gnupic: Thread: Re: [gnupic] CVS GPASM Preprocessor problem

Hi James,

On Mon, 3 Sep 2007 18:31:40 -0400 you wrote:
>  
> I'm having trouble with unpredictable output from the following preprocessor
> macro, which is designed to calculate an 8 or 16-bit BRG value:
>  
> #define __CALCBAUD   ((_FOSC/(.4*_SER_HIGHM*_SER_16BITM)*_SER_BAUD)-.1)
>  

Unpredictable in what sense?

> _FOSC = .8000000
> _SER_HIGHM = .4
> _SER_16BITM = .1
>  
> When _SER_BAUD is .38400, I'm expecting the result to be _ 
>  
> HIGH __CALCBAUD evaluates to .191
> LOW __CALCBAUD evaluates to .255
>  
And when I ran a quick test that was indeed what I got.

rob@zechariah ~/temp $ gpasm -v
gpasm-0.13.4 beta
rob@zechariah ~/temp $ head -n 30 test.lst 
gpasm-0.13.4 beta               test.asm    9-4-2007  22:14:34           PAGE  1


LOC  OBJECT CODE     LINE SOURCE TEXT
  VALUE
 
               00001         list    p=16f871
               00002         radix dec
               00003         include "p16f871.inc"
               00001         LIST
               00002 ; P16F871.INC  Standard Header File, Version 1.00    Microchip Technology, Inc.
               00306         LIST
               00004 
               00005 
  007A1200     00006 _FOSC       equ .8000000
  00000004     00007 _SER_HIGHM  equ .4
  00000001     00008 _SER_16BITM equ .1
               00009 
               00010 
  00009600     00011 _SER_BAUD   equ .38400
               00012 
               00013 #define _CALCBAUD   ((_FOSC/(.4*_SER_HIGHM*_SER_16BITM)*_SER_BAUD)-.1)
               00014 
0000           00015  org    0
               00016  
0000 30BF      00017  movlw  high(_CALCBAUD)
0001 00A0      00018  movwf  0x20
0002 30FF      00019  movlw  low(_CALCBAUD)
0003 00A1      00020  movwf  0x21
               00021 
rob@zechariah ~/temp $ 

What do you get?