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 #elif defined(__arch_swab16p)
  51         return __arch_swab16p(&val);
  52 #else
  53         return __const_swab16(val);
  54 #endif
  55 }
  56
  57 static inline __attribute_const__ __u32 ___swab32(__u32 val)
  58 {
  59 #ifdef __arch_swab32
  60         return __arch_swab32(val);
  61 #elif defined(__arch_swab32p)
  62         return __arch_swab32p(&val);
  63 #else
  64         return __const_swab32(val);
  65 #endif
  66 }
  67
  68 static inline __attribute_const__ __u64 ___swab64(__u64 val)
  69 {
  70 #ifdef __arch_swab64
  71         return __arch_swab64(val);
  72 #elif defined(__arch_swab64p)
  73         return __arch_swab64p(&val);
  74 #elif defined(__SWAB_64_THRU_32__)
  75         __u32 h = val >> 32;
  76         __u32 l = val & ((1ULL << 32) - 1);
  77         return (((__u64)___swab32(l)) << 32) | ((__u64)(___swab32(h)));
  78 #else
  79         return __const_swab64(val);
  80 #endif
  81 }
  82
  83 static inline __attribute_const__ __u32 ___swahw32(__u32 val)
  84 {
  85 #ifdef __arch_swahw32
  86         return __arch_swahw32(val);
  87 #elif defined(__arch_swahw32p)
  88         return __arch_swahw32p(&val);
  89 #else
  90         return __const_swahw32(val);
  91 #endif
  92 }
  93
  94 static inline __attribute_const__ __u32 ___swahb32(__u32 val)
  95 {
  96 #ifdef __arch_swahb32
  97         return __arch_swahb32(val);
  98 #elif defined(__arch_swahb32p)
  99         return __arch_swahb32p(&val);
 100 #else
 101         return __const_swahb32(val);
 102 #endif
 103 }
 104
 105 /**
 106  * __swab16 - return a byteswapped 16-bit value
 107  * @x: value to byteswap
 108  */
 109 #define __swab16(x)                             \
 110         (__builtin_constant_p((__u16)(x)) ?     \
 111         __const_swab16((x)) :                   \
 112         ___swab16((x)))
 113
 114 /**
 115  * __swab32 - return a byteswapped 32-bit value
 116  * @x: value to byteswap
 117  */
 118 #define __swab32(x)                             \
 119         (__builtin_constant_p((__u32)(x)) ?     \
 120         __const_swab32((x)) :                   \
 121         ___swab32((x)))
 122
 123 /**
 124  * __swab64 - return a byteswapped 64-bit value
 125  * @x: value to byteswap
 126  */
 127 #define __swab64(x)                             \
 128         (__builtin_constant_p((__u64)(x)) ?     \
 129         __const_swab64((x)) :                   \
 130         ___swab64((x)))
 131
 132 /**
 133  * __swahw32 - return a word-swapped 32-bit value
 134  * @x: value to wordswap
 135  *
 136  * __swahw32(0x12340000) is 0x00001234
 137  */
 138 #define __swahw32(x)                            \
 139         (__builtin_constant_p((__u32)(x)) ?     \
 140         __const_swahw32((x)) :                  \
 141         ___swahw32((x)))
 142
 143 /**
 144  * __swahb32 - return a high and low byte-swapped 32-bit value
 145  * @x: value to byteswap
 146  *
 147  * __swahb32(0x12345678) is 0x34127856
 148  */
 149 #define __swahb32(x)                            \
 150         (__builtin_constant_p((__u32)(x)) ?     \
 151         __const_swahb32((x)) :                  \
 152         ___swahb32((x)))
 153
 154 /**
 155  * __swab16p - return a byteswapped 16-bit value from a pointer
 156  * @p: pointer to a naturally-aligned 16-bit value
 157  */
 158 static inline __u16 __swab16p(const __u16 *p)
 159 {
 160 #ifdef __arch_swab16p
 161         return __arch_swab16p(p);
 162 #else
 163         return __swab16(*p);
 164 #endif
 165 }
 166
 167 /**
 168  * __swab32p - return a byteswapped 32-bit value from a pointer
 169  * @p: pointer to a naturally-aligned 32-bit value
 170  */
 171 static inline __u32 __swab32p(const __u32 *p)
 172 {
 173 #ifdef __arch_swab32p
 174         return __arch_swab32p(p);
 175 #else
 176         return __swab32(*p);
 177 #endif
 178 }
 179
 180 /**
 181  * __swab64p - return a byteswapped 64-bit value from a pointer
 182  * @p: pointer to a naturally-aligned 64-bit value
 183  */
 184 static inline __u64 __swab64p(const __u64 *p)
 185 {
 186 #ifdef __arch_swab64p
 187         return __arch_swab64p(p);
 188 #else
 189         return __swab64(*p);
 190 #endif
 191 }
 192
 193 /**
 194  * __swahw32p - return a wordswapped 32-bit value from a pointer
 195  * @p: pointer to a naturally-aligned 32-bit value
 196  *
 197  * See __swahw32() for details of wordswapping.
