Sophie: sdcc-3.0.0-0.fc14 x86

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<H2><A NAME="SECTION00551000000000000000"></A><A NAME="2951"></A><A NAME="2952"></A>
<BR>
4.5.1 PIC Code Pages and Memory Banks
</H2>

<P>
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 <I>static</I> functions of a single
.c file into the same code page.
<BR>
<BR>
To get the best results, follow these guidelines:

<OL>
<LI>Make local functions static, as non static functions require code
page selection overhead.
<BR>
Due to the way sdcc handles functions, place called functions prior
to calling functions in the file wherever possible: Otherwise sdcc
will insert unnecessary pagesel directives around the call, believing
that the called function is externally defined.
</LI>
<LI>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.
</LI>
<LI>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'.
</LI>
</OL>

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2011-03-20
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