2 * This file is derived from crc32.c from the zlib-1.1.3 distribution
3 * by Jean-loup Gailly and Mark Adler.
6 /* crc32.c -- compute the CRC-32 of a data stream
7 * Copyright (C) 1995-1998 Mark Adler
8 * For conditions of distribution and use, see copyright notice in zlib.h
11 #ifndef USE_HOSTCC /* Shut down "ANSI does not permit..." warnings */
12 #include <common.h> /* to get command definitions like CFG_CMD_JFFS2 */
18 #define ZEXPORT /* empty */
19 unsigned long crc32 (unsigned long, const unsigned char *, unsigned int);
21 #ifdef DYNAMIC_CRC_TABLE
23 local int crc_table_empty = 1;
24 local uLongf crc_table[256];
25 local void make_crc_table OF((void));
28 Generate a table for a byte-wise 32-bit CRC calculation on the polynomial:
29 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.
31 Polynomials over GF(2) are represented in binary, one bit per coefficient,
32 with the lowest powers in the most significant bit. Then adding polynomials
33 is just exclusive-or, and multiplying a polynomial by x is a right shift by
34 one. If we call the above polynomial p, and represent a byte as the
35 polynomial q, also with the lowest power in the most significant bit (so the
36 byte 0xb1 is the polynomial x^7+x^3+x+1), then the CRC is (q*x^32) mod p,
37 where a mod b means the remainder after dividing a by b.
39 This calculation is done using the shift-register method of multiplying and
40 taking the remainder. The register is initialized to zero, and for each
41 incoming bit, x^32 is added mod p to the register if the bit is a one (where
42 x^32 mod p is p+x^32 = x^26+...+1), and the register is multiplied mod p by
43 x (which is shifting right by one and adding x^32 mod p if the bit shifted
44 out is a one). We start with the highest power (least significant bit) of
45 q and repeat for all eight bits of q.
47 The table is simply the CRC of all possible eight bit values. This is all
48 the information needed to generate CRC's on data a byte at a time for all
49 combinations of CRC register values and incoming bytes.
51 local void make_crc_table(){
54 uLong poly; /* polynomial exclusive-or pattern */
55 /* terms of polynomial defining this crc (except x^32): */
56 static const Byte p[] = {0,1,2,4,5,7,8,10,11,12,16,22,23,26};
58 /* make exclusive-or pattern from polynomial (0xedb88320L) */
60 for (n = 0; n < sizeof(p)/sizeof(Byte); n++)
61 poly |= 1L << (31 - p[n]);
63 for (n = 0; n < 256; n++)
66 for (k = 0; k < 8; k++)
67 c = c & 1 ? poly ^ (c >> 1) : c >> 1;
73 /* ========================================================================
74 * Table of CRC-32's of all single-byte values (made by make_crc_table)
76 local const uLongf crc_table[256] = {
77 0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L,
78 0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L,
79 0xe0d5e91eL, 0x97d2d988L, 0x09b64c2bL, 0x7eb17cbdL, 0xe7b82d07L,
80 0x90bf1d91L, 0x1db71064L, 0x6ab020f2L, 0xf3b97148L, 0x84be41deL,
81 0x1adad47dL, 0x6ddde4ebL, 0xf4d4b551L, 0x83d385c7L, 0x136c9856L,
82 0x646ba8c0L, 0xfd62f97aL, 0x8a65c9ecL, 0x14015c4fL, 0x63066cd9L,
83 0xfa0f3d63L, 0x8d080df5L, 0x3b6e20c8L, 0x4c69105eL, 0xd56041e4L,
84 0xa2677172L, 0x3c03e4d1L, 0x4b04d447L, 0xd20d85fdL, 0xa50ab56bL,
85 0x35b5a8faL, 0x42b2986cL, 0xdbbbc9d6L, 0xacbcf940L, 0x32d86ce3L,
86 0x45df5c75L, 0xdcd60dcfL, 0xabd13d59L, 0x26d930acL, 0x51de003aL,
