J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 3 | * |
| 4 | * This code is free software; you can redistribute it and/or modify it |
| 5 | * under the terms of the GNU General Public License version 2 only, as |
| 6 | * published by the Free Software Foundation. Sun designates this |
| 7 | * particular file as subject to the "Classpath" exception as provided |
| 8 | * by Sun in the LICENSE file that accompanied this code. |
| 9 | * |
| 10 | * This code is distributed in the hope that it will be useful, but WITHOUT |
| 11 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 12 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 13 | * version 2 for more details (a copy is included in the LICENSE file that |
| 14 | * accompanied this code). |
| 15 | * |
| 16 | * You should have received a copy of the GNU General Public License version |
| 17 | * 2 along with this work; if not, write to the Free Software Foundation, |
| 18 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| 19 | * |
| 20 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 21 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 22 | * have any questions. |
| 23 | * |
| 24 | * THIS FILE WAS MODIFIED BY SUN MICROSYSTEMS, INC. |
| 25 | */ |
| 26 | |
| 27 | /* |
| 28 | * This file is available under and governed by the GNU General Public |
| 29 | * License version 2 only, as published by the Free Software Foundation. |
| 30 | * However, the following notice accompanied the original version of this |
| 31 | * file and, per its terms, should not be removed: |
| 32 | * |
| 33 | * crc32.c -- compute the CRC-32 of a data stream |
| 34 | * Copyright (C) 1995-1998 Mark Adler |
| 35 | * For conditions of distribution and use, see copyright notice in zlib.h |
| 36 | */ |
| 37 | |
| 38 | #include "zlib.h" |
| 39 | |
| 40 | #define local static |
| 41 | |
| 42 | #ifdef DYNAMIC_CRC_TABLE |
| 43 | |
| 44 | local int crc_table_empty = 1; |
| 45 | local uLongf crc_table[256]; |
| 46 | local void make_crc_table OF((void)); |
| 47 | |
| 48 | /* |
| 49 | Generate a table for a byte-wise 32-bit CRC calculation on the polynomial: |
| 50 | x^32+x^26+x^23+x^22+x^16+x^12+x^11+x^10+x^8+x^7+x^5+x^4+x^2+x+1. |
| 51 | |
| 52 | Polynomials over GF(2) are represented in binary, one bit per coefficient, |
| 53 | with the lowest powers in the most significant bit. Then adding polynomials |
| 54 | is just exclusive-or, and multiplying a polynomial by x is a right shift by |
| 55 | one. If we call the above polynomial p, and represent a byte as the |
| 56 | polynomial q, also with the lowest power in the most significant bit (so the |
| 57 | byte 0xb1 is the polynomial x^7+x^3+x+1), then the CRC is (q*x^32) mod p, |
| 58 | where a mod b means the remainder after dividing a by b. |
| 59 | |
| 60 | This calculation is done using the shift-register method of multiplying and |
| 61 | taking the remainder. The register is initialized to zero, and for each |
| 62 | incoming bit, x^32 is added mod p to the register if the bit is a one (where |
| 63 | x^32 mod p is p+x^32 = x^26+...+1), and the register is multiplied mod p by |
| 64 | x (which is shifting right by one and adding x^32 mod p if the bit shifted |
| 65 | out is a one). We start with the highest power (least significant bit) of |
| 66 | q and repeat for all eight bits of q. |
