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      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__) && 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 __u32 __fswahw32(__u32 x)
     96 {
     97 	return __arch__swahw32(x);
     98 }
     99 
    100 static inline __u32 __swahw32p(__u32 *x)
    101 {
    102 	return __arch__swahw32p(x);
    103 }
    104 
    105 static inline void __swahw32s(__u32 *addr)
    106 {
    107 	__arch__swahw32s(addr);
    108 }
    109 
    110 static inline __u32 __fswahb32(__u32 x)
    111 {
    112 	return __arch__swahb32(x);
    113 }
    114 
    115 static inline __u32 __swahb32p(__u32 *x)
    116 {
    117 	return __arch__swahb32p(x);
    118 }
    119 
    120 static inline void __swahb32s(__u32 *addr)
    121 {
    122 	__arch__swahb32s(addr);
    123 }
    124 
    125 #ifdef __BYTEORDER_HAS_U64__
    126 /*
    127  * Not supported yet
    128  */
    129 #endif /* __BYTEORDER_HAS_U64__ */
    130 
    131 #if defined(__KERNEL__)
    132 #define swahw32 __swahw32
    133 #define swahb32 __swahb32
    134 #define swahw32p __swahw32p
    135 #define swahb32p __swahb32p
    136 #define swahw32s __swahw32s
    137 #define swahb32s __swahb32s
    138 #endif
    139 
    140 #endif /* _LINUX_BYTEORDER_SWABB_H */
    141