 198  */
 199 static inline __u32 __swahw32p(const __u32 *p)
 200 {
 201 #ifdef __arch_swahw32p
 202         return __arch_swahw32p(p);
 203 #else
 204         return __swahw32(*p);
 205 #endif
 206 }
 207
 208 /**
 209  * __swahb32p - return a high and low byteswapped 32-bit value from a pointer
 210  * @p: pointer to a naturally-aligned 32-bit value
 211  *
 212  * See __swahb32() for details of high/low byteswapping.
 213  */
 214 static inline __u32 __swahb32p(const __u32 *p)
 215 {
 216 #ifdef __arch_swahb32p
 217         return __arch_swahb32p(p);
 218 #else
 219         return __swahb32(*p);
 220 #endif
 221 }
 222
 223 /**
 224  * __swab16s - byteswap a 16-bit value in-place
 225  * @p: pointer to a naturally-aligned 16-bit value
 226  */
 227 static inline void __swab16s(__u16 *p)
 228 {
 229 #ifdef __arch_swab16s
 230         __arch_swab16s(p);
 231 #else
 232         *p = __swab16p(p);
 233 #endif
 234 }
 235 /**
 236  * __swab32s - byteswap a 32-bit value in-place
 237  * @p: pointer to a naturally-aligned 32-bit value
 238  */
 239 static inline void __swab32s(__u32 *p)
 240 {
 241 #ifdef __arch_swab32s
 242         __arch_swab32s(p);
 243 #else
 244         *p = __swab32p(p);
 245 #endif
 246 }
 247
 248 /**
 249  * __swab64s - byteswap a 64-bit value in-place
 250  * @p: pointer to a naturally-aligned 64-bit value
 251  */
 252 static inline void __swab64s(__u64 *p)
 253 {
 254 #ifdef __arch_swab64s
 255         __arch_swab64s(p);
 256 #else
 257         *p = __swab64p(p);
 258 #endif
 259 }
 260
 261 /**
 262  * __swahw32s - wordswap a 32-bit value in-place
 263  * @p: pointer to a naturally-aligned 32-bit value
 264  *
 265  * See __swahw32() for details of wordswapping
 266  */
 267 static inline void __swahw32s(__u32 *p)
 268 {
 269 #ifdef __arch_swahw32s
 270         __arch_swahw32s(p);
 271 #else
 272         *p = __swahw32p(p);
 273 #endif
 274 }
 275
 276 /**
 277  * __swahb32s - high and low byteswap a 32-bit value in-place
 278  * @p: pointer to a naturally-aligned 32-bit value
 279  *
 280  * See __swahb32() for details of high and low byte swapping
 281  */
 282 static inline void __swahb32s(__u32 *p)
 283 {
 284 #ifdef __arch_swahb32s
 285         __arch_swahb32s(p);
 286 #else
 287         *p = __swahb32p(p);
 288 #endif
 289 }
 290
 291 #ifdef __KERNEL__
 292 # define swab16 __swab16
 293 # define swab32 __swab32
 294 # define swab64 __swab64
 295 # define swahw32 __swahw32
 296 # define swahb32 __swahb32
 297 # define swab16p __swab16p
 298 # define swab32p __swab32p
 299 # define swab64p __swab64p
 300 # define swahw32p __swahw32p
 301 # define swahb32p __swahb32p
 302 # define swab16s __swab16s
 303 # define swab32s __swab32s
 304 # define swab64s __swab64s
 305 # define swahw32s __swahw32s
 306 # define swahb32s __swahb32s
 307 #endif /* __KERNEL__ */
 308
 309 #endif /* _LINUX_SWAB_H */