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view libtommath/bn_mp_reduce_2k_setup.c @ 1682:a53e7d2d60be
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author | Matt Johnston <matt@ucc.asn.au> |
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date | Mon, 25 May 2020 20:23:02 +0800 |
parents | f52919ffd3b1 |
children | 1051e4eea25a |
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#include "tommath_private.h" #ifdef BN_MP_REDUCE_2K_SETUP_C /* LibTomMath, multiple-precision integer library -- Tom St Denis * * LibTomMath is a library that provides multiple-precision * integer arithmetic as well as number theoretic functionality. * * The library was designed directly after the MPI library by * Michael Fromberger but has been written from scratch with * additional optimizations in place. * * SPDX-License-Identifier: Unlicense */ /* determines the setup value */ int mp_reduce_2k_setup(const mp_int *a, mp_digit *d) { int res, p; mp_int tmp; if ((res = mp_init(&tmp)) != MP_OKAY) { return res; } p = mp_count_bits(a); if ((res = mp_2expt(&tmp, p)) != MP_OKAY) { mp_clear(&tmp); return res; } if ((res = s_mp_sub(&tmp, a, &tmp)) != MP_OKAY) { mp_clear(&tmp); return res; } *d = tmp.dp[0]; mp_clear(&tmp); return MP_OKAY; } #endif /* ref: HEAD -> master, tag: v1.1.0 */ /* git commit: 08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */ /* commit time: 2019-01-28 20:32:32 +0100 */