1 /* mpz_and -- Logical and. 2 3 Copyright 1991, 1993, 1994, 1996, 1997, 2000, 2001, 2003, 2005, 2012 Free 4 Software Foundation, Inc. 5 6 This file is part of the GNU MP Library. 7 8 The GNU MP Library is free software; you can redistribute it and/or modify 9 it 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 15 or 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 21 or both in parallel, as here. 22 23 The GNU MP Library is distributed in the hope that it will be useful, but 24 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 25 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 26 for more details. 27 28 You should have received copies of the GNU General Public License and the 29 GNU Lesser General Public License along with the GNU MP Library. If not, 30 see https://www.gnu.org/licenses/. */ 31 32 #include "gmp.h" 33 #include "gmp-impl.h" 34 35 void 36 mpz_and (mpz_ptr res, mpz_srcptr op1, mpz_srcptr op2) 37 { 38 mp_srcptr op1_ptr, op2_ptr; 39 mp_size_t op1_size, op2_size; 40 mp_ptr res_ptr; 41 mp_size_t res_size; 42 mp_size_t i; 43 TMP_DECL; 44 45 TMP_MARK; 46 op1_size = SIZ(op1); 47 op2_size = SIZ(op2); 48 49 op1_ptr = PTR(op1); 50 op2_ptr = PTR(op2); 51 52 if (op1_size >= 0) 53 { 54 if (op2_size >= 0) 55 { 56 res_size = MIN (op1_size, op2_size); 57 /* First loop finds the size of the result. */ 58 for (i = res_size - 1; i >= 0; i--) 59 if ((op1_ptr[i] & op2_ptr[i]) != 0) 60 break; 61 res_size = i + 1; 62 63 /* Handle allocation, now then we know exactly how much space is 64 needed for the result. */ 65 res_ptr = MPZ_REALLOC (res, res_size); 66 /* Don't re-read op1_ptr and op2_ptr. Since res_size <= 67 MIN(op1_size, op2_size), res is not changed when op1 68 is identical to res or op2 is identical to res. */ 69 70 SIZ(res) = res_size; 71 if (LIKELY (res_size != 0)) 72 mpn_and_n (res_ptr, op1_ptr, op2_ptr, res_size); 73 return; 74 } 75 else /* op2_size < 0 */ 76 { 77 /* Fall through to the code at the end of the function. */ 78 } 79 } 80 else 81 { 82 if (op2_size < 0) 83 { 84 mp_ptr opx, opy; 85 mp_limb_t cy; 86 87 /* Both operands are negative, so will be the result. 88 -((-OP1) & (-OP2)) = -(~(OP1 - 1) & ~(OP2 - 1)) = 89 = ~(~(OP1 - 1) & ~(OP2 - 1)) + 1 = 90 = ((OP1 - 1) | (OP2 - 1)) + 1 */ 91 92 /* It might seem as we could end up with an (invalid) result with 93 a leading zero-limb here when one of the operands is of the 94 type 1,,0,,..,,.0. But some analysis shows that we surely 95 would get carry into the zero-limb in this situation... */ 96 97 op1_size = -op1_size; 98 op2_size = -op2_size; 99 100 if (op1_size > op2_size) 101 MPN_SRCPTR_SWAP (op1_ptr, op1_size, op2_ptr, op2_size); 102 103 TMP_ALLOC_LIMBS_2 (opx, op1_size, opy, op2_size); 104 mpn_sub_1 (opx, op1_ptr, op1_size, (mp_limb_t) 1); 105 op1_ptr = opx; 106 107 mpn_sub_1 (opy, op2_ptr, op2_size, (mp_limb_t) 1); 108 op2_ptr = opy; 109 110 res_ptr = MPZ_REALLOC (res, 1 + op2_size); 111 /* Don't re-read OP1_PTR and OP2_PTR. They point to temporary 112 space--never to the space PTR(res) used to point to before 113 reallocation. */ 114 115 MPN_COPY (res_ptr + op1_size, op2_ptr + op1_size, 116 op2_size - op1_size); 117 mpn_ior_n (res_ptr, op1_ptr, op2_ptr, op1_size); 118 res_size = op2_size; 119 120 cy = mpn_add_1 (res_ptr, res_ptr, res_size, (mp_limb_t) 1); 121 res_ptr[res_size] = cy; 122 res_size += (cy != 0); 123 124 SIZ(res) = -res_size; 125 TMP_FREE; 126 return; 127 } 128 else 129 { 130 /* We should compute -OP1 & OP2. Swap OP1 and OP2 and fall 131 through to the code that handles OP1 & -OP2. */ 132 MPN_SRCPTR_SWAP (op1_ptr, op1_size, op2_ptr, op2_size); 133 } 134 135 } 136 137 { 138 #if ANDNEW 139 mp_size_t op2_lim; 140 mp_size_t count; 141 142 /* OP2 must be negated as with infinite precision. 