include/babeltrace/bitfield.h

   1 #ifndef _BABELTRACE_BITFIELD_H
   2 #define _BABELTRACE_BITFIELD_H
   3
   4 /*
   5  * BabelTrace
   6  *
   7  * Bitfields read/write functions.
   8  *
   9  * Copyright 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  10  *
  11  * Permission is hereby granted, free of charge, to any person obtaining a copy
  12  * of this software and associated documentation files (the "Software"), to deal
  13  * in the Software without restriction, including without limitation the rights
  14  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  15  * copies of the Software, and to permit persons to whom the Software is
  16  * furnished to do so, subject to the following conditions:
  17  *
  18  * The above copyright notice and this permission notice shall be included in
  19  * all copies or substantial portions of the Software.
  20  *
  21  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  22  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  23  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  24  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  25  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  26  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  27  * SOFTWARE.
  28  */
  29
  30 #include <stdint.h>     /* C99 5.2.4.2 Numerical limits */
  31 #include <limits.h>     /* C99 5.2.4.2 Numerical limits */
  32 #include <assert.h>
  33 #include <babeltrace/endian.h>  /* Non-standard BIG_ENDIAN, LITTLE_ENDIAN, BYTE_ORDER */
  34
  35 /* We can't shift a int from 32 bit, >> 32 and << 32 on int is undefined */
  36 #define _bt_piecewise_rshift(_v, _shift)                                \
  37 ({                                                                      \
  38         typeof(_v) ___v = (_v);                                         \
  39         typeof(_shift) ___shift = (_shift);                             \
  40         unsigned long sb = (___shift) / (sizeof(___v) * CHAR_BIT - 1);  \
  41         unsigned long final = (___shift) % (sizeof(___v) * CHAR_BIT - 1); \
  42                                                                         \
  43         for (; sb; sb--)                                                \
  44                 ___v >>= sizeof(___v) * CHAR_BIT - 1;                   \
  45         ___v >>= final;                                                 \
  46 })
  47
  48 #define _bt_piecewise_lshift(_v, _shift)                                \
  49 ({                                                                      \
  50         typeof(_v) ___v = (_v);                                         \
  51         typeof(_shift) ___shift = (_shift);                             \
  52         unsigned long sb = (___shift) / (sizeof(___v) * CHAR_BIT - 1);  \
  53         unsigned long final = (___shift) % (sizeof(___v) * CHAR_BIT - 1); \
  54                                                                         \
  55         for (; sb; sb--)                                                \
  56                 ___v <<= sizeof(___v) * CHAR_BIT - 1;                   \
  57         ___v <<= final;                                                 \
  58 })
  59
  60 #define _bt_is_signed_type(type)        ((type) -1 < (type) 0)
  61
  62 #define _bt_unsigned_cast(type, v)                                      \
  63 ({                                                                      \
  64         (sizeof(v) < sizeof(type)) ?                                    \
  65                 ((type) (v)) & (~(~(type) 0 << (sizeof(v) * CHAR_BIT))) : \
  66                 (type) (v);                                             \
  67 })
  68
  69 /*
  70  * bt_bitfield_write - write integer to a bitfield in native endianness
  71  *
  72  * Save integer to the bitfield, which starts at the "start" bit, has "len"
  73  * bits.
  74  * The inside of a bitfield is from high bits to low bits.
  75  * Uses native endianness.
  76  * For unsigned "v", pad MSB with 0 if bitfield is larger than v.
  77  * For signed "v", sign-extend v if bitfield is larger than v.
  78  *
  79  * On little endian, bytes are placed from the less significant to the most
  80  * significant. Also, consecutive bitfields are placed from lower bits to higher
  81  * bits.
  82  *
  83  * On big endian, bytes are places from most significant to less significant.
  84  * Also, consecutive bitfields are placed from higher to lower bits.
