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
  14 extern u8 const byte_rev_table[256];
  15 static inline u8 __bitrev8(u8 byte)
  16 {
  17         return byte_rev_table[byte];
  18 }
  19
  20 static inline u16 __bitrev16(u16 x)
  21 {
  22         return (__bitrev8(x & 0xff) << 8) | __bitrev8(x >> 8);
  23 }
  24
  25 static 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 */