include/linux/byteorder/swabb.h

   1 #ifndef _LINUX_BYTEORDER_SWABB_H
   2 #define _LINUX_BYTEORDER_SWABB_H
   3
   4 /*
   5  * linux/byteorder/swabb.h
   6  * SWAp Bytes Bizarrely
   7  *      swaHHXX[ps]?(foo)
   8  *
   9  * Support for obNUXIous pdp-endian and other bizarre architectures.
  10  * Will Linux ever run on such ancient beasts? if not, this file
  11  * will be but a programming pearl. Still, it's a reminder that we
  12  * shouldn't be making too many assumptions when trying to be portable.
  13  *
  14  */
  15
  16 /*
  17  * Meaning of the names I chose (vaxlinux people feel free to correct them):
  18  * swahw32      swap 16-bit half-words in a 32-bit word
  19  * swahb32      swap 8-bit halves of each 16-bit half-word in a 32-bit word
  20  *
  21  * No 64-bit support yet. I don't know NUXI conventions for long longs.
  22  * I guarantee it will be a mess when it's there, though :->
  23  * It will be even worse if there are conflicting 64-bit conventions.
  24  * Hopefully, no one ever used 64-bit objects on NUXI machines.
  25  *
  26  */
  27
  28 #define ___swahw32(x) \
  29 ({ \
  30         __u32 __x = (x); \
  31         ((__u32)( \
  32                 (((__u32)(__x) & (__u32)0x0000ffffUL) << 16) | \
  33                 (((__u32)(__x) & (__u32)0xffff0000UL) >> 16) )); \
  34 })
  35 #define ___swahb32(x) \
  36 ({ \
  37         __u32 __x = (x); \
  38         ((__u32)( \
  39                 (((__u32)(__x) & (__u32)0x00ff00ffUL) << 8) | \
  40                 (((__u32)(__x) & (__u32)0xff00ff00UL) >> 8) )); \
  41 })
  42
  43 #define ___constant_swahw32(x) \
  44         ((__u32)( \
  45                 (((__u32)(x) & (__u32)0x0000ffffUL) << 16) | \
  46                 (((__u32)(x) & (__u32)0xffff0000UL) >> 16) ))
  47 #define ___constant_swahb32(x) \
  48         ((__u32)( \
  49                 (((__u32)(x) & (__u32)0x00ff00ffUL) << 8) | \
  50                 (((__u32)(x) & (__u32)0xff00ff00UL) >> 8) ))
  51
  52 /*
  53  * provide defaults when no architecture-specific optimization is detected
  54  */
  55 #ifndef __arch__swahw32
  56 #  define __arch__swahw32(x) ___swahw32(x)
  57 #endif
  58 #ifndef __arch__swahb32
  59 #  define __arch__swahb32(x) ___swahb32(x)
  60 #endif
  61
  62 #ifndef __arch__swahw32p
  63 #  define __arch__swahw32p(x) __swahw32(*(x))
  64 #endif
  65 #ifndef __arch__swahb32p
  66 #  define __arch__swahb32p(x) __swahb32(*(x))
  67 #endif
  68
  69 #ifndef __arch__swahw32s
  70 #  define __arch__swahw32s(x) do { *(x) = __swahw32p((x)); } while (0)
  71 #endif
  72 #ifndef __arch__swahb32s
  73 #  define __arch__swahb32s(x) do { *(x) = __swahb32p((x)); } while (0)
  74 #endif
  75
  76
  77 /*
  78  * Allow constant folding
  79  */
  80 #if defined(__GNUC__) && (__GNUC__ >= 2) && defined(__OPTIMIZE__)
  81 #  define __swahw32(x) \
  82 (__builtin_constant_p((__u32)(x)) ? \
  83  ___swahw32((x)) : \
  84  __fswahw32((x)))
  85 #  define __swahb32(x) \
  86 (__builtin_constant_p((__u32)(x)) ? \
  87  ___swahb32((x)) : \
  88  __fswahb32((x)))
  89 #else
  90 #  define __swahw32(x) __fswahw32(x)
  91 #  define __swahb32(x) __fswahb32(x)
  92 #endif /* OPTIMIZE */
  93
  94
  95 static __inline__ __const__ __u32 __fswahw32(__u32 x)
  96 {
  97         return __arch__swahw32(x);
  98 }
  99 static __inline__ __u32 __swahw32p(__u32 *x)
 100 {
 101         return __arch__swahw32p(x);
 102 }
 103 static __inline__ void __swahw32s(__u32 *addr)
 104 {
 105         __arch__swahw32s(addr);
 106 }
 107
 108
 109 static __inline__ __const__ __u32 __fswahb32(__u32 x)
 110 {
 111         return __arch__swahb32(x);
 112 }
 113 static __inline__ __u32 __swahb32p(__u32 *x)
 114 {
 115         return __arch__swahb32p(x);
 116 }
 117 static __inline__ void __swahb32s(__u32 *addr)
 118 {
 119         __arch__swahb32s(addr);
 120 }
 121
 122 #ifdef __BYTEORDER_HAS_U64__
 123 /*
 124  * Not supported yet
 125  */
 126 #endif /* __BYTEORDER_HAS_U64__ */
 127
 128 #if defined(__KERNEL__)
 129 #define swahw32 __swahw32
 130 #define swahb32 __swahb32
 131 #define swahw32p __swahw32p
 132 #define swahb32p __swahb32p
 133 #define swahw32s __swahw32s
 134 #define swahb32s __swahb32s
 135 #endif
 136
 137 #endif /* _LINUX_BYTEORDER_SWABB_H */