143 144 Scan from the low end for a non-zero limb. The first non-zero 145 limb is simply negated (two's complement). Any subsequent 146 limbs are one's complemented. Of course, we don't need to 147 handle more limbs than there are limbs in the other, positive 148 operand as the result for those limbs is going to become zero 149 anyway. */ 150 151 /* Scan for the least significant non-zero OP2 limb, and zero the 152 result meanwhile for those limb positions. (We will surely 153 find a non-zero limb, so we can write the loop with one 154 termination condition only.) */ 155 for (i = 0; op2_ptr[i] == 0; i++) 156 res_ptr[i] = 0; 157 op2_lim = i; 158 159 op2_size = -op2_size; 160 161 if (op1_size <= op2_size) 162 { 163 /* The ones-extended OP2 is >= than the zero-extended OP1. 164 RES_SIZE <= OP1_SIZE. Find the exact size. */ 165 for (i = op1_size - 1; i > op2_lim; i--) 166 if ((op1_ptr[i] & ~op2_ptr[i]) != 0) 167 break; 168 res_size = i + 1; 169 for (i = res_size - 1; i > op2_lim; i--) 170 res_ptr[i] = op1_ptr[i] & ~op2_ptr[i]; 171 res_ptr[op2_lim] = op1_ptr[op2_lim] & -op2_ptr[op2_lim]; 172 /* Yes, this *can* happen! */ 173 MPN_NORMALIZE (res_ptr, res_size); 174 } 175 else 176 { 177 /* The ones-extended OP2 is < than the zero-extended OP1. 178 RES_SIZE == OP1_SIZE, since OP1 is normalized. */ 179 res_size = op1_size; 180 MPN_COPY (res_ptr + op2_size, op1_ptr + op2_size, op1_size - op2_size); 181 for (i = op2_size - 1; i > op2_lim; i--) 182 res_ptr[i] = op1_ptr[i] & ~op2_ptr[i]; 183 res_ptr[op2_lim] = op1_ptr[op2_lim] & -op2_ptr[op2_lim]; 184 } 185 186 SIZ(res) = res_size; 187 #else 188 189 /* OP1 is positive and zero-extended, 190 OP2 is negative and ones-extended. 191 The result will be positive. 192 OP1 & -OP2 = OP1 & ~(OP2 - 1). */ 193 194 mp_ptr opx; 195 196 op2_size = -op2_size; 197 opx = TMP_ALLOC_LIMBS (op2_size); 198 mpn_sub_1 (opx, op2_ptr, op2_size, (mp_limb_t) 1); 199 op2_ptr = opx; 200 201 if (op1_size > op2_size) 202 { 203 /* The result has the same size as OP1, since OP1 is normalized 204 and longer than the ones-extended OP2. */ 205 res_size = op1_size; 206 207 /* Handle allocation, now then we know exactly how much space is 208 needed for the result. */ 209 res_ptr = MPZ_REALLOC (res, res_size); 210 /* Don't re-read OP1_PTR or OP2_PTR. Since res_size = op1_size, 211 op1 is not changed if it is identical to res. 212 OP2_PTR points to temporary space. */ 213 214 MPN_COPY (res_ptr + op2_size, op1_ptr + op2_size, res_size - op2_size); 215 mpn_andn_n (res_ptr, op1_ptr, op2_ptr, op2_size); 216 217 SIZ(res) = res_size; 218 } 219 else 220 { 221 /* Find out the exact result size. Ignore the high limbs of OP2, 222 OP1 is zero-extended and would make the result zero. */ 223 for (i = op1_size - 1; i >= 0; i--) 224 if ((op1_ptr[i] & ~op2_ptr[i]) != 0) 225 break; 226 res_size = i + 1; 227 228 /* Handle allocation, now then we know exactly how much space is 229 needed for the result. */ 230 res_ptr = MPZ_REALLOC (res, res_size); 231 /* Don't re-read OP1_PTR. Since res_size <= op1_size, 232 op1 is not changed if it is identical to res. 233 Don't re-read OP2_PTR. It points to temporary space--never 234 to the space PTR(res) used to point to before reallocation. */ 235 236 if (LIKELY (res_size != 0)) 237 mpn_andn_n (res_ptr, op1_ptr, op2_ptr, res_size); 238 239 SIZ(res) = res_size; 240 } 241 #endif 242 } 243 TMP_FREE; 244 } 245