1 /* mpz_export -- create word data from mpz.
2
3 Copyright 2002, 2003, 2012 Free Software Foundation, Inc.
4
5 This file is part of the GNU MP Library.
6
7 The GNU MP Library is free software; you can redistribute it and/or modify
8 it under the terms of either:
9
10 * the GNU Lesser General Public License as published by the Free
11 Software Foundation; either version 3 of the License, or (at your
12 option) any later version.
13
14 or
15
16 * the GNU General Public License as published by the Free Software
17 Foundation; either version 2 of the License, or (at your option) any
18 later version.
19
20 or both in parallel, as here.
21
22 The GNU MP Library is distributed in the hope that it will be useful, but
23 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
24 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
25 for more details.
26
27 You should have received copies of the GNU General Public License and the
28 GNU Lesser General Public License along with the GNU MP Library. If not,
29 see https://www.gnu.org/licenses/. */
30
31 #include <stdio.h> /* for NULL */
32 #include "gmp-impl.h"
33 #include "longlong.h"
34
35
36 #if HAVE_LIMB_BIG_ENDIAN
37 #define HOST_ENDIAN 1
38 #endif
39 #if HAVE_LIMB_LITTLE_ENDIAN
40 #define HOST_ENDIAN (-1)
41 #endif
42 #ifndef HOST_ENDIAN
43 static const mp_limb_t endian_test = (CNST_LIMB(1) << (GMP_LIMB_BITS-7)) - 1;
44 #define HOST_ENDIAN (* (signed char *) &endian_test)
45 #endif
46
47 void *
48 mpz_export (void *data, size_t *countp, int order,
49 size_t size, int endian, size_t nail, mpz_srcptr z)
50 {
51 mp_size_t zsize;
52 mp_srcptr zp;
53 size_t count, dummy;
54 unsigned long numb;
55 unsigned align;
56
57 ASSERT (order == 1 || order == -1);
58 ASSERT (endian == 1 || endian == 0 || endian == -1);
59 ASSERT (nail <= 8*size);
60 ASSERT (nail < 8*size || SIZ(z) == 0); /* nail < 8*size+(SIZ(z)==0) */
61
62 if (countp == NULL)
63 countp = &dummy;
64
65 zsize = SIZ(z);
66 if (zsize == 0)
67 {
68 *countp = 0;
69 return data;
70 }
71
72 zsize = ABS (zsize);
73 zp = PTR(z);
74 numb = 8*size - nail;
75 MPN_SIZEINBASE_2EXP (count, zp, zsize, numb);
76 *countp = count;
77
78 if (data == NULL)
79 data = (*__gmp_allocate_func) (count*size);
80
81 if (endian == 0)
82 endian = HOST_ENDIAN;
83
84 align = ((char *) data - (char *) NULL) % sizeof (mp_limb_t);
85
86 if (nail == GMP_NAIL_BITS)
87 {
88 if (size == sizeof (mp_limb_t) && align == 0)
89 {
90 if (order == -1 && endian == HOST_ENDIAN)
91 {
92 MPN_COPY ((mp_ptr) data, zp, (mp_size_t) count);
93 return data;
94 }
95 if (order == 1 && endian == HOST_ENDIAN)
96 {
97 MPN_REVERSE ((mp_ptr) data, zp, (mp_size_t) count);
98 return data;
99 }
100
101 if (order == -1 && endian == -HOST_ENDIAN)
102 {
103 MPN_BSWAP ((mp_ptr) data, zp, (mp_size_t) count);
104 return data;
105 }
106 if (order == 1 && endian == -HOST_ENDIAN)
107 {
108 MPN_BSWAP_REVERSE ((mp_ptr) data, zp, (mp_size_t) count);
109 return data;
110 }
111 }
112 }
113
114 {
115 mp_limb_t limb, wbitsmask;
116 size_t i, numb;
117 mp_size_t j, wbytes, woffset;
118 unsigned char *dp;
119 int lbits, wbits;
120 mp_srcptr zend;
121
122 numb = size * 8 - nail;
123
124 /* whole bytes per word */
125 wbytes = numb / 8;
126
127 /* possible partial byte */
128 wbits = numb % 8;
129 wbitsmask = (CNST_LIMB(1) << wbits) - 1;
130
131 /* offset to get to the next word */
132 woffset = (endian >= 0 ? size : - (mp_size_t) size)
133 + (order < 0 ? size : - (mp_size_t) size);
134
135 /* least significant byte */
136 dp = (unsigned char *) data
137 + (order >= 0 ? (count-1)*size : 0) + (endian >= 0 ? size-1 : 0);
138
139 #define EXTRACT(N, MASK) \
140 do { \
141 if (lbits >= (N)) \
142 { \
143 *dp = limb MASK; \
144 limb >>= (N); \
145 lbits -= (N); \
146 } \
147 else \
148 { \
149 mp_limb_t newlimb; \
150 newlimb = (zp == zend ? 0 : *zp++); \
151 *dp = (limb | (newlimb << lbits)) MASK; \
152 limb = newlimb >> ((N)-lbits); \
153 lbits += GMP_NUMB_BITS - (N); \
154 } \
155 } while (0)
156
157 zend = zp + zsize;
158 lbits = 0;
159 limb = 0;
160 for (i = 0; i < count; i++)
161 {
162 for (j = 0; j < wbytes; j++)
163 {
164 EXTRACT (8, + 0);
165 dp -= endian;
166 }
167 if (wbits != 0)
168 {
169 EXTRACT (wbits, & wbitsmask);
170 dp -= endian;
171 j++;
172 }
173 for ( ; j < size; j++)
174 {
175 *dp = '\0';
176 dp -= endian;
177 }
178 dp += woffset;
179 }
180
181 ASSERT (zp == PTR(z) + ABSIZ(z));
182
183 /* low byte of word after most significant */
184 ASSERT (dp == (unsigned char *) data
185 + (order < 0 ? count*size : - (mp_size_t) size)
186 + (endian >= 0 ? (mp_size_t) size - 1 : 0));
187 }
188 return data;
189 }