87 0xc8d75180L, 0xbfd06116L, 0x21b4f4b5L, 0x56b3c423L, 0xcfba9599L,
88 0xb8bda50fL, 0x2802b89eL, 0x5f058808L, 0xc60cd9b2L, 0xb10be924L,
89 0x2f6f7c87L, 0x58684c11L, 0xc1611dabL, 0xb6662d3dL, 0x76dc4190L,
90 0x01db7106L, 0x98d220bcL, 0xefd5102aL, 0x71b18589L, 0x06b6b51fL,
91 0x9fbfe4a5L, 0xe8b8d433L, 0x7807c9a2L, 0x0f00f934L, 0x9609a88eL,
92 0xe10e9818L, 0x7f6a0dbbL, 0x086d3d2dL, 0x91646c97L, 0xe6635c01L,
93 0x6b6b51f4L, 0x1c6c6162L, 0x856530d8L, 0xf262004eL, 0x6c0695edL,
94 0x1b01a57bL, 0x8208f4c1L, 0xf50fc457L, 0x65b0d9c6L, 0x12b7e950L,
95 0x8bbeb8eaL, 0xfcb9887cL, 0x62dd1ddfL, 0x15da2d49L, 0x8cd37cf3L,
96 0xfbd44c65L, 0x4db26158L, 0x3ab551ceL, 0xa3bc0074L, 0xd4bb30e2L,
97 0x4adfa541L, 0x3dd895d7L, 0xa4d1c46dL, 0xd3d6f4fbL, 0x4369e96aL,
98 0x346ed9fcL, 0xad678846L, 0xda60b8d0L, 0x44042d73L, 0x33031de5L,
99 0xaa0a4c5fL, 0xdd0d7cc9L, 0x5005713cL, 0x270241aaL, 0xbe0b1010L,
100 0xc90c2086L, 0x5768b525L, 0x206f85b3L, 0xb966d409L, 0xce61e49fL,
101 0x5edef90eL, 0x29d9c998L, 0xb0d09822L, 0xc7d7a8b4L, 0x59b33d17L,
102 0x2eb40d81L, 0xb7bd5c3bL, 0xc0ba6cadL, 0xedb88320L, 0x9abfb3b6L,
103 0x03b6e20cL, 0x74b1d29aL, 0xead54739L, 0x9dd277afL, 0x04db2615L,
104 0x73dc1683L, 0xe3630b12L, 0x94643b84L, 0x0d6d6a3eL, 0x7a6a5aa8L,
105 0xe40ecf0bL, 0x9309ff9dL, 0x0a00ae27L, 0x7d079eb1L, 0xf00f9344L,
106 0x8708a3d2L, 0x1e01f268L, 0x6906c2feL, 0xf762575dL, 0x806567cbL,
107 0x196c3671L, 0x6e6b06e7L, 0xfed41b76L, 0x89d32be0L, 0x10da7a5aL,
108 0x67dd4accL, 0xf9b9df6fL, 0x8ebeeff9L, 0x17b7be43L, 0x60b08ed5L,
109 0xd6d6a3e8L, 0xa1d1937eL, 0x38d8c2c4L, 0x4fdff252L, 0xd1bb67f1L,
110 0xa6bc5767L, 0x3fb506ddL, 0x48b2364bL, 0xd80d2bdaL, 0xaf0a1b4cL,
111 0x36034af6L, 0x41047a60L, 0xdf60efc3L, 0xa867df55L, 0x316e8eefL,
112 0x4669be79L, 0xcb61b38cL, 0xbc66831aL, 0x256fd2a0L, 0x5268e236L,
113 0xcc0c7795L, 0xbb0b4703L, 0x220216b9L, 0x5505262fL, 0xc5ba3bbeL,
114 0xb2bd0b28L, 0x2bb45a92L, 0x5cb36a04L, 0xc2d7ffa7L, 0xb5d0cf31L,
115 0x2cd99e8bL, 0x5bdeae1dL, 0x9b64c2b0L, 0xec63f226L, 0x756aa39cL,
116 0x026d930aL, 0x9c0906a9L, 0xeb0e363fL, 0x72076785L, 0x05005713L,
117 0x95bf4a82L, 0xe2b87a14L, 0x7bb12baeL, 0x0cb61b38L, 0x92d28e9bL,
118 0xe5d5be0dL, 0x7cdcefb7L, 0x0bdbdf21L, 0x86d3d2d4L, 0xf1d4e242L,
119 0x68ddb3f8L, 0x1fda836eL, 0x81be16cdL, 0xf6b9265bL, 0x6fb077e1L,
120 0x18b74777L, 0x88085ae6L, 0xff0f6a70L, 0x66063bcaL, 0x11010b5cL,
121 0x8f659effL, 0xf862ae69L, 0x616bffd3L, 0x166ccf45L, 0xa00ae278L,
122 0xd70dd2eeL, 0x4e048354L, 0x3903b3c2L, 0xa7672661L, 0xd06016f7L,
123 0x4969474dL, 0x3e6e77dbL, 0xaed16a4aL, 0xd9d65adcL, 0x40df0b66L,
124 0x37d83bf0L, 0xa9bcae53L, 0xdebb9ec5L, 0x47b2cf7fL, 0x30b5ffe9L,
125 0xbdbdf21cL, 0xcabac28aL, 0x53b39330L, 0x24b4a3a6L, 0xbad03605L,
126 0xcdd70693L, 0x54de5729L, 0x23d967bfL, 0xb3667a2eL, 0xc4614ab8L,
127 0x5d681b02L, 0x2a6f2b94L, 0xb40bbe37L, 0xc30c8ea1L, 0x5a05df1bL,
132 /* ========================================================================= */
133 #define DO1(buf) crc = crc_table[((int)crc ^ (*buf++)) & 0xff] ^ (crc >> 8);
134 #define DO2(buf) DO1(buf); DO1(buf);
135 #define DO4(buf) DO2(buf); DO2(buf);
136 #define DO8(buf) DO4(buf); DO4(buf);
138 /* ========================================================================= */
139 uLong ZEXPORT crc32(crc, buf, len)
144 #ifdef DYNAMIC_CRC_TABLE
148 crc = crc ^ 0xffffffffL;
157 return crc ^ 0xffffffffL;