emph default
+ keyword.
+\end_layout
+
+\begin_layout LyX-Code
+void isr(void) interrupt
+\emph on
+n
+\end_layout
+
+\begin_layout LyX-Code
+{
+\end_layout
+
+\begin_layout LyX-Code
+...
+\end_layout
+
+\begin_layout LyX-Code
+}
+\end_layout
+
+\begin_layout Standard
+
+\emph on
+n
+\emph default
+ is the interrupt number, which for PIC18F devices can be:
+\end_layout
+
+\begin_layout Standard
+\align center
+\begin_inset Tabular
+<lyxtabular version="3" rows="4" columns="3">
+<features>
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\emph on
+n
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Interrupt Vector
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Interrupt Vector Address
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+0
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+RESET vector
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+0x000000
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+1
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+HIGH priority interrupts
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+0x000008
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+2
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+LOW priority interrupts
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+0x000018
+\end_layout
+
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+When generating assembly code for ISR the code generator places a
+\noun on
+goto
+\noun default
+instruction at the
+\emph on
+Interrupt Vector Address
+\emph default
+ which points at the genetated ISR.
+ This single GOTO instruction is part of an automatically generated
+\emph on
+interrupt entry point
+\emph default
+ function.
+ The actuall ISR code is placed as normally would in the code space.
+ Upon interrupt request, the GOTO instruction is executed which jumps to
+ the ISR code.
+ When declaring interrupt functions as _naked this GOTO instruction is
+\series bold
+not
+\series default
+ generated.
+ The whole interrupt functions is therefore placed at the Interrupt Vector
+ Address of the specific interrupt.
+ This is not a problem for the LOW priority interrupts, but it is a problem
+ for the RESET and the HIGH priority interrupts because code may be written
+ at the next interrupt´s vector address and cause undeterminate program
+ behaviour if that interrupt is raised.
+\begin_inset Foot
+status open
+
+\begin_layout Standard
+This is not a problem when
+\end_layout
+
+\begin_layout Enumerate
+this is a HIGH interrupt ISR and LOW interrupts are
+\emph on
+disabled
+\emph default
+ or not used.
+\end_layout
+
+\begin_layout Enumerate
+when the ISR is small enough not to reach the next interrupt´s vector address.
+\end_layout
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+
+\emph on
+n
+\emph default
+ is possible to be omitted.
+ This way a function is generated similar to an ISR, but it is not assigned
+ to any interrupt.
+\end_layout
+
+\begin_layout Standard
+When entering an interrupt, currently the PIC16
+\begin_inset LatexCommand \index{PIC16}
+
+\end_inset
+
+ port automatically saves the following registers:
+\end_layout
+
+\begin_layout Itemize
+WREG
+\end_layout
+
+\begin_layout Itemize
+STATUS
+\end_layout
+
+\begin_layout Itemize
+BSR
+\end_layout
+
+\begin_layout Itemize
+PROD (PRODL and PRODH)
+\end_layout
+
+\begin_layout Itemize
+FSR0 (FSR0L and FSR0H)
+\end_layout
+
+\begin_layout Standard
+These registers are restored upon return from the interrupt routine.
+\begin_inset Foot
+status open
+
+\begin_layout Standard
+NOTE that when the _naked attribute is specified for an interrupt routine,
+ then NO registers are stored or restored.
+\end_layout
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Subsection
+Generic Pointers
+\end_layout
+
+\begin_layout Standard
+Generic pointers are implemented in PIC16 port as 3-byte (24-bit) types.
+ There are 3 types of generic pointers currently implemented data, code
+ and eeprom pointers.
+ They are differentiated by the value of the 7th and 6th bits of the upper
+ byte:
+\end_layout
+
+\begin_layout Standard
+\align center
+\begin_inset Tabular
+<lyxtabular version="3" rows="5" columns="5">
+<features>
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<column alignment="center" valignment="top" width="0">
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<column alignment="center" valignment="top" width="0">
+<column alignment="left" valignment="top" rightline="true" width="0">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+pointer type
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+7th bit
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+6th bit
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+rest of the pointer
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+description
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+data
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+1
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+0
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\family typewriter
+\shape slanted
+\emph on
+uuuuuu uuuuxxxx xxxxxxxx
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+a 12-bit data pointer in data RAM memory
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+code
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+0
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+0
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\family typewriter
+\shape slanted
+\emph on
+uxxxxx xxxxxxxx xxxxxxxx
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+a 21-bit code pointer in FLASH memory
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+eeprom
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+0
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+1
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\family typewriter
+\shape slanted
+\emph on
+uuuuuu uuuuuuxx xxxxxxxx
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+a 10-bit eeprom pointer in EEPROM memory
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+(unimplemented)
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+1
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+1
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\family typewriter
+\shape slanted
+\emph on
+xxxxxx xxxxxxxx xxxxxxxx
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+unimplemented pointer type
+\end_layout
+
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+Generic pointer are read and written with a set of library functions which
+ read/write 1, 2, 3, 4 bytes.
+\end_layout
+
+\begin_layout Subsection
+PIC16 C Libraries
+\end_layout
+
+\begin_layout Subsubsection
+Standard I/O Streams
+\end_layout
+
+\begin_layout Standard
+In the
+\emph on
+stdio.h
+\emph default
+ the type FILE is defined as:
+\end_layout
+
+\begin_layout LyX-Code
+typedef char * FILE;
+\end_layout
+
+\begin_layout Standard
+This type is the stream type implemented I/O in the PIC18F devices.
+ Also the standard input and output streams are declared in stdio.h:
+\end_layout
+
+\begin_layout LyX-Code
+extern FILE * stdin;
+\end_layout
+
+\begin_layout LyX-Code
+extern FILE * stdout;
+\end_layout
+
+\begin_layout Standard
+The FILE type is actually a generic pointer which defines one more type
+ of generic pointers, the
+\emph on
+stream
+\emph default
+pointer.
