Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Oct 15, 2000 Matt Domsch <Matt_Domsch@dell.com> |
| 3 | * Nicer crc32 functions/docs submitted by linux@horizon.com. Thanks! |
| 4 | * Code was from the public domain, copyright abandoned. Code was |
| 5 | * subsequently included in the kernel, thus was re-licensed under the |
| 6 | * GNU GPL v2. |
| 7 | * |
| 8 | * Oct 12, 2000 Matt Domsch <Matt_Domsch@dell.com> |
| 9 | * Same crc32 function was used in 5 other places in the kernel. |
| 10 | * I made one version, and deleted the others. |
| 11 | * There are various incantations of crc32(). Some use a seed of 0 or ~0. |
| 12 | * Some xor at the end with ~0. The generic crc32() function takes |
| 13 | * seed as an argument, and doesn't xor at the end. Then individual |
| 14 | * users can do whatever they need. |
| 15 | * drivers/net/smc9194.c uses seed ~0, doesn't xor with ~0. |
| 16 | * fs/jffs2 uses seed 0, doesn't xor with ~0. |
| 17 | * fs/partitions/efi.c uses seed ~0, xor's with ~0. |
| 18 | * |
| 19 | * This source code is licensed under the GNU General Public License, |
| 20 | * Version 2. See the file COPYING for more details. |
| 21 | */ |
| 22 | |
Bob Pearson | fbedceb | 2012-03-23 15:02:22 -0700 | [diff] [blame^] | 23 | /* see: Documentation/crc32.txt for a description of algorithms */ |
| 24 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 25 | #include <linux/crc32.h> |
| 26 | #include <linux/kernel.h> |
| 27 | #include <linux/module.h> |
| 28 | #include <linux/compiler.h> |
| 29 | #include <linux/types.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 30 | #include <linux/init.h> |
Arun Sharma | 60063497 | 2011-07-26 16:09:06 -0700 | [diff] [blame] | 31 | #include <linux/atomic.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 32 | #include "crc32defs.h" |
| 33 | #if CRC_LE_BITS == 8 |
Joakim Tjernlund | 4f2a9463 | 2010-03-05 13:43:55 -0800 | [diff] [blame] | 34 | # define tole(x) __constant_cpu_to_le32(x) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 35 | #else |
Joakim Tjernlund | 4f2a9463 | 2010-03-05 13:43:55 -0800 | [diff] [blame] | 36 | # define tole(x) (x) |
| 37 | #endif |
| 38 | |
| 39 | #if CRC_BE_BITS == 8 |
| 40 | # define tobe(x) __constant_cpu_to_be32(x) |
| 41 | #else |
| 42 | # define tobe(x) (x) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 43 | #endif |
| 44 | #include "crc32table.h" |
| 45 | |
| 46 | MODULE_AUTHOR("Matt Domsch <Matt_Domsch@dell.com>"); |
| 47 | MODULE_DESCRIPTION("Ethernet CRC32 calculations"); |
| 48 | MODULE_LICENSE("GPL"); |
| 49 | |
Joakim Tjernlund | ddcaccb | 2009-12-14 18:01:33 -0800 | [diff] [blame] | 50 | #if CRC_LE_BITS == 8 || CRC_BE_BITS == 8 |
| 51 | |
| 52 | static inline u32 |
Joakim Tjernlund | 836e2af | 2010-05-24 14:33:31 -0700 | [diff] [blame] | 53 | crc32_body(u32 crc, unsigned char const *buf, size_t len, const u32 (*tab)[256]) |
Joakim Tjernlund | ddcaccb | 2009-12-14 18:01:33 -0800 | [diff] [blame] | 54 | { |
Andrew Morton | 0d2daf5 | 2010-05-25 23:43:03 -0700 | [diff] [blame] | 55 | # ifdef __LITTLE_ENDIAN |
Joakim Tjernlund | 5742332 | 2012-01-10 15:10:18 -0800 | [diff] [blame] | 56 | # define DO_CRC(x) crc = t0[(crc ^ (x)) & 255] ^ (crc >> 8) |
