c3-lang/libtommath/bn_mp_signed_rsh.c

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• Hash : 1af0de1f
  Author :
  Date : 2019-05-20T19:11:25
  

  deprecate mp_tc_(and|or|xor) in favor of mp_(and|or|xor) * same behavior for positive numbers * generalisation for negative numbers, treating them as two complement * improve algorithm, iterate once over the digits, manually perform two complement * simplify mp_add_d, mp_sub_d * functions are safe in case of a==c or b==c * renamed mp_tc_div_2d to mp_signed_rsh (signed right shift)

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• bn_mp_signed_rsh.c

• #include "tommath_private.h"
  #ifdef BN_MP_SIGNED_RSH_C
  /* LibTomMath, multiple-precision integer library -- Tom St Denis */
  /* SPDX-License-Identifier: Unlicense */
  
  /* shift right by a certain bit count with sign extension */
  mp_err mp_signed_rsh(const mp_int *a, int b, mp_int *c)
  {
     mp_err res;
     if (a->sign == MP_ZPOS) {
        return mp_div_2d(a, b, c, NULL);
     }
  
     res = mp_add_d(a, 1uL, c);
     if (res != MP_OKAY) {
        return res;
     }
  
     res = mp_div_2d(c, b, c, NULL);
     return (res == MP_OKAY) ? mp_sub_d(c, 1uL, c) : res;
  }
  #endif
  

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