61 lines
1.5 KiB
C
61 lines
1.5 KiB
C
#include <tommath.h>
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#ifdef BN_MP_LCM_C
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/* LibTomMath, multiple-precision integer library -- Tom St Denis
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*
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* LibTomMath is a library that provides multiple-precision
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* integer arithmetic as well as number theoretic functionality.
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*
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* The library was designed directly after the MPI library by
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* Michael Fromberger but has been written from scratch with
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* additional optimizations in place.
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*
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* The library is free for all purposes without any express
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* guarantee it works.
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*
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* Tom St Denis, tomstdenis@iahu.ca, http://math.libtomcrypt.org
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*/
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/* computes least common multiple as |a*b|/(a, b) */
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int mp_lcm (mp_int * a, mp_int * b, mp_int * c)
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{
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int res;
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mp_int t1, t2;
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if ((res = mp_init_multi (&t1, &t2, NULL)) != MP_OKAY) {
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return res;
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}
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/* t1 = get the GCD of the two inputs */
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if ((res = mp_gcd (a, b, &t1)) != MP_OKAY) {
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goto LBL_T;
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}
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/* divide the smallest by the GCD */
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if (mp_cmp_mag(a, b) == MP_LT) {
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/* store quotient in t2 such that t2 * b is the LCM */
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if ((res = mp_div(a, &t1, &t2, NULL)) != MP_OKAY) {
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goto LBL_T;
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}
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res = mp_mul(b, &t2, c);
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} else {
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/* store quotient in t2 such that t2 * a is the LCM */
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if ((res = mp_div(b, &t1, &t2, NULL)) != MP_OKAY) {
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goto LBL_T;
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}
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res = mp_mul(a, &t2, c);
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}
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/* fix the sign to positive */
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c->sign = MP_ZPOS;
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LBL_T:
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mp_clear_multi (&t1, &t2, NULL);
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return res;
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}
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#endif
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/* $Source$ */
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/* $Revision$ */
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/* $Date$ */
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