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kc3-lang/libtommath/bn_mp_decr.c

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  • Author : Francois Perrad
    Date : 2019-05-19 15:32:46
    Hash : fd68b652
    Message : refactor without err initialization

  • bn_mp_decr.c
  • #include "tommath_private.h"
    #ifdef BN_MP_DECR_C
    /* LibTomMath, multiple-precision integer library -- Tom St Denis */
    /* SPDX-License-Identifier: Unlicense */
    
    /* Decrement "a" by one like "a--". Changes input! */
    mp_err mp_decr(mp_int *a)
    {
       if (MP_IS_ZERO(a)) {
          mp_set(a,1uL);
          a->sign = MP_NEG;
          return MP_OKAY;
       } else if (a->sign == MP_NEG) {
          mp_err err;
          a->sign = MP_ZPOS;
          if ((err = mp_incr(a)) != MP_OKAY) {
             return err;
          }
          /* There is no -0 in LTM */
          if (!MP_IS_ZERO(a)) {
             a->sign = MP_NEG;
          }
          return MP_OKAY;
       } else if (a->dp[0] > 1uL) {
          a->dp[0]--;
          if (a->dp[0] == 0u) {
             mp_zero(a);
          }
          return MP_OKAY;
       } else {
          return mp_sub_d(a, 1uL,a);
       }
    }
    #endif