+ This new type has the format:
+\end_layout
+
+\begin_layout Standard
+\align center
+\begin_inset Tabular
+<lyxtabular version="3" rows="2" columns="7">
+<features>
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<column alignment="center" valignment="top" width="0">
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<column alignment="center" valignment="top" width="0">
+<column alignment="left" valignment="top" rightline="true" width="0">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+pointer type
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+<7:6>
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+<5>
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+<4>
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+<3:0>
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+rest of the pointer
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+descrption
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+stream
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+00
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+1
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+0
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+nnnn
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\family typewriter
+\shape slanted
+\emph on
+uuuuuuuu uuuuuuuu
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+upper byte high nubble is 0x2n, the rest are zeroes
+\end_layout
+
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+Currently implemented there are 3 types of streams defined:
+\end_layout
+
+\begin_layout Standard
+\align center
+\begin_inset Tabular
+<lyxtabular version="3" rows="4" columns="4">
+<features>
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+stream type
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+value
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+module
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+description
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+STREAM_USART
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\family typewriter
+0x200000UL
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+USART
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Writes/Reads characters via the USART peripheral
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+STREAM_MSSP
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\family typewriter
+0x210000UL
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+MSSP
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Writes/Reads characters via the MSSP peripheral
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+STREAM_USER
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\family typewriter
+0x2f0000UL
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+(none)
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Writes/Reads characters via used defined functions
+\end_layout
+
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+The stream identifiers are declared as macros in the stdio.h header.
+\end_layout
+
+\begin_layout Standard
+In the libc library there exist the functions that are used to write to
+ each of the above streams.
+ These are
+\end_layout
+
+\begin_layout Description
+_
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+_stream_usart_putchar writes a character at the USART stream
+\end_layout
+
+\begin_layout Description
+_
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+_stream_mssp_putchar writes a character at the MSSP stream
+\end_layout
+
+\begin_layout Description
+putchar dummy function.
+ This writes a character to a user specified manner.
+\end_layout
+
+\begin_layout Standard
+In order to increase performance
+\emph on
+putchar
+\emph default
+is declared in stdio.h as having its parameter in WREG (it has the wparam
+ keyword).
+ In stdio.h exists the macro PUTCHAR(arg) that defines the putchar function
+ in a user-friendly way.
+
+\emph on
+arg
+\emph default
+ is the name of the variable that holds the character to print.
+ An example follows:
+\end_layout
+
+\begin_layout LyX-Code
+#include <pic18fregs.h>
+\newline
+#include <stdio.h>
+\newline
+
+\newline
+PUTCHAR( c )
+\end_layout
+
+\begin_layout LyX-Code
+{
+\end_layout
+
+\begin_layout LyX-Code
+ PORTA = c; /* dump character c to PORTA */
+\end_layout
+
+\begin_layout LyX-Code
+}
+\newline
+
+\newline
+void main(void)
+\end_layout
+
+\begin_layout LyX-Code
+{
+\end_layout
+
+\begin_layout LyX-Code
+ stdout = STREAM_USER; /* this is not necessary, since stdout points
+\end_layout
+
+\begin_layout LyX-Code
+ * by default to STREAM_USER */
+\end_layout
+
+\begin_layout LyX-Code
+ printf (
+\begin_inset Quotes sld
+\end_inset
+
+This is a printf test
+\backslash
+n
+\begin_inset Quotes srd
+\end_inset
+
+);
+\end_layout
+
+\begin_layout LyX-Code
+}
+\end_layout
+
+\begin_layout LyX-Code
+
+\end_layout
+
+\begin_layout Subsubsection
+Printing functions
+\end_layout
+
+\begin_layout Standard
+PIC16 contains an implementation of the printf-family of functions.
+ There exist the following functions:
+\end_layout
+
+\begin_layout LyX-Code
+extern unsigned int sprintf(char *buf, char *fmt, ...);
+\end_layout
+
+\begin_layout LyX-Code
+extern unsigned int vsprintf(char *buf, char *fmt, va_list ap);
+\end_layout
+
+\begin_layout LyX-Code
+
+\end_layout
+
+\begin_layout LyX-Code
+extern unsigned int printf(char *fmt, ...);
+\end_layout
+
+\begin_layout LyX-Code
+extern unsigned int vprintf(char *fmt, va_lista ap);
+\end_layout
+
+\begin_layout LyX-Code
+
+\end_layout
+
+\begin_layout LyX-Code
+extern unsigned int fprintf(FILE *fp, char *fmt, ...);
+\end_layout
+
+\begin_layout LyX-Code
+extern unsigned int vfprintf(FILE *fp, char *fmt, va_list ap);
+\end_layout
+
+\begin_layout Standard
+For sprintf and vsprintf
+\emph on
+buf
+\emph default
+should normally be a data pointer where the resulting string will be placed.
+ No range checking is done so the user should allocate the necessery buffer.
+ For fprintf and vfprintf
+\emph on
+fp
+\emph default
+ should be a stream pointer (i.e.
+ stdout, STREAM_MSSP, etc...).
+\end_layout
+
+\begin_layout Subsubsection
+Signals
+\end_layout
+
+\begin_layout Standard
+The PIC18F family of microcontrollers supports a number of interrupt sources.
+ A list of these interrupts is shown in the following table:
+\end_layout
+
+\begin_layout Standard
+\align center
+\begin_inset Tabular
+<lyxtabular version="3" rows="11" columns="4">
+<features>
+<column alignment="left" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<column alignment="left" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+signal name
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+description
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+signal name
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+descritpion
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+SIG_RB
+\end_layout
+
+\end_inset
+</cell>
+<cell multicolumn="1" alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+PORTB change interrupt
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+SIG_EE
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+EEPROM/FLASH write complete interrupt
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+SIG_INT0
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+INT0 external interrupt
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+SIG_BCOL
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Bus collision interrupt
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+SIG_INT1
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+INT1 external interrupt
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+SIG_LVD
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Low voltage detect interrupt
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+SIG_INT2
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+INT2 external interrupt
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+SIG_PSP
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Parallel slave port interrupt
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+SIG_CCP1
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+CCP1 module interrupt
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+SIG_AD
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+AD convertion complete interrupt
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+SIG_CCP2
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+CCP2 module interrupt
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+SIG_RC
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+USART receive interrupt
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+SIG_TMR0
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+TMR0 overflow interrupt
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+SIG_TX
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+USART transmit interrupt
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+SIG_TMR1
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+TMR1 overflow interrupt
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+SIG_MSSP
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+SSP receive/transmit interrupt
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+SIG_TMR2
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+TMR2 matches PR2 interrupt
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+SIG_TMR3
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+TMR3 overflow interrupt
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\end_layout
+
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+The prototypes for these names are defined in the header file
+\emph on
+signal.h
+\emph default
+ .
