1 /* mpz_inp_raw -- read an mpz_t in raw format. 2 3 Copyright 2001, 2002, 2005, 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 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 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 xp = MPZ_REALLOC (x, abs_xsize); 90 91 /* Get limb boundaries right in the read, for the benefit of the 92 non-nails case. */ 93 xp[0] = 0; 94 cp = (char *) (xp + abs_xsize) - abs_csize; 95 if (fread (cp, abs_csize, 1, fp) != 1) 96 return 0; 97 98 if (GMP_NAIL_BITS == 0) 99 { 100 /* Reverse limbs to least significant first, and byte swap. If 101 abs_xsize is odd then on the last iteration elimb and slimb are 102 the same. It doesn't seem extra code to handle that case 103 separately, to save an NTOH. */ 104 sp = xp; 105 ep = xp + abs_xsize-1; 106 for (i = 0; i < (abs_xsize+1)/2; i++) 107 { 108 NTOH_LIMB_FETCH (elimb, ep); 109 NTOH_LIMB_FETCH (slimb, sp); 110 *sp++ = elimb; 111 *ep-- = slimb; 112 } 113 } 114 else 115 { 116 /* It ought to be possible to do the transformation in-place, but 117 for now it's easier to use an extra temporary area. */ 118 mp_limb_t byte, limb; 119 int bits; 120 mp_size_t tpos; 121 mp_ptr tp; 122 TMP_DECL; 123 124 TMP_MARK; 125 tp = TMP_ALLOC_LIMBS (abs_xsize); 126 limb = 0; 127 bits = 0; 128 tpos = 0; 129 for (i = abs_csize-1; i >= 0; i--) 130 { 131 byte = (unsigned char) cp[i]; 132 limb |= (byte << bits); 133 bits += 8; 134 if (bits >= GMP_NUMB_BITS) 135 { 136 ASSERT (tpos < abs_xsize); 137 tp[tpos++] = limb & GMP_NUMB_MASK; 138 bits -= GMP_NUMB_BITS; 139 ASSERT (bits < 8); 140 limb = byte >> (8 - bits); 141 } 142 } 143 if (bits != 0) 144 { 145 ASSERT (tpos < abs_xsize); 146 tp[tpos++] = limb; 147 } 148 ASSERT (tpos == abs_xsize); 149 150 MPN_COPY (xp, tp, abs_xsize); 151 TMP_FREE; 152 } 153 154 /* GMP 1.x mpz_out_raw wrote high zero bytes, strip any high zero 155 limbs resulting from this. Should be a non-zero value here, but 156 for safety don't assume that. */ 157 MPN_NORMALIZE (xp, abs_xsize); 158 } 159 160 SIZ(x) = (csize >= 0 ? abs_xsize : -abs_xsize); 161 return abs_csize + 4; 162 } 163