include/linux/swab.h

   1 #ifndef _LINUX_SWAB_H
   2 #define _LINUX_SWAB_H
   3
   4 #include <linux/types.h>
   5 #include <linux/compiler.h>
   6 #include <asm/byteorder.h>
   7
   8 /*
   9  * casts are necessary for constants, because we never know how for sure
  10  * how U/UL/ULL map to __u16, __u32, __u64. At least not in a portable way.
  11  */
  12 #define __const_swab16(x) ((__u16)(                             \
  13         (((__u16)(x) & (__u16)0x00ffU) << 8) |                  \
  14         (((__u16)(x) & (__u16)0xff00U) >> 8)))
  15
  16 #define __const_swab32(x) ((__u32)(                             \
  17         (((__u32)(x) & (__u32)0x000000ffUL) << 24) |            \
  18         (((__u32)(x) & (__u32)0x0000ff00UL) <<  8) |            \
  19         (((__u32)(x) & (__u32)0x00ff0000UL) >>  8) |            \
  20         (((__u32)(x) & (__u32)0xff000000UL) >> 24)))
  21
  22 #define __const_swab64(x) ((__u64)(                             \
  23         (((__u64)(x) & (__u64)0x00000000000000ffULL) << 56) |   \
  24         (((__u64)(x) & (__u64)0x000000000000ff00ULL) << 40) |   \
  25         (((__u64)(x) & (__u64)0x0000000000ff0000ULL) << 24) |   \
  26         (((__u64)(x) & (__u64)0x00000000ff000000ULL) <<  8) |   \
  27         (((__u64)(x) & (__u64)0x000000ff00000000ULL) >>  8) |   \
  28         (((__u64)(x) & (__u64)0x0000ff0000000000ULL) >> 24) |   \
  29         (((__u64)(x) & (__u64)0x00ff000000000000ULL) >> 40) |   \
  30         (((__u64)(x) & (__u64)0xff00000000000000ULL) >> 56)))
  31
  32 #define __const_swahw32(x) ((__u32)(                            \
  33         (((__u32)(x) & (__u32)0x0000ffffUL) << 16) |            \
  34         (((__u32)(x) & (__u32)0xffff0000UL) >> 16)))
  35
  36 #define __const_swahb32(x) ((__u32)(                            \
  37         (((__u32)(x) & (__u32)0x00ff00ffUL) << 8) |             \
  38         (((__u32)(x) & (__u32)0xff00ff00UL) >> 8)))
  39
  40 /*
  41  * Implement the following as inlines, but define the interface using
  42  * macros to allow constant folding when possible:
  43  * ___swab16, ___swab32, ___swab64, ___swahw32, ___swahb32
  44  */
  45
  46 static inline __attribute_const__ __u16 ___swab16(__u16 val)
  47 {
  48 #ifdef __arch_swab16
  49         return __arch_swab16(val);
  50 #else
  51         return __const_swab16(val);
  52 #endif
  53 }
  54
  55 static inline __attribute_const__ __u32 ___swab32(__u32 val)
  56 {
  57 #ifdef __arch_swab32
  58         return __arch_swab32(val);
  59 #else
  60         return __const_swab32(val);
  61 #endif
  62 }
  63
  64 static inline __attribute_const__ __u64 ___swab64(__u64 val)
  65 {
  66 #ifdef __arch_swab64
  67         return __arch_swab64(val);
  68 #elif defined(__SWAB_64_THRU_32__)
  69         __u32 h = val >> 32;
  70         __u32 l = val & ((1ULL << 32) - 1);
  71         return (((__u64)___swab32(l)) << 32) | ((__u64)(___swab32(h)));
  72 #else
  73         return __const_swab64(val);
  74 #endif
  75 }
  76
  77 static inline __attribute_const__ __u32 ___swahw32(__u32 val)
  78 {
  79 #ifdef __arch_swahw32
  80         return __arch_swahw32(val);
  81 #else
  82         return __const_swahw32(val);
  83 #endif
  84 }
  85
  86 static inline __attribute_const__ __u32 ___swahb32(__u32 val)
  87 {
  88 #ifdef __arch_swahb32
  89         return __arch_swahb32(val);
  90 #else
  91         return __const_swahb32(val);
  92 #endif
  93 }
  94
  95 /**
  96  * __swab16 - return a byteswapped 16-bit value
  97  * @x: value to byteswap
  98  */
  99 #define __swab16(x)                             \
 100         (__builtin_constant_p((__u16)(x)) ?     \
 101         __const_swab16((x)) :                   \
 102         ___swab16((x)))
 103
 104 /**
 105  * __swab32 - return a byteswapped 32-bit value
 106  * @x: value to byteswap
 107  */
 108 #define __swab32(x)                             \
 109         (__builtin_constant_p((__u32)(x)) ?     \
 110         __const_swab32((x)) :                   \
 111         ___swab32((x)))
 112
 113 /**
 114  * __swab64 - return a byteswapped 64-bit value
 115  * @x: value to byteswap
 116  */
 117 #define __swab64(x)                             \
 118         (__builtin_constant_p((__u64)(x)) ?     \
 119         __const_swab64((x)) :                   \
 120         ___swab64((x)))
 121
 122 /**
 123  * __swahw32 - return a word-swapped 32-bit value
 124  * @x: value to wordswap
 125  *
 126  * __swahw32(0x12340000) is 0x00001234
 127  */
 128 #define __swahw32(x)                            \
