\size footnotesize
\newline
-$Date$
+$Date:: $
\newline
$Revision$
\family typewriter
signed
\family default
-. In some embedded enviornments the default signedness of
+.
+ In some embedded environments the default signedness of
\family typewriter
char
\family default
\family typewriter
unsigned
\family default
-. To set the signess for characters to unsigned, use the option --funsigned-char.
- If this option is set and no signedness keyword (unsigned/signed) is given, a char will be signed.
+.
+ To set the signess for characters to unsigned, use the option --funsigned-char.
+ If this option is set and no signedness keyword (unsigned/signed) is given,
+ a char will be signed.
All other types are unaffected.
\layout List
\layout Standard
+\backslash
+/
+
+\end_inset
+
+-no-gen-comments
+\begin_inset LatexCommand \index{-\/-no-gen-comments}
+
+\end_inset
+
+
+\series default
+ Will not include code generator comments in the generated files.
+
+\layout List
+\labelwidthstring 00.00.0000
+
+\series bold
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+
\backslash
/
\layout Verse
\family typewriter
-volatile
-\begin_inset LatexCommand \index{volatile}
+volatile
+\begin_inset LatexCommand \index{volatile}
+
+\end_inset
+
+ bit resource_is_free;
+\newline
+
+\newline
+if (resource_is_free)
+\newline
+\SpecialChar ~
+\SpecialChar ~
+{
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+resource_is_free=0;
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+...
+
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+resource_is_free=1;
+\newline
+\SpecialChar ~
+\SpecialChar ~
+}
+
+\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).
+
+\layout Section
+Functions using private register banks
+\begin_inset LatexCommand \label{sub:Functions-using-private-banks}
+
+\end_inset
+
+ (mcs51/ds390)
+
+\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.
+
+\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
+collapsed false
+
+\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_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
+)
+
+\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.
+
+\layout Standard
+\added_space_bottom bigskip
+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.
+
+
+
+
+\layout Section
+Startup Code
+\begin_inset LatexCommand \label{sub:Startup-Code}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{Startup code}
+
+\end_inset
+
+
+
+\layout Subsection
+MCS51/DS390 Startup Code
+
+\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:
+
+\layout Verse
+
+\family typewriter
+\series bold
+\size footnotesize
+(main.asm)
+
+\layout Verse
+
+\family typewriter
+\size footnotesize
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+.area HOME (CODE)
+\newline
+__interrupt_vect:
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ljmp __sdcc_gsinit_startup
+
+\layout Verse
+
+\family typewriter
+\series bold
+\size footnotesize
+(crtstart.asm)
+
+\layout Verse
+
+\family typewriter
+\size footnotesize
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+.area GSINIT0 (CODE)
+\newline
+__sdcc_gsinit_startup::
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov sp,#__start__stack - 1
+
+\layout Verse
+
+\family typewriter
+\series bold
+\size footnotesize
+(crtxstack.asm)
+
+\layout Verse
+
+\family typewriter
+\size footnotesize
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+.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
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov __XPAGE,#(__start__x
+stack >> 8)
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov _spx,#__start__xstack
+
+\layout Verse
+
+\family typewriter
+\series bold
+\size footnotesize
+(crtstart.asm)
+
+\layout Verse
+
+\family typewriter
+\size footnotesize
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+.area GSINIT2 (CODE)
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+lcall __sdcc_external_startup
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov a,dpl
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+jz __sdcc_init_data
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ljmp
+ __sdcc_program_startup
+\newline
+__sdcc_init_data:
+
+\layout Verse
+
+\family typewriter
+\series bold
+\size footnotesize
+(crtxinit.asm)
+
+\layout Verse
+
+\family typewriter
+\size footnotesize
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+.area GSINIT3 (CODE)
+\newline
+__mcs51_genXINIT::
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov r1,#l_XINIT
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov a,r1
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+orl a,#(l_XINIT
+ >> 8)
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+jz 00003$
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov r2,#((l_XINIT+255) >> 8)
