view libtommath/bn_mp_lcm.c @ 1655:f52919ffd3b1

update ltm to 1.1.0 and enable FIPS 186.4 compliant key-generation (#79) * make key-generation compliant to FIPS 186.4 * fix includes in tommath_class.h * update fuzzcorpus instead of error-out * fixup fuzzing make-targets * update Makefile.in * apply necessary patches to ltm sources * clean-up not required ltm files * update to vanilla ltm 1.1.0 this already only contains the required files * remove set/get double
author Steffen Jaeckel <s_jaeckel@gmx.de>
date Mon, 16 Sep 2019 15:50:38 +0200
parents 8bba51a55704
children 1051e4eea25a
line wrap: on
line source
#include "tommath_private.h"
#ifdef BN_MP_LCM_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis
 *
 * LibTomMath is a library that provides multiple-precision
 * integer arithmetic as well as number theoretic functionality.
 *
 * The library was designed directly after the MPI library by
 * Michael Fromberger but has been written from scratch with
 * additional optimizations in place.
 *
 * SPDX-License-Identifier: Unlicense
 */

/* computes least common multiple as |a*b|/(a, b) */
int mp_lcm(const mp_int *a, const mp_int *b, mp_int *c)
{
   int     res;
   mp_int  t1, t2;


   if ((res = mp_init_multi(&t1, &t2, NULL)) != MP_OKAY) {
      return res;
   }

   /* t1 = get the GCD of the two inputs */
   if ((res = mp_gcd(a, b, &t1)) != MP_OKAY) {
      goto LBL_T;
   }

   /* divide the smallest by the GCD */
   if (mp_cmp_mag(a, b) == MP_LT) {
      /* store quotient in t2 such that t2 * b is the LCM */
      if ((res = mp_div(a, &t1, &t2, NULL)) != MP_OKAY) {
         goto LBL_T;
      }
      res = mp_mul(b, &t2, c);
   } else {
      /* store quotient in t2 such that t2 * a is the LCM */
      if ((res = mp_div(b, &t1, &t2, NULL)) != MP_OKAY) {
         goto LBL_T;
      }
      res = mp_mul(a, &t2, c);
   }

   /* fix the sign to positive */
   c->sign = MP_ZPOS;

LBL_T:
   mp_clear_multi(&t1, &t2, NULL);
   return res;
}
#endif

/* ref:         HEAD -> master, tag: v1.1.0 */
/* git commit:  08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */
/* commit time: 2019-01-28 20:32:32 +0100 */