  85  */
  86
  87 #define _bt_bitfield_write_le(_ptr, type, _start, _length, _v)          \
  88 do {                                                                    \
  89         typeof(_v) __v = (_v);                                          \
  90         type *__ptr = (void *) (_ptr);                                  \
  91         unsigned long __start = (_start), __length = (_length);         \
  92         type mask, cmask;                                               \
  93         unsigned long ts = sizeof(type) * CHAR_BIT; /* type size */     \
  94         unsigned long start_unit, end_unit, this_unit;                  \
  95         unsigned long end, cshift; /* cshift is "complement shift" */   \
  96                                                                         \
  97         if (!__length)                                                  \
  98                 break;                                                  \
  99                                                                         \
 100         end = __start + __length;                                       \
 101         start_unit = __start / ts;                                      \
 102         end_unit = (end + (ts - 1)) / ts;                               \
 103                                                                         \
 104         /* Trim v high bits */                                          \
 105         if (__length < sizeof(__v) * CHAR_BIT)                          \
 106                 __v &= ~((~(typeof(__v)) 0) << __length);               \
 107                                                                         \
 108         /* We can now append v with a simple "or", shift it piece-wise */ \
 109         this_unit = start_unit;                                         \
 110         if (start_unit == end_unit - 1) {                               \
 111                 mask = ~((~(type) 0) << (__start % ts));                \
 112                 if (end % ts)                                           \
 113                         mask |= (~(type) 0) << (end % ts);              \
 114                 cmask = (type) __v << (__start % ts);                   \
 115                 cmask &= ~mask;                                         \
 116                 __ptr[this_unit] &= mask;                               \
 117                 __ptr[this_unit] |= cmask;                              \
 118                 break;                                                  \
 119         }                                                               \
 120         if (__start % ts) {                                             \
 121                 cshift = __start % ts;                                  \
 122                 mask = ~((~(type) 0) << cshift);                        \
 123                 cmask = (type) __v << cshift;                           \
 124                 cmask &= ~mask;                                         \
 125                 __ptr[this_unit] &= mask;                               \
 126                 __ptr[this_unit] |= cmask;                              \
 127                 __v = _bt_piecewise_rshift(__v, ts - cshift);           \
 128                 __start += ts - cshift;                                 \
 129                 this_unit++;                                            \
 130         }                                                               \
 131         for (; this_unit < end_unit - 1; this_unit++) {                 \
 132                 __ptr[this_unit] = (type) __v;                          \
 133                 __v = _bt_piecewise_rshift(__v, ts);                    \
 134                 __start += ts;                                          \
 135         }                                                               \
 136         if (end % ts) {                                                 \
 137                 mask = (~(type) 0) << (end % ts);                       \
 138                 cmask = (type) __v;                                     \
 139                 cmask &= ~mask;                                         \
 140                 __ptr[this_unit] &= mask;                               \
 141                 __ptr[this_unit] |= cmask;                              \
 142         } else                                                          \
 143                 __ptr[this_unit] = (type) __v;                          \
 144 } while (0)
 145
 146 #define _bt_bitfield_write_be(_ptr, type, _start, _length, _v)          \
 147 do {                                                                    \
 148         typeof(_v) __v = (_v);                                          \
 149         type *__ptr = (void *) (_ptr);                                  \
 150         unsigned long __start = (_start), __length = (_length);         \
 151         type mask, cmask;                                               \
 152         unsigned long ts = sizeof(type) * CHAR_BIT; /* type size */     \
 153         unsigned long start_unit, end_unit, this_unit;                  \
 154         unsigned long end, cshift; /* cshift is "complement shift" */   \
 155                                                                         \
 156         if (!__length)                                                  \
 157                 break;                                                  \
 158                                                                         \
 159         end = __start + __length;                                       \
 160         start_unit = __start / ts;                                      \
 161         end_unit = (end + (ts - 1)) / ts;                               \
 162                                                                         \
 163         /* Trim v high bits */                                          \
 164         if (__length < sizeof(__v) * CHAR_BIT)                          \
 165                 __v &= ~((~(typeof(__v)) 0) << __length);               \
 166                                                                         \
 167         /* We can now append v with a simple "or", shift it piece-wise */ \
 168         this_unit = end_unit - 1;                                       \
 169         if (start_unit == end_unit - 1) {                               \
 170                 mask = ~((~(type) 0) << ((ts - (end % ts)) % ts));      \
 171                 if (__start % ts)                                       \
 172                         mask |= (~((type) 0)) << (ts - (__start % ts)); \
 173                 cmask = (type) __v << ((ts - (end % ts)) % ts);         \