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov dptr,#s_XINIT
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov r0,#s_XISEG
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov
+ __XPAGE,#(s_XISEG >> 8)
+\newline
+00001$:\SpecialChar ~
+clr a
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+movc a,@a+dptr
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+movx @r0,a
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+inc dptr
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+inc
+ r0
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+cjne r0,#0,00002$
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+inc __XPAGE
+\newline
+00002$:\SpecialChar ~
+djnz r1,00001$
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+djnz r2,00001$
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov __XPAGE,#0
+xFF
+\newline
+00003$:
+
+\layout Verse
+
+\family typewriter
+\series bold
+\size footnotesize
+(crtclear.asm)
+
+\layout Verse
+
+\family typewriter
+\size footnotesize
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+.area GSINIT4 (CODE)
+\newline
+__mcs51_genRAMCLEAR::
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+clr a
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov r0,#(l_IRAM-1)
+\newline
+00004$:\SpecialChar ~
+mov
+ @r0,a
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+djnz r0,00004$
+\newline
+; _mcs51_genRAMCLEAR() end
+
+\layout Verse
+
+\family typewriter
+\series bold
+\size footnotesize
+(crtxclear.asm)
+
+\layout Verse
+
+\family typewriter
+\size footnotesize
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+.area GSINIT4 (CODE)
+\newline
+__mcs51_genXRAMCLEAR::
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov r0,#l_PSEG
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov a,r0
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+jz 00006$
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov
+ r1,#s_PSEG
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov __XPAGE,#(s_PSEG >> 8)
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+clr a
+\newline
+00005$:\SpecialChar ~
+movx @r1,a
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+inc r1
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+djnz r0,00005$
+\newline
+0
+0006$:
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov r0,#l_XSEG
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov a,r0
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+orl a,#(l_XSEG >> 8)
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+jz 00008$
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov r1,#((l_XSEG
+ + 255) >> 8)
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov dptr,#s_XSEG
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+clr a
+\newline
+00007$:\SpecialChar ~
+movx @dptr,a
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+inc dptr
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+djnz r0,00007$
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+djnz
+ r1,00007$
+\newline
+00008$:
+
+\layout Verse
+
+\family typewriter
+\series bold
+\size footnotesize
+(crtxstack.asm)
+
+\layout Verse
+
+\family typewriter
+\size footnotesize
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+.area GSINIT5 (CODE)
+\newline
+; Need to initialize in GSINIT5 because __mcs51_genXINIT
+ modifies __XPAGE
+\newline
+; and __mcs51_genRAMCLEAR modifies _spx.
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov __XPAGE,#(__start__x
+stack >> 8)
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov _spx,#__start__xstack
+
+\layout Verse
+
+\family typewriter
+\series bold
+\size footnotesize
+(application modules)
+
+\layout Verse
+
+\family typewriter
+\size footnotesize
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+.area GSINIT (CODE)
+
+\layout Verse
+
+\family typewriter
+\series bold
+\size footnotesize
+(main.asm)
-\end_inset
+\layout Verse
- bit resource_is_free;
+\family typewriter
+\size footnotesize
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+.area GSFINAL (CODE)
\newline
-
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ljmp __sdcc_program_startup
\newline
-if (resource_is_free)
+;---------------------------------
+-----------------------
+\newline
+; Home
+\newline
+;--------------------------------------------------
+------
\newline
\SpecialChar ~
\SpecialChar ~
-{
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-resource_is_free=0;
+\SpecialChar ~
+\SpecialChar ~
+.area HOME (CODE)
\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-...
-
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-resource_is_free=1;
+.area CSEG (CODE)
+\newline
+__sdcc_program_startup:
\newline
\SpecialChar ~
\SpecialChar ~
-}
-
-\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).
