bn_mp_prime_is_divisible.c 1.2 KB
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#include "tommath_private.h"
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#ifdef BN_MP_PRIME_IS_DIVISIBLE_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.
 *
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 * SPDX-License-Identifier: Unlicense
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 */

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/* determines if an integers is divisible by one
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 * of the first PRIME_SIZE primes or not
 *
 * sets result to 0 if not, 1 if yes
 */
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int mp_prime_is_divisible(const mp_int *a, int *result)
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{
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   int     err, ix;
   mp_digit res;
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   /* default to not */
   *result = MP_NO;
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   for (ix = 0; ix < PRIME_SIZE; ix++) {
      /* what is a mod LBL_prime_tab[ix] */
      if ((err = mp_mod_d(a, ltm_prime_tab[ix], &res)) != MP_OKAY) {
         return err;
      }
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      /* is the residue zero? */
      if (res == 0u) {
         *result = MP_YES;
         return MP_OKAY;
      }
   }
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   return MP_OKAY;
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}
#endif

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