1/* mpz_xor -- Logical xor. 2 3Copyright 1991, 1993, 1994, 1996, 1997, 2000, 2001, 2005, 2012, 42015-2018 Free Software Foundation, Inc. 5 6This file is part of the GNU MP Library. 7 8The GNU MP Library is free software; you can redistribute it and/or modify 9it under the terms of either: 10 11 * the GNU Lesser General Public License as published by the Free 12 Software Foundation; either version 3 of the License, or (at your 13 option) any later version. 14 15or 16 17 * the GNU General Public License as published by the Free Software 18 Foundation; either version 2 of the License, or (at your option) any 19 later version. 20 21or both in parallel, as here. 22 23The GNU MP Library is distributed in the hope that it will be useful, but 24WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 25or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 26for more details. 27 28You should have received copies of the GNU General Public License and the 29GNU Lesser General Public License along with the GNU MP Library. If not, 30see https://www.gnu.org/licenses/. */ 31 32#include "gmp-impl.h" 33 34void 35mpz_xor (mpz_ptr res, mpz_srcptr op1, mpz_srcptr op2) 36{ 37 mp_srcptr op1_ptr, op2_ptr; 38 mp_size_t op1_size, op2_size; 39 mp_ptr res_ptr; 40 mp_size_t res_size; 41 42 op1_size = SIZ(op1); 43 op2_size = SIZ(op2); 44 45 if (op1_size < op2_size) 46 { 47 MPZ_SRCPTR_SWAP (op1, op2); 48 MP_SIZE_T_SWAP (op1_size, op2_size); 49 } 50 51 op1_ptr = PTR(op1); 52 res_ptr = PTR(res); 53 54 if (op2_size >= 0) 55 { 56 if (res_ptr != op1_ptr) 57 { 58 res_ptr = MPZ_REALLOC (res, op1_size); 59 MPN_COPY (res_ptr + op2_size, op1_ptr + op2_size, 60 op1_size - op2_size); 61 } 62 if (LIKELY (op2_size != 0)) 63 mpn_xor_n (res_ptr, op1_ptr, PTR(op2), op2_size); 64 res_size = op1_size; 65 66 MPN_NORMALIZE (res_ptr, res_size); 67 SIZ(res) = res_size; 68 } 69 else 70 { 71 mp_ptr opx; 72 TMP_DECL; 73 74 op2_size = -op2_size; 75 TMP_MARK; 76 if (op1_size < 0) 77 { 78 mp_ptr opy; 79 80 /* Both operands are negative, the result will be positive. 81 (-OP1) ^ (-OP2) = 82 = ~(OP1 - 1) ^ ~(OP2 - 1) = 83 = (OP1 - 1) ^ (OP2 - 1) */ 84 85 op1_size = -op1_size; 86 87 /* Possible optimization: Decrease mpn_sub precision, 88 as we won't use the entire res of both. */ 89 TMP_ALLOC_LIMBS_2 (opx, op1_size, opy, op2_size); 90 mpn_sub_1 (opx, op1_ptr, op1_size, (mp_limb_t) 1); 91 op1_ptr = opx; 92 93 mpn_sub_1 (opy, PTR(op2), op2_size, (mp_limb_t) 1); 94 op2_ptr = opy; 95 96 res_ptr = MPZ_NEWALLOC (res, op2_size); 97 /* Don't re-read OP1_PTR and OP2_PTR. They point to temporary 98 space--never to the space PTR(res) used to point to before 99 reallocation. */ 100 101 MPN_COPY (res_ptr + op1_size, op2_ptr + op1_size, 102 op2_size - op1_size); 103 mpn_xor_n (res_ptr, op1_ptr, op2_ptr, op1_size); 104 TMP_FREE; 105 res_size = op2_size; 106 107 MPN_NORMALIZE (res_ptr, res_size); 108 SIZ(res) = res_size; 109 } 110 else 111 { 112 /* Operand 2 negative, so will be the result. 113 -(OP1 ^ (-OP2)) = -(OP1 ^ ~(OP2 - 1)) = 114 = ~(OP1 ^ ~(OP2 - 1)) + 1 = 115 = (OP1 ^ (OP2 - 1)) + 1 */ 116 117 res_size = MAX (op1_size, op2_size); 118 res_ptr = MPZ_REALLOC (res, res_size + 1); 119 op1_ptr = PTR(op1); 120 121 opx = TMP_ALLOC_LIMBS (op2_size); 122 mpn_sub_1 (opx, PTR(op2), op2_size, (mp_limb_t) 1); 123 op2_ptr = opx; 124 125 if (res_size == op1_size) 126 { 127 MPN_COPY (res_ptr + op2_size, op1_ptr + op2_size, op1_size - op2_size); 128 mpn_xor_n (res_ptr, op1_ptr, op2_ptr, op2_size); 129 } 130 else 131 { 132 MPN_COPY (res_ptr + op1_size, op2_ptr + op1_size, op2_size - op1_size); 133 if (LIKELY (op1_size != 0)) 134 mpn_xor_n (res_ptr, op1_ptr, op2_ptr, op1_size); 135 } 136 TMP_FREE; 137 138 res_ptr[res_size] = 0; 139 MPN_INCR_U (res_ptr, res_size + 1, (mp_limb_t) 1); 140 res_size += res_ptr[res_size]; 141 142 MPN_NORMALIZE_NOT_ZERO (res_ptr, res_size); 143 SIZ(res) = -res_size; 144 } 145 } 146} 147