| 67 | |
| 68 | The table is simply the CRC of all possible eight bit values. This is all |
| 69 | the information needed to generate CRC's on data a byte at a time for all |
| 70 | combinations of CRC register values and incoming bytes. |
| 71 | */ |
| 72 | local void make_crc_table() |
| 73 | { |
| 74 | uLong c; |
| 75 | int n, k; |
| 76 | uLong poly; /* polynomial exclusive-or pattern */ |
| 77 | /* terms of polynomial defining this crc (except x^32): */ |
| 78 | static const Byte p[] = {0,1,2,4,5,7,8,10,11,12,16,22,23,26}; |
| 79 | |
| 80 | /* make exclusive-or pattern from polynomial (0xedb88320UL) */ |
| 81 | poly = 0UL; |
| 82 | for (n = 0; n < sizeof(p)/sizeof(Byte); n++) |
| 83 | poly |= 1L << (31 - p[n]); |
| 84 | |
| 85 | for (n = 0; n < 256; n++) |
| 86 | { |
| 87 | c = (uLong)n; |
| 88 | for (k = 0; k < 8; k++) |
| 89 | c = c & 1 ? poly ^ (c >> 1) : c >> 1; |
| 90 | crc_table[n] = c; |
| 91 | } |
| 92 | crc_table_empty = 0; |
| 93 | } |
| 94 | #else |
| 95 | /* ======================================================================== |
| 96 | * Table of CRC-32's of all single-byte values (made by make_crc_table) |
| 97 | */ |
| 98 | local const uLongf crc_table[256] = { |
| 99 | 0x00000000UL, 0x77073096UL, 0xee0e612cUL, 0x990951baUL, 0x076dc419UL, |
| 100 | 0x706af48fUL, 0xe963a535UL, 0x9e6495a3UL, 0x0edb8832UL, 0x79dcb8a4UL, |
| 101 | 0xe0d5e91eUL, 0x97d2d988UL, 0x09b64c2bUL, 0x7eb17cbdUL, 0xe7b82d07UL, |
| 102 | 0x90bf1d91UL, 0x1db71064UL, 0x6ab020f2UL, 0xf3b97148UL, 0x84be41deUL, |
| 103 | 0x1adad47dUL, 0x6ddde4ebUL, 0xf4d4b551UL, 0x83d385c7UL, 0x136c9856UL, |
| 104 | 0x646ba8c0UL, 0xfd62f97aUL, 0x8a65c9ecUL, 0x14015c4fUL, 0x63066cd9UL, |
| 105 | 0xfa0f3d63UL, 0x8d080df5UL, 0x3b6e20c8UL, 0x4c69105eUL, 0xd56041e4UL, |
| 106 | 0xa2677172UL, 0x3c03e4d1UL, 0x4b04d447UL, 0xd20d85fdUL, 0xa50ab56bUL, |
| 107 | 0x35b5a8faUL, 0x42b2986cUL, 0xdbbbc9d6UL, 0xacbcf940UL, 0x32d86ce3UL, |
| 108 | 0x45df5c75UL, 0xdcd60dcfUL, 0xabd13d59UL, 0x26d930acUL, 0x51de003aUL, |
| 109 | 0xc8d75180UL, 0xbfd06116UL, 0x21b4f4b5UL, 0x56b3c423UL, 0xcfba9599UL, |
| 110 | 0xb8bda50fUL, 0x2802b89eUL, 0x5f058808UL, 0xc60cd9b2UL, 0xb10be924UL, |
| 111 | 0x2f6f7c87UL, 0x58684c11UL, 0xc1611dabUL, 0xb6662d3dUL, 0x76dc4190UL, |
| 112 | 0x01db7106UL, 0x98d220bcUL, 0xefd5102aUL, 0x71b18589UL, 0x06b6b51fUL, |
| 113 | 0x9fbfe4a5UL, 0xe8b8d433UL, 0x7807c9a2UL, 0x0f00f934UL, 0x9609a88eUL, |
| 114 | 0xe10e9818UL, 0x7f6a0dbbUL, 0x086d3d2dUL, 0x91646c97UL, 0xe6635c01UL, |
| 115 | 0x6b6b51f4UL, 0x1c6c6162UL, 0x856530d8UL, 0xf262004eUL, 0x6c0695edUL, |
| 116 | 0x1b01a57bUL, 0x8208f4c1UL, 0xf50fc457UL, 0x65b0d9c6UL, 0x12b7e950UL, |
| 117 | 0x8bbeb8eaUL, 0xfcb9887cUL, 0x62dd1ddfUL, 0x15da2d49UL, 0x8cd37cf3UL, |
| 118 | 0xfbd44c65UL, 0x4db26158UL, 0x3ab551ceUL, 0xa3bc0074UL, 0xd4bb30e2UL, |
| 119 | 0x4adfa541UL, 0x3dd895d7UL, 0xa4d1c46dUL, 0xd3d6f4fbUL, 0x4369e96aUL, |
| 120 | 0x346ed9fcUL, 0xad678846UL, 0xda60b8d0UL, 0x44042d73UL, 0x33031de5UL, |
| 121 | 0xaa0a4c5fUL, 0xdd0d7cc9UL, 0x5005713cUL, 0x270241aaUL, 0xbe0b1010UL, |
| 122 | 0xc90c2086UL, 0x5768b525UL, 0x206f85b3UL, 0xb966d409UL, 0xce61e49fUL, |
| 123 | 0x5edef90eUL, 0x29d9c998UL, 0xb0d09822UL, 0xc7d7a8b4UL, 0x59b33d17UL, |
| 124 | 0x2eb40d81UL, 0xb7bd5c3bUL, 0xc0ba6cadUL, 0xedb88320UL, 0x9abfb3b6UL, |
| 125 | 0x03b6e20cUL, 0x74b1d29aUL, 0xead54739UL, 0x9dd277afUL, 0x04db2615UL, |
