build/mtd-utils/include/mtd_swab.h

#ifndef MTD_SWAB_H
#define MTD_SWAB_H

#include <endian.h>

#define swab16(x) \
        ((uint16_t)( \
                (((uint16_t)(x) & (uint16_t)0x00ffU) << 8) | \
                (((uint16_t)(x) & (uint16_t)0xff00U) >> 8) ))
#define swab32(x) \
        ((uint32_t)( \
                (((uint32_t)(x) & (uint32_t)0x000000ffUL) << 24) | \
                (((uint32_t)(x) & (uint32_t)0x0000ff00UL) <<  8) | \
                (((uint32_t)(x) & (uint32_t)0x00ff0000UL) >>  8) | \
                (((uint32_t)(x) & (uint32_t)0xff000000UL) >> 24) ))

#define swab64(x) \
		((uint64_t)( \
				(((uint64_t)(x) & (uint64_t)0x00000000000000ffULL) << 56) | \
				(((uint64_t)(x) & (uint64_t)0x000000000000ff00ULL) << 40) | \
				(((uint64_t)(x) & (uint64_t)0x0000000000ff0000ULL) << 24) | \
				(((uint64_t)(x) & (uint64_t)0x00000000ff000000ULL) << 8) | \
				(((uint64_t)(x) & (uint64_t)0x000000ff00000000ULL) >> 8) | \
				(((uint64_t)(x) & (uint64_t)0x0000ff0000000000ULL) >> 24) | \
				(((uint64_t)(x) & (uint64_t)0x00ff000000000000ULL) >> 40) | \
				(((uint64_t)(x) & (uint64_t)0xff00000000000000ULL) >> 56) ))


#if __BYTE_ORDER == __BIG_ENDIAN
#define cpu_to_le16(x) ({ uint16_t _x = x; swab16(_x); })
#define cpu_to_le32(x) ({ uint32_t _x = x; swab32(_x); })
#define cpu_to_le64(x) ({ uint64_t _x = x; swab64(_x); })
#define cpu_to_be16(x) (x)
#define cpu_to_be32(x) (x)
#define cpu_to_be64(x) (x)
#else
#define cpu_to_le16(x) (x)
#define cpu_to_le32(x) (x)
#define cpu_to_le64(x) (x)
#define cpu_to_be16(x) ({ uint16_t _x = x; swab16(_x); })
#define cpu_to_be32(x) ({ uint32_t _x = x; swab32(_x); })
#define cpu_to_be64(x) ({ uint64_t _x = x; swab64(_x); })
#endif
#define le16_to_cpu(x) cpu_to_le16(x)
#define be16_to_cpu(x) cpu_to_be16(x)
#define le32_to_cpu(x) cpu_to_le32(x)
#define be32_to_cpu(x) cpu_to_be32(x)
#define le64_to_cpu(x) cpu_to_le64(x)
#define be64_to_cpu(x) cpu_to_be64(x)

#endif