tmpvecsub.c - plan9port - [fork] Plan 9 from user space
  HTML git clone git://src.adamsgaard.dk/plan9port
   DIR Log
   DIR Files
   DIR Refs
   DIR README
   DIR LICENSE
       ---
       tmpvecsub.c (526B)
       ---
            1 #include "os.h"
            2 #include <mp.h>
            3 #include "dat.h"
            4 
            5 /* prereq: a >= b, alen >= blen, diff has at least alen digits */
            6 void
            7 mpvecsub(mpdigit *a, int alen, mpdigit *b, int blen, mpdigit *diff)
            8 {
            9         int i, borrow;
           10         mpdigit x, y;
           11 
           12         borrow = 0;
           13         for(i = 0; i < blen; i++){
           14                 x = *a++;
           15                 y = *b++;
           16                 y += borrow;
           17                 if(y < borrow)
           18                         borrow = 1;
           19                 else
           20                         borrow = 0;
           21                 if(x < y)
           22                         borrow++;
           23                 *diff++ = x - y;
           24         }
           25         for(; i < alen; i++){
           26                 x = *a++;
           27                 y = x - borrow;
           28                 if(y > x)
           29                         borrow = 1;
           30                 else
           31                         borrow = 0;
           32                 *diff++ = y;
           33         }
           34 }