LXR linux/include/linux/bitrev.h

   1#ifndef _LINUX_BITREV_H
   2#define _LINUX_BITREV_H
   3
   4#include <linux/types.h>
   5
   6#ifdef CONFIG_HAVE_ARCH_BITREVERSE
   7#include <asm/bitrev.h>
   8
   9#define __bitrev32 __arch_bitrev32
  10#define __bitrev16 __arch_bitrev16
  11#define __bitrev8 __arch_bitrev8
  12
  13#else
  14extern u8 const byte_rev_table[256];
  15static inline u8 __bitrev8(u8 byte)
  16{
  17        return byte_rev_table[byte];
  18}
  19
  20static inline u16 __bitrev16(u16 x)
  21{
  22        return (__bitrev8(x & 0xff) << 8) | __bitrev8(x >> 8);
  23}
  24
  25static inline u32 __bitrev32(u32 x)
  26{
  27        return (__bitrev16(x & 0xffff) << 16) | __bitrev16(x >> 16);
  28}
  29
  30#endif /* CONFIG_HAVE_ARCH_BITREVERSE */
  31
  32#define __constant_bitrev32(x)  \
  33({                                      \
  34        u32 __x = x;                    \
  35        __x = (__x >> 16) | (__x << 16);        \
  36        __x = ((__x & (u32)0xFF00FF00UL) >> 8) | ((__x & (u32)0x00FF00FFUL) << 8);      \
  37        __x = ((__x & (u32)0xF0F0F0F0UL) >> 4) | ((__x & (u32)0x0F0F0F0FUL) << 4);      \
  38        __x = ((__x & (u32)0xCCCCCCCCUL) >> 2) | ((__x & (u32)0x33333333UL) << 2);      \
  39        __x = ((__x & (u32)0xAAAAAAAAUL) >> 1) | ((__x & (u32)0x55555555UL) << 1);      \
  40        __x;                                                            \
  41})
  42
  43#define __constant_bitrev16(x)  \
  44({                                      \
  45        u16 __x = x;                    \
  46        __x = (__x >> 8) | (__x << 8);  \
  47        __x = ((__x & (u16)0xF0F0U) >> 4) | ((__x & (u16)0x0F0FU) << 4);        \
  48        __x = ((__x & (u16)0xCCCCU) >> 2) | ((__x & (u16)0x3333U) << 2);        \
  49        __x = ((__x & (u16)0xAAAAU) >> 1) | ((__x & (u16)0x5555U) << 1);        \
  50        __x;                                                            \
  51})
  52
  53#define __constant_bitrev8(x)   \
  54({                                      \
  55        u8 __x = x;                     \
  56        __x = (__x >> 4) | (__x << 4);  \
  57        __x = ((__x & (u8)0xCCU) >> 2) | ((__x & (u8)0x33U) << 2);      \
  58        __x = ((__x & (u8)0xAAU) >> 1) | ((__x & (u8)0x55U) << 1);      \
  59        __x;                                                            \
  60})
  61
  62#define bitrev32(x) \
  63({                      \
  64        u32 __x = x;    \
  65        __builtin_constant_p(__x) ?     \
  66        __constant_bitrev32(__x) :                      \
  67        __bitrev32(__x);                                \
  68})
  69
  70#define bitrev16(x) \
  71({                      \
  72        u16 __x = x;    \
  73        __builtin_constant_p(__x) ?     \
  74        __constant_bitrev16(__x) :                      \
  75        __bitrev16(__x);                                \
  76 })
  77
  78#define bitrev8(x) \
  79({                      \
  80        u8 __x = x;     \
  81        __builtin_constant_p(__x) ?     \
  82        __constant_bitrev8(__x) :                       \
  83        __bitrev8(__x)  ;                       \
  84 })
  85#endif /* _LINUX_BITREV_H */
  86