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/* SPDX-License-Identifier: GPL-2.0-only */
#ifndef _LINUX_CRC32_H
#define _LINUX_CRC32_H
#include <linux/types.h>
#include <linux/bitrev.h>
/**
* 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);
/* This is just an alias for crc32_le(). */
static inline u32 crc32(u32 crc, const void *p, size_t len)
{
return crc32_le(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);
/**
* 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
* functions are using architecture-specific optimizations. Unlike
* IS_ENABLED(CONFIG_CRC32_ARCH) it takes into account the different CRC32
* variants and also whether any needed CPU features are available at runtime.
*/
#define CRC32_LE_OPTIMIZATION BIT(0) /* crc32_le() is optimized */
#define CRC32_BE_OPTIMIZATION BIT(1) /* crc32_be() is optimized */
#define CRC32C_OPTIMIZATION BIT(2) /* crc32c() is optimized */
#if IS_ENABLED(CONFIG_CRC32_ARCH)
u32 crc32_optimizations(void);
#else
static inline u32 crc32_optimizations(void) { return 0; }
#endif
/*
* Helpers for hash table generation of ethernet nics:
*
* Ethernet sends the least significant bit of a byte first, thus crc32_le
* is used. The output of crc32_le is bit reversed [most significant bit
* is in bit nr 0], thus it must be reversed before use. Except for
* nics that bit swap the result internally...
*/
#define ether_crc(length, data) bitrev32(crc32_le(~0, data, length))
#define ether_crc_le(length, data) crc32_le(~0, data, length)
#endif /* _LINUX_CRC32_H */
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