Line data    Source code

       1             : #include "tommath_private.h"
       2             : #ifdef BN_MP_LCM_C
       3             : /* LibTomMath, multiple-precision integer library -- Tom St Denis */
       4             : /* SPDX-License-Identifier: Unlicense */
       5             : 
       6             : /* computes least common multiple as |a*b|/(a, b) */
       7           0 : mp_err mp_lcm(const mp_int *a, const mp_int *b, mp_int *c)
       8             : {
       9           0 :    mp_err  err;
      10           0 :    mp_int  t1, t2;
      11             : 
      12             : 
      13           0 :    if ((err = mp_init_multi(&t1, &t2, NULL)) != MP_OKAY) {
      14           0 :       return err;
      15             :    }
      16             : 
      17             :    /* t1 = get the GCD of the two inputs */
      18           0 :    if ((err = mp_gcd(a, b, &t1)) != MP_OKAY) {
      19           0 :       goto LBL_T;
      20             :    }
      21             : 
      22             :    /* divide the smallest by the GCD */
      23           0 :    if (mp_cmp_mag(a, b) == MP_LT) {
      24             :       /* store quotient in t2 such that t2 * b is the LCM */
      25           0 :       if ((err = mp_div(a, &t1, &t2, NULL)) != MP_OKAY) {
      26           0 :          goto LBL_T;
      27             :       }
      28           0 :       err = mp_mul(b, &t2, c);
      29             :    } else {
      30             :       /* store quotient in t2 such that t2 * a is the LCM */
      31           0 :       if ((err = mp_div(b, &t1, &t2, NULL)) != MP_OKAY) {
      32           0 :          goto LBL_T;
      33             :       }
      34           0 :       err = mp_mul(a, &t2, c);
      35             :    }
      36             : 
      37             :    /* fix the sign to positive */
      38           0 :    c->sign = MP_ZPOS;
      39             : 
      40           0 : LBL_T:
      41           0 :    mp_clear_multi(&t1, &t2, NULL);
      42           0 :    return err;
      43             : }
      44             : #endif