 129         (__builtin_constant_p((__u32)(x)) ?     \
 130         __const_swahw32((x)) :                  \
 131         ___swahw32((x)))
 132
 133 /**
 134  * __swahb32 - return a high and low byte-swapped 32-bit value
 135  * @x: value to byteswap
 136  *
 137  * __swahb32(0x12345678) is 0x34127856
 138  */
 139 #define __swahb32(x)                            \
 140         (__builtin_constant_p((__u32)(x)) ?     \
 141         __const_swahb32((x)) :                  \
 142         ___swahb32((x)))
 143
 144 /**
 145  * __swab16p - return a byteswapped 16-bit value from a pointer
 146  * @p: pointer to a naturally-aligned 16-bit value
 147  */
 148 static inline __u16 __swab16p(const __u16 *p)
 149 {
 150 #ifdef __arch_swab16p
 151         return __arch_swab16p(p);
 152 #else
 153         return __swab16(*p);
 154 #endif
 155 }
 156
 157 /**
 158  * __swab32p - return a byteswapped 32-bit value from a pointer
 159  * @p: pointer to a naturally-aligned 32-bit value
 160  */
 161 static inline __u32 __swab32p(const __u32 *p)
 162 {
 163 #ifdef __arch_swab32p
 164         return __arch_swab32p(p);
 165 #else
 166         return __swab32(*p);
 167 #endif
 168 }
 169
 170 /**
 171  * __swab64p - return a byteswapped 64-bit value from a pointer
 172  * @p: pointer to a naturally-aligned 64-bit value
 173  */
 174 static inline __u64 __swab64p(const __u64 *p)
 175 {
 176 #ifdef __arch_swab64p
 177         return __arch_swab64p(p);
 178 #else
 179         return __swab64(*p);
 180 #endif
 181 }
 182
 183 /**
 184  * __swahw32p - return a wordswapped 32-bit value from a pointer
 185  * @p: pointer to a naturally-aligned 32-bit value
 186  *
 187  * See __swahw32() for details of wordswapping.
 188  */
 189 static inline __u32 __swahw32p(const __u32 *p)
 190 {
 191 #ifdef __arch_swahw32p
 192         return __arch_swahw32p(p);
 193 #else
 194         return __swahw32(*p);
 195 #endif
 196 }
 197
 198 /**
 199  * __swahb32p - return a high and low byteswapped 32-bit value from a pointer
 200  * @p: pointer to a naturally-aligned 32-bit value
 201  *
 202  * See __swahb32() for details of high/low byteswapping.
 203  */
 204 static inline __u32 __swahb32p(const __u32 *p)
 205 {
 206 #ifdef __arch_swahb32p
 207         return __arch_swahb32p(p);
 208 #else
 209         return __swahb32(*p);
 210 #endif
 211 }
 212
 213 /**
 214  * __swab16s - byteswap a 16-bit value in-place
 215  * @p: pointer to a naturally-aligned 16-bit value
 216  */
 217 static inline void __swab16s(__u16 *p)
 218 {
 219 #ifdef __arch_swab16s
 220         __arch_swab16s(p);
 221 #else
 222         *p = __swab16p(p);
 223 #endif
 224 }
 225 /**
 226  * __swab32s - byteswap a 32-bit value in-place
 227  * @p: pointer to a naturally-aligned 32-bit value
 228  */
 229 static inline void __swab32s(__u32 *p)
 230 {
 231 #ifdef __arch_swab32s
 232         __arch_swab32s(p);
 233 #else
 234         *p = __swab32p(p);
 235 #endif
 236 }
 237
 238 /**
 239  * __swab64s - byteswap a 64-bit value in-place
 240  * @p: pointer to a naturally-aligned 64-bit value
 241  */
 242 static inline void __swab64s(__u64 *p)
 243 {
 244 #ifdef __arch_swab64s
 245         __arch_swab64s(p);
 246 #else
 247         *p = __swab64p(p);
 248 #endif
 249 }
 250
 251 /**
 252  * __swahw32s - wordswap a 32-bit value in-place
 253  * @p: pointer to a naturally-aligned 32-bit value
 254  *
 255  * See __swahw32() for details of wordswapping
 256  */
 257 static inline void __swahw32s(__u32 *p)
 258 {
 259 #ifdef __arch_swahw32s
 260         __arch_swahw32s(p);
 261 #else
 262         *p = __swahw32p(p);
 263 #endif
 264 }
 265
 266 /**
 267  * __swahb32s - high and low byteswap a 32-bit value in-place
 268  * @p: pointer to a naturally-aligned 32-bit value
 269  *
 270  * See __swahb32() for details of high and low byte swapping
 271  */
 272 static inline void __swahb32s(__u32 *p)
 273 {
 274 #ifdef __arch_swahb32s
 275         __arch_swahb32s(p);
 276 #else
 277         *p = __swahb32p(p);
 278 #endif
 279 }
 280
 281 #ifdef __KERNEL__
 282 # define swab16 __swab16
 283 # define swab32 __swab32
 284 # define swab64 __swab64
 285 # define swahw32 __swahw32
 286 # define swahb32 __swahb32
 287 # define swab16p __swab16p
 288 # define swab32p __swab32p
 289 # define swab64p __swab64p
 290 # define swahw32p __swahw32p
 291 # define swahb32p __swahb32p
 292 # define swab16s __swab16s
 293 # define swab32s __swab32s
 294 # define swab64s __swab64s
 295 # define swahw32s __swahw32s
 296 # define swahb32s __swahb32s
 297 #endif /* __KERNEL__ */
 298
 299 #endif /* _LINUX_SWAB_H */