2 * lib/crypto/crc32/crc.c
4 * Copyright 1990 by the Massachusetts Institute of Technology.
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24 * CRC-32/AUTODIN-II routines
30 /* This table and block of comments are taken from code labeled: */
32 * Copyright (C) 1986 Gary S. Brown. You may use this program, or
33 * code or tables extracted from it, as desired without restriction.
36 /* First, the polynomial itself and its table of feedback terms. The */
38 /* 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+X^0 */
39 /* Note that we take it "backwards" and put the highest-order term in */
40 /* the lowest-order bit. The X^32 term is "implied"; the LSB is the */
41 /* X^31 term, etc. The X^0 term (usually shown as "+1") results in */
42 /* the MSB being 1. */
44 /* Note that the usual hardware shift register implementation, which */
45 /* is what we're using (we're merely optimizing it by doing eight-bit */
46 /* chunks at a time) shifts bits into the lowest-order term. In our */
47 /* implementation, that means shifting towards the right. Why do we */
48 /* do it this way? Because the calculated CRC must be transmitted in */
49 /* order from highest-order term to lowest-order term. UARTs transmit */
50 /* characters in order from LSB to MSB. By storing the CRC this way, */
51 /* we hand it to the UART in the order low-byte to high-byte; the UART */
52 /* sends each low-bit to hight-bit; and the result is transmission bit */
53 /* by bit from highest- to lowest-order term without requiring any bit */
54 /* shuffling on our part. Reception works similarly. */
56 /* The feedback terms table consists of 256, 32-bit entries. Notes: */
58 /* 1. The table can be generated at runtime if desired; code to do so */
59 /* is shown later. It might not be obvious, but the feedback */
60 /* terms simply represent the results of eight shift/xor opera- */
61 /* tions for all combinations of data and CRC register values. */
63 /* 2. The CRC accumulation logic is the same for all CRC polynomials, */
64 /* be they sixteen or thirty-two bits wide. You simply choose the */
65 /* appropriate table. Alternatively, because the table can be */
66 /* generated at runtime, you can start by generating the table for */
67 /* the polynomial in question and use exactly the same "updcrc", */
68 /* if your application needn't simultaneously handle two CRC */
69 /* polynomials. (Note, however, that XMODEM is strange.) */
71 /* 3. For 16-bit CRCs, the table entries need be only 16 bits wide; */
72 /* of course, 32-bit entries work OK if the high 16 bits are zero. */
74 /* 4. The values must be right-shifted by eight bits by the "updcrc" */
75 /* logic; the shift must be unsigned (bring in zeroes). On some */
76 /* hardware you could probably optimize the shift in assembler by */
77 /* using byte-swap instructions. */
79 static u_long const crc_table[256] = {
80 0x00000000, 0x77073096, 0xee0e612c, 0x990951ba,
81 0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3,
82 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
83 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91,
84 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,
85 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
86 0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec,
87 0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5,
88 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
89 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
90 0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940,
91 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
92 0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116,
93 0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f,
94 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
95 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d,
96 0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a,
97 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
98 0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818,
99 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
100 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
101 0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457,
102 0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c,
103 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
104 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,
105 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb,
106 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
107 0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9,
108 0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086,
109 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
110 0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4,
111 0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad,
112 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
113 0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683,
114 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,
115 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
116 0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe,
117 0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7,
118 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
119 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
120 0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252,
121 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
122 0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60,
123 0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79,
124 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
125 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f,
126 0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04,
127 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
128 0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a,
129 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
130 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
131 0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21,
132 0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e,
133 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
134 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,
135 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45,
136 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
137 0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db,
138 0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0,
139 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
140 0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6,
141 0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf,
142 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
143 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
146 krb5_error_code INTERFACE
147 crc32_sum_func NPROTOTYPE((krb5_pointer in, size_t in_length,
148 krb5_pointer seed, size_t seed_length, krb5_checksum *outcksum));
150 krb5_error_code INTERFACE
151 crc32_sum_func(in, in_length, seed, seed_length, outcksum)
156 krb5_checksum FAR *outcksum;
158 register u_char *data;
159 register u_long c = 0;
164 for (i = 0; i < in_length; i++) {
165 idx = (int) (data[i] ^ c);
170 /* c now holds the result */
171 outcksum->checksum_type = CKSUMTYPE_CRC32;
172 outcksum->length = 4;
173 outcksum->contents[0] = (krb5_octet) (c & 0xff);
174 outcksum->contents[1] = (krb5_octet) ((c >> 8) & 0xff);
175 outcksum->contents[2] = (krb5_octet) ((c >> 16) & 0xff);
176 outcksum->contents[3] = (krb5_octet) ((c >> 24) & 0xff);
181 krb5_checksum_entry crc32_cksumtable_entry = {
184 CRC32_CKSUM_LENGTH, /* CRC-32 is 4 octets */
185 0, /* not collision proof */
186 0, /* doesn't use key */