56 lines
1.1 KiB
C
56 lines
1.1 KiB
C
/* TomsFastMath, a fast ISO C bignum library.
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*
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* This project is meant to fill in where LibTomMath
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* falls short. That is speed ;-)
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*
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* This project is public domain and free for all purposes.
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*
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* Tom St Denis, tomstdenis@gmail.com
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*/
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#include <tfm_private.h>
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/* c = (a, b) */
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void fp_gcd(fp_int *a, fp_int *b, fp_int *c)
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{
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fp_int u, v, r;
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/* either zero than gcd is the largest */
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if (fp_iszero (a) == 1 && fp_iszero (b) == 0) {
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fp_abs (b, c);
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return;
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}
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if (fp_iszero (a) == 0 && fp_iszero (b) == 1) {
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fp_abs (a, c);
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return;
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}
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/* optimized. At this point if a == 0 then
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* b must equal zero too
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*/
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if (fp_iszero (a) == 1) {
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fp_zero(c);
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return;
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}
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/* sort inputs */
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if (fp_cmp_mag(a, b) != FP_LT) {
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fp_init_copy(&u, a);
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fp_init_copy(&v, b);
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} else {
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fp_init_copy(&u, b);
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fp_init_copy(&v, a);
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}
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fp_zero(&r);
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while (fp_iszero(&v) == FP_NO) {
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fp_mod(&u, &v, &r);
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fp_copy(&v, &u);
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fp_copy(&r, &v);
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}
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fp_copy(&u, c);
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}
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/* $Source$ */
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/* $Revision$ */
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/* $Date$ */
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