tomsfastmath/src/addsub/s_fp_add.c
2010-07-22 10:06:30 +02:00

43 lines
839 B
C

/* TomsFastMath, a fast ISO C bignum library.
*
* This project is meant to fill in where LibTomMath
* falls short. That is speed ;-)
*
* This project is public domain and free for all purposes.
*
* Tom St Denis, tomstdenis@gmail.com
*/
#include <tfm.h>
/* unsigned addition */
void s_fp_add(fp_int *a, fp_int *b, fp_int *c)
{
int x, y, oldused;
register fp_word t;
y = MAX(a->used, b->used);
oldused = c->used;
c->used = y;
t = 0;
for (x = 0; x < y; x++) {
t += ((fp_word)a->dp[x]) + ((fp_word)b->dp[x]);
c->dp[x] = (fp_digit)t;
t >>= DIGIT_BIT;
}
if (t != 0 && x < FP_SIZE) {
c->dp[c->used++] = (fp_digit)t;
++x;
}
c->used = x;
for (; x < oldused; x++) {
c->dp[x] = 0;
}
fp_clamp(c);
}
/* $Source$ */
/* $Revision$ */
/* $Date$ */