| 126 | 0x73dc1683UL, 0xe3630b12UL, 0x94643b84UL, 0x0d6d6a3eUL, 0x7a6a5aa8UL, |
| 127 | 0xe40ecf0bUL, 0x9309ff9dUL, 0x0a00ae27UL, 0x7d079eb1UL, 0xf00f9344UL, |
| 128 | 0x8708a3d2UL, 0x1e01f268UL, 0x6906c2feUL, 0xf762575dUL, 0x806567cbUL, |
| 129 | 0x196c3671UL, 0x6e6b06e7UL, 0xfed41b76UL, 0x89d32be0UL, 0x10da7a5aUL, |
| 130 | 0x67dd4accUL, 0xf9b9df6fUL, 0x8ebeeff9UL, 0x17b7be43UL, 0x60b08ed5UL, |
| 131 | 0xd6d6a3e8UL, 0xa1d1937eUL, 0x38d8c2c4UL, 0x4fdff252UL, 0xd1bb67f1UL, |
| 132 | 0xa6bc5767UL, 0x3fb506ddUL, 0x48b2364bUL, 0xd80d2bdaUL, 0xaf0a1b4cUL, |
| 133 | 0x36034af6UL, 0x41047a60UL, 0xdf60efc3UL, 0xa867df55UL, 0x316e8eefUL, |
| 134 | 0x4669be79UL, 0xcb61b38cUL, 0xbc66831aUL, 0x256fd2a0UL, 0x5268e236UL, |
| 135 | 0xcc0c7795UL, 0xbb0b4703UL, 0x220216b9UL, 0x5505262fUL, 0xc5ba3bbeUL, |
| 136 | 0xb2bd0b28UL, 0x2bb45a92UL, 0x5cb36a04UL, 0xc2d7ffa7UL, 0xb5d0cf31UL, |
| 137 | 0x2cd99e8bUL, 0x5bdeae1dUL, 0x9b64c2b0UL, 0xec63f226UL, 0x756aa39cUL, |
| 138 | 0x026d930aUL, 0x9c0906a9UL, 0xeb0e363fUL, 0x72076785UL, 0x05005713UL, |
| 139 | 0x95bf4a82UL, 0xe2b87a14UL, 0x7bb12baeUL, 0x0cb61b38UL, 0x92d28e9bUL, |
| 140 | 0xe5d5be0dUL, 0x7cdcefb7UL, 0x0bdbdf21UL, 0x86d3d2d4UL, 0xf1d4e242UL, |
| 141 | 0x68ddb3f8UL, 0x1fda836eUL, 0x81be16cdUL, 0xf6b9265bUL, 0x6fb077e1UL, |
| 142 | 0x18b74777UL, 0x88085ae6UL, 0xff0f6a70UL, 0x66063bcaUL, 0x11010b5cUL, |
| 143 | 0x8f659effUL, 0xf862ae69UL, 0x616bffd3UL, 0x166ccf45UL, 0xa00ae278UL, |
| 144 | 0xd70dd2eeUL, 0x4e048354UL, 0x3903b3c2UL, 0xa7672661UL, 0xd06016f7UL, |
| 145 | 0x4969474dUL, 0x3e6e77dbUL, 0xaed16a4aUL, 0xd9d65adcUL, 0x40df0b66UL, |
| 146 | 0x37d83bf0UL, 0xa9bcae53UL, 0xdebb9ec5UL, 0x47b2cf7fUL, 0x30b5ffe9UL, |
| 147 | 0xbdbdf21cUL, 0xcabac28aUL, 0x53b39330UL, 0x24b4a3a6UL, 0xbad03605UL, |
| 148 | 0xcdd70693UL, 0x54de5729UL, 0x23d967bfUL, 0xb3667a2eUL, 0xc4614ab8UL, |
| 149 | 0x5d681b02UL, 0x2a6f2b94UL, 0xb40bbe37UL, 0xc30c8ea1UL, 0x5a05df1bUL, |
| 150 | 0x2d02ef8dUL |
| 151 | }; |
| 152 | #endif |
| 153 | |
| 154 | /* ========================================================================= |
| 155 | * This function can be used by asm versions of crc32() |
| 156 | */ |
| 157 | const uLongf * ZEXPORT get_crc_table() |
| 158 | { |
| 159 | #ifdef DYNAMIC_CRC_TABLE |
| 160 | if (crc_table_empty) make_crc_table(); |
| 161 | #endif |
| 162 | return (const uLongf *)crc_table; |
| 163 | } |
| 164 | |
| 165 | /* ========================================================================= */ |
| 166 | #define DO1(buf) crc = crc_table[((int)crc ^ (*buf++)) & 0xff] ^ (crc >> 8); |
| 167 | #define DO2(buf) DO1(buf); DO1(buf); |
| 168 | #define DO4(buf) DO2(buf); DO2(buf); |
| 169 | #define DO8(buf) DO4(buf); DO4(buf); |
| 170 | |
| 171 | /* ========================================================================= */ |
| 172 | uLong ZEXPORT crc32(crc, buf, len) |
| 173 | uLong crc; |
| 174 | const Bytef *buf; |
| 175 | uInt len; |
| 176 | { |
| 177 | if (buf == Z_NULL) return 0UL; |
| 178 | #ifdef DYNAMIC_CRC_TABLE |
| 179 | if (crc_table_empty) |
| 180 | make_crc_table(); |
| 181 | #endif |
| 182 | crc = crc ^ 0xffffffffUL; |
| 183 | while (len >= 8) |
| 184 | { |
| 185 | DO8(buf); |
| 186 | len -= 8; |
| 187 | } |
| 188 | if (len) do { |
| 189 | DO1(buf); |
| 190 | } while (--len); |
| 191 | return crc ^ 0xffffffffUL; |
| 192 | } |