s_mp_prime_is_divisible.c

   1 #include "tommath_private.h"
   2 #ifdef S_MP_PRIME_IS_DIVISIBLE_C
   3 /* LibTomMath, multiple-precision integer library -- Tom St Denis */
   4 /* SPDX-License-Identifier: Unlicense */
   5
   6 /* determines if an integers is divisible by one
   7  * of the first PRIME_SIZE primes or not
   8  *
   9  * sets result to 0 if not, 1 if yes
  10  */
  11 mp_err s_mp_prime_is_divisible(const mp_int *a, bool *result)
  12 {
  13    int i;
  14    for (i = 0; i < MP_PRIME_TAB_SIZE; i++) {
  15       /* what is a mod LBL_prime_tab[i] */
  16       mp_err err;
  17       mp_digit res;
  18       if ((err = mp_mod_d(a, s_mp_prime_tab[i], &res)) != MP_OKAY) {
  19          return err;
  20       }
  21
  22       /* is the residue zero? */
  23       if (res == 0u) {
  24          *result = true;
  25          return MP_OKAY;
  26       }
  27    }
  28
  29    /* default to not */
  30    *result = false;
  31    return MP_OKAY;
  32 }
  33 #endif