/* * Oct 28, 2015 Song Liu simplified the code and port it to mdadm * * Aug 8, 2011 Bob Pearson with help from Joakim Tjernlund and George Spelvin * cleaned up code to current version of sparse and added the slicing-by-8 * algorithm to the closely similar existing slicing-by-4 algorithm. * * Oct 15, 2000 Matt Domsch <Matt_Domsch@dell.com> * Nicer crc32 functions/docs submitted by linux@horizon.com. Thanks! * Code was from the public domain, copyright abandoned. Code was * subsequently included in the kernel, thus was re-licensed under the * GNU GPL v2. * * Oct 12, 2000 Matt Domsch <Matt_Domsch@dell.com> * Same crc32 function was used in 5 other places in the kernel. * I made one version, and deleted the others. * There are various incantations of crc32(). Some use a seed of 0 or ~0. * Some xor at the end with ~0. The generic crc32() function takes * seed as an argument, and doesn't xor at the end. Then individual * users can do whatever they need. * drivers/net/smc9194.c uses seed ~0, doesn't xor with ~0. * fs/jffs2 uses seed 0, doesn't xor with ~0. * fs/partitions/efi.c uses seed ~0, xor's with ~0. * * This source code is licensed under the GNU General Public License, * Version 2. See the file COPYING for more details. */ #include <sys/types.h> #include <asm/types.h> #include <stdlib.h> /* * There are multiple 16-bit CRC polynomials in common use, but this is * *the* standard CRC-32 polynomial, first popularized by Ethernet. * 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 */ #define CRCPOLY_LE 0xedb88320 #define CRCPOLY_BE 0x04c11db7 /* * This is the CRC32c polynomial, as outlined by Castagnoli. * 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 */ #define CRC32C_POLY_LE 0x82F63B78 /** * crc32_le_generic() - Calculate bitwise little-endian Ethernet AUTODIN II * CRC32/CRC32C * @crc: seed value for computation. ~0 for Ethernet, sometimes 0 for other * uses, or the previous crc32/crc32c value if computing incrementally. * @p: pointer to buffer over which CRC32/CRC32C is run * @len: length of buffer @p * @polynomial: CRC32/CRC32c LE polynomial */ static inline __u32 crc32_le_generic(__u32 crc, unsigned char const *p, size_t len, __u32 polynomial) { int i; while (len--) { crc ^= *p++; for (i = 0; i < 8; i++) crc = (crc >> 1) ^ ((crc & 1) ? polynomial : 0); } return crc; } __u32 crc32_le(__u32 crc, unsigned char const *p, size_t len) { return crc32_le_generic(crc, p, len, CRCPOLY_LE); } __u32 crc32c_le(__u32 crc, unsigned char const *p, size_t len) { return crc32_le_generic(crc, p, len, CRC32C_POLY_LE); } /** * crc32_be_generic() - Calculate bitwise big-endian Ethernet AUTODIN II CRC32 * @crc: seed value for computation. ~0 for Ethernet, sometimes 0 for * other uses, or the previous crc32 value if computing incrementally. * @p: pointer to buffer over which CRC32 is run * @len: length of buffer @p * @polynomial: CRC32 BE polynomial */ static inline __u32 crc32_be_generic(__u32 crc, unsigned char const *p, size_t len, __u32 polynomial) { int i; while (len--) { crc ^= *p++ << 24; for (i = 0; i < 8; i++) crc = (crc << 1) ^ ((crc & 0x80000000) ? polynomial : 0); } return crc; } __u32 crc32_be(__u32 crc, unsigned char const *p, size_t len) { return crc32_be_generic(crc, p, len, CRCPOLY_BE); }