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      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 (at) 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 #include <linux/compiler.h>
     19 
     20 /* casts are necessary for constants, because we never know how for sure
     21  * how U/UL/ULL map to __u16, __u32, __u64. At least not in a portable way.
     22  */
     23 #define ___swab16(x) \
     24 ({ \
     25 	__u16 __x = (x); \
     26 	((__u16)( \
     27 		(((__u16)(__x) & (__u16)0x00ffU) << 8) | \
     28 		(((__u16)(__x) & (__u16)0xff00U) >> 8) )); \
     29 })
     30 
     31 #define ___swab32(x) \
     32 ({ \
     33 	__u32 __x = (x); \
     34 	((__u32)( \
     35 		(((__u32)(__x) & (__u32)0x000000ffUL) << 24) | \
     36 		(((__u32)(__x) & (__u32)0x0000ff00UL) <<  8) | \
     37 		(((__u32)(__x) & (__u32)0x00ff0000UL) >>  8) | \
     38 		(((__u32)(__x) & (__u32)0xff000000UL) >> 24) )); \
     39 })
     40 
     41 #define ___swab64(x) \
     42 ({ \
     43 	__u64 __x = (x); \
     44 	((__u64)( \
     45 		(__u64)(((__u64)(__x) & (__u64)0x00000000000000ffULL) << 56) | \
     46 		(__u64)(((__u64)(__x) & (__u64)0x000000000000ff00ULL) << 40) | \
     47 		(__u64)(((__u64)(__x) & (__u64)0x0000000000ff0000ULL) << 24) | \
     48 		(__u64)(((__u64)(__x) & (__u64)0x00000000ff000000ULL) <<  8) | \
     49 	        (__u64)(((__u64)(__x) & (__u64)0x000000ff00000000ULL) >>  8) | \
     50 		(__u64)(((__u64)(__x) & (__u64)0x0000ff0000000000ULL) >> 24) | \
     51 		(__u64)(((__u64)(__x) & (__u64)0x00ff000000000000ULL) >> 40) | \
     52 		(__u64)(((__u64)(__x) & (__u64)0xff00000000000000ULL) >> 56) )); \
     53 })
     54 
     55 #define ___constant_swab16(x) \
     56 	((__u16)( \
     57 		(((__u16)(x) & (__u16)0x00ffU) << 8) | \
     58 		(((__u16)(x) & (__u16)0xff00U) >> 8) ))
     59 #define ___constant_swab32(x) \
     60 	((__u32)( \
     61 		(((__u32)(x) & (__u32)0x000000ffUL) << 24) | \
     62 		(((__u32)(x) & (__u32)0x0000ff00UL) <<  8) | \
     63 		(((__u32)(x) & (__u32)0x00ff0000UL) >>  8) | \
     64 		(((__u32)(x) & (__u32)0xff000000UL) >> 24) ))
     65 #define ___constant_swab64(x) \
     66 	((__u64)( \
     67 		(__u64)(((__u64)(x) & (__u64)0x00000000000000ffULL) << 56) | \
     68 		(__u64)(((__u64)(x) & (__u64)0x000000000000ff00ULL) << 40) | \
     69 		(__u64)(((__u64)(x) & (__u64)0x0000000000ff0000ULL) << 24) | \
     70 		(__u64)(((__u64)(x) & (__u64)0x00000000ff000000ULL) <<  8) | \
     71 	        (__u64)(((__u64)(x) & (__u64)0x000000ff00000000ULL) >>  8) | \
     72 		(__u64)(((__u64)(x) & (__u64)0x0000ff0000000000ULL) >> 24) | \
     73 		(__u64)(((__u64)(x) & (__u64)0x00ff000000000000ULL) >> 40) | \
     74 		(__u64)(((__u64)(x) & (__u64)0xff00000000000000ULL) >> 56) ))
     75 
     76 /*
     77  * provide defaults when no architecture-specific optimization is detected
     78  */
     79 #ifndef __arch__swab16
     80 #  define __arch__swab16(x) ({ __u16 __tmp = (x) ; ___swab16(__tmp); })
     81 #endif
     82 #ifndef __arch__swab32
     83 #  define __arch__swab32(x) ({ __u32 __tmp = (x) ; ___swab32(__tmp); })
     84 #endif
     85 #ifndef __arch__swab64
     86 #  define __arch__swab64(x) ({ __u64 __tmp = (x) ; ___swab64(__tmp); })
