#include <stdlib.h>
/**
- * crc32 - 32 bit crc of string of bytes
+ * 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:
+ * // Check that iovec has the crc we expect (Castagnoli version)
+ * bool check_crc(uint32_t expected, const struct iovec *iov, int iovcnt)
+ * {
+ * uint32_t crc = 0;
+ * while (iovcnt >= 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.
+ * void check_user_crc_table(const uint32_t *usertab)
+ * {
+ * const uint32_t *ctab = crc32c_table();
+ * if (!ieee_tab || memcmp(ieee_tab, 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.
*/
-uint32_t crc32(const void *buf, size_t size);
+const uint32_t *crc32_ieee_table(void);
#endif /* CCAN_CRC_H */