view libtommath/bn_mp_signed_rsh.c @ 1702:8f93f37c01de

Allow DH to be completely disabled (#97) Reduces binary size by ~2kB by default and by 21kB with no other libtommath functions users, ex. with curve25519 kex and ed25519 key only.
author Vladislav Grishenko <themiron@users.noreply.github.com>
date Thu, 28 May 2020 20:01:48 +0500
parents 1051e4eea25a
children
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#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