1 /* mpz_mul -- Multiply two integers.
2
3 Copyright 1991, 1993, 1994, 1996, 2000, 2001, 2005, 2009, 2011, 2012,
4 2015 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 <stdio.h> /* for NULL */
33 #include "gmp-impl.h"
34
35
36 void
37 mpz_mul (mpz_ptr w, mpz_srcptr u, mpz_srcptr v)
38 {
39 mp_size_t usize;
40 mp_size_t vsize;
41 mp_size_t wsize;
42 mp_size_t sign_product;
43 mp_ptr up, vp;
44 mp_ptr wp;
45 mp_ptr free_me;
46 size_t free_me_size;
47 mp_limb_t cy_limb;
48 TMP_DECL;
49
50 usize = SIZ (u);
51 vsize = SIZ (v);
52 sign_product = usize ^ vsize;
53 usize = ABS (usize);
54 vsize = ABS (vsize);
55
56 if (usize < vsize)
57 {
58 MPZ_SRCPTR_SWAP (u, v);
59 MP_SIZE_T_SWAP (usize, vsize);
60 }
61
62 if (vsize == 0)
63 {
64 SIZ (w) = 0;
65 return;
66 }
67
68 #if HAVE_NATIVE_mpn_mul_2
69 if (vsize <= 2)
70 {
71 wp = MPZ_REALLOC (w, usize+vsize);
72 if (vsize == 1)
73 cy_limb = mpn_mul_1 (wp, PTR (u), usize, PTR (v)[0]);
74 else
75 {
76 cy_limb = mpn_mul_2 (wp, PTR (u), usize, PTR (v));
77 usize++;
78 }
79 wp[usize] = cy_limb;
80 usize += (cy_limb != 0);
81 SIZ (w) = (sign_product >= 0 ? usize : -usize);
82 return;
83 }
84 #else
85 if (vsize == 1)
86 {
87 wp = MPZ_REALLOC (w, usize+1);
88 cy_limb = mpn_mul_1 (wp, PTR (u), usize, PTR (v)[0]);
89 wp[usize] = cy_limb;
90 usize += (cy_limb != 0);
91 SIZ (w) = (sign_product >= 0 ? usize : -usize);
92 return;
93 }
94 #endif
95
96 TMP_MARK;
97 free_me = NULL;
98 up = PTR (u);
99 vp = PTR (v);
100 wp = PTR (w);
101
102 /* Ensure W has space enough to store the result. */
103 wsize = usize + vsize;
104 if (ALLOC (w) < wsize)
105 {
106 if (ALLOC (w) != 0)
107 {
108 if (wp == up || wp == vp)
109 {
110 free_me = wp;
111 free_me_size = ALLOC (w);
112 }
113 else
114 (*__gmp_free_func) (wp, (size_t) ALLOC (w) * GMP_LIMB_BYTES);
115 }
116
117 ALLOC (w) = wsize;
118 wp = __GMP_ALLOCATE_FUNC_LIMBS (wsize);
119 PTR (w) = wp;
120 }
121 else
122 {
123 /* Make U and V not overlap with W. */
124 if (wp == up)
125 {
126 /* W and U are identical. Allocate temporary space for U. */
127 up = TMP_ALLOC_LIMBS (usize);
128 /* Is V identical too? Keep it identical with U. */
129 if (wp == vp)
130 vp = up;
131 /* Copy to the temporary space. */
132 MPN_COPY (up, wp, usize);
133 }
134 else if (wp == vp)
135 {
136 /* W and V are identical. Allocate temporary space for V. */
137 vp = TMP_ALLOC_LIMBS (vsize);
138 /* Copy to the temporary space. */
139 MPN_COPY (vp, wp, vsize);
140 }
141 }
142
143 if (up == vp)
144 {
145 mpn_sqr (wp, up, usize);
146 cy_limb = wp[wsize - 1];
147 }
148 else
149 {
150 cy_limb = mpn_mul (wp, up, usize, vp, vsize);
151 }
152
153 wsize -= cy_limb == 0;
154
155 SIZ (w) = sign_product < 0 ? -wsize : wsize;
156 if (free_me != NULL)
157 (*__gmp_free_func) (free_me, free_me_size * GMP_LIMB_BYTES);
158 TMP_FREE;
159 }