 174                 cmask &= ~mask;                                         \
 175                 __ptr[this_unit] &= mask;                               \
 176                 __ptr[this_unit] |= cmask;                              \
 177                 break;                                                  \
 178         }                                                               \
 179         if (end % ts) {                                                 \
 180                 cshift = end % ts;                                      \
 181                 mask = ~((~(type) 0) << (ts - cshift));                 \
 182                 cmask = (type) __v << (ts - cshift);                    \
 183                 cmask &= ~mask;                                         \
 184                 __ptr[this_unit] &= mask;                               \
 185                 __ptr[this_unit] |= cmask;                              \
 186                 __v = _bt_piecewise_rshift(__v, cshift);                \
 187                 end -= cshift;                                          \
 188                 this_unit--;                                            \
 189         }                                                               \
 190         for (; (long) this_unit >= (long) start_unit + 1; this_unit--) { \
 191                 __ptr[this_unit] = (type) __v;                          \
 192                 __v = _bt_piecewise_rshift(__v, ts);                    \
 193                 end -= ts;                                              \
 194         }                                                               \
 195         if (__start % ts) {                                             \
 196                 mask = (~(type) 0) << (ts - (__start % ts));            \
 197                 cmask = (type) __v;                                     \
 198                 cmask &= ~mask;                                         \
 199                 __ptr[this_unit] &= mask;                               \
 200                 __ptr[this_unit] |= cmask;                              \
 201         } else                                                          \
 202                 __ptr[this_unit] = (type) __v;                          \
 203 } while (0)
 204
 205 /*
 206  * bt_bitfield_write - write integer to a bitfield in native endianness
 207  * bt_bitfield_write_le - write integer to a bitfield in little endian
 208  * bt_bitfield_write_be - write integer to a bitfield in big endian
 209  */
 210
 211 #if (BYTE_ORDER == LITTLE_ENDIAN)
 212
 213 #define bt_bitfield_write(ptr, type, _start, _length, _v)               \
 214         _bt_bitfield_write_le(ptr, type, _start, _length, _v)
 215
 216 #define bt_bitfield_write_le(ptr, type, _start, _length, _v)            \
 217         _bt_bitfield_write_le(ptr, type, _start, _length, _v)
 218
 219 #define bt_bitfield_write_be(ptr, type, _start, _length, _v)            \
 220         _bt_bitfield_write_be(ptr, unsigned char, _start, _length, _v)
 221
 222 #elif (BYTE_ORDER == BIG_ENDIAN)
 223
 224 #define bt_bitfield_write(ptr, type, _start, _length, _v)               \
 225         _bt_bitfield_write_be(ptr, type, _start, _length, _v)
 226
 227 #define bt_bitfield_write_le(ptr, type, _start, _length, _v)            \
 228         _bt_bitfield_write_le(ptr, unsigned char, _start, _length, _v)
 229
 230 #define bt_bitfield_write_be(ptr, type, _start, _length, _v)            \
 231         _bt_bitfield_write_be(ptr, type, _start, _length, _v)
 232
 233 #else /* (BYTE_ORDER == PDP_ENDIAN) */
 234
 235 #error "Byte order not supported"
 236
 237 #endif
 238
 239 #define _bt_bitfield_read_le(_ptr, type, _start, _length, _vptr)        \
 240 do {                                                                    \
 241         typeof(*(_vptr)) *__vptr = (_vptr);                             \
 242         typeof(*__vptr) __v;                                            \
 243         type *__ptr = (void *) (_ptr);                                  \
 244         unsigned long __start = (_start), __length = (_length);         \
 245         type mask, cmask;                                               \
 246         unsigned long ts = sizeof(type) * CHAR_BIT; /* type size */     \
 247         unsigned long start_unit, end_unit, this_unit;                  \
 248         unsigned long end, cshift; /* cshift is "complement shift" */   \
 249                                                                         \
 250         if (!__length) {                                                \
 251                 *__vptr = 0;                                            \
 252                 break;                                                  \
 253         }                                                               \
 254                                                                         \
 255         end = __start + __length;                                       \
 256         start_unit = __start / ts;                                      \
 257         end_unit = (end + (ts - 1)) / ts;                               \
 258                                                                         \
 259         this_unit = end_unit - 1;                                       \
 260         if (_bt_is_signed_type(typeof(__v))                             \
 261             && (__ptr[this_unit] & ((type) 1 << ((end % ts ? : ts) - 1)))) \
 262                 __v = ~(typeof(__v)) 0;                                 \
 263         else                                                            \
 264                 __v = 0;                                                \
 265         if (start_unit == end_unit - 1) {                               \
 266                 cmask = __ptr[this_unit];                               \
 267                 cmask >>= (__start % ts);                               \
 268                 if ((end - __start) % ts) {                             \
 269                         mask = ~((~(type) 0) << (end - __start));       \
 270                         cmask &= mask;                                  \
 271                 }                                                       \
 272                 __v = _bt_piecewise_lshift(__v, end - __start);         \
 273                 __v |= _bt_unsigned_cast(typeof(__v), cmask);           \
 274                 *__vptr = __v;                                          \
 275                 break;                                                  \
 276         }                                                               \
 277         if (end % ts) {                                                 \
