151d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o/* 251d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o * There are multiple 16-bit CRC polynomials in common use, but this is 351d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o * *the* standard CRC-32 polynomial, first popularized by Ethernet. 451d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o * 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 551d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o */ 651d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o#define CRCPOLY_LE 0xedb88320 751d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o#define CRCPOLY_BE 0x04c11db7 851d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o 951d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o/* How many bits at a time to use. Requires a table of 4<<CRC_xx_BITS bytes. */ 1051d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o/* For less performance-sensitive, use 4 */ 1151d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o#ifndef CRC_LE_BITS 1251d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o# define CRC_LE_BITS 8 1351d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o#endif 1451d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o#ifndef CRC_BE_BITS 1551d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o# define CRC_BE_BITS 8 1651d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o#endif 1751d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o 1851d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o/* 1951d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o * Little-endian CRC computation. Used with serial bit streams sent 2051d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o * lsbit-first. Be sure to use cpu_to_le32() to append the computed CRC. 2151d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o */ 2251d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o#if CRC_LE_BITS > 8 || CRC_LE_BITS < 1 || CRC_LE_BITS & CRC_LE_BITS-1 2351d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o# error CRC_LE_BITS must be a power of 2 between 1 and 8 2451d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o#endif 2551d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o 2651d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o/* 2751d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o * Big-endian CRC computation. Used with serial bit streams sent 2851d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o * msbit-first. Be sure to use cpu_to_be32() to append the computed CRC. 2951d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o */ 3051d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o#if CRC_BE_BITS > 8 || CRC_BE_BITS < 1 || CRC_BE_BITS & CRC_BE_BITS-1 3151d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o# error CRC_BE_BITS must be a power of 2 between 1 and 8 3251d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o#endif 3351d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o 3451d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o#define ___constant_swab32(x) \ 3551d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o ((__u32)( \ 3651d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o (((__u32)(x) & (__u32)0x000000ffUL) << 24) | \ 3751d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o (((__u32)(x) & (__u32)0x0000ff00UL) << 8) | \ 3851d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o (((__u32)(x) & (__u32)0x00ff0000UL) >> 8) | \ 3951d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o (((__u32)(x) & (__u32)0xff000000UL) >> 24) )) 4051d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o 4151d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o 4251d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o#ifdef WORDS_BIGENDIAN 4351d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o#define __constant_cpu_to_le32(x) ___constant_swab32((x)) 4451d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o#define __constant_cpu_to_be32(x) (x) 4551d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o#define __be32_to_cpu(x) (x) 4651d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o#define __cpu_to_be32(x) (x) 4751d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o#define __cpu_to_le32(x) (ext2fs_swab32((x))) 4851d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o#define __le32_to_cpu(x) (ext2fs_swab32((x))) 4951d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o#else 5051d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o#define __constant_cpu_to_le32(x) (x) 5151d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o#define __constant_cpu_to_be32(x) ___constant_swab32((x)) 5251d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o#define __be32_to_cpu(x) (ext2fs_swab32((x))) 5351d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o#define __cpu_to_be32(x) (ext2fs_swab32((x))) 5451d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o#define __cpu_to_le32(x) (x) 5551d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o#define __le32_to_cpu(x) (x) 5651d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o#endif 5751d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o 58387df00577fa94f49da58bc74de4f9c4afd2cb41Theodore Ts'o#if (__GNUC__ >= 3) 5951d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o#define likely(x) __builtin_expect(!!(x), 1) 6051d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o#define unlikely(x) __builtin_expect(!!(x), 0) 6151d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o#else 6251d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o#define likely(x) (x) 6351d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o#define unlikely(x) (x) 6451d12cebb61ca00f5455fe6e25938cd79fea15abTheodore Ts'o#endif 65