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--- how_to_mix_c_and_asm [2006/05/11 10:37]
audiocommander created
+++ how_to_mix_c_and_asm [2008/09/29 12:27] (current)
wackazong
@@ Line 1: / Line 1: @@
+It's actually quite easy!
+As you can see in the example below, just enclose the ASM part with //_////_asm// and //_////_endasm;//
+You might have to declare some additional variables, but the concept is quite straightforward.
+Do not forget to include the header file of your processor from the SDCC header files, or variables like PRODL will not be defined: e.g. #include <pic18f4685.h>
+<code c>
+unsigned char Scale_7bit(unsigned char evnt2, unsigned char min, unsigned char max) {
+  // scaled value is (<8-bit random> * ) >> 8
+  PRODL = evnt2 << 1; // 8bit value
+  PRODH = max-min+1;  // range
+__asm
+    movf _PRODL, W
+    mulwf _PRODH, 0
+__endasm;
+  return min + PRODH;
+}
+</code>
+Also, as well as the above example of 'inline ASM', it is possible to include ASM code in .inc include files, and call that ASM code from within your C application. Please see the forum thread [[http://www.midibox.org/forum/index.php?topic=7698.0|using assembler in C - question about _ in front of macro names]] for more info.

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