kc3-lang/libtommath/bn_mp_signed_rsh.c
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Hash : 1af0de1f
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Date : 2019-05-20T19:11:25
deprecate mp_tc_(and|or|xor) in favor of mp_(and|or|xor) * same behavior for positive numbers * generalisation for negative numbers, treating them as two complement * improve algorithm, iterate once over the digits, manually perform two complement * simplify mp_add_d, mp_sub_d * functions are safe in case of a==c or b==c * renamed mp_tc_div_2d to mp_signed_rsh (signed right shift)
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bn_mp_signed_rsh.c
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#include "tommath_private.h" #ifdef BN_MP_SIGNED_RSH_C /* LibTomMath, multiple-precision integer library -- Tom St Denis */ /* SPDX-License-Identifier: Unlicense */ /* shift right by a certain bit count with sign extension */ mp_err mp_signed_rsh(const mp_int *a, int b, mp_int *c) { mp_err res; if (a->sign == MP_ZPOS) { return mp_div_2d(a, b, c, NULL); } res = mp_add_d(a, 1uL, c); if (res != MP_OKAY) { return res; } res = mp_div_2d(c, b, c, NULL); return (res == MP_OKAY) ? mp_sub_d(c, 1uL, c) : res; } #endif