mp_reduce_2k_setup_l.c

   1 #include "tommath_private.h"
   2 #ifdef MP_REDUCE_2K_SETUP_L_C
   3 /* LibTomMath, multiple-precision integer library -- Tom St Denis */
   4 /* SPDX-License-Identifier: Unlicense */
   5
   6 /* determines the setup value */
   7 mp_err mp_reduce_2k_setup_l(const mp_int *a, mp_int *d)
   8 {
   9    mp_err err;
  10    mp_int tmp;
  11
  12    if ((err = mp_init(&tmp)) != MP_OKAY) {
  13       return err;
  14    }
  15
  16    if ((err = mp_2expt(&tmp, mp_count_bits(a))) != MP_OKAY) {
  17       goto LBL_ERR;
  18    }
  19
  20    if ((err = s_mp_sub(&tmp, a, d)) != MP_OKAY) {
  21       goto LBL_ERR;
  22    }
  23
  24 LBL_ERR:
  25    mp_clear(&tmp);
  26    return err;
  27 }
  28 #endif