+\end_layout
+
+\begin_layout Standard
+In order to simplify signal handling, a number of macros is provided:
+\end_layout
+
+\begin_layout List
+\labelwidthstring 00.00.0000
+DEF_INTHIGH(name) begin the definition of the interrupt dispatch table for
+ high priority interrupts.
+
+\emph on
+name
+\emph default
+ is the function name to use.
+\end_layout
+
+\begin_layout List
+\labelwidthstring 00.00.0000
+DEF_INTLOW(name) begin the definition of the interrupt dispatch table fo
+ low priority interrupt.
+
+\emph on
+name
+\emph default
+ is the function name to use.
+\end_layout
+
+\begin_layout List
+\labelwidthstring 00.00.0000
+DEF_HANDLER(sig,handler) define a handler for signal
+\emph on
+sig.
+\end_layout
+
+\begin_layout List
+\labelwidthstring 00.00.0000
+END_DEF end the declaration of the dispatch table.
+\end_layout
+
+\begin_layout Standard
+Additionally there are two more macros to simplify the declaration of the
+ signal handler:
+\end_layout
+
+\begin_layout List
+\labelwidthstring 00.00.0000
+
+\series medium
+SIGHANDLER(handler)
+\series default
+this declares the function prototype for the
+\emph on
+handler
+\emph default
+ function.
+\end_layout
+
+\begin_layout List
+\labelwidthstring 00.00.0000
+SIGHANDLERNAKED(handler) same as SIGHANDLER() but declares a naked function.
+\end_layout
+
+\begin_layout Standard
+An example of using the macros above is shown below:
+\end_layout
+
+\begin_layout LyX-Code
+#include <pic18fregs.h>
+\end_layout
+
+\begin_layout LyX-Code
+#include <signal.h>
+\newline
+
+\newline
+DEF_INTHIGH(high_int)
+\end_layout
+
+\begin_layout LyX-Code
+DEF_HANDLER(SIG_TMR0, _tmr0_handler)
+\end_layout
+
+\begin_layout LyX-Code
+DEF_HANDLER(SIG_BCOL, _bcol_handler)
+\end_layout
+
+\begin_layout LyX-Code
+END_DEF
+\newline
+
+\newline
+SIGHANDLER(_tmr0_handler)
+\end_layout
+
+\begin_layout LyX-Code
+{
+\end_layout
+
+\begin_layout LyX-Code
+ /* action to be taken when timer 0 overflows */
+\end_layout
+
+\begin_layout LyX-Code
+}
+\newline
+
+\newline
+SIGHANDLERNAKED(_bcol_handler)
+\end_layout
+
+\begin_layout LyX-Code
+{
+\end_layout
+
+\begin_layout LyX-Code
+ _asm
+\end_layout
+
+\begin_layout LyX-Code
+ /* action to be taken when bus collision occurs */
+\end_layout
+
+\begin_layout LyX-Code
+ retfie
+\end_layout
+
+\begin_layout LyX-Code
+ _endasm;
+\end_layout
+
+\begin_layout LyX-Code
+}
+\end_layout
+
+\begin_layout Standard
+
+\series bold
+NOTES:
+\series default
+ Special care should be taken when using the above scheme:
+\end_layout
+
+\begin_layout Itemize
+do not place a colon (;) at the end of the DEF_* and END_DEF macros.
+\end_layout
+
+\begin_layout Itemize
+when declaring SIGHANDLERNAKED handler never forget to use
+\emph on
+retfie
+\emph default
+ for proper returning.
+\end_layout
+
+\begin_layout Subsection
+PIC16 Port -- Tips
+\end_layout
+
+\begin_layout Standard
+Here you can find some general tips for compiling programs with SDCC/pic16.
+\end_layout
+
+\begin_layout Subsubsection
+Stack size
+\end_layout
+
+\begin_layout Standard
+The default stack
+\begin_inset LatexCommand \index{PIC16!stack}
+
+\end_inset
+
+ size (that is 64 bytes) probably is enough for many programs.
+ One must take care that when there are many levels of function nesting,
+ or there is excessive usage of stack, its size should be extended.
+ An example of such a case is the printf/sprintf family of functions.
+ If you encounter problems like not being able to print integers, then you
+ need to set the stack size around the maximum (256 for small stack model).
+ The following diagram shows what happens when calling printf to print an
+ integer:
+\end_layout
+
+\begin_layout LyX-Code
+printf () --> ltoa () --> ultoa () --> divschar ()
+\end_layout
+
+\begin_layout Standard
+It is should be understood that stack is easily consumed when calling complicate
+d functions.
+ Using command line arguments like -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-fommit-frame-pointer might reduce stack usage by not creating unnecessery
+ stack frames.
+ Other ways to reduce stack usage may exist.
+\end_layout
+
+\begin_layout Subsection
+Known Bugs
+\end_layout
+
+\begin_layout Standard
+The PIC16 Port currently does not pass SDCC's regression test
+\begin_inset LatexCommand \index{Regression test (PIC16)}
+
+\end_inset
+
+ suite (see section
+\begin_inset LatexCommand \ref{sec:Quality-control}
+
+\end_inset
+
+) and thus the snapshot build regression tests for the PIC16 target are
+ currently disabled for all hosts
+\emph on
+.
+\end_layout
+
+\begin_layout Chapter
+Debugging
+\end_layout
+
+\begin_layout Standard
+There are several approaches to debugging your code.
+ This chapter is meant to show your options and to give detail on some of
+ them:
+\newline
+
+\newline
+When writing your code:
+\end_layout
+
+\begin_layout Itemize
+write your code with debugging in mind (avoid duplicating code, put conceptually
+ similar variables into structs, use structured code, have strategic points
+ within your code where all variables are consistent, ...)
+\end_layout
+
+\begin_layout Itemize
+run a syntax-checking tool like splint
+\begin_inset LatexCommand \index{splint (syntax checking tool)}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{lint (syntax checking tool)}
+
+\end_inset
+
+ (see -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-more-pedantic
+\begin_inset LatexCommand \ref{lyx:more-pedantic-SPLINT}
+
+\end_inset
+
+) over the code.
