libs/libtommath/bn_mp_submod.c

   1 #include <tommath.h>
   2 #ifdef BN_MP_SUBMOD_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://libtom.org
  16  */
  17
  18 /* d = a - b (mod c) */
  19 int
  20 mp_submod (mp_int * a, mp_int * b, mp_int * c, mp_int * d)
  21 {
  22   int     res;
  23   mp_int  t;
  24
  25
  26   if ((res = mp_init (&t)) != MP_OKAY) {
  27     return res;
  28   }
  29
  30   if ((res = mp_sub (a, b, &t)) != MP_OKAY) {
  31     mp_clear (&t);
  32     return res;
  33   }
  34   res = mp_mod (&t, c, d);
  35   mp_clear (&t);
  36   return res;
  37 }
  38 #endif
  39
  40 /* $Source: /cvs/libtom/libtommath/bn_mp_submod.c,v $ */
  41 /* $Revision: 1.4 $ */
  42 /* $Date: 2006/12/28 01:25:13 $ */