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crc32defs.h
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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