## File: bn_mp_tc_xor.c

package info (click to toggle)
libtommath 1.1.0-3
 `123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990` ``````#include "tommath_private.h" #ifdef BN_MP_TC_XOR_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 */ /* two complement xor */ int mp_tc_xor(const mp_int *a, const mp_int *b, mp_int *c) { int res = MP_OKAY, bits, abits, bbits; int as = mp_isneg(a), bs = mp_isneg(b); mp_int *mx = NULL, _mx, acpy, bcpy; if ((as != MP_NO) || (bs != MP_NO)) { abits = mp_count_bits(a); bbits = mp_count_bits(b); bits = MAX(abits, bbits); res = mp_init_set_int(&_mx, 1uL); if (res != MP_OKAY) { goto end; } mx = &_mx; res = mp_mul_2d(mx, bits + 1, mx); if (res != MP_OKAY) { goto end; } if (as != MP_NO) { res = mp_init(&acpy); if (res != MP_OKAY) { goto end; } res = mp_add(mx, a, &acpy); if (res != MP_OKAY) { mp_clear(&acpy); goto end; } a = &acpy; } if (bs != MP_NO) { res = mp_init(&bcpy); if (res != MP_OKAY) { goto end; } res = mp_add(mx, b, &bcpy); if (res != MP_OKAY) { mp_clear(&bcpy); goto end; } b = &bcpy; } } res = mp_xor(a, b, c); if ((as != bs) && (res == MP_OKAY)) { res = mp_sub(c, mx, c); } end: if (a == &acpy) { mp_clear(&acpy); } if (b == &bcpy) { mp_clear(&bcpy); } if (mx == &_mx) { mp_clear(mx); } return res; } #endif /* ref: HEAD -> master, tag: v1.1.0 */ /* git commit: 08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */ /* commit time: 2019-01-28 20:32:32 +0100 */ ``````