bn_mp_submod.c 964 Bytes
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#include "tommath_private.h"
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#ifdef BN_MP_SUBMOD_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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 */

/* d = a - b (mod c) */
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int mp_submod(const mp_int *a, const mp_int *b, const mp_int *c, mp_int *d)
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{
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   int     res;
   mp_int  t;
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   if ((res = mp_init(&t)) != MP_OKAY) {
      return res;
   }
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   if ((res = mp_sub(a, b, &t)) != MP_OKAY) {
      mp_clear(&t);
      return res;
   }
   res = mp_mod(&t, c, d);
   mp_clear(&t);
   return res;
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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 */