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

   1 #include <tommath.h>
   2 #ifdef BN_MP_MOD_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 /* c = a mod b, 0 <= c < b */
  19 int
  20 mp_mod (mp_int * a, mp_int * b, mp_int * c)
  21 {
  22   mp_int  t;
  23   int     res;
  24
  25   if ((res = mp_init_size (&t, b->used)) != MP_OKAY) {
  26     return res;
  27   }
  28
  29   if ((res = mp_div (a, b, NULL, &t)) != MP_OKAY) {
  30     mp_clear (&t);
  31     return res;
  32   }
  33
  34   if (t.sign != b->sign) {
  35     res = mp_add (b, &t, c);
  36   } else {
  37     res = MP_OKAY;
  38     mp_exch (&t, c);
  39   }
  40
  41   mp_clear (&t);
  42   return res;
  43 }
  44 #endif
  45
  46 /* $Source: /cvs/libtom/libtommath/bn_mp_mod.c,v $ */
  47 /* $Revision: 1.3 $ */
  48 /* $Date: 2006/03/31 14:18:44 $ */