Root/lib/crc32defs.h

1/*
2 * There are multiple 16-bit CRC polynomials in common use, but this is
3 * *the* standard CRC-32 polynomial, first popularized by Ethernet.
4 * 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
5 */
6#define CRCPOLY_LE 0xedb88320
7#define CRCPOLY_BE 0x04c11db7
8
9/*
10 * This is the CRC32c polynomial, as outlined by Castagnoli.
11 * 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+
12 * x^8+x^6+x^0
13 */
14#define CRC32C_POLY_LE 0x82F63B78
15
16/* Try to choose an implementation variant via Kconfig */
17#ifdef CONFIG_CRC32_SLICEBY8
18# define CRC_LE_BITS 64
19# define CRC_BE_BITS 64
20#endif
21#ifdef CONFIG_CRC32_SLICEBY4
22# define CRC_LE_BITS 32
23# define CRC_BE_BITS 32
24#endif
25#ifdef CONFIG_CRC32_SARWATE
26# define CRC_LE_BITS 8
27# define CRC_BE_BITS 8
28#endif
29#ifdef CONFIG_CRC32_BIT
30# define CRC_LE_BITS 1
31# define CRC_BE_BITS 1
32#endif
33
34/*
35 * How many bits at a time to use. Valid values are 1, 2, 4, 8, 32 and 64.
36 * For less performance-sensitive, use 4 or 8 to save table size.
37 * For larger systems choose same as CPU architecture as default.
38 * This works well on X86_64, SPARC64 systems. This may require some
39 * elaboration after experiments with other architectures.
40 */
41#ifndef CRC_LE_BITS
42# ifdef CONFIG_64BIT
43# define CRC_LE_BITS 64
44# else
45# define CRC_LE_BITS 32
46# endif
47#endif
48#ifndef CRC_BE_BITS
49# ifdef CONFIG_64BIT
50# define CRC_BE_BITS 64
51# else
52# define CRC_BE_BITS 32
53# endif
54#endif
55
56/*
57 * Little-endian CRC computation. Used with serial bit streams sent
58 * lsbit-first. Be sure to use cpu_to_le32() to append the computed CRC.
59 */
60#if CRC_LE_BITS > 64 || CRC_LE_BITS < 1 || CRC_LE_BITS == 16 || \
61    CRC_LE_BITS & CRC_LE_BITS-1
62# error "CRC_LE_BITS must be one of {1, 2, 4, 8, 32, 64}"
63#endif
64
65/*
66 * Big-endian CRC computation. Used with serial bit streams sent
67 * msbit-first. Be sure to use cpu_to_be32() to append the computed CRC.
68 */
69#if CRC_BE_BITS > 64 || CRC_BE_BITS < 1 || CRC_BE_BITS == 16 || \
70    CRC_BE_BITS & CRC_BE_BITS-1
71# error "CRC_BE_BITS must be one of {1, 2, 4, 8, 32, 64}"
72#endif
73

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