1 /* Licensed under GPLv2+ - see LICENSE file for details */
8 * crc32c - Castagnoli 32 bit crc of string of bytes
9 * @start_crc: the initial crc (usually 0)
10 * @buf: pointer to bytes
11 * @size: length of buffer
13 * If you don't know what crc32 to use, use this one: it's the best.
15 * @Article{castagnoli-crc,
16 * author = { Guy Castagnoli and Stefan Braeuer and Martin Herrman},
17 * title = {{Optimization of Cyclic Redundancy-Check Codes with 24
18 * and 32 Parity Bits}},
19 * journal = IEEE Transactions on Communication,
26 * 32 bit CRC checksum using polynomial
27 * X^32+X^28+X^27+X^26+X^25+X^23+X^22+X^20+X^19+X^18+X^14+X^13+X^11+X^10+X^9+X^8+X^6+X^0.
29 * You can calculate the CRC of non-contiguous arrays by passing @start_crc
30 * as 0 the first time, and the current crc result from then on.
33 * #include <sys/uio.h>
35 * // Check that iovec has the crc we expect (Castagnoli version)
36 * static bool check_crc(uint32_t expected, const struct iovec *iov, int l)
40 * crc = crc32c(crc, iov->iov_base, iov->iov_len);
43 * return crc == expected;
46 uint32_t crc32c(uint32_t start_crc, const void *buf, size_t size);
49 * crc32c_table - Get the Castagnoli CRC table
51 * For special effects, you might want direct access to the table; this is
52 * the standard 256-entry table for this algorithm.
54 * In theory, this might need to malloc(), and thus return NULL.
57 * // This dumb code only handles Castagnoli, so assert that here.
58 * static void check_user_crc_table(const uint32_t *usertab)
60 * const uint32_t *ctab = crc32c_table();
61 * if (!ctab || memcmp(ctab, usertab, 1024) != 0)
65 const uint32_t *crc32c_table(void);
68 * crc32_ieee - IEEE 802.3 32 bit crc of string of bytes
69 * @start_crc: the initial crc (usually 0)
70 * @buf: pointer to bytes
71 * @size: length of buffer
73 * 32 bit CRC checksum using polynomial
74 * 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.
76 * See crc32c() for details.
78 uint32_t crc32_ieee(uint32_t start_crc, const void *buf, size_t size);
81 * crc32_ieee_table - Get the IEEE 802.3 CRC table
83 * See crc32c_table() for details.
85 const uint32_t *crc32_ieee_table(void);
88 * crc64_iso - ISO 3309
89 * @start_crc: the initial crc (usually 0)
90 * @buf: pointer to bytes
91 * @size: length of buffer
93 * 64 bit CRC checksum using polynomial
94 * X^64 + X^4 + X^3 + X^1 + X^0
96 * See crc32c() for details.
98 uint64_t crc64_iso(uint64_t start_crc, const void *buf, size_t size);
101 * crc64_iso_table - Get the ISO 3309 CRC table
103 * See crc32c_table() for details.
105 const uint64_t *crc64_iso_table(void);
107 #endif /* CCAN_CRC_H */