1 #include <tommath.h> 2 #ifdef BN_MP_LCM_C 3 /* LibTomMath, multiple-precision integer library -- Tom St Denis 4 * 5 * LibTomMath is a library that provides multiple-precision 6 * integer arithmetic as well as number theoretic functionality. 7 * 8 * The library was designed directly after the MPI library by 9 * Michael Fromberger but has been written from scratch with 10 * additional optimizations in place. 11 * 12 * The library is free for all purposes without any express 13 * guarantee it works. 14 * 15 * Tom St Denis, tomstdenis (at) gmail.com, http://math.libtomcrypt.com 16 */ 17 18 /* computes least common multiple as |a*b|/(a, b) */ 19 int mp_lcm (mp_int * a, mp_int * b, mp_int * c) 20 { 21 int res; 22 mp_int t1, t2; 23 24 25 if ((res = mp_init_multi (&t1, &t2, NULL)) != MP_OKAY) { 26 return res; 27 } 28 29 /* t1 = get the GCD of the two inputs */ 30 if ((res = mp_gcd (a, b, &t1)) != MP_OKAY) { 31 goto LBL_T; 32 } 33 34 /* divide the smallest by the GCD */ 35 if (mp_cmp_mag(a, b) == MP_LT) { 36 /* store quotient in t2 such that t2 * b is the LCM */ 37 if ((res = mp_div(a, &t1, &t2, NULL)) != MP_OKAY) { 38 goto LBL_T; 39 } 40 res = mp_mul(b, &t2, c); 41 } else { 42 /* store quotient in t2 such that t2 * a is the LCM */ 43 if ((res = mp_div(b, &t1, &t2, NULL)) != MP_OKAY) { 44 goto LBL_T; 45 } 46 res = mp_mul(a, &t2, c); 47 } 48 49 /* fix the sign to positive */ 50 c->sign = MP_ZPOS; 51 52 LBL_T: 53 mp_clear_multi (&t1, &t2, NULL); 54 return res; 55 } 56 #endif 57 58 /* $Source: /cvs/libtom/libtommath/bn_mp_lcm.c,v $ */ 59 /* $Revision: 1.3 $ */ 60 /* $Date: 2006/03/31 14:18:44 $ */ 61
