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 #include <linux/types.h>
  29
  30 #define ___swahw32(x) \
  31 ({ \
  32         __u32 __x = (x); \
  33         ((__u32)( \
  34                 (((__u32)(__x) & (__u32)0x0000ffffUL) << 16) | \
  35                 (((__u32)(__x) & (__u32)0xffff0000UL) >> 16) )); \
  36 })
  37 #define ___swahb32(x) \
  38 ({ \
  39         __u32 __x = (x); \
  40         ((__u32)( \
  41                 (((__u32)(__x) & (__u32)0x00ff00ffUL) << 8) | \
  42                 (((__u32)(__x) & (__u32)0xff00ff00UL) >> 8) )); \
  43 })
  44
  45 #define ___constant_swahw32(x) \
  46         ((__u32)( \
  47                 (((__u32)(x) & (__u32)0x0000ffffUL) << 16) | \
  48                 (((__u32)(x) & (__u32)0xffff0000UL) >> 16) ))
  49 #define ___constant_swahb32(x) \
  50         ((__u32)( \
  51                 (((__u32)(x) & (__u32)0x00ff00ffUL) << 8) | \
  52                 (((__u32)(x) & (__u32)0xff00ff00UL) >> 8) ))
  53
  54 /*
  55  * provide defaults when no architecture-specific optimization is detected
  56  */
  57 #ifndef __arch__swahw32
  58 #  define __arch__swahw32(x) ___swahw32(x)
  59 #endif
  60 #ifndef __arch__swahb32
  61 #  define __arch__swahb32(x) ___swahb32(x)
  62 #endif
  63
  64 #ifndef __arch__swahw32p
  65 #  define __arch__swahw32p(x) __swahw32(*(x))
  66 #endif
  67 #ifndef __arch__swahb32p
  68 #  define __arch__swahb32p(x) __swahb32(*(x))
  69 #endif
  70
  71 #ifndef __arch__swahw32s
  72 #  define __arch__swahw32s(x) do { *(x) = __swahw32p((x)); } while (0)
  73 #endif
  74 #ifndef __arch__swahb32s
  75 #  define __arch__swahb32s(x) do { *(x) = __swahb32p((x)); } while (0)
  76 #endif
  77
  78
  79 /*
  80  * Allow constant folding
  81  */
  82 #define __swahw32(x) \
  83 (__builtin_constant_p((__u32)(x)) ? \
  84  ___swahw32((x)) : \
  85  __fswahw32((x)))
  86 #define __swahb32(x) \
  87 (__builtin_constant_p((__u32)(x)) ? \
  88  ___swahb32((x)) : \
  89  __fswahb32((x)))
  90
  91
  92 static inline __u32 __fswahw32(__u32 x)
  93 {
  94         return __arch__swahw32(x);
  95 }
  96
  97 static inline __u32 __swahw32p(__u32 *x)
  98 {
  99         return __arch__swahw32p(x);
 100 }
 101
 102 static inline void __swahw32s(__u32 *addr)
 103 {
 104         __arch__swahw32s(addr);
 105 }
 106
 107 static inline __u32 __fswahb32(__u32 x)
 108 {
 109         return __arch__swahb32(x);
 110 }
 111
 112 static inline __u32 __swahb32p(__u32 *x)
 113 {
 114         return __arch__swahb32p(x);
 115 }
 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 #define swahw32 __swahw32
 129 #define swahb32 __swahb32
 130 #define swahw32p __swahw32p
 131 #define swahb32p __swahb32p
 132 #define swahw32s __swahw32s
 133 #define swahb32s __swahb32s
 134
 135 #endif /* _LINUX_BYTEORDER_SWABB_H */