45 lines
1.0 KiB
C
45 lines
1.0 KiB
C
#include "tommath_private.h"
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#ifdef BN_MP_REDUCE_2K_SETUP_C
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/* LibTomMath, multiple-precision integer library -- Tom St Denis
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*
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* LibTomMath is a library that provides multiple-precision
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* integer arithmetic as well as number theoretic functionality.
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*
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* The library was designed directly after the MPI library by
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* Michael Fromberger but has been written from scratch with
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* additional optimizations in place.
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*
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* SPDX-License-Identifier: Unlicense
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*/
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/* determines the setup value */
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int mp_reduce_2k_setup(const mp_int *a, mp_digit *d)
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{
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int res, p;
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mp_int tmp;
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if ((res = mp_init(&tmp)) != MP_OKAY) {
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return res;
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}
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p = mp_count_bits(a);
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if ((res = mp_2expt(&tmp, p)) != MP_OKAY) {
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mp_clear(&tmp);
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return res;
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}
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if ((res = s_mp_sub(&tmp, a, &tmp)) != MP_OKAY) {
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mp_clear(&tmp);
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return res;
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}
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*d = tmp.dp[0];
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mp_clear(&tmp);
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return MP_OKAY;
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}
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#endif
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/* ref: $Format:%D$ */
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/* git commit: $Format:%H$ */
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/* commit time: $Format:%ai$ */
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