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      1 /*	$NetBSD: bn_mp_lcm.c,v 1.2 2017/01/28 21:31:47 christos Exp $	*/
      2 
      3 #include <tommath.h>
      4 #ifdef BN_MP_LCM_C
      5 /* LibTomMath, multiple-precision integer library -- Tom St Denis
      6  *
      7  * LibTomMath is a library that provides multiple-precision
      8  * integer arithmetic as well as number theoretic functionality.
      9  *
     10  * The library was designed directly after the MPI library by
     11  * Michael Fromberger but has been written from scratch with
     12  * additional optimizations in place.
     13  *
     14  * The library is free for all purposes without any express
     15  * guarantee it works.
     16  *
     17  * Tom St Denis, tomstdenis (at) gmail.com, http://libtom.org
     18  */
     19 
     20 /* computes least common multiple as |a*b|/(a, b) */
     21 int mp_lcm (mp_int * a, mp_int * b, mp_int * c)
     22 {
     23   int     res;
     24   mp_int  t1, t2;
     25 
     26 
     27   if ((res = mp_init_multi (&t1, &t2, NULL)) != MP_OKAY) {
     28     return res;
     29   }
     30 
     31   /* t1 = get the GCD of the two inputs */
     32   if ((res = mp_gcd (a, b, &t1)) != MP_OKAY) {
     33     goto LBL_T;
     34   }
     35 
     36   /* divide the smallest by the GCD */
     37   if (mp_cmp_mag(a, b) == MP_LT) {
     38      /* store quotient in t2 such that t2 * b is the LCM */
     39      if ((res = mp_div(a, &t1, &t2, NULL)) != MP_OKAY) {
     40         goto LBL_T;
     41      }
     42      res = mp_mul(b, &t2, c);
     43   } else {
     44      /* store quotient in t2 such that t2 * a is the LCM */
     45      if ((res = mp_div(b, &t1, &t2, NULL)) != MP_OKAY) {
     46         goto LBL_T;
     47      }
     48      res = mp_mul(a, &t2, c);
     49   }
     50 
     51   /* fix the sign to positive */
     52   c->sign = MP_ZPOS;
     53 
     54 LBL_T:
     55   mp_clear_multi (&t1, &t2, NULL);
     56   return res;
     57 }
     58 #endif
     59 
     60 /* Source: /cvs/libtom/libtommath/bn_mp_lcm.c,v  */
     61 /* Revision: 1.4  */
     62 /* Date: 2006/12/28 01:25:13  */
     63