+\end_layout
+
+\begin_layout Itemize
+for the high level code use a C-compiler (like f.e.
+ GCC) to compile run and debug the code on your host.
+ See (see -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-more-pedantic
+\begin_inset LatexCommand \ref{lyx:more-pedantic-SPLINT}
+
+\end_inset
+
+) on how to handle syntax extensions like __xdata, __at(), ...
+
+\end_layout
+
+\begin_layout Itemize
+use another C-compiler to compile code for your target.
+ Always an option but not recommended:) And not very likely to help you.
+ If you seriously consider walking this path you should at least occasionally
+ check portability of your code.
+ Most commercial compiler vendors will offer an evaluation version so you
+ can test compile your code or snippets of your code.
+\end_layout
+
+\begin_layout Standard
+Debugging on a simulator:
+\end_layout
+
+\begin_layout Itemize
+there is a separate section about SDCDB (section
+\begin_inset LatexCommand \ref{cha:Debugging-with-SDCDB}
+
+\end_inset
+
+) below.
+\end_layout
+
+\begin_layout Itemize
+or (8051 specific) use a freeware/commercial simulator which interfaces
+ to the AOMF
+\begin_inset LatexCommand \index{AOMF, AOMF51}
+
+\end_inset
+
+ file (see
+\begin_inset LatexCommand \ref{OMF file}
+
+\end_inset
+
+) optionally generated by SDCC.
+\end_layout
+
+\begin_layout Standard
+Debugging On-target:
+\end_layout
+
+\begin_layout Itemize
+use a MCU port pin to serially output debug data to the RS232 port of your
+ host.
+ You'll probably want some level shifting device typically involving a MAX232
+ or similar IC.
+ If the hardware serial port of the MCU is not available search for 'Software
+ UART' in your favourite search machine.
+\end_layout
+
+\begin_layout Itemize
+use an on-target monitor.
+ In this context a monitor is a small program which usually accepts commands
+ via a serial line and allows to set program counter, to single step through
+ a program and read/write memory locations.
+ For the 8051 good examples of monitors are paulmon and cmon51 (see section
+
+\begin_inset LatexCommand \ref{sec:Related-open-source-tools}
+
+\end_inset
+
+).
+\end_layout
+
+\begin_layout Itemize
+toggle MCU port pins at strategic points within your code and use an oscilloscop
+e.
+ A
+\emph on
+digital oscilloscope
+\emph default
+
+\begin_inset LatexCommand \index{Oscilloscope}
+
+\end_inset
+
+ with deep trace memory is really helpful especially if you have to debug
+ a realtime application.
+ If you need to monitor more pins than your oscilloscope provides you can
+ sometimes get away with a small R-2R network.
+ On a single channel oscilloscope you could f.e.
+ monitor 2 push-pull driven pins by connecting one via a 10\InsetSpace ~
+k
+\begin_inset Formula $\Omega$
+\end_inset
+
+ resistor and the other one by a 5\InsetSpace ~
+k
+\begin_inset Formula $\Omega$
+\end_inset
+
+ resistor to the oscilloscope probe (check output drive capability of the
+ pins you want to monitor).
+ If you need to monitor many more pins a
+\emph on
+logic analyzer
+\emph default
+ will be handy.
+\end_layout
+
+\begin_layout Itemize
+use an ICE (
+\emph on
+i
+\emph default
+n
+\emph on
+c
+\emph default
+ircuit
+\emph on
+e
+\emph default
+mulator
+\begin_inset LatexCommand \index{ICE (in circuit emulator)}
+
+\end_inset
+
+).
+ Usually very expensive.
+ And very nice to have too.
+ And usually locks you (for years...) to the devices the ICE can emulate.
+
+\end_layout
+
+\begin_layout Itemize
+use a remote debugger.
+ In most 8-bit systems the symbol information is not available on the target,
+ and a complete debugger is too bulky for the target system.
+ Therefore usually a debugger on the host system connects to an on-target
+ debugging stub which accepts only primitive commands.
+
+\newline
+Terms to enter into your favourite search engine could be 'remote debugging',
+ 'gdb stub' or 'inferior debugger'.
+ (is there one?)
+\end_layout
+
+\begin_layout Itemize
+use an on target hardware debugger.
+ Some of the more modern MCUs include hardware support for setting break
+ points and monitoring/changing variables by using dedicated hardware pins.
+ This facility doesn't require additional code to run on the target and
+
+\emph on
+usually
+\emph default
+ doesn't affect runtime behaviour until a breakpoint is hit.
+ For the mcs51 most hardware debuggers use the AOMF
+\begin_inset LatexCommand \index{AOMF, AOMF51}
+
+\end_inset
+
+ file (see
+\begin_inset LatexCommand \ref{OMF file}
+
+\end_inset
+
+) as input file.
+
+\end_layout
+
+\begin_layout Standard
+Last not least:
+\end_layout
+
+\begin_layout Itemize
+if you are not familiar with any of the following terms you're likely to
+ run into problems rather sooner than later:
+\emph on
+volatile
+\emph default
+,
+\emph on
+atomic
+\emph default
+,
+\emph on
+memory map
+\emph default
+,
+\emph on
+overlay
+\emph default
+.
+ As an embedded programmer you
+\emph on
+have
+\emph default
+ to know them so why not look them up
+\emph on
+before
+\emph default
+ you have problems?)
+\end_layout
+
+\begin_layout Itemize
+tell someone else about your problem (actually this is a surprisingly effective
+ means to hunt down the bug even if the listener is not familiar with your
+ environment).
+ As 'failure to communicate' is probably one of the job-induced deformations
+ of an embedded programmer this is highly encouraged.
+\end_layout
+
+\begin_layout Section
+Debugging with SDCDB
+\begin_inset LatexCommand \label{cha:Debugging-with-SDCDB}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{SDCDB (debugger)}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+SDCC is distributed with a source level debugger
+\begin_inset LatexCommand \index{Debugger}
+
+\end_inset
+
+.
+ The debugger uses a command line interface, the command repertoire of the
+ debugger has been kept as close to gdb
+\begin_inset LatexCommand \index{gdb}
+
+\end_inset
+
+ (the GNU debugger) as possible.
