49 lines
1.1 KiB
C
49 lines
1.1 KiB
C
#include "tommath_private.h"
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#ifdef BN_MP_DECR_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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/* Decrement "a" by one like "a--". Changes input! */
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int mp_decr(mp_int *a)
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{
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int e = MP_OKAY;
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if (IS_ZERO(a)) {
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mp_set(a,1uL);
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a->sign = MP_NEG;
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return MP_OKAY;
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} else if (a->sign == MP_NEG) {
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a->sign = MP_ZPOS;
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if ((e = mp_incr(a)) != MP_OKAY) {
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return e;
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}
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/* There is no -0 in LTM */
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if (!IS_ZERO(a)) {
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a->sign = MP_NEG;
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}
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return MP_OKAY;
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} else if (a->dp[0] > 1uL) {
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a->dp[0]--;
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if (a->dp[0] == 0) {
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mp_zero(a);
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}
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return MP_OKAY;
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}
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return mp_sub_d(a, 1uL,a);
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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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