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/* Licensed under GPLv2+ - see LICENSE file for details */
#ifndef CCAN_CRC_H
#define CCAN_CRC_H
#include <stdint.h>
#include <stdlib.h>
/**
* crc32c - Castagnoli 32 bit crc of string of bytes
* @start_crc: the initial crc (usually 0)
* @buf: pointer to bytes
* @size: length of buffer
*
* If you don't know what crc32 to use, use this one: it's the best.
*
* @Article{castagnoli-crc,
* author = { Guy Castagnoli and Stefan Braeuer and Martin Herrman},
* title = {{Optimization of Cyclic Redundancy-Check Codes with 24
* and 32 Parity Bits}},
* journal = IEEE Transactions on Communication,
* year = {1993},
* volume = {41},
* number = {6},
* pages = {},
* month = {June},
*}
* 32 bit CRC checksum using polynomial
* 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.
*
* You can calculate the CRC of non-contiguous arrays by passing @start_crc
* as 0 the first time, and the current crc result from then on.
*
* Example:
* #include <sys/uio.h>
* ...
* // Check that iovec has the crc we expect (Castagnoli version)
* static bool check_crc(uint32_t expected, const struct iovec *iov, int l)
* {
* uint32_t crc = 0;
* while (l >= 0) {
* crc = crc32c(crc, iov->iov_base, iov->iov_len);
* iov++;
* }
* return crc == expected;
* }
*/
uint32_t crc32c(uint32_t start_crc, const void *buf, size_t size);
/**
* crc32c_table - Get the Castagnoli CRC table
*
* For special effects, you might want direct access to the table; this is
* the standard 256-entry table for this algorithm.
*
* In theory, this might need to malloc(), and thus return NULL.
*
* Example:
* // This dumb code only handles Castagnoli, so assert that here.
* static void check_user_crc_table(const uint32_t *usertab)
* {
* const uint32_t *ctab = crc32c_table();
* if (!ctab || memcmp(ctab, usertab, 1024) != 0)
* abort();
* }
*/
const uint32_t *crc32c_table(void);
/**
* crc32_ieee - IEEE 802.3 32 bit crc of string of bytes
* @start_crc: the initial crc (usually 0)
* @buf: pointer to bytes
* @size: length of buffer
*
* 32 bit CRC checksum using polynomial
* 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.
*
* See crc32c() for details.
*/
uint32_t crc32_ieee(uint32_t start_crc, const void *buf, size_t size);
/**
* crc32_ieee_table - Get the IEEE 802.3 CRC table
*
* See crc32c_table() for details.
*/
const uint32_t *crc32_ieee_table(void);
/**
* crc64_iso - ISO 3309
* @start_crc: the initial crc (usually 0)
* @buf: pointer to bytes
* @size: length of buffer
*
* 64 bit CRC checksum using polynomial
* X^64 + X^4 + X^3 + X^1 + X^0
*
* See crc32c() for details.
*/
uint64_t crc64_iso(uint64_t start_crc, const void *buf, size_t size);
/**
* crc64_iso_table - Get the ISO 3309 CRC table
*
* See crc32c_table() for details.
*/
const uint64_t *crc64_iso_table(void);
#endif /* CCAN_CRC_H */
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