+ The configuration and build process is part of the standard compiler installati
+on, which also builds and installs the debugger in the target directory
+ specified during configuration.
+ The debugger allows you debug BOTH at the C source and at the ASM source
+ level.
+\end_layout
+
+\begin_layout Subsection
+Compiling for Debugging
+\end_layout
+
+\begin_layout Standard
+The -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-debug
+\begin_inset LatexCommand \index{-\/-debug}
+
+\end_inset
+
+ option must be specified for all files for which debug information is to
+ be generated.
+ The compiler generates a .adb file for each of these files.
+ The linker creates the .cdb
+\begin_inset LatexCommand \index{<file>.cdb}
+
+\end_inset
+
+ file from the .adb
+\begin_inset LatexCommand \index{<file>.adb}
+
+\end_inset
+
+ files and the address information.
+ This .cdb is used by the debugger.
+\end_layout
+
+\begin_layout Subsection
+How the Debugger Works
+\end_layout
+
+\begin_layout Standard
+When the -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-debug option is specified the compiler generates extra symbol information
+ some of which are put into the assembler source and some are put into the
+ .adb file.
+ Then the linker creates the .cdb file from the individual .adb files with
+ the address information for the symbols.
+ The debugger reads the symbolic information generated by the compiler &
+ the address information generated by the linker.
+ It uses the SIMULATOR (Daniel's S51) to execute the program, the program
+ execution is controlled by the debugger.
+ When a command is issued for the debugger, it translates it into appropriate
+ commands for the simulator.
+ (Currently SDCDM only connects to the simulator but
+\emph on
+newcdb
+\emph default
+ at
+\begin_inset LatexCommand \url{http://ec2drv.sf.net/}
+
+\end_inset
+
+ is an effort to connect directly to the hardware.)
+\end_layout
+
+\begin_layout Subsection
+Starting the Debugger SDCDB
+\end_layout
+
+\begin_layout Standard
+The debugger can be started using the following command line.
+ (Assume the file you are debugging has the file name foo).
+\newline
+
+\newline
+
+\family sans
+\series bold
+sdcdb foo
+\newline
+
+\family default
+\series default
+
+\newline
+The debugger will look for the following files.
+\end_layout
+
+\begin_layout Itemize
+foo.c - the source file.
+\end_layout
+
+\begin_layout Itemize
+foo.cdb - the debugger symbol information file.
+\end_layout
+
+\begin_layout Itemize
+foo.ihx - the Intel hex format
+\begin_inset LatexCommand \index{Intel hex format}
+
+\end_inset
+
+ object file.
+\end_layout
+
+\begin_layout Subsection
+SDCDB Command Line Options
+\end_layout
+
+\begin_layout Itemize
+-
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-directory=<source file directory> this option can used to specify the directory
+ search list.
+ The debugger will look into the directory list specified for source, cdb
+ & ihx files.
+ The items in the directory list must be separated by ':', e.g.
+ if the source files can be in the directories /home/src1 and /home/src2,
+ the -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-directory option should be -
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+-directory=/home/src1:/home/src2.
+ Note there can be no spaces in the option.
+
+\end_layout
+
+\begin_layout Itemize
+-cd <directory> - change to the <directory>.
+\end_layout
+
+\begin_layout Itemize
+-fullname - used by GUI front ends.
+\end_layout
+
+\begin_layout Itemize
+-cpu <cpu-type> - this argument is passed to the simulator please see the
+ simulator docs for details.
+\end_layout
+
+\begin_layout Itemize
+-X <Clock frequency > this options is passed to the simulator please see
+ the simulator docs for details.
+\end_layout
+
+\begin_layout Itemize
+-s <serial port file> passed to simulator see the simulator docs for details.
+\end_layout
+
+\begin_layout Itemize
+-S <serial in,out> passed to simulator see the simulator docs for details.
+\end_layout
+
+\begin_layout Itemize
+-k <port number> passed to simulator see the simulator docs for details.
+\end_layout
+
+\begin_layout Subsection
+SDCDB Debugger Commands
+\end_layout
+
+\begin_layout Standard
+As mentioned earlier the command interface for the debugger has been deliberatel
+y kept as close the GNU debugger gdb, as possible.
+ This will help the integration with existing graphical user interfaces
+ (like ddd, xxgdb or xemacs) existing for the GNU debugger.
+ If you use a graphical user interface for the debugger you can skip this
+ section.
+\end_layout
+
+\begin_layout Subsubsection*
+break [line | file:line | function | file:function]
+\end_layout
+
+\begin_layout Standard
+Set breakpoint at specified line or function:
+\newline
+
+\newline
+
+\family sans
+\series bold
+sdcdb>break 100
+\newline
+sdcdb>break foo.c:100
+\newline
+sdcdb>break funcfoo
+\newline
+sdcdb>break foo.c:funcfoo
+\end_layout
+
+\begin_layout Subsubsection*
+clear [line | file:line | function | file:function ]
+\end_layout
+
+\begin_layout Standard
+Clear breakpoint at specified line or function:
+\newline
+
+\newline
+
+\family sans
+\series bold
+sdcdb>clear 100
+\newline
+sdcdb>clear foo.c:100
+\newline
+sdcdb>clear funcfoo
+\newline
+sdcdb>clear foo.c:funcfoo
+\end_layout
+
+\begin_layout Subsubsection*
+continue
+\end_layout
+
+\begin_layout Standard
+Continue program being debugged, after breakpoint.
+\end_layout
+
+\begin_layout Subsubsection*
+finish
+\end_layout
+
+\begin_layout Standard
+Execute till the end of the current function.
+\end_layout
+
+\begin_layout Subsubsection*
+delete [n]
+\end_layout
+
+\begin_layout Standard
+Delete breakpoint number 'n'.
+ If used without any option clear ALL user defined break points.
+\end_layout
+
+\begin_layout Subsubsection*
+info [break | stack | frame | registers ]
+\end_layout
+
+\begin_layout Itemize
+info break - list all breakpoints
+\end_layout
+
+\begin_layout Itemize
+info stack - show the function call stack.
+\end_layout
+
+\begin_layout Itemize
+info frame - show information about the current execution frame.
