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