<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
<HTML>
<HEAD>
- <META NAME="GENERATOR" CONTENT="SGML-Tools 1.0.9">
- <TITLE>SDCC Compiler User Guide: Interfacing with assembly routines.</TITLE>
+ <META NAME="GENERATOR" CONTENT="SGML-Tools 1.0.7">
+ <TITLE>SDCC Compiler User Guide: Library routines.</TITLE>
<LINK HREF="SDCCUdoc-21.html" REL=next>
<LINK HREF="SDCCUdoc-19.html" REL=previous>
<LINK HREF="SDCCUdoc.html#toc20" REL=contents>
<A HREF="SDCCUdoc-19.html">Previous</A>
<A HREF="SDCCUdoc.html#toc20">Contents</A>
<HR>
-<H2><A NAME="Interface_asm"></A> <A NAME="s20">20. Interfacing with assembly routines.</A> </H2>
+<H2><A NAME="Library"></A> <A NAME="s20">20. Library routines.</A> </H2>
-<H2><A NAME="ss20.1">20.1 Global registers used for parameter passing.</A>
- </H2>
-
-<P>By default the compiler uses the global registers "DPL,DPH,B,ACC" to pass
-the first parameter to a routine, the second parameter onwards is either allocated
-on the stack (for reentrant routines or --stack-auto is used) or in the internal
-/ external ram (depending on the memory model).
-<H3>Assembler routine non-reentrant </H3>
-
-<P>In the following example the function<B> cfunc</B> calls an assembler routine
-<B>asm_func</B>, which takes two parameters.
-<P>extern int asm_func( unsigned short, unsigned short);
-<P>
-<PRE>
-
-int c_func (unsigned short i, unsigned short j)
-{
- return
- asm_func(i,j);
-}
-int main()
-{
- return c_func(10,9);
-}
-
-</PRE>
-<P>The corresponding assembler function is:-
-<P>
-<PRE>
- .globl _asm_func_PARM_2
- .globl _asm_func
- .area
- OSEG
-_asm_func_PARM_2: .ds 1
- .area CSEG
-_asm_func:
-
- mov a,dpl
- add a,_asm_func_PARM_2
- mov dpl,a
-
- mov dpl,#0x00
- ret
-
-</PRE>
-<P>Note here that the return values are placed in 'dpl' - One byte return
-value, 'dpl' LSB & 'dph' MSB for two byte values. 'dpl', 'dph' and 'b'
-for three byte values (generic pointers) and 'dpl','dph','b' & 'acc' for
-four byte values.
-<P>The parameter naming convention is <B>_<function_name>_PARM_<n>,</B>
-where n is the parameter number starting from 1, and counting from the left.
-The first parameter is passed in "dpl" for One bye parameter, "dptr" if two bytes,
-"b,dptr" for three bytes and "acc,b,dptr" for four bytes, the <CODE></CODE><CODE><B>varaible name for
-the second parameter will be _<function_name>_PARM_2.</B></CODE>
-<P>Assemble the assembler routine with the following command.
-<P>
-<PRE>
-asx8051 -losg asmfunc.asm
-
-</PRE>
-<P>Then compile and link the assembler routine to the C source file with the
-following command,
-<P>
-<PRE>
-sdcc cfunc.c asmfunc.rel
-
-</PRE>
-<H3>Assembler routine is reentrant </H3>
-
-<P>In this case the second parameter onwards will be passed on the stack ,
-the parameters are pushed from right to left i.e. after the call the left most
-parameter will be on the top of the stack. Here is an example.
-<P>extern int asm_func( unsigned short, unsigned short);
-<P>
-<PRE>
- int c_func (unsigned short i, unsigned short j) reentrant
-{
-
- return asm_func(i,j);
-}
-int main()
-{
- return c_func(10,9);
-
-}
-
-</PRE>
-<P>The corresponding assembler routine is.
-<P>
-<PRE>
- .globl _asm_func
-_asm_func:
- push _bp
- mov _bp,sp
-
- mov r2,dpl
- mov a,_bp
- clr c
- add a,#0xfd
-
- mov r0,a
- add a,#0xfc
- mov r1,a
- mov
- a,@r0
- add a,r2
- mov dpl,a
- mov dph,#0x00
-
- mov sp,_bp
- pop _bp
- ret
-
-</PRE>
-<P>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.
-<H2><A NAME="ss20.2">20.2 With --noregparms option.</A>
- </H2>
-
-<P>When the source is compiled with --noregparms option , space is allocated
-for each of the parameters passed to a routine.
-<H3>Assembler routine non-reentrant. </H3>
-
-<P>In the following example the function<B> cfunc</B> calls an assembler routine
-<B>asm_func</B>, which takes two parameters.
