bitrev.h
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#ifndef _LINUX_BITREV_H
#define _LINUX_BITREV_H
#include <linux/types.h>
#ifdef CONFIG_HAVE_ARCH_BITREVERSE
#include <asm/bitrev.h>
#define __bitrev32 __arch_bitrev32
#define __bitrev16 __arch_bitrev16
#define __bitrev8 __arch_bitrev8
#else
extern u8 const byte_rev_table[256];
static inline u8 __bitrev8(u8 byte)
{
return byte_rev_table[byte];
}
static inline u16 __bitrev16(u16 x)
{
return (__bitrev8(x & 0xff) << 8) | __bitrev8(x >> 8);
}
static inline u32 __bitrev32(u32 x)
{
return (__bitrev16(x & 0xffff) << 16) | __bitrev16(x >> 16);
}
#endif /* CONFIG_HAVE_ARCH_BITREVERSE */
#define __constant_bitrev32(x) \
({ \
u32 __x = x; \
__x = (__x >> 16) | (__x << 16); \
__x = ((__x & (u32)0xFF00FF00UL) >> 8) | ((__x & (u32)0x00FF00FFUL) << 8); \
__x = ((__x & (u32)0xF0F0F0F0UL) >> 4) | ((__x & (u32)0x0F0F0F0FUL) << 4); \
__x = ((__x & (u32)0xCCCCCCCCUL) >> 2) | ((__x & (u32)0x33333333UL) << 2); \
__x = ((__x & (u32)0xAAAAAAAAUL) >> 1) | ((__x & (u32)0x55555555UL) << 1); \
__x; \
})
#define __constant_bitrev16(x) \
({ \
u16 __x = x; \
__x = (__x >> 8) | (__x << 8); \
__x = ((__x & (u16)0xF0F0U) >> 4) | ((__x & (u16)0x0F0FU) << 4); \
__x = ((__x & (u16)0xCCCCU) >> 2) | ((__x & (u16)0x3333U) << 2); \
__x = ((__x & (u16)0xAAAAU) >> 1) | ((__x & (u16)0x5555U) << 1); \
__x; \
})
#define __constant_bitrev8(x) \
({ \
u8 __x = x; \
__x = (__x >> 4) | (__x << 4); \
__x = ((__x & (u8)0xCCU) >> 2) | ((__x & (u8)0x33U) << 2); \
__x = ((__x & (u8)0xAAU) >> 1) | ((__x & (u8)0x55U) << 1); \
__x; \
})
#define bitrev32(x) \
({ \
u32 __x = x; \
__builtin_constant_p(__x) ? \
__constant_bitrev32(__x) : \
__bitrev32(__x); \
})
#define bitrev16(x) \
({ \
u16 __x = x; \
__builtin_constant_p(__x) ? \
__constant_bitrev16(__x) : \
__bitrev16(__x); \
})
#define bitrev8(x) \
({ \
u8 __x = x; \
__builtin_constant_p(__x) ? \
__constant_bitrev8(__x) : \
__bitrev8(__x) ; \
})
#endif /* _LINUX_BITREV_H */