+\end_layout
+
+\begin_layout Itemize
+info registers - show content of all registers.
+\end_layout
+
+\begin_layout Subsubsection*
+step
+\end_layout
+
+\begin_layout Standard
+Step program until it reaches a different source line.
+ Note: pressing <return> repeats the last command.
+\end_layout
+
+\begin_layout Subsubsection*
+next
+\end_layout
+
+\begin_layout Standard
+Step program, proceeding through subroutine calls.
+\end_layout
+
+\begin_layout Subsubsection*
+run
+\end_layout
+
+\begin_layout Standard
+Start debugged program.
+\end_layout
+
+\begin_layout Subsubsection*
+ptype variable
+\end_layout
+
+\begin_layout Standard
+Print type information of the variable.
+\end_layout
+
+\begin_layout Subsubsection*
+print variable
+\end_layout
+
+\begin_layout Standard
+print value of variable.
+\end_layout
+
+\begin_layout Subsubsection*
+file filename
+\end_layout
+
+\begin_layout Standard
+load the given file name.
+ Note this is an alternate method of loading file for debugging.
+\end_layout
+
+\begin_layout Subsubsection*
+frame
+\end_layout
+
+\begin_layout Standard
+print information about current frame.
+\end_layout
+
+\begin_layout Subsubsection*
+set srcmode
+\end_layout
+
+\begin_layout Standard
+Toggle between C source & assembly source.
+\end_layout
+
+\begin_layout Subsubsection*
+! simulator command
+\end_layout
+
+\begin_layout Standard
+Send the string following '!' to the simulator, the simulator response is
+ displayed.
+ Note the debugger does not interpret the command being sent to the simulator,
+ so if a command like 'go' is sent the debugger can loose its execution
+ context and may display incorrect values.
+\end_layout
+
+\begin_layout Subsubsection*
+quit
+\end_layout
+
+\begin_layout Standard
+"Watch me now.
+ Iam going Down.
+ My name is Bobby Brown"
+\end_layout
+
+\begin_layout Subsection
+Interfacing SDCDB with DDD
+\end_layout
+
+\begin_layout Standard
+\begin_inset Note Note
+status collapsed
+
+\begin_layout Standard
+The screenshot was converted from png to eps with:
+\begin_inset Quotes sld
+\end_inset
+
+bmeps -c -e8f -p3 ddd_example.png >ddd_example.eps
+\begin_inset Quotes srd
+\end_inset
+
+ which produces a pretty compact eps file which is free from compression
+ artifacts.
+\end_layout
+
+\begin_layout Standard
+The screenshot was included in sdccman.lyx cvs version 1.120 but later removed
+ as this broke the build system on Sourceforge (pdf-file was broken.
+ pdflatex does not accept eps files).
+\end_layout
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+The
+\emph on
+p
+\emph default
+ortable
+\emph on
+n
+\emph default
+etwork
+\emph on
+g
+\emph default
+raphics File
+\size footnotesize
+
+\begin_inset LatexCommand \url{http://sdcc.svn.sourceforge.net/viewvc/*checkout*/sdcc/trunk/sdcc/doc/figures/ddd_example.png}
+
+\end_inset
+
+
+\size default
+ shows a screenshot of a debugging session with DDD
+\begin_inset LatexCommand \index{DDD (debugger)}
+
+\end_inset
+
+ (Unix only) on a simulated 8032.
+ The debugging session might not run as smoothly as the screenshot suggests.
+ The debugger allows setting of breakpoints, displaying and changing variables,
+ single stepping through C and assembler code.
+
+\newline
+The source was compiled with
+\family sans
+\series bold
+
+\newline
+
+\newline
+sdcc -
+\family default
+\series default
+
+\begin_inset ERT
+status collapsed
+
+\begin_layout Standard
+
+
+\backslash
+/
+\end_layout
+
+\end_inset
+
+
+\family sans
+\series bold
+-debug ddd_example.c
+\family default
+\series default
+
+\family sans
+\series bold
+
+\newline
+
+\family default
+\series default
+
+\newline
+and DDD was invoked with
+\family sans
+\series bold
+
+\newline
+
+\newline
+ddd -debugger "sdcdb -cpu 8032 ddd_example"
+\end_layout
+
+\begin_layout Standard
+\begin_inset Note Note
+status open
+
+\begin_layout Standard
+Check that the double quotes or an apostroph within the command line survive
+ the LyX tool chain.
+ Previously the apostrophs got slanted in the PDF output so a cut and paste
+ did not work.
+\end_layout
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Subsection
+Interfacing SDCDB with XEmacs
+\begin_inset LatexCommand \index{XEmacs}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{Emacs}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+Two files (in emacs lisp) are provided for the interfacing with XEmacs,
+ sdcdb.el and sdcdbsrc.el.
+ These two files can be found in the $(prefix)/bin directory after the installat
+ion is complete.
+ These files need to be loaded into XEmacs for the interface to work.
+ This can be done at XEmacs startup time by inserting the following into
+ your '.xemacs' file (which can be found in your HOME directory):
+\newline
+
+\newline
+
+\family typewriter
+(load-file sdcdbsrc.el)
+\family default
+
+\newline
+
+\newline
+.xemacs is a lisp file so the () around the command is REQUIRED.
+ The files can also be loaded dynamically while XEmacs is running, set the
+ environment variable 'EMACSLOADPATH' to the installation bin directory
+ (<installdir>/bin), then enter the following command ESC-x load-file sdcdbsrc.
+ To start the interface enter the following command:
+\newline
+
+\newline
+
+\family sans
+\series bold
+ESC-x sdcdbsrc
+\family default
+\series default
+
+\newline
+
+\newline
+You will prompted to enter the file name to be debugged.
+
+\newline
+
+\newline
+The command line options that are passed to the simulator directly are
+ bound to default values in the file sdcdbsrc.el.
+ The variables are listed below, these values maybe changed as required.
+\end_layout
+
+\begin_layout Itemize
+sdcdbsrc-cpu-type '51
+\end_layout
+
+\begin_layout Itemize
+sdcdbsrc-frequency '11059200
+\end_layout
+
+\begin_layout Itemize
+sdcdbsrc-serial nil
+\end_layout
+
+\begin_layout Standard
+The following is a list of key mapping for the debugger interface.
