conterm/libmp/mpvecadd.c

36 lines
519 B
C

#include "os.h"
#include <mp.h>
#include "dat.h"
// prereq: alen >= blen, sum has at least blen+1 digits
void
mpvecadd(mpdigit *a, int alen, mpdigit *b, int blen, mpdigit *sum)
{
int i, carry;
mpdigit x, y;
carry = 0;
for(i = 0; i < blen; i++){
x = *a++;
y = *b++;
x += carry;
if(x < carry)
carry = 1;
else
carry = 0;
x += y;
if(x < y)
carry++;
*sum++ = x;
}
for(; i < alen; i++){
x = *a++ + carry;
if(x < carry)
carry = 1;
else
carry = 0;
*sum++ = x;
}
*sum = carry;
}