include/linux/byteorder/swab.h

   1 #ifndef _LINUX_BYTEORDER_SWAB_H
   2 #define _LINUX_BYTEORDER_SWAB_H
   3
   4 /*
   5  * linux/byteorder/swab.h
   6  * Byte-swapping, independently from CPU endianness
   7  *      swabXX[ps]?(foo)
   8  *
   9  * Francois-Rene Rideau <fare@tunes.org> 19971205
  10  *    separated swab functions from cpu_to_XX,
  11  *    to clean up support for bizarre-endian architectures.
  12  *
  13  * See asm-i386/byteorder.h and suches for examples of how to provide
  14  * architecture-dependent optimized versions
  15  *
  16  */
  17
  18 /* casts are necessary for constants, because we never know how for sure
  19  * how U/UL/ULL map to __u16, __u32, __u64. At least not in a portable way.
  20  */
  21 #define ___swab16(x) \
  22         ((__u16)( \
  23                 (((__u16)(x) & (__u16)0x00ffU) << 8) | \
  24                 (((__u16)(x) & (__u16)0xff00U) >> 8) ))
  25 #define ___swab32(x) \
  26         ((__u32)( \
  27                 (((__u32)(x) & (__u32)0x000000ffUL) << 24) | \
  28                 (((__u32)(x) & (__u32)0x0000ff00UL) <<  8) | \
  29                 (((__u32)(x) & (__u32)0x00ff0000UL) >>  8) | \
  30                 (((__u32)(x) & (__u32)0xff000000UL) >> 24) ))
  31 #define ___swab64(x) \
  32         ((__u64)( \
  33                 (__u64)(((__u64)(x) & (__u64)0x00000000000000ffULL) << 56) | \
  34                 (__u64)(((__u64)(x) & (__u64)0x000000000000ff00ULL) << 40) | \
  35                 (__u64)(((__u64)(x) & (__u64)0x0000000000ff0000ULL) << 24) | \
  36                 (__u64)(((__u64)(x) & (__u64)0x00000000ff000000ULL) <<  8) | \
  37                 (__u64)(((__u64)(x) & (__u64)0x000000ff00000000ULL) >>  8) | \
  38                 (__u64)(((__u64)(x) & (__u64)0x0000ff0000000000ULL) >> 24) | \
  39                 (__u64)(((__u64)(x) & (__u64)0x00ff000000000000ULL) >> 40) | \
  40                 (__u64)(((__u64)(x) & (__u64)0xff00000000000000ULL) >> 56) ))
  41
  42 /*
  43  * provide defaults when no architecture-specific optimization is detected
  44  */
  45 #ifndef __arch__swab16
  46 #  define __arch__swab16(x) ___swab16(x)
  47 #endif
  48 #ifndef __arch__swab32
  49 #  define __arch__swab32(x) ___swab32(x)
  50 #endif
  51 #ifndef __arch__swab64
  52 #  define __arch__swab64(x) ___swab64(x)
  53 #endif
  54
  55 #ifndef __arch__swab16p
  56 #  define __arch__swab16p(x) __swab16(*(x))
  57 #endif
  58 #ifndef __arch__swab32p
  59 #  define __arch__swab32p(x) __swab32(*(x))
  60 #endif
  61 #ifndef __arch__swab64p
  62 #  define __arch__swab64p(x) __swab64(*(x))
  63 #endif
  64
  65 #ifndef __arch__swab16s
  66 #  define __arch__swab16s(x) do { *(x) = __swab16p((x)); } while (0)
  67 #endif
  68 #ifndef __arch__swab32s
  69 #  define __arch__swab32s(x) do { *(x) = __swab32p((x)); } while (0)
  70 #endif
  71 #ifndef __arch__swab64s
  72 #  define __arch__swab64s(x) do { *(x) = __swab64p((x)); } while (0)
  73 #endif
  74
  75
  76 /*
  77  * Allow constant folding
  78  */
  79 #if defined(__GNUC__) && (__GNUC__ >= 2) && defined(__OPTIMIZE__)
  80 #  define __swab16(x) \
  81 (__builtin_constant_p((__u16)(x)) ? \
  82  ___swab16((x)) : \
  83  __fswab16((x)))
  84 #  define __swab32(x) \
  85 (__builtin_constant_p((__u32)(x)) ? \
  86  ___swab32((x)) : \
  87  __fswab32((x)))
  88 #  define __swab64(x) \
  89 (__builtin_constant_p((__u64)(x)) ? \
  90  ___swab64((x)) : \
  91  __fswab64((x)))
  92 #else
  93 #  define __swab16(x) __fswab16(x)
  94 #  define __swab32(x) __fswab32(x)
  95 #  define __swab64(x) __fswab64(x)
  96 #endif /* OPTIMIZE */
  97
  98
  99 static __inline__ __attribute__((const)) __u16 __fswab16(__u16 x)
 100 {
 101         return __arch__swab16(x);
 102 }
 103 static __inline__ __u16 __swab16p(const __u16 *x)
 104 {
 105         return __arch__swab16p(x);
 106 }
 107 static __inline__ void __swab16s(__u16 *addr)
 108 {
 109         __arch__swab16s(addr);
 110 }
 111
 112 static __inline__ __attribute__((const)) __u32 __fswab32(__u32 x)
 113 {
 114         return __arch__swab32(x);
 115 }
 116 static __inline__ __u32 __swab32p(const __u32 *x)
 117 {
 118         return __arch__swab32p(x);
 119 }
 120 static __inline__ void __swab32s(__u32 *addr)
 121 {
 122         __arch__swab32s(addr);
 123 }
 124
 125 static __inline__ __attribute__((const)) __u64 __fswab64(__u64 x)
 126 {
 127 #  ifdef __SWAB_64_THRU_32__
 128         __u32 h = x >> 32;
 129         __u32 l = x & ((1ULL<<32)-1);
 130         return (((__u64)__swab32(l)) << 32) | ((__u64)(__swab32(h)));
 131 #  else
 132         return __arch__swab64(x);
 133 #  endif
 134 }
 135 static __inline__ __u64 __swab64p(const __u64 *x)
 136 {
 137         return __arch__swab64p(x);
 138 }
 139 static __inline__ void __swab64s(__u64 *addr)
 140 {
 141         __arch__swab64s(addr);
 142 }
 143
 144 #if defined(__KERNEL__)
 145 #define swab16 __swab16
 146 #define swab32 __swab32
 147 #define swab64 __swab64
 148 #define swab16p __swab16p
 149 #define swab32p __swab32p
 150 #define swab64p __swab64p
 151 #define swab16s __swab16s
 152 #define swab32s __swab32s
 153 #define swab64s __swab64s
 154 #endif
 155
 156 #endif /* _LINUX_BYTEORDER_SWAB_H */