+\end_layout
+
+\begin_layout Standard
+\InsetSpace ~
+
+\family typewriter
+
+\newline
+;;\InsetSpace ~
+Current Listing ::
+\newline
+;;key\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+binding\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+Comment
+\newline
+;;---\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+-------\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+-------
+\newline
+;;
+\newline
+;;\InsetSpace ~
+n\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+sdcdb-next-fro
+m-src\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+SDCDB next command
+\newline
+;;\InsetSpace ~
+b\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+sdcdb-back-from-src\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+SDCDB back command
+\newline
+;;\InsetSpace ~
+c\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+sdcdb-cont-f
+rom-src\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+SDCDB continue command
+\newline
+;;\InsetSpace ~
+s\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+sdcdb-step-from-src\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+SDCDB step command
+\newline
+;;\InsetSpace ~
+?\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+sdcdb-w
+hatis-c-sexp\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+SDCDB ptypecommand for data at
+\newline
+;;\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+buffer point
+\newline
+;;\InsetSpace ~
+x\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+sdcdbsrc-delete\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+SDCD
+B Delete all breakpoints if no arg
+\newline
+;;\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+given or delete arg (C-u arg x)
+\newline
+;;\InsetSpace ~
+m\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+sdcdbsrc
+-frame\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+SDCDB Display current frame if no arg,
+\newline
+;;\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+given or display frame arg
+
+\newline
+;;\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+buffer point
+\newline
+;;\InsetSpace ~
+!\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+sdcdbsrc-goto-sdcdb\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+Goto the SDCDB output buffer
+\newline
+;;\InsetSpace ~
+p\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+sdcdb-prin
+t-c-sexp\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+SDCDB print command for data at
+\newline
+;;\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+buffer point
+\newline
+;;\InsetSpace ~
+g\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+sdcdbsrc-goto-sdcdb\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+Got
+o the SDCDB output buffer
+\newline
+;;\InsetSpace ~
+t\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+sdcdbsrc-mode\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+Toggles Sdcdbsrc mode (turns it
+ off)
+\newline
+;;
+\newline
+;;\InsetSpace ~
+C-c\InsetSpace ~
+C-f\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+sdcdb-finish-from-src\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+SDCDB finish command
+\newline
+;;
+\newline
+;;\InsetSpace ~
+C-x\InsetSpace ~
+SPC\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+sdcdb-brea
+k\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+Set break for line with point
+\newline
+;;\InsetSpace ~
+ESC\InsetSpace ~
+t\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+sdcdbsrc-mode\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+Toggle Sdcdbsrc mode
+\newline
+;;\InsetSpace ~
+ESC\InsetSpace ~
+m\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+sdc
+dbsrc-srcmode\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+Toggle list mode
+\newline
+;;
+\newline
+
+\family default
+
+\newpage
+
+\end_layout
+
+\begin_layout Chapter
+TIPS
+\end_layout
+
+\begin_layout Standard
+Here are a few guidelines that will help the compiler generate more efficient
+ code, some of the tips are specific to this compiler others are generally
+ good programming practice.
+\end_layout
+
+\begin_layout Itemize
+Use the smallest data type to represent your data-value.
+ If it is known in advance that the value is going to be less than 256 then
+ use an 'unsigned char' instead of a 'short' or 'int'.
+ Please note, that ANSI C requires both signed and unsigned chars to be
+ promoted to 'signed int'
+\begin_inset LatexCommand \index{promotion to signed int}
+
+\end_inset
+
+
+\begin_inset Marginal
+status collapsed
+
+\begin_layout Standard
+
+\series bold
+\InsetSpace ~
+!
+\end_layout
+
+\end_inset
+
+ before doing any operation.
+ This promotion
+\begin_inset LatexCommand \index{type promotion}
+
+\end_inset
+
+
+\begin_inset LatexCommand \label{type promotion}
+
+\end_inset
+
+ can be omitted, if the result is the same.
+ The effect of the promotion rules together with the sign-extension is often
+ surprising:
+\end_layout
+
+\begin_deeper
+\begin_layout Verse
+
+\family typewriter
+unsigned char uc = 0xfe;
+\newline
+if (uc * uc < 0) /* this is true! */
+\newline
+{
+\newline
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
+....
+\newline
+}
+\end_layout
+
+\begin_layout Standard
+
+\family typewriter
+uc * uc
+\family default
+ is evaluated as
+\family typewriter
+(int) uc * (int) uc = (int) 0xfe * (int) 0xfe = (int) 0xfc04 = -1024
+\family default
+.
+
+\newline
+Another one:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+(unsigned char) -12 / (signed char) -3 = ...
+\end_layout
+
+\begin_layout Standard
+No, the result is not 4:
+\end_layout
+
+\begin_layout Verse
+
+\family typewriter
+(int) (unsigned char) -12 / (int) (signed char) -3 =
+\newline
+(int) (unsigned char)
+ 0xf4 / (int) (signed char) 0xfd =
+\newline
+(int) 0x00f4 / (int) 0xfffd =
+\newline
+(int) 0x00f4
+ / (int) 0xfffd =
+\newline
+(int) 244 / (int) -3 =
+\newline
+(int) -81 = (int) 0xffaf;
+\end_layout
+
+\begin_layout Standard
+Don't complain, that gcc gives you a different result.
+ gcc uses 32 bit ints, while SDCC uses 16 bit ints.
+ Therefore the results are different.
+\newline
+From
+\begin_inset Quotes sld
+\end_inset
+
+comp.lang.c FAQ
+\begin_inset Quotes srd
+\end_inset
+
+:
+\end_layout
+
+\begin_layout Quote
+
+\emph on
+If well-defined overflow characteristics are important and negative values
+ are not, or if you want to steer clear of sign-extension problems when
+ manipulating bits or bytes, use one of the corresponding unsigned types.
+ (Beware when mixing signed and unsigned values in expressions, though.)
+\newline
+Although
+ character types (especially unsigned char) can be used as "tiny" integers,
+ doing so is sometimes more trouble than it's worth, due to unpredictable
+ sign extension and increased code size.
+\end_layout
+
+\end_deeper
+\begin_layout Itemize
+Use unsigned when it is known in advance that the value is not going to
+ be negative.
