1 /* mpz_ior -- Logical inclusive or.
2
3 Copyright 1991, 1993, 1994, 1996, 1997, 2000, 2001, 2005, 2012, 2013,
4 2015-2018 Free 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-impl.h"
33
34 void
35 mpz_ior (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 mp_size_t i;
42
43 op1_size = SIZ(op1);
44 op2_size = SIZ(op2);
45
46 if (op1_size < op2_size)
47 {
48 MPZ_SRCPTR_SWAP (op1, op2);
49 MP_SIZE_T_SWAP (op1_size, op2_size);
50 }
51
52 op1_ptr = PTR(op1);
53 res_ptr = PTR(res);
54
55 if (op2_size >= 0)
56 {
57 if (res_ptr != op1_ptr)
58 {
59 res_ptr = MPZ_REALLOC (res, op1_size);
60 /* No overlapping possible: op1_ptr = PTR(op1); */
61 MPN_COPY (res_ptr + op2_size, op1_ptr + op2_size,
62 op1_size - op2_size);
63 }
64 if (LIKELY (op2_size != 0))
65 mpn_ior_n (res_ptr, op1_ptr, PTR(op2), op2_size);
66
67 SIZ(res) = op1_size;
68 }
69 else
70 {
71 mp_ptr opx;
72 TMP_DECL;
73
74 TMP_MARK;
75 if (op1_size < 0)
76 {
77 mp_ptr opy;
78
79 /* Both operands are negative, so will be the result.
80 -((-OP1) | (-OP2)) = -(~(OP1 - 1) | ~(OP2 - 1)) =
81 = ~(~(OP1 - 1) | ~(OP2 - 1)) + 1 =
82 = ((OP1 - 1) & (OP2 - 1)) + 1 */
83
84 res_size = -op1_size;
85
86 /* Possible optimization: Decrease mpn_sub precision,
87 as we won't use the entire res of both. */
88 TMP_ALLOC_LIMBS_2 (opx, res_size, opy, res_size);
89 mpn_sub_1 (opx, op1_ptr, res_size, (mp_limb_t) 1);
90 op1_ptr = opx;
91
92 mpn_sub_1 (opy, PTR(op2), res_size, (mp_limb_t) 1);
93 op2_ptr = opy;
94
95 /* First loop finds the size of the result. */
96 for (i = res_size; --i >= 0;)
97 if ((op1_ptr[i] & op2_ptr[i]) != 0)
98 break;
99 res_size = i + 1;
100
101 res_ptr = MPZ_NEWALLOC (res, res_size + 1);
102
103 if (res_size != 0)
104 {
105 /* Second loop computes the real result. */
106 mpn_and_n (res_ptr, op1_ptr, op2_ptr, res_size);
107
108 res_ptr[res_size] = 0;
109 MPN_INCR_U (res_ptr, res_size + 1, 1);
110 res_size += res_ptr[res_size];
111 }
112 else
113 {
114 res_ptr[0] = 1;
115 res_size = 1;
116 }
117
118 SIZ(res) = -res_size;
119 }
120 else
121 {
122 mp_limb_t cy;
123 mp_size_t count;
124
125 /* Operand 2 negative, so will be the result.
126 -(OP1 | (-OP2)) = -(OP1 | ~(OP2 - 1)) =
127 = ~(OP1 | ~(OP2 - 1)) + 1 =
128 = (~OP1 & (OP2 - 1)) + 1 */
129
130 op2_size = -op2_size;
131
132 res_ptr = MPZ_REALLOC (res, op2_size);
133 op1_ptr = PTR(op1);
134
135 opx = TMP_ALLOC_LIMBS (op2_size);
136 mpn_sub_1 (opx, PTR(op2), op2_size, (mp_limb_t) 1);
137 op2_ptr = opx;
138 op2_size -= op2_ptr[op2_size - 1] == 0;
139
140 if (op1_size >= op2_size)
141 {
142 /* We can just ignore the part of OP1 that stretches above OP2,
143 because the result limbs are zero there. */
144
145 /* First loop finds the size of the result. */
146 for (i = op2_size; --i >= 0;)
147 if ((~op1_ptr[i] & op2_ptr[i]) != 0)
148 break;
149 res_size = i + 1;
150 count = res_size;
151 }
152 else
153 {
154 res_size = op2_size;
155
156 /* Copy the part of OP2 that stretches above OP1, to RES. */
157 MPN_COPY (res_ptr + op1_size, op2_ptr + op1_size, op2_size - op1_size);
158 count = op1_size;
159 }
160
161 if (res_size != 0)
162 {
163 /* Second loop computes the real result. */
164 if (LIKELY (count != 0))
165 mpn_andn_n (res_ptr, op2_ptr, op1_ptr, count);
166
167 cy = mpn_add_1 (res_ptr, res_ptr, res_size, (mp_limb_t) 1);
168 if (cy)
169 {
170 res_ptr[res_size] = cy;
171 ++res_size;
172 }
173 }
174 else
175 {
176 res_ptr[0] = 1;
177 res_size = 1;
178 }
179
180 SIZ(res) = -res_size;
181 }
182 TMP_FREE;
183 }
184 }