| 1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
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| 2 | #ifndef _LINUX_CRC32_H |
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| 3 | #define _LINUX_CRC32_H |
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| 4 | |
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| 5 | #include <linux/types.h> |
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| 6 | #include <linux/bitrev.h> |
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| 7 | |
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| 8 | /** |
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| 9 | * crc32_le() - Compute least-significant-bit-first IEEE CRC-32 |
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| 10 | * @crc: Initial CRC value. ~0 (recommended) or 0 for a new CRC computation, or |
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| 11 | * the previous CRC value if computing incrementally. |
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| 12 | * @p: Pointer to the data buffer |
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| 13 | * @len: Length of data in bytes |
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| 14 | * |
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| 15 | * This implements the CRC variant that is often known as the IEEE CRC-32, or |
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| 16 | * simply CRC-32, and is widely used in Ethernet and other applications: |
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| 17 | * |
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| 18 | * - Polynomial: x^32 + x^26 + x^23 + x^22 + x^16 + x^12 + x^11 + x^10 + x^8 + |
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| 19 | * x^7 + x^5 + x^4 + x^2 + x^1 + x^0 |
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| 20 | * - Bit order: Least-significant-bit-first |
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| 21 | * - Polynomial in integer form: 0xedb88320 |
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| 22 | * |
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| 23 | * This does *not* invert the CRC at the beginning or end. The caller is |
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| 24 | * expected to do that if it needs to. Inverting at both ends is recommended. |
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| 25 | * |
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| 26 | * For new applications, prefer to use CRC-32C instead. See crc32c(). |
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| 27 | * |
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| 28 | * Context: Any context |
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| 29 | * Return: The new CRC value |
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| 30 | */ |
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| 31 | u32 crc32_le(u32 crc, const void *p, size_t len); |
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| 32 | |
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| 33 | /* This is just an alias for crc32_le(). */ |
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| 34 | static inline u32 crc32(u32 crc, const void *p, size_t len) |
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| 35 | { |
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| 36 | return crc32_le(crc, p, len); |
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| 37 | } |
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| 38 | |
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| 39 | /** |
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| 40 | * crc32_be() - Compute most-significant-bit-first IEEE CRC-32 |
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| 41 | * @crc: Initial CRC value. ~0 (recommended) or 0 for a new CRC computation, or |
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| 42 | * the previous CRC value if computing incrementally. |
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| 43 | * @p: Pointer to the data buffer |
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| 44 | * @len: Length of data in bytes |
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| 45 | * |
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| 46 | * crc32_be() is the same as crc32_le() except that crc32_be() computes the |
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| 47 | * *most-significant-bit-first* variant of the CRC. I.e., within each byte, the |
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| 48 | * most significant bit is processed first (treated as highest order polynomial |
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| 49 | * coefficient). The same bit order is also used for the CRC value itself: |
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| 50 | * |
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| 51 | * - Polynomial: x^32 + x^26 + x^23 + x^22 + x^16 + x^12 + x^11 + x^10 + x^8 + |
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| 52 | * x^7 + x^5 + x^4 + x^2 + x^1 + x^0 |
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| 53 | * - Bit order: Most-significant-bit-first |
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| 54 | * - Polynomial in integer form: 0x04c11db7 |
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| 55 | * |
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| 56 | * Context: Any context |
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| 57 | * Return: The new CRC value |
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| 58 | */ |
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| 59 | u32 crc32_be(u32 crc, const void *p, size_t len); |
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| 60 | |
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| 61 | /** |
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| 62 | * crc32c() - Compute CRC-32C |
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| 63 | * @crc: Initial CRC value. ~0 (recommended) or 0 for a new CRC computation, or |
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| 64 | * the previous CRC value if computing incrementally. |
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| 65 | * @p: Pointer to the data buffer |
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| 66 | * @len: Length of data in bytes |
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| 67 | * |
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| 68 | * This implements CRC-32C, i.e. the Castagnoli CRC. This is the recommended |
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| 69 | * CRC variant to use in new applications that want a 32-bit CRC. |
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| 70 | * |
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| 71 | * - Polynomial: x^32 + x^28 + x^27 + x^26 + x^25 + x^23 + x^22 + x^20 + x^19 + |
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| 72 | * x^18 + x^14 + x^13 + x^11 + x^10 + x^9 + x^8 + x^6 + x^0 |
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| 73 | * - Bit order: Least-significant-bit-first |
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| 74 | * - Polynomial in integer form: 0x82f63b78 |
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| 75 | * |
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| 76 | * This does *not* invert the CRC at the beginning or end. The caller is |
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| 77 | * expected to do that if it needs to. Inverting at both ends is recommended. |
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| 78 | * |
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| 79 | * Context: Any context |
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| 80 | * Return: The new CRC value |
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| 81 | */ |
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| 82 | u32 crc32c(u32 crc, const void *p, size_t len); |
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| 83 | |
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| 84 | /* |
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| 85 | * crc32_optimizations() returns flags that indicate which CRC32 library |
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| 86 | * functions are using architecture-specific optimizations. Unlike |
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| 87 | * IS_ENABLED(CONFIG_CRC32_ARCH) it takes into account the different CRC32 |
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| 88 | * variants and also whether any needed CPU features are available at runtime. |
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| 89 | */ |
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| 90 | #define CRC32_LE_OPTIMIZATION BIT(0) /* crc32_le() is optimized */ |
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| 91 | #define CRC32_BE_OPTIMIZATION BIT(1) /* crc32_be() is optimized */ |
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| 92 | #define CRC32C_OPTIMIZATION BIT(2) /* crc32c() is optimized */ |
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| 93 | #if IS_ENABLED(CONFIG_CRC32_ARCH) |
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| 94 | u32 crc32_optimizations(void); |
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| 95 | #else |
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| 96 | static inline u32 crc32_optimizations(void) { return 0; } |
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| 97 | #endif |
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| 98 | |
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| 99 | /* |
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| 100 | * Helpers for hash table generation of ethernet nics: |
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| 101 | * |
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| 102 | * Ethernet sends the least significant bit of a byte first, thus crc32_le |
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| 103 | * is used. The output of crc32_le is bit reversed [most significant bit |
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| 104 | * is in bit nr 0], thus it must be reversed before use. Except for |
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| 105 | * nics that bit swap the result internally... |
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| 106 | */ |
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| 107 | #define ether_crc(length, data) bitrev32(crc32_le(~0, data, length)) |
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| 108 | #define ether_crc_le(length, data) crc32_le(~0, data, length) |
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| 109 | |
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| 110 | #endif /* _LINUX_CRC32_H */ |
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| 111 | |
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