| 57 | # define DO_CRC4 crc = t3[(crc) & 255] ^ \ |
| 58 | t2[(crc >> 8) & 255] ^ \ |
| 59 | t1[(crc >> 16) & 255] ^ \ |
| 60 | t0[(crc >> 24) & 255] |
Joakim Tjernlund | ddcaccb | 2009-12-14 18:01:33 -0800 | [diff] [blame] | 61 | # else |
Joakim Tjernlund | 5742332 | 2012-01-10 15:10:18 -0800 | [diff] [blame] | 62 | # define DO_CRC(x) crc = t0[((crc >> 24) ^ (x)) & 255] ^ (crc << 8) |
| 63 | # define DO_CRC4 crc = t0[(crc) & 255] ^ \ |
| 64 | t1[(crc >> 8) & 255] ^ \ |
| 65 | t2[(crc >> 16) & 255] ^ \ |
| 66 | t3[(crc >> 24) & 255] |
Joakim Tjernlund | ddcaccb | 2009-12-14 18:01:33 -0800 | [diff] [blame] | 67 | # endif |
Joakim Tjernlund | 4f2a9463 | 2010-03-05 13:43:55 -0800 | [diff] [blame] | 68 | const u32 *b; |
Joakim Tjernlund | ddcaccb | 2009-12-14 18:01:33 -0800 | [diff] [blame] | 69 | size_t rem_len; |
Joakim Tjernlund | 5742332 | 2012-01-10 15:10:18 -0800 | [diff] [blame] | 70 | const u32 *t0=tab[0], *t1=tab[1], *t2=tab[2], *t3=tab[3]; |
Joakim Tjernlund | ddcaccb | 2009-12-14 18:01:33 -0800 | [diff] [blame] | 71 | |
| 72 | /* Align it */ |
Joakim Tjernlund | 4f2a9463 | 2010-03-05 13:43:55 -0800 | [diff] [blame] | 73 | if (unlikely((long)buf & 3 && len)) { |
Joakim Tjernlund | ddcaccb | 2009-12-14 18:01:33 -0800 | [diff] [blame] | 74 | do { |
Joakim Tjernlund | 4f2a9463 | 2010-03-05 13:43:55 -0800 | [diff] [blame] | 75 | DO_CRC(*buf++); |
| 76 | } while ((--len) && ((long)buf)&3); |
Joakim Tjernlund | ddcaccb | 2009-12-14 18:01:33 -0800 | [diff] [blame] | 77 | } |
| 78 | rem_len = len & 3; |
| 79 | /* load data 32 bits wide, xor data 32 bits wide. */ |
| 80 | len = len >> 2; |
Joakim Tjernlund | 4f2a9463 | 2010-03-05 13:43:55 -0800 | [diff] [blame] | 81 | b = (const u32 *)buf; |
Joakim Tjernlund | ddcaccb | 2009-12-14 18:01:33 -0800 | [diff] [blame] | 82 | for (--b; len; --len) { |
| 83 | crc ^= *++b; /* use pre increment for speed */ |
Joakim Tjernlund | 836e2af | 2010-05-24 14:33:31 -0700 | [diff] [blame] | 84 | DO_CRC4; |
Joakim Tjernlund | ddcaccb | 2009-12-14 18:01:33 -0800 | [diff] [blame] | 85 | } |
| 86 | len = rem_len; |
| 87 | /* And the last few bytes */ |
| 88 | if (len) { |
| 89 | u8 *p = (u8 *)(b + 1) - 1; |
| 90 | do { |
| 91 | DO_CRC(*++p); /* use pre increment for speed */ |
| 92 | } while (--len); |
| 93 | } |
| 94 | return crc; |
Joakim Tjernlund | 4f2a9463 | 2010-03-05 13:43:55 -0800 | [diff] [blame] | 95 | #undef DO_CRC |
Joakim Tjernlund | 836e2af | 2010-05-24 14:33:31 -0700 | [diff] [blame] | 96 | #undef DO_CRC4 |
Joakim Tjernlund | ddcaccb | 2009-12-14 18:01:33 -0800 | [diff] [blame] | 97 | } |
| 98 | #endif |
Randy Dunlap | 2f72100 | 2006-06-25 05:48:59 -0700 | [diff] [blame] | 99 | /** |
| 100 | * crc32_le() - Calculate bitwise little-endian Ethernet AUTODIN II CRC32 |
| 101 | * @crc: seed value for computation. ~0 for Ethernet, sometimes 0 for |
| 102 | * other uses, or the previous crc32 value if computing incrementally. |
| 103 | * @p: pointer to buffer over which CRC is run |
| 104 | * @len: length of buffer @p |
| 105 | */ |
Ralf Baechle | e8c4431 | 2007-10-18 03:07:07 -0700 | [diff] [blame] | 106 | u32 __pure crc32_le(u32 crc, unsigned char const *p, size_t len); |
Randy Dunlap | 2f72100 | 2006-06-25 05:48:59 -0700 | [diff] [blame] | 107 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 108 | #if CRC_LE_BITS == 1 |