+ This helps especially if you are doing division or multiplication, bit-shifting
+ or are using an array index.
+\end_layout
+
+\begin_layout Itemize
+NEVER jump into a LOOP.
+\end_layout
+
+\begin_layout Itemize
+Declare the variables to be local
+\begin_inset LatexCommand \index{local variables}
+
+\end_inset
+
+ whenever possible, especially loop control variables (induction).
+\end_layout
+
+\begin_layout Itemize
+Have a look at the assembly listing to get a
+\begin_inset Quotes sld
+\end_inset
+
+feeling
+\begin_inset Quotes srd
+\end_inset
+
+ for the code generation.
+\end_layout
+
+\begin_layout Section
+Porting code from or to other compilers
+\begin_inset LatexCommand \label{sec:Porting-code-to-other-compilers}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Itemize
+check whether endianness of the compilers differs and adapt where needed.
+\end_layout
+
+\begin_layout Itemize
+check the device specific header files
+\begin_inset LatexCommand \index{Header files}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{Include files}
+
+\end_inset
+
+ for compiler specific syntax.
+ Eventually include the file <compiler.h
+\begin_inset LatexCommand \index{compiler.h (include file)}
+
+\end_inset
+
+>
+\begin_inset LatexCommand \url{http://sdcc.svn.sourceforge.net/viewvc/sdcc/trunk/sdcc/device/include/mcs51/compiler.h?view=markup}
+
+\end_inset
+
+ to allow using common header files.
+ (see f.e.
+ cc2510fx.h
+\begin_inset LatexCommand \url{http://sdcc.svn.sourceforge.net/viewvc/sdcc/trunk/sdcc/device/include/mcs51/cc2510fx.h?view=markup}
+
+\end_inset
+
+).
+\end_layout
+
+\begin_layout Itemize
+check whether the startup code contains the correct initialization (watchdog,
+ peripherals).
+\end_layout
+
+\begin_layout Itemize
+check whether the sizes of short, int, long match.
+\end_layout
+
+\begin_layout Itemize
+check if some 16 or 32 bit hardware registers require a specific addressing
+ order (least significant or most significant byte first) and adapt if needed
+ (
+\emph on
+first
+\emph default
+ and
+\emph on
+last
+\emph default
+ relate to time and not to lower/upper memory location here, so this is
+
+\emph on
+not
+\emph default
+ the same as endianness).
+\end_layout
+
+\begin_layout Itemize
+check whether the keyword
+\emph on
+volatile
+\emph default
+ is used where needed.
+ The compilers might differ in their optimization characteristics (as different
+ versions of the same compiler might also use more clever optimizations
+ this is good idea anyway).
+ See section
+\begin_inset LatexCommand \ref{sub:Common-interrupt-pitfall-volatile}
+
+\end_inset
+
+.
+\end_layout
+
+\begin_layout Itemize
+check that the compilers are not told to supress warnings.
+\end_layout
+
+\begin_layout Itemize
+check and convert compiler specific extensions (interrupts, memory areas,
+ pragmas etc.).
+\end_layout
+
+\begin_layout Itemize
+check for differences in type promotion.
+ Especially check for math operations on
+\family typewriter
+char
+\family default
+ or
+\family typewriter
+unsigned char
+\family default
+ variables.
+ For the sake of C99 compatibility SDCC will probably promote these to
+\family typewriter
+int
+\family default
+ more often than other compilers.
+ Eventually insert explicit casts to
+\family typewriter
+(char)
+\family default
+or
+\family typewriter
+ (unsigned char)
+\family default
+.
+ Also check that the ~\InsetSpace ~
+operator
+\begin_inset LatexCommand \index{\~\/ Operator}
+
+\end_inset
+
+ is not used on
+\family typewriter
+bit
+\begin_inset LatexCommand \index{bit}
+
+\end_inset
+
+
+\family default
+ variables, use the !\InsetSpace ~
+operator instead.
+ See sections
+\begin_inset LatexCommand \ref{type promotion}
+
+\end_inset
+
+ and
+\begin_inset LatexCommand \ref{sec:Compatibility-with-previous}
+
+\end_inset
+
+.
+\end_layout
+
+\begin_layout Itemize
+check the assembly code generated for interrupt routines (f.e.
+ for calls to possibly non-reentrant library functions).
+\end_layout
+
+\begin_layout Itemize
+check whether timing loops result in proper timing (or preferably consider
+ a rewrite of the code with timer based delays instead).
+\end_layout
+
+\begin_layout Itemize
+check for differences in printf parameters (some compilers push (va_arg
+\begin_inset LatexCommand \index{vararg, va\_arg}
+
+\end_inset
+
+) char variables as
+\family typewriter
+int
+\family default
+ others push them as
+\family typewriter
+char
+\family default
+.
+ See section
+\begin_inset LatexCommand \ref{sec:Compatibility-with-previous}
+
+\end_inset
+
+).
+\end_layout
+
+\begin_layout Itemize
+check the resulting memory map
+\begin_inset LatexCommand \index{Memory map}
+
+\end_inset
+
+.
+ Usage of different memory spaces: code, stack, data (for mcs51/ds390 additional
+ly idata, pdata, xdata).
+ Eventually check if unexpected library functions are included.
+\end_layout
+
+\begin_layout Section
+Tools
+\begin_inset LatexCommand \index{Tools}
+
+\end_inset
+
+ included in the distribution
+\end_layout
+
+\begin_layout Standard
+\align left
+\begin_inset Tabular
+<lyxtabular version="3" rows="12" columns="3">
+<features>
+<column alignment="left" valignment="top" leftline="true" width="0pt">
+<column alignment="left" valignment="top" leftline="true" width="0pt">
+<column alignment="left" valignment="top" leftline="true" rightline="true" width="0pt">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\series bold
+Name
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\series bold
+Purpose
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+
+\series bold
+Directory
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+uCsim
+\begin_inset LatexCommand \index{uCsim}
+
+\end_inset
+
+
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+Simulator for various architectures
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+sdcc/sim/ucsim
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+keil2sdcc.pl
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+header file
+\begin_inset LatexCommand \index{Header files}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{Include files}
+
+\end_inset
+
+ conversion
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+sdcc/support/scripts
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+mh2h.c
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+header file conversion
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard