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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 #define CRC32C_POLY_BE 0x1EDC6F41
16 
17 /* How many bits at a time to use.  Valid values are 1, 2, 4, 8, 32 and 64. */
18 /* For less performance-sensitive, use 4 */
19 #ifndef CRC_LE_BITS
20 # define CRC_LE_BITS 64
21 #endif
22 #ifndef CRC_BE_BITS
23 # define CRC_BE_BITS 64
24 #endif
25 
26 /*
27  * Little-endian CRC computation.  Used with serial bit streams sent
28  * lsbit-first.  Be sure to use cpu_to_le32() to append the computed CRC.
29  */
30 #if CRC_LE_BITS > 64 || CRC_LE_BITS < 1 || CRC_LE_BITS == 16 || \
31 	CRC_LE_BITS & CRC_LE_BITS-1
32 # error "CRC_LE_BITS must be one of {1, 2, 4, 8, 32, 64}"
33 #endif
34 
35 /*
36  * Big-endian CRC computation.  Used with serial bit streams sent
37  * msbit-first.  Be sure to use cpu_to_be32() to append the computed CRC.
38  */
39 #if CRC_BE_BITS > 64 || CRC_BE_BITS < 1 || CRC_BE_BITS == 16 || \
40 	CRC_BE_BITS & CRC_BE_BITS-1
41 # error "CRC_BE_BITS must be one of {1, 2, 4, 8, 32, 64}"
42 #endif
43 
44 
45 #define ___constant_swab32(x) \
46 	((uint32_t)( \
47 		(((uint32_t)(x) & (uint32_t)0x000000ffUL) << 24) | \
48 		(((uint32_t)(x) & (uint32_t)0x0000ff00UL) <<  8) | \
49 		(((uint32_t)(x) & (uint32_t)0x00ff0000UL) >>  8) | \
50 		(((uint32_t)(x) & (uint32_t)0xff000000UL) >> 24)))
51 
52 
53 #if (__GNUC__ >= 3)
54 #define likely(x)	__builtin_expect(!!(x), 1)
55 #define unlikely(x)	__builtin_expect(!!(x), 0)
56 #else
57 #define likely(x)	(x)
58 #define unlikely(x)	(x)
59 #endif
60