-<P>
-<PRE>
-extern int asm_func( unsigned short, unsigned short);
-int c_func (unsigned short i, unsigned short j)
-{
- return
- asm_func(i,j);
-}
-int main()
-{
- return c_func(10,9);
-}
-
-</PRE>
-<P>The corresponding assembler function is:-
-<P>
-<PRE>
- .globl _asm_func_PARM_1
- .globl _asm_func_PARM_2
-
- .globl _asm_func
- .area OSEG
-_asm_func_PARM_1: .ds 1
-_asm_func_PARM_2:
- .ds 1
- .area CSEG
-_asm_func:
- mov a,_asm_func_PARM_1
-
- add a,_asm_func_PARM_2
- mov dpl,a
- mov
- dpl,#0x00
- ret
-
-</PRE>
-<P>Note here that the return values are placed in 'dpl' - One byte return
-value, 'dpl' LSB & 'dph' MSB for two byte values. 'dpl', 'dph' and 'b'
-for three byte values (generic pointers) and 'dpl','dph','b' & 'acc' for
-four byte values.
-<P>The parameter naming convention is <B>_<function_name>_PARM_<n>,</B>
-where n is the parameter number starting from 1, and counting from the left.
-i.e. the <CODE></CODE><CODE><B>left-most parameter name will be _<function_name>_PARM_1.</B></CODE>
-<P>Assemble the assembler routine with the following command.
+<P>The following library routines are provided for your convenience.
+<P><B>stdio.h </B>- Contains the following functions printf & sprintf these routines
+are developed by Martijn van Balen <balen@natlab.research.philips.com>.
<P>
-<PRE>
-asx8051 -losg asmfunc.asm
-
-</PRE>
-<P>Then compile and link the assembler routine to the C source file with the
-following command,
<P>
<PRE>
-sdcc cfunc.c asmfunc.rel
+%[flags][width][b|B|l|L]type flags: - left justify output in specified field width
+
+ + prefix output with +/- sign if output is signed
+ type
+ space prefix output with a blank if it's a signed
+ positive value
+ width: specifies minimum number of characters
+ outputted for numbers
+ or strings.
+
+ - For numbers, spaces are added on the left when needed.
+
+ If width starts with a zero character, zeroes and used
+
+ instead of spaces.
+ - For strings, spaces are are
+ added on the left or right (when
+ flag '-' is used)
+ when needed.
+
+ b/B: byte argument
+ (used by d, u, o, x, X)
+ l/L: long argument (used by d,
+ u, o, x, X)
+ type: d decimal number
+ u
+ unsigned decimal number
+ o unsigned octal number
+
+ x unsigned hexadecimal number (0-9, a-f)
+ X
+ unsigned hexadecimal number (0-9, A-F)
+ c character
+
+ s string (generic pointer)
+ p
+ generic pointer (I:data/idata, C:code, X:xdata, P:paged)
+
+ f float (still to be implemented)
</PRE>
-<H3>Assembler routine is reentrant. </H3>
-
-<P>In this case the parameters will be passed on the stack , the parameters
-are pushed from right to left i.e. after the call the left most parameter will
-be on the top of the stack. Here is an example.
-<P>extern int asm_func( unsigned short, unsigned short);
+<P>Also contains a very simple version of printf (<B>printf_small</B>). This simplified
+version of printf supports only the following formats.
<P>
<PRE>
- int c_func (unsigned short i, unsigned short j) reentrant
-{
-
- return asm_func(i,j);
-}
-int main()
-{
- return c_func(10,9);
-
-}
-
-</PRE>
-<P>The corresponding assembler routine is.
-<P>
-<PRE>
- .globl _asm_func
-_asm_func:
- push _bp
- mov _bp,sp
-
- mov a,_bp
- clr c
- add a,#0xfd
- mov
- r0,a
- mov a,_bp
- clr c
- add a,#0xfc
-
- mov r1,a
- mov a,@r0
- add a,@r1
- mov dpl,a
-
- mov dph,#0x00
- mov sp,_bp
- pop _bp
- ret
+format output type argument-type <bf>
+%d decimal
+ int
+%ld decimal long
+%hd decimal short/char
+
+%x hexadecimal int
+%lx hexadecimal long
+
+%hx hexadecimal short/char
+%o octal int
+
+%lo octal long
+%ho octal short/char
+
+%c character char/short
+%s character _generic
+ pointer
+ <p><tt>The routine is <tt><bf>very stack intesive , --stack-after-data parameter should
+ be used when using this routine, the routine also takes about 1K of code space
+ .It also expects an external function named putchar(char ) to be present (this
+ can be changed). When using the %s format the string / pointer should
+ be cast to a generic pointer. eg.
</PRE>
-<P>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.
<HR>
<A HREF="SDCCUdoc-21.html">Next</A>
<A HREF="SDCCUdoc-19.html">Previous</A>
projects / fw / sdcc / blobdiff