Sophie: sdcc-3.0.0-0.fc14 x86

sdcc-3.0.0-0.fc14.x86_64.rpm

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">

<!--Converted with LaTeX2HTML 2008 (1.71)
original version by:  Nikos Drakos, CBLU, University of Leeds
* revised and updated by:  Marcus Hennecke, Ross Moore, Herb Swan
* with significant contributions from:
  Jens Lippmann, Marek Rouchal, Martin Wilck and others -->
<HTML>
<HEAD>
<TITLE>4.6.13 Functions</TITLE>
<META NAME="description" CONTENT="4.6.13 Functions">
<META NAME="keywords" CONTENT="sdccman">
<META NAME="resource-type" CONTENT="document">
<META NAME="distribution" CONTENT="global">

<META NAME="Generator" CONTENT="LaTeX2HTML v2008">
<META HTTP-EQUIV="Content-Style-Type" CONTENT="text/css">

<LINK REL="STYLESHEET" HREF="sdccman.css">

<LINK REL="next" HREF="node133.html">
<LINK REL="previous" HREF="node131.html">
<LINK REL="up" HREF="node119.html">
<LINK REL="next" HREF="node133.html">
</HEAD>

<BODY >
<!--Navigation Panel-->
<A NAME="tex2html2732"
  HREF="node133.html">
<IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="next.png"></A> 
<A NAME="tex2html2726"
  HREF="node119.html">
<IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="up.png"></A> 
<A NAME="tex2html2720"
  HREF="node131.html">
<IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="prev.png"></A> 
<A NAME="tex2html2728"
  HREF="node1.html">
<IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="contents.png"></A> 
<A NAME="tex2html2730"
  HREF="node191.html">
<IMG WIDTH="43" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="index" SRC="index.png"></A> 
<BR>
<B> Next:</B> <A NAME="tex2html2733"
  HREF="node133.html">4.6.14 Function return values</A>
<B> Up:</B> <A NAME="tex2html2727"
  HREF="node119.html">4.6 The PIC16 port</A>
<B> Previous:</B> <A NAME="tex2html2721"
  HREF="node131.html">4.6.12 Stack</A>
 &nbsp; <B>  <A NAME="tex2html2729"
  HREF="node1.html">Contents</A></B> 
 &nbsp; <B>  <A NAME="tex2html2731"
  HREF="node191.html">Index</A></B> 
<BR>
<BR>
<!--End of Navigation Panel-->

<H2><A NAME="SECTION005613000000000000000">
4.6.13 Functions</A>
</H2>

<P>
In addition to the standard SDCC function keywords, PIC16<A NAME="3304"></A>
port makes available two more:
<DL>
<DT><STRONG>wparam<A NAME="3306"></A></STRONG></DT>
<DD>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:
</DD>
</DL>

<P>

<DL COMPACT>
<DT>
<DD>void&nbsp;func_wparam(int&nbsp;a)&nbsp;wparam

<P>
{

<P>
&nbsp;&nbsp;&nbsp;&nbsp;/*&nbsp;WREG&nbsp;hold&nbsp;the&nbsp;lower&nbsp;part&nbsp;of&nbsp;a&nbsp;*/

<P>
&nbsp;&nbsp;&nbsp;&nbsp;/*&nbsp;the&nbsp;high&nbsp;part&nbsp;of&nbsp;a&nbsp;is&nbsp;stored&nbsp;in&nbsp;FSR2+2&nbsp;(or&nbsp;+3&nbsp;for&nbsp;large&nbsp;stack&nbsp;model)&nbsp;*/

<P>
...

<P>
}
</DD>

<DT><STRONG>shadowregs<A NAME="3315"></A></STRONG></DT>
<DD>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 <I>shadowregs</I> before the
<I>interrupt</I> keyword in the function's header.
</DD>
</DL>

<P>

<DL COMPACT>
<DT>
<DD>void&nbsp;isr_shadow(void)&nbsp;shadowregs&nbsp;interrupt&nbsp;1

<P>
{

<P>
...

<P>
}
</DD>
</DL><I>shadowregs</I> instructs the code generator not to store/restore
WREG, STATUS, BSR when entering/exiting the ISR.

<P>
<BR><HR>
<ADDRESS>

2011-03-20
</ADDRESS>
</BODY>
</HTML>