-
-\layout Section
-Functions using private register banks
-\begin_inset LatexCommand \label{sub:Functions-using-private-banks}
-
-\end_inset
-
- (mcs51/ds390)
-
-\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.
-
-\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
-collapsed false
-
-\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_inset
-
-).
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+lcall _main
\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
-)
-
-\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.
-
-\layout Standard
-\added_space_bottom bigskip
-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.
-
-
-
-
-\layout Section
-Startup Code
-\begin_inset LatexCommand \label{sub:Startup-Code}
-
-\end_inset
-
-
-\begin_inset LatexCommand \index{Startup code}
-
-\end_inset
-
-
-
-\layout Subsection
-MCS51/DS390 Startup Code
+;
+ return from main will lock up
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+sjmp .
\layout Standard
-The compiler inserts a call to the C routine
+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()}
\series default
at the start of the CODE area.
- This routine is in the runtime library
+ This routine is also in the runtime library
\begin_inset LatexCommand \index{Runtime library}
\end_inset
-.
- By default this routine returns 0, if this routine returns a non-zero value,
- the static & global variable initialization will be skipped and the function
- main will be invoked.
+ 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 a
+ You could add an
\emph on
_sdcc_external_startup()
\emph default
not
\emph default
support long variables and field widths).
- Be sure to only use only one of these printf options within a project.
+ Be sure to use only one of these printf options within a project.
\newline
\layout Verse
\family typewriter
-__sfr __at (0x92) _XPAGE; /* Cypress EZ-USB family */
+__sfr __at (0x85) _XPAGE; /* Ramtron VRS51 family a.k.a.
+ MPAGE */
+
+\layout Verse
+
+\family typewriter
+__sfr __at (0x92) _XPAGE; /* Cypress EZ-USB family, Texas Instruments (Chipcon)
+ a.k.a.
+ MPAGE */
\layout Verse
\family typewriter
-__sfr __at (0xaf) _XPAGE; /* some Silicon Labs (Cygnal) chips */
+__sfr __at (0x91) _XPAGE; /* Infineon (Siemens) C500 family a.k.a.
+ XPAGE */
\layout Verse
\family typewriter
-__sfr __at (0xaa) _XPAGE; /* some Silicon Labs (Cygnal) chips */
+__sfr __at (0xaf) _XPAGE; /* some Silicon Labs (Cygnal) chips a.k.a.
+ EMI0CN */
+
+\layout Verse
+
+\family typewriter
+__sfr __at (0xaa) _XPAGE; /* some Silicon Labs (Cygnal) chips a.k.a.
+ EMI0CN */
\layout Standard
For more exotic implementations further customizations may be needed.
inline assembly and so are not yet usable.
\layout Standard
-\added_space_bottom bigskip
\pagebreak_bottom
+\added_space_bottom bigskip
The HC08 port passes the regression test suite (see section
\begin_inset LatexCommand \ref{sec:Quality-control}
pages and there's less page selection overhead.
\layout Enumerate
- And as for any 8 bit micro (especially for PIC 14 as they have a very simple
+And as for any 8 bit micro (especially for PIC 14 as they have a very simple
instruction set), use 'unsigned char' whereever possible instead of 'int'.
\layout Subsection
initialized data
\layout Standard
-Currently, data can only be initialized if it resides in the source file
\pagebreak_bottom
+Currently, data can only be initialized if it resides in the source file
together with
\emph on
main()
\end_inset
+\family default
+
\layout Section
The following is a list of key mapping for the debugger interface.
\layout Standard
-\SpecialChar ~
\pagebreak_bottom
+\SpecialChar ~
\family typewriter
;;
\newline
+\family default
+
\layout Chapter
see a world wide impact
\layout Standard
-then SDCC is probably among the first choices.
\pagebreak_bottom
+then SDCC is probably among the first choices.
Well, probably SDCC might be the only choice.
projects / fw / sdcc / blobdiff