     87 #endif
     88 
     89 #ifndef __arch__swab16p
     90 #  define __arch__swab16p(x) __arch__swab16(*(x))
     91 #endif
     92 #ifndef __arch__swab32p
     93 #  define __arch__swab32p(x) __arch__swab32(*(x))
     94 #endif
     95 #ifndef __arch__swab64p
     96 #  define __arch__swab64p(x) __arch__swab64(*(x))
     97 #endif
     98 
     99 #ifndef __arch__swab16s
    100 #  define __arch__swab16s(x) do { *(x) = __arch__swab16p((x)); } while (0)
    101 #endif
    102 #ifndef __arch__swab32s
    103 #  define __arch__swab32s(x) do { *(x) = __arch__swab32p((x)); } while (0)
    104 #endif
    105 #ifndef __arch__swab64s
    106 #  define __arch__swab64s(x) do { *(x) = __arch__swab64p((x)); } while (0)
    107 #endif
    108 
    109 
    110 /*
    111  * Allow constant folding
    112  */
    113 #if defined(__GNUC__) && defined(__OPTIMIZE__)
    114 #  define __swab16(x) \
    115 (__builtin_constant_p((__u16)(x)) ? \
    116  ___swab16((x)) : \
    117  __fswab16((x)))
    118 #  define __swab32(x) \
    119 (__builtin_constant_p((__u32)(x)) ? \
    120  ___swab32((x)) : \
    121  __fswab32((x)))
    122 #  define __swab64(x) \
    123 (__builtin_constant_p((__u64)(x)) ? \
    124  ___swab64((x)) : \
    125  __fswab64((x)))
    126 #else
    127 #  define __swab16(x) __fswab16(x)
    128 #  define __swab32(x) __fswab32(x)
    129 #  define __swab64(x) __fswab64(x)
    130 #endif /* OPTIMIZE */
    131 
    132 
    133 static __inline__ __attribute_const__ __u16 __fswab16(__u16 x)
    134 {
    135 	return __arch__swab16(x);
    136 }
    137 static __inline__ __u16 __swab16p(const __u16 *x)
    138 {
    139 	return __arch__swab16p(x);
    140 }
    141 static __inline__ void __swab16s(__u16 *addr)
    142 {
    143 	__arch__swab16s(addr);
    144 }
    145 
    146 static __inline__ __attribute_const__ __u32 __fswab32(__u32 x)
    147 {
    148 	return __arch__swab32(x);
    149 }
    150 static __inline__ __u32 __swab32p(const __u32 *x)
    151 {
    152 	return __arch__swab32p(x);
    153 }
    154 static __inline__ void __swab32s(__u32 *addr)
    155 {
    156 	__arch__swab32s(addr);
    157 }
    158 
    159 #ifdef __BYTEORDER_HAS_U64__
    160 static __inline__ __attribute_const__ __u64 __fswab64(__u64 x)
    161 {
    162 #  ifdef __SWAB_64_THRU_32__
    163 	__u32 h = x >> 32;
    164         __u32 l = x & ((1ULL<<32)-1);
    165         return (((__u64)__swab32(l)) << 32) | ((__u64)(__swab32(h)));
    166 #  else
    167 	return __arch__swab64(x);
    168 #  endif
    169 }
    170 static __inline__ __u64 __swab64p(const __u64 *x)
    171 {
    172 	return __arch__swab64p(x);
    173 }
    174 static __inline__ void __swab64s(__u64 *addr)
    175 {
    176 	__arch__swab64s(addr);
    177 }
    178 #endif /* __BYTEORDER_HAS_U64__ */
    179 
    180 #if defined(__KERNEL__)
    181 #define swab16 __swab16
    182 #define swab32 __swab32
    183 #define swab64 __swab64
    184 #define swab16p __swab16p
    185 #define swab32p __swab32p
    186 #define swab64p __swab64p
    187 #define swab16s __swab16s
    188 #define swab32s __swab32s
    189 #define swab64s __swab64s
    190 #endif
    191 
    192 #endif /* _LINUX_BYTEORDER_SWAB_H */
    193