1 /* mpz_inp_raw -- read an mpz_t in raw format.
2
3 Copyright 2001, 2002, 2005 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 the GNU Lesser General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or (at your
10 option) any later version.
11
12 The GNU MP Library is distributed in the hope that it will be useful, but
13 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
14 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
15 License for more details.
16
17 You should have received a copy of the GNU Lesser General Public License
18 along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */
19
20 #include <stdio.h>
21 #include "gmp.h"
22 #include "gmp-impl.h"
23
24
25 /* NTOH_LIMB_FETCH fetches a limb which is in network byte order (ie. big
26 endian) and produces a normal host byte order result. */
27
28 #if HAVE_LIMB_BIG_ENDIAN
29 #define NTOH_LIMB_FETCH(limb, src) do { (limb) = *(src); } while (0)
30 #endif
31
32 #if HAVE_LIMB_LITTLE_ENDIAN
33 #define NTOH_LIMB_FETCH(limb, src) BSWAP_LIMB_FETCH (limb, src)
34 #endif
35
36 #ifndef NTOH_LIMB_FETCH
37 #define NTOH_LIMB_FETCH(limb, src) \
38 do { \
39 const unsigned char *__p = (const unsigned char *) (src); \
40 mp_limb_t __limb; \
41 int __i; \
42 __limb = 0; \
43 for (__i = 0; __i < BYTES_PER_MP_LIMB; __i++) \
44 __limb = (__limb << 8) | __p[__i]; \
45 (limb) = __limb; \
46 } while (0)
47 #endif
48
49
50 /* Enhancement: The byte swap loop ought to be safe to vectorize on Cray
51 etc, but someone who knows what they're doing needs to check it. */
52
53 size_t
mpz_inp_raw(mpz_ptr x,FILE * fp)54 mpz_inp_raw (mpz_ptr x, FILE *fp)
55 {
56 unsigned char csize_bytes[4];
57 mp_size_t csize, abs_xsize, i;
58 size_t abs_csize;
59 char *cp;
60 mp_ptr xp, sp, ep;
61 mp_limb_t slimb, elimb;
62
63 if (fp == 0)
64 fp = stdin;
65
66 /* 4 bytes for size */
67 if (fread (csize_bytes, sizeof (csize_bytes), 1, fp) != 1)
68 return 0;
69
70 csize =
71 ( (mp_size_t) csize_bytes[0] << 24)
72 + ((mp_size_t) csize_bytes[1] << 16)
73 + ((mp_size_t) csize_bytes[2] << 8)
74 + ((mp_size_t) csize_bytes[3]);
75
76 /* Sign extend if necessary.
77 Could write "csize -= ((csize & 0x80000000L) << 1)", but that tickles a
78 bug in gcc 3.0 for powerpc64 on AIX. */
79 if (sizeof (csize) > 4 && csize & 0x80000000L)
80 csize -= 0x80000000L << 1;
81
82 abs_csize = ABS (csize);
83
84 /* round up to a multiple of limbs */
85 abs_xsize = (abs_csize*8 + GMP_NUMB_BITS-1) / GMP_NUMB_BITS;
86
87 if (abs_xsize != 0)
88 {
89 MPZ_REALLOC (x, abs_xsize);
90 xp = PTR(x);
91
92 /* Get limb boundaries right in the read, for the benefit of the
93 non-nails case. */
94 xp[0] = 0;
95 cp = (char *) (xp + abs_xsize) - abs_csize;
96 if (fread (cp, abs_csize, 1, fp) != 1)
97 return 0;
98
99 if (GMP_NAIL_BITS == 0)
100 {
101 /* Reverse limbs to least significant first, and byte swap. If
102 abs_xsize is odd then on the last iteration elimb and slimb are
103 the same. It doesn't seem extra code to handle that case
104 separately, to save an NTOH. */
105 sp = xp;
106 ep = xp + abs_xsize-1;
107 for (i = 0; i < (abs_xsize+1)/2; i++)
108 {
109 NTOH_LIMB_FETCH (elimb, ep);
110 NTOH_LIMB_FETCH (slimb, sp);
111 *sp++ = elimb;
112 *ep-- = slimb;
113 }
114 }
115 else
116 {
117 /* It ought to be possible to do the transformation in-place, but
118 for now it's easier to use an extra temporary area. */
119 mp_limb_t byte, limb;
120 int bits;
121 mp_size_t tpos;
122 mp_ptr tp;
123 TMP_DECL;
124
125 TMP_MARK;
126 tp = TMP_ALLOC_LIMBS (abs_xsize);
127 limb = 0;
128 bits = 0;
129 tpos = 0;
130 for (i = abs_csize-1; i >= 0; i--)
131 {
132 byte = (unsigned char) cp[i];
133 limb |= (byte << bits);
134 bits += 8;
135 if (bits >= GMP_NUMB_BITS)
136 {
137 ASSERT (tpos < abs_xsize);
138 tp[tpos++] = limb & GMP_NUMB_MASK;
139 bits -= GMP_NUMB_BITS;
140 ASSERT (bits < 8);
141 limb = byte >> (8 - bits);
142 }
143 }
144 if (bits != 0)
145 {
146 ASSERT (tpos < abs_xsize);
147 tp[tpos++] = limb;
148 }
149 ASSERT (tpos == abs_xsize);
150
151 MPN_COPY (xp, tp, abs_xsize);
152 TMP_FREE;
153 }
154
155 /* GMP 1.x mpz_out_raw wrote high zero bytes, strip any high zero
156 limbs resulting from this. Should be a non-zero value here, but
157 for safety don't assume that. */
158 MPN_NORMALIZE (xp, abs_xsize);
159 }
160
161 SIZ(x) = (csize >= 0 ? abs_xsize : -abs_xsize);
162 return abs_csize + 4;
163 }
164