56 lines
1.1 KiB
C
56 lines
1.1 KiB
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_private.h>
|
||
|
|
|
||
|
|
/* c = (a, b) */
|
||
|
|
void fp_gcd(fp_int *a, fp_int *b, fp_int *c)
|
||
|
|
{
|
||
|
|
fp_int u, v, r;
|
||
|
|
|
||
|
|
/* either zero than gcd is the largest */
|
||
|
|
if (fp_iszero (a) == 1 && fp_iszero (b) == 0) {
|
||
|
|
fp_abs (b, c);
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
if (fp_iszero (a) == 0 && fp_iszero (b) == 1) {
|
||
|
|
fp_abs (a, c);
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* optimized. At this point if a == 0 then
|
||
|
|
* b must equal zero too
|
||
|
|
*/
|
||
|
|
if (fp_iszero (a) == 1) {
|
||
|
|
fp_zero(c);
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* sort inputs */
|
||
|
|
if (fp_cmp_mag(a, b) != FP_LT) {
|
||
|
|
fp_init_copy(&u, a);
|
||
|
|
fp_init_copy(&v, b);
|
||
|
|
} else {
|
||
|
|
fp_init_copy(&u, b);
|
||
|
|
fp_init_copy(&v, a);
|
||
|
|
}
|
||
|
|
|
||
|
|
fp_zero(&r);
|
||
|
|
while (fp_iszero(&v) == FP_NO) {
|
||
|
|
fp_mod(&u, &v, &r);
|
||
|
|
fp_copy(&v, &u);
|
||
|
|
fp_copy(&r, &v);
|
||
|
|
}
|
||
|
|
fp_copy(&u, c);
|
||
|
|
}
|
||
|
|
|
||
|
|
/* $Source$ */
|
||
|
|
/* $Revision$ */
|
||
|
|
/* $Date$ */
|