| 109 | /* |
| 110 | * In fact, the table-based code will work in this case, but it can be |
| 111 | * simplified by inlining the table in ?: form. |
| 112 | */ |
| 113 | |
Ralf Baechle | e8c4431 | 2007-10-18 03:07:07 -0700 | [diff] [blame] | 114 | u32 __pure crc32_le(u32 crc, unsigned char const *p, size_t len) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 115 | { |
| 116 | int i; |
| 117 | while (len--) { |
| 118 | crc ^= *p++; |
| 119 | for (i = 0; i < 8; i++) |
| 120 | crc = (crc >> 1) ^ ((crc & 1) ? CRCPOLY_LE : 0); |
| 121 | } |
| 122 | return crc; |
| 123 | } |
| 124 | #else /* Table-based approach */ |
| 125 | |
Ralf Baechle | e8c4431 | 2007-10-18 03:07:07 -0700 | [diff] [blame] | 126 | u32 __pure crc32_le(u32 crc, unsigned char const *p, size_t len) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 127 | { |
| 128 | # if CRC_LE_BITS == 8 |
Joakim Tjernlund | 836e2af | 2010-05-24 14:33:31 -0700 | [diff] [blame] | 129 | const u32 (*tab)[] = crc32table_le; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 130 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 131 | crc = __cpu_to_le32(crc); |
Joakim Tjernlund | ddcaccb | 2009-12-14 18:01:33 -0800 | [diff] [blame] | 132 | crc = crc32_body(crc, p, len, tab); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 133 | return __le32_to_cpu(crc); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 134 | # elif CRC_LE_BITS == 4 |
| 135 | while (len--) { |
| 136 | crc ^= *p++; |
| 137 | crc = (crc >> 4) ^ crc32table_le[crc & 15]; |
| 138 | crc = (crc >> 4) ^ crc32table_le[crc & 15]; |
| 139 | } |
| 140 | return crc; |
| 141 | # elif CRC_LE_BITS == 2 |
| 142 | while (len--) { |
| 143 | crc ^= *p++; |
| 144 | crc = (crc >> 2) ^ crc32table_le[crc & 3]; |
| 145 | crc = (crc >> 2) ^ crc32table_le[crc & 3]; |
| 146 | crc = (crc >> 2) ^ crc32table_le[crc & 3]; |
| 147 | crc = (crc >> 2) ^ crc32table_le[crc & 3]; |
| 148 | } |
| 149 | return crc; |
| 150 | # endif |
| 151 | } |
| 152 | #endif |
| 153 | |
Randy Dunlap | 2f72100 | 2006-06-25 05:48:59 -0700 | [diff] [blame] | 154 | /** |
| 155 | * crc32_be() - Calculate bitwise big-endian Ethernet AUTODIN II CRC32 |
| 156 | * @crc: seed value for computation. ~0 for Ethernet, sometimes 0 for |
| 157 | * other uses, or the previous crc32 value if computing incrementally. |
| 158 | * @p: pointer to buffer over which CRC is run |
| 159 | * @len: length of buffer @p |
| 160 | */ |
Ralf Baechle | e8c4431 | 2007-10-18 03:07:07 -0700 | [diff] [blame] | 161 | u32 __pure crc32_be(u32 crc, unsigned char const *p, size_t len); |
Randy Dunlap | 2f72100 | 2006-06-25 05:48:59 -0700 | [diff] [blame] | 162 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 163 | #if CRC_BE_BITS == 1 |
| 164 | /* |
| 165 | * In fact, the table-based code will work in this case, but it can be |
| 166 | * simplified by inlining the table in ?: form. |
| 167 | */ |
| 168 | |
Ralf Baechle | e8c4431 | 2007-10-18 03:07:07 -0700 | [diff] [blame] | 169 | u32 __pure crc32_be(u32 crc, unsigned char const *p, size_t len) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 170 | { |
| 171 | int i; |
| 172 | while (len--) { |
| 173 | crc ^= *p++ << 24; |
