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 /* How many bits at a time to use. Requires a table of 4<<CRC_xx_BITS bytes. */ 10 /* For less performance-sensitive, use 4 */ 11 #ifndef CRC_LE_BITS 12 # define CRC_LE_BITS 8 13 #endif 14 #ifndef CRC_BE_BITS 15 # define CRC_BE_BITS 8 16 #endif 17 18 /* 19 * Little-endian CRC computation. Used with serial bit streams sent 20 * lsbit-first. Be sure to use cpu_to_le32() to append the computed CRC. 21 */ 22 #if CRC_LE_BITS > 8 || CRC_LE_BITS < 1 || CRC_LE_BITS & CRC_LE_BITS-1 23 # error CRC_LE_BITS must be a power of 2 between 1 and 8 24 #endif 25 26 /* 27 * Big-endian CRC computation. Used with serial bit streams sent 28 * msbit-first. Be sure to use cpu_to_be32() to append the computed CRC. 29 */ 30 #if CRC_BE_BITS > 8 || CRC_BE_BITS < 1 || CRC_BE_BITS & CRC_BE_BITS-1 31 # error CRC_BE_BITS must be a power of 2 between 1 and 8 32 #endif 33 34 #define ___constant_swab32(x) \ 35 ((__u32)( \ 36 (((__u32)(x) & (__u32)0x000000ffUL) << 24) | \ 37 (((__u32)(x) & (__u32)0x0000ff00UL) << 8) | \ 38 (((__u32)(x) & (__u32)0x00ff0000UL) >> 8) | \ 39 (((__u32)(x) & (__u32)0xff000000UL) >> 24) )) 40 41 42 #ifdef WORDS_BIGENDIAN 43 #define __constant_cpu_to_le32(x) ___constant_swab32((x)) 44 #define __constant_cpu_to_be32(x) (x) 45 #define __be32_to_cpu(x) (x) 46 #define __cpu_to_be32(x) (x) 47 #define __cpu_to_le32(x) (ext2fs_swab32((x))) 48 #define __le32_to_cpu(x) (ext2fs_swab32((x))) 49 #else 50 #define __constant_cpu_to_le32(x) (x) 51 #define __constant_cpu_to_be32(x) ___constant_swab32((x)) 52 #define __be32_to_cpu(x) (ext2fs_swab32((x))) 53 #define __cpu_to_be32(x) (ext2fs_swab32((x))) 54 #define __cpu_to_le32(x) (x) 55 #define __le32_to_cpu(x) (x) 56 #endif 57 58 #if (__GNUC__ >= 3) 59 #define likely(x) __builtin_expect(!!(x), 1) 60 #define unlikely(x) __builtin_expect(!!(x), 0) 61 #else 62 #define likely(x) (x) 63 #define unlikely(x) (x) 64 #endif 65