diff options
Diffstat (limited to 'include/linux/crc32.h')
| -rw-r--r-- | include/linux/crc32.h | 119 |
1 files changed, 70 insertions, 49 deletions
diff --git a/include/linux/crc32.h b/include/linux/crc32.h index 8c1883b81b42..da78b215ff2e 100644 --- a/include/linux/crc32.h +++ b/include/linux/crc32.h @@ -5,33 +5,81 @@ #include <linux/types.h> #include <linux/bitrev.h> -u32 crc32_le_arch(u32 crc, const u8 *p, size_t len); -u32 crc32_le_base(u32 crc, const u8 *p, size_t len); -u32 crc32_be_arch(u32 crc, const u8 *p, size_t len); -u32 crc32_be_base(u32 crc, const u8 *p, size_t len); -u32 crc32c_arch(u32 crc, const u8 *p, size_t len); -u32 crc32c_base(u32 crc, const u8 *p, size_t len); +/** + * crc32_le() - Compute least-significant-bit-first IEEE CRC-32 + * @crc: Initial CRC value. ~0 (recommended) or 0 for a new CRC computation, or + * the previous CRC value if computing incrementally. + * @p: Pointer to the data buffer + * @len: Length of data in bytes + * + * This implements the CRC variant that is often known as the IEEE CRC-32, or + * simply CRC-32, and is widely used in Ethernet and other applications: + * + * - 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 + * - Bit order: Least-significant-bit-first + * - Polynomial in integer form: 0xedb88320 + * + * This does *not* invert the CRC at the beginning or end. The caller is + * expected to do that if it needs to. Inverting at both ends is recommended. + * + * For new applications, prefer to use CRC-32C instead. See crc32c(). + * + * Context: Any context + * Return: The new CRC value + */ +u32 crc32_le(u32 crc, const void *p, size_t len); -static inline u32 crc32_le(u32 crc, const void *p, size_t len) +/* This is just an alias for crc32_le(). */ +static inline u32 crc32(u32 crc, const void *p, size_t len) { - if (IS_ENABLED(CONFIG_CRC32_ARCH)) - return crc32_le_arch(crc, p, len); - return crc32_le_base(crc, p, len); + return crc32_le(crc, p, len); } -static inline u32 crc32_be(u32 crc, const void *p, size_t len) -{ - if (IS_ENABLED(CONFIG_CRC32_ARCH)) - return crc32_be_arch(crc, p, len); - return crc32_be_base(crc, p, len); -} +/** + * crc32_be() - Compute most-significant-bit-first IEEE CRC-32 + * @crc: Initial CRC value. ~0 (recommended) or 0 for a new CRC computation, or + * the previous CRC value if computing incrementally. + * @p: Pointer to the data buffer + * @len: Length of data in bytes + * + * crc32_be() is the same as crc32_le() except that crc32_be() computes the + * *most-significant-bit-first* variant of the CRC. I.e., within each byte, the + * most significant bit is processed first (treated as highest order polynomial + * coefficient). The same bit order is also used for the CRC value itself: + * + * - 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 + * - Bit order: Most-significant-bit-first + * - Polynomial in integer form: 0x04c11db7 + * + * Context: Any context + * Return: The new CRC value + */ +u32 crc32_be(u32 crc, const void *p, size_t len); -static inline u32 crc32c(u32 crc, const void *p, size_t len) -{ - if (IS_ENABLED(CONFIG_CRC32_ARCH)) - return crc32c_arch(crc, p, len); - return crc32c_base(crc, p, len); -} +/** + * crc32c() - Compute CRC-32C + * @crc: Initial CRC value. ~0 (recommended) or 0 for a new CRC computation, or + * the previous CRC value if computing incrementally. + * @p: Pointer to the data buffer + * @len: Length of data in bytes + * + * This implements CRC-32C, i.e. the Castagnoli CRC. This is the recommended + * CRC variant to use in new applications that want a 32-bit CRC. + * + * - 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 + * - Bit order: Least-significant-bit-first + * - Polynomial in integer form: 0x82f63b78 + * + * This does *not* invert the CRC at the beginning or end. The caller is + * expected to do that if it needs to. Inverting at both ends is recommended. + * + * Context: Any context + * Return: The new CRC value + */ +u32 crc32c(u32 crc, const void *p, size_t len); /* * crc32_optimizations() returns flags that indicate which CRC32 library @@ -48,33 +96,6 @@ u32 crc32_optimizations(void); static inline u32 crc32_optimizations(void) { return 0; } #endif -/** - * crc32_le_combine - Combine two crc32 check values into one. For two - * sequences of bytes, seq1 and seq2 with lengths len1 - * and len2, crc32_le() check values were calculated - * for each, crc1 and crc2. - * - * @crc1: crc32 of the first block - * @crc2: crc32 of the second block - * @len2: length of the second block - * - * Return: The crc32_le() check value of seq1 and seq2 concatenated, - * requiring only crc1, crc2, and len2. Note: If seq_full denotes - * the concatenated memory area of seq1 with seq2, and crc_full - * the crc32_le() value of seq_full, then crc_full == - * crc32_le_combine(crc1, crc2, len2) when crc_full was seeded - * with the same initializer as crc1, and crc2 seed was 0. See - * also crc32_combine_test(). - */ -u32 crc32_le_shift(u32 crc, size_t len); - -static inline u32 crc32_le_combine(u32 crc1, u32 crc2, size_t len2) -{ - return crc32_le_shift(crc1, len2) ^ crc2; -} - -#define crc32(seed, data, length) crc32_le(seed, (unsigned char const *)(data), length) - /* * Helpers for hash table generation of ethernet nics: * |