| 174 | for (i = 0; i < 8; i++) |
| 175 | crc = |
| 176 | (crc << 1) ^ ((crc & 0x80000000) ? CRCPOLY_BE : |
| 177 | 0); |
| 178 | } |
| 179 | return crc; |
| 180 | } |
| 181 | |
| 182 | #else /* Table-based approach */ |
Ralf Baechle | e8c4431 | 2007-10-18 03:07:07 -0700 | [diff] [blame] | 183 | u32 __pure crc32_be(u32 crc, unsigned char const *p, size_t len) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 184 | { |
| 185 | # if CRC_BE_BITS == 8 |
Joakim Tjernlund | 836e2af | 2010-05-24 14:33:31 -0700 | [diff] [blame] | 186 | const u32 (*tab)[] = crc32table_be; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 187 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 188 | crc = __cpu_to_be32(crc); |
Joakim Tjernlund | ddcaccb | 2009-12-14 18:01:33 -0800 | [diff] [blame] | 189 | crc = crc32_body(crc, p, len, tab); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 190 | return __be32_to_cpu(crc); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 191 | # elif CRC_BE_BITS == 4 |
| 192 | while (len--) { |
| 193 | crc ^= *p++ << 24; |
| 194 | crc = (crc << 4) ^ crc32table_be[crc >> 28]; |
| 195 | crc = (crc << 4) ^ crc32table_be[crc >> 28]; |
| 196 | } |
| 197 | return crc; |
| 198 | # elif CRC_BE_BITS == 2 |
| 199 | while (len--) { |
| 200 | crc ^= *p++ << 24; |
| 201 | crc = (crc << 2) ^ crc32table_be[crc >> 30]; |
| 202 | crc = (crc << 2) ^ crc32table_be[crc >> 30]; |
| 203 | crc = (crc << 2) ^ crc32table_be[crc >> 30]; |
| 204 | crc = (crc << 2) ^ crc32table_be[crc >> 30]; |
| 205 | } |
| 206 | return crc; |
| 207 | # endif |
| 208 | } |
| 209 | #endif |
| 210 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 211 | EXPORT_SYMBOL(crc32_le); |
| 212 | EXPORT_SYMBOL(crc32_be); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 213 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 214 | #ifdef UNITTEST |
| 215 | |
| 216 | #include <stdlib.h> |
| 217 | #include <stdio.h> |
| 218 | |
| 219 | #if 0 /*Not used at present */ |
| 220 | static void |
| 221 | buf_dump(char const *prefix, unsigned char const *buf, size_t len) |
| 222 | { |
| 223 | fputs(prefix, stdout); |
| 224 | while (len--) |
| 225 | printf(" %02x", *buf++); |
| 226 | putchar('\n'); |
| 227 | |
| 228 | } |
| 229 | #endif |
| 230 | |
| 231 | static void bytereverse(unsigned char *buf, size_t len) |
| 232 | { |
| 233 | while (len--) { |
Akinobu Mita | 906d66d | 2006-12-08 02:36:25 -0800 | [diff] [blame] | 234 | unsigned char x = bitrev8(*buf); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 235 | *buf++ = x; |
| 236 | } |
| 237 | } |
| 238 | |
| 239 | static void random_garbage(unsigned char *buf, size_t len) |
| 240 | { |
| 241 | while (len--) |
| 242 | *buf++ = (unsigned char) random(); |
| 243 | } |
| 244 | |
| 245 | #if 0 /* Not used at present */ |
| 246 | static void store_le(u32 x, unsigned char *buf) |
| 247 | { |
| 248 | buf[0] = (unsigned char) x; |
| 249 | buf[1] = (unsigned char) (x >> 8); |
| 250 | buf[2] = (unsigned char) (x >> 16); |
| 251 | buf[3] = (unsigned char) (x >> 24); |
| 252 | } |
| 253 | #endif |
| 254 | |
| 255 | static void store_be(u32 x, unsigned char *buf) |
| 256 | { |
| 257 | buf[0] = (unsigned char) (x >> 24); |
| 258 | buf[1] = (unsigned char) (x >> 16); |
