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Diffstat (limited to 'gmp-6.3.0/mpz/xor.c')
| -rw-r--r-- | gmp-6.3.0/mpz/xor.c | 146 |
1 files changed, 146 insertions, 0 deletions
diff --git a/gmp-6.3.0/mpz/xor.c b/gmp-6.3.0/mpz/xor.c new file mode 100644 index 0000000..5ec657a --- /dev/null +++ b/gmp-6.3.0/mpz/xor.c @@ -0,0 +1,146 @@ +/* mpz_xor -- Logical xor. + +Copyright 1991, 1993, 1994, 1996, 1997, 2000, 2001, 2005, 2012, +2015-2018 Free Software Foundation, Inc. + +This file is part of the GNU MP Library. + +The GNU MP Library is free software; you can redistribute it and/or modify +it under the terms of either: + + * the GNU Lesser General Public License as published by the Free + Software Foundation; either version 3 of the License, or (at your + option) any later version. + +or + + * the GNU General Public License as published by the Free Software + Foundation; either version 2 of the License, or (at your option) any + later version. + +or both in parallel, as here. + +The GNU MP Library is distributed in the hope that it will be useful, but +WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY +or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +for more details. + +You should have received copies of the GNU General Public License and the +GNU Lesser General Public License along with the GNU MP Library. If not, +see https://www.gnu.org/licenses/. */ + +#include "gmp-impl.h" + +void +mpz_xor (mpz_ptr res, mpz_srcptr op1, mpz_srcptr op2) +{ + mp_srcptr op1_ptr, op2_ptr; + mp_size_t op1_size, op2_size; + mp_ptr res_ptr; + mp_size_t res_size; + + op1_size = SIZ(op1); + op2_size = SIZ(op2); + + if (op1_size < op2_size) + { + MPZ_SRCPTR_SWAP (op1, op2); + MP_SIZE_T_SWAP (op1_size, op2_size); + } + + op1_ptr = PTR(op1); + res_ptr = PTR(res); + + if (op2_size >= 0) + { + if (res_ptr != op1_ptr) + { + res_ptr = MPZ_REALLOC (res, op1_size); + MPN_COPY (res_ptr + op2_size, op1_ptr + op2_size, + op1_size - op2_size); + } + if (LIKELY (op2_size != 0)) + mpn_xor_n (res_ptr, op1_ptr, PTR(op2), op2_size); + res_size = op1_size; + + MPN_NORMALIZE (res_ptr, res_size); + SIZ(res) = res_size; + } + else + { + mp_ptr opx; + TMP_DECL; + + op2_size = -op2_size; + TMP_MARK; + if (op1_size < 0) + { + mp_ptr opy; + + /* Both operands are negative, the result will be positive. + (-OP1) ^ (-OP2) = + = ~(OP1 - 1) ^ ~(OP2 - 1) = + = (OP1 - 1) ^ (OP2 - 1) */ + + op1_size = -op1_size; + + /* Possible optimization: Decrease mpn_sub precision, + as we won't use the entire res of both. */ + TMP_ALLOC_LIMBS_2 (opx, op1_size, opy, op2_size); + mpn_sub_1 (opx, op1_ptr, op1_size, (mp_limb_t) 1); + op1_ptr = opx; + + mpn_sub_1 (opy, PTR(op2), op2_size, (mp_limb_t) 1); + op2_ptr = opy; + + res_ptr = MPZ_NEWALLOC (res, op2_size); + /* Don't re-read OP1_PTR and OP2_PTR. They point to temporary + space--never to the space PTR(res) used to point to before + reallocation. */ + + MPN_COPY (res_ptr + op1_size, op2_ptr + op1_size, + op2_size - op1_size); + mpn_xor_n (res_ptr, op1_ptr, op2_ptr, op1_size); + TMP_FREE; + res_size = op2_size; + + MPN_NORMALIZE (res_ptr, res_size); + SIZ(res) = res_size; + } + else + { + /* Operand 2 negative, so will be the result. + -(OP1 ^ (-OP2)) = -(OP1 ^ ~(OP2 - 1)) = + = ~(OP1 ^ ~(OP2 - 1)) + 1 = + = (OP1 ^ (OP2 - 1)) + 1 */ + + res_size = MAX (op1_size, op2_size); + res_ptr = MPZ_REALLOC (res, res_size + 1); + op1_ptr = PTR(op1); + + opx = TMP_ALLOC_LIMBS (op2_size); + mpn_sub_1 (opx, PTR(op2), op2_size, (mp_limb_t) 1); + op2_ptr = opx; + + if (res_size == op1_size) + { + MPN_COPY (res_ptr + op2_size, op1_ptr + op2_size, op1_size - op2_size); + mpn_xor_n (res_ptr, op1_ptr, op2_ptr, op2_size); + } + else + { + MPN_COPY (res_ptr + op1_size, op2_ptr + op1_size, op2_size - op1_size); + if (LIKELY (op1_size != 0)) + mpn_xor_n (res_ptr, op1_ptr, op2_ptr, op1_size); + } + TMP_FREE; + + res_ptr[res_size] = 0; + MPN_INCR_U (res_ptr, res_size + 1, (mp_limb_t) 1); + res_size += res_ptr[res_size]; + + MPN_NORMALIZE_NOT_ZERO (res_ptr, res_size); + SIZ(res) = -res_size; + } + } +} |