release/src/router/dropbear/libtommath/bn_mp_prime_is_divisible.c

   1 #include <tommath.h>
   2 #ifdef BN_MP_PRIME_IS_DIVISIBLE_C
   3 /* LibTomMath, multiple-precision integer library -- Tom St Denis
   4  *
   5  * LibTomMath is a library that provides multiple-precision
   6  * integer arithmetic as well as number theoretic functionality.
   7  *
   8  * The library was designed directly after the MPI library by
   9  * Michael Fromberger but has been written from scratch with
  10  * additional optimizations in place.
  11  *
  12  * The library is free for all purposes without any express
  13  * guarantee it works.
  14  *
  15  * Tom St Denis, tomstdenis@gmail.com, http://math.libtomcrypt.com
  16  */
  17
  18 /* determines if an integers is divisible by one
  19  * of the first PRIME_SIZE primes or not
  20  *
  21  * sets result to 0 if not, 1 if yes
  22  */
  23 int mp_prime_is_divisible (mp_int * a, int *result)
  24 {
  25   int     err, ix;
  26   mp_digit res;
  27
  28   /* default to not */
  29   *result = MP_NO;
  30
  31   for (ix = 0; ix < PRIME_SIZE; ix++) {
  32     /* what is a mod LBL_prime_tab[ix] */
  33     if ((err = mp_mod_d (a, ltm_prime_tab[ix], &res)) != MP_OKAY) {
  34       return err;
  35     }
  36
  37     /* is the residue zero? */
  38     if (res == 0) {
  39       *result = MP_YES;
  40       return MP_OKAY;
  41     }
  42   }
  43
  44   return MP_OKAY;
  45 }
  46 #endif
  47
  48 /* $Source: /cvs/libtom/libtommath/bn_mp_prime_is_divisible.c,v $ */
  49 /* $Revision: 1.3 $ */
  50 /* $Date: 2006/03/31 14:18:44 $ */