FFmpeg/libavutil/intreadwrite.h

#ifndef INTREADWRITE_H
#define INTREADWRITE_H

#ifdef __GNUC__

struct unaligned_64 { uint64_t l; } __attribute__((packed));
struct unaligned_32 { uint32_t l; } __attribute__((packed));
struct unaligned_16 { uint16_t l; } __attribute__((packed));

#define LD16(a) (((const struct unaligned_16 *) (a))->l)
#define LD32(a) (((const struct unaligned_32 *) (a))->l)
#define LD64(a) (((const struct unaligned_64 *) (a))->l)

#define ST16(a, b) (((struct unaligned_16 *) (a))->l) = (b)
#define ST32(a, b) (((struct unaligned_32 *) (a))->l) = (b)

#else /* __GNUC__ */

#define LD16(a) (*((uint16_t*)(a)))
#define LD32(a) (*((uint32_t*)(a)))
#define LD64(a) (*((uint64_t*)(a)))

#define ST16(a, b) *((uint16_t*)(a)) = (b)
#define ST32(a, b) *((uint32_t*)(a)) = (b)

#endif /* !__GNUC__ */

/* endian macros */
#define AV_RB8(x)  (((uint8_t*)(x))[0])
#define AV_WB8(p, d)  { ((uint8_t*)(p))[0] = (d); }

#define AV_RB16(x) ((((uint8_t*)(x))[0] << 8) | ((uint8_t*)(x))[1])
#define AV_WB16(p, d) { \
                    ((uint8_t*)(p))[1] = (d); \
                    ((uint8_t*)(p))[0] = (d)>>8; }

#define AV_RB32(x) ((((uint8_t*)(x))[0] << 24) | \
                   (((uint8_t*)(x))[1] << 16) | \
                   (((uint8_t*)(x))[2] << 8) | \
                    ((uint8_t*)(x))[3])
#define AV_WB32(p, d) { \
                    ((uint8_t*)(p))[3] = (d); \
                    ((uint8_t*)(p))[2] = (d)>>8; \
                    ((uint8_t*)(p))[1] = (d)>>16; \
                    ((uint8_t*)(p))[0] = (d)>>24; }

#define AV_RL8(x)  AV_RB8(x)
#define AV_WL8(p, d)  AV_WB8(p, d)

#define AV_RL16(x) ((((uint8_t*)(x))[1] << 8) | ((uint8_t*)(x))[0])
#define AV_WL16(p, d) { \
                    ((uint8_t*)(p))[0] = (d); \
                    ((uint8_t*)(p))[1] = (d)>>8; }

#define AV_RL32(x) ((((uint8_t*)(x))[3] << 24) | \
                   (((uint8_t*)(x))[2] << 16) | \
                   (((uint8_t*)(x))[1] << 8) | \
                    ((uint8_t*)(x))[0])
#define AV_WL32(p, d) { \
                    ((uint8_t*)(p))[0] = (d); \
                    ((uint8_t*)(p))[1] = (d)>>8; \
                    ((uint8_t*)(p))[2] = (d)>>16; \
                    ((uint8_t*)(p))[3] = (d)>>24; }

#endif /* INTREADWRITE_H */