1 #include "tommath_private.h" 2 #ifdef BN_MP_REDUCE_2K_SETUP_C 3 /* LibTomMath, multiple-precision integer library -- Tom St Denis */ 4 /* SPDX-License-Identifier: Unlicense */ 5 6 /* determines the setup value */ mp_reduce_2k_setup(const mp_int * a,mp_digit * d)7mp_err mp_reduce_2k_setup(const mp_int *a, mp_digit *d) 8 { 9 mp_err err; 10 mp_int tmp; 11 int p; 12 13 if ((err = mp_init(&tmp)) != MP_OKAY) { 14 return err; 15 } 16 17 p = mp_count_bits(a); 18 if ((err = mp_2expt(&tmp, p)) != MP_OKAY) { 19 mp_clear(&tmp); 20 return err; 21 } 22 23 if ((err = s_mp_sub(&tmp, a, &tmp)) != MP_OKAY) { 24 mp_clear(&tmp); 25 return err; 26 } 27 28 *d = tmp.dp[0]; 29 mp_clear(&tmp); 30 return MP_OKAY; 31 } 32 #endif 33