| 259 | buf[2] = (unsigned char) (x >> 8); |
| 260 | buf[3] = (unsigned char) x; |
| 261 | } |
| 262 | |
| 263 | /* |
| 264 | * This checks that CRC(buf + CRC(buf)) = 0, and that |
| 265 | * CRC commutes with bit-reversal. This has the side effect |
| 266 | * of bytewise bit-reversing the input buffer, and returns |
| 267 | * the CRC of the reversed buffer. |
| 268 | */ |
| 269 | static u32 test_step(u32 init, unsigned char *buf, size_t len) |
| 270 | { |
| 271 | u32 crc1, crc2; |
| 272 | size_t i; |
| 273 | |
| 274 | crc1 = crc32_be(init, buf, len); |
| 275 | store_be(crc1, buf + len); |
| 276 | crc2 = crc32_be(init, buf, len + 4); |
| 277 | if (crc2) |
| 278 | printf("\nCRC cancellation fail: 0x%08x should be 0\n", |
| 279 | crc2); |
| 280 | |
| 281 | for (i = 0; i <= len + 4; i++) { |
| 282 | crc2 = crc32_be(init, buf, i); |
| 283 | crc2 = crc32_be(crc2, buf + i, len + 4 - i); |
| 284 | if (crc2) |
| 285 | printf("\nCRC split fail: 0x%08x\n", crc2); |
| 286 | } |
| 287 | |
| 288 | /* Now swap it around for the other test */ |
| 289 | |
| 290 | bytereverse(buf, len + 4); |
Akinobu Mita | 906d66d | 2006-12-08 02:36:25 -0800 | [diff] [blame] | 291 | init = bitrev32(init); |
| 292 | crc2 = bitrev32(crc1); |
| 293 | if (crc1 != bitrev32(crc2)) |
Dominik Hackl | cfc646f | 2005-08-07 09:42:53 -0700 | [diff] [blame] | 294 | printf("\nBit reversal fail: 0x%08x -> 0x%08x -> 0x%08x\n", |
Akinobu Mita | 906d66d | 2006-12-08 02:36:25 -0800 | [diff] [blame] | 295 | crc1, crc2, bitrev32(crc2)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 296 | crc1 = crc32_le(init, buf, len); |
| 297 | if (crc1 != crc2) |
| 298 | printf("\nCRC endianness fail: 0x%08x != 0x%08x\n", crc1, |
| 299 | crc2); |
| 300 | crc2 = crc32_le(init, buf, len + 4); |
| 301 | if (crc2) |
| 302 | printf("\nCRC cancellation fail: 0x%08x should be 0\n", |
| 303 | crc2); |
| 304 | |
| 305 | for (i = 0; i <= len + 4; i++) { |
| 306 | crc2 = crc32_le(init, buf, i); |
| 307 | crc2 = crc32_le(crc2, buf + i, len + 4 - i); |
| 308 | if (crc2) |
| 309 | printf("\nCRC split fail: 0x%08x\n", crc2); |
| 310 | } |
| 311 | |
| 312 | return crc1; |
| 313 | } |
| 314 | |
| 315 | #define SIZE 64 |
| 316 | #define INIT1 0 |
| 317 | #define INIT2 0 |
| 318 | |
| 319 | int main(void) |
| 320 | { |
| 321 | unsigned char buf1[SIZE + 4]; |
| 322 | unsigned char buf2[SIZE + 4]; |
| 323 | unsigned char buf3[SIZE + 4]; |
| 324 | int i, j; |
| 325 | u32 crc1, crc2, crc3; |
| 326 | |
| 327 | for (i = 0; i <= SIZE; i++) { |
| 328 | printf("\rTesting length %d...", i); |
| 329 | fflush(stdout); |
| 330 | random_garbage(buf1, i); |
| 331 | random_garbage(buf2, i); |
| 332 | for (j = 0; j < i; j++) |
| 333 | buf3[j] = buf1[j] ^ buf2[j]; |
| 334 | |
| 335 | crc1 = test_step(INIT1, buf1, i); |
| 336 | crc2 = test_step(INIT2, buf2, i); |
| 337 | /* Now check that CRC(buf1 ^ buf2) = CRC(buf1) ^ CRC(buf2) */ |
| 338 | crc3 = test_step(INIT1 ^ INIT2, buf3, i); |
| 339 | if (crc3 != (crc1 ^ crc2)) |
| 340 | printf("CRC XOR fail: 0x%08x != 0x%08x ^ 0x%08x\n", |
| 341 | crc3, crc1, crc2); |
| 342 | } |
| 343 | printf("\nAll test complete. No failures expected.\n"); |
| 344 | return 0; |
| 345 | } |
| 346 | |
| 347 | #endif /* UNITTEST */ |