math32.c

用５１单片机读取ＣＦ卡的程序。对许多项目有参考价值

// Hoarder board software http://vadim.www.media.mit.edu/Hoarder/Hoarder.htm
// Copyright (C) 2001-2002 MIT Media Laboratory
// Programmed by Vadim Gerasimov <[e-mail]>

// 32-bit arithmetic 
#define move32(to,from) {to[0]=from[0];to[1]=from[1];to[2]=from[2];to[3]=from[3];}
#define zero32(n) {n[0]=0;n[1]=0;n[2]=0;n[3]=0;}
#define is_zero32(n) ((n[0]|n[1]|n[2]|n[3])==0)
#define inc32(n) {if(++n[0]==0)if(++n[1]==0)if(++n[2]==0)++n[3];}

void dec32 (char* n) {
  if (n[0]--==0) if(n[1]--==0) if (n[2]--==0) --n[3];
}

void add32 (char* a, char* b)
{
   byte r[4];

   r[0] = *(b);
   r[1] = *(b + 1);
   r[2] = *(b + 2);
   r[3] = *(b + 3);

#asm
   movf    a,w
   movwf   4
   movf    r[0],w
   addwf   0,f
   movf    r[1],w
   incf    4,f
   btfsc   3,0
   incfsz  r[1],w
   addwf   0,f
   movf    r[2],w
   incf    4,f
   btfsc   3,0
   incfsz  r[2],w
   addwf   0,f
   movf    r[3],w
   incf    4,f
   btfsc   3,0
   incfsz  r[3],w
   addwf   0,f
#endasm
}

void sub32(char* a, char* b) { // a = a - b
   byte r[4];
   r[0] = *(b);
   r[1] = *(b + 1);
   r[2] = *(b + 2);
   r[3] = *(b + 3);
#asm
   movf    a,w
   movwf   4
   movf    r[0],w
   subwf   0,f
   movf    r[1],w
   incf    4,f
   btfss   3,0
   incfsz  r[1],w
   subwf   0,f
   movf    r[2],w
   incf    4,f
   btfss   3,0
   incfsz  r[2],w
   subwf   0,f
   movf    r[3],w
   incf    4,f
   btfss   3,0
   incfsz  r[3],w
   subwf   0,f
#endasm
}