 278                 cshift = end % ts;                                      \
 279                 mask = ~((~(type) 0) << cshift);                        \
 280                 cmask = __ptr[this_unit];                               \
 281                 cmask &= mask;                                          \
 282                 __v = _bt_piecewise_lshift(__v, cshift);                \
 283                 __v |= _bt_unsigned_cast(typeof(__v), cmask);           \
 284                 end -= cshift;                                          \
 285                 this_unit--;                                            \
 286         }                                                               \
 287         for (; (long) this_unit >= (long) start_unit + 1; this_unit--) { \
 288                 __v = _bt_piecewise_lshift(__v, ts);                    \
 289                 __v |= _bt_unsigned_cast(typeof(__v), __ptr[this_unit]);\
 290                 end -= ts;                                              \
 291         }                                                               \
 292         if (__start % ts) {                                             \
 293                 mask = ~((~(type) 0) << (ts - (__start % ts)));         \
 294                 cmask = __ptr[this_unit];                               \
 295                 cmask >>= (__start % ts);                               \
 296                 cmask &= mask;                                          \
 297                 __v = _bt_piecewise_lshift(__v, ts - (__start % ts));   \
 298                 __v |= _bt_unsigned_cast(typeof(__v), cmask);           \
 299         } else {                                                        \
 300                 __v = _bt_piecewise_lshift(__v, ts);                    \
 301                 __v |= _bt_unsigned_cast(typeof(__v), __ptr[this_unit]);\
 302         }                                                               \
 303         *__vptr = __v;                                                  \
 304 } while (0)
 305
 306 #define _bt_bitfield_read_be(_ptr, type, _start, _length, _vptr)        \
 307 do {                                                                    \
 308         typeof(*(_vptr)) *__vptr = (_vptr);                             \
 309         typeof(*__vptr) __v;                                            \
 310         type *__ptr = (void *) (_ptr);                                  \
 311         unsigned long __start = (_start), __length = (_length);         \
 312         type mask, cmask;                                               \
 313         unsigned long ts = sizeof(type) * CHAR_BIT; /* type size */     \
 314         unsigned long start_unit, end_unit, this_unit;                  \
 315         unsigned long end, cshift; /* cshift is "complement shift" */   \
 316                                                                         \
 317         if (!__length) {                                                \
 318                 *__vptr = 0;                                            \
 319                 break;                                                  \
 320         }                                                               \
 321                                                                         \
 322         end = __start + __length;                                       \
 323         start_unit = __start / ts;                                      \
 324         end_unit = (end + (ts - 1)) / ts;                               \
 325                                                                         \
 326         this_unit = start_unit;                                         \
 327         if (_bt_is_signed_type(typeof(__v))                             \
 328             && (__ptr[this_unit] & ((type) 1 << (ts - (__start % ts) - 1)))) \
 329                 __v = ~(typeof(__v)) 0;                                 \
 330         else                                                            \
 331                 __v = 0;                                                \
 332         if (start_unit == end_unit - 1) {                               \
 333                 cmask = __ptr[this_unit];                               \
 334                 cmask >>= (ts - (end % ts)) % ts;                       \
 335                 if ((end - __start) % ts) {                             \
 336                         mask = ~((~(type) 0) << (end - __start));       \
 337                         cmask &= mask;                                  \
 338                 }                                                       \
 339                 __v = _bt_piecewise_lshift(__v, end - __start);         \
 340                 __v |= _bt_unsigned_cast(typeof(__v), cmask);           \
 341                 *__vptr = __v;                                          \
 342                 break;                                                  \
 343         }                                                               \
 344         if (__start % ts) {                                             \
 345                 cshift = __start % ts;                                  \
 346                 mask = ~((~(type) 0) << (ts - cshift));                 \
 347                 cmask = __ptr[this_unit];                               \
 348                 cmask &= mask;                                          \
 349                 __v = _bt_piecewise_lshift(__v, ts - cshift);           \
 350                 __v |= _bt_unsigned_cast(typeof(__v), cmask);           \
 351                 __start += ts - cshift;                                 \
 352                 this_unit++;                                            \
 353         }                                                               \
 354         for (; this_unit < end_unit - 1; this_unit++) {                 \
 355                 __v = _bt_piecewise_lshift(__v, ts);                    \
 356                 __v |= _bt_unsigned_cast(typeof(__v), __ptr[this_unit]);\
 357                 __start += ts;                                          \
 358         }                                                               \
 359         if (end % ts) {                                                 \
 360                 mask = ~((~(type) 0) << (end % ts));                    \
 361                 cmask = __ptr[this_unit];                               \
 362                 cmask >>= ts - (end % ts);                              \
 363                 cmask &= mask;                                          \
 364                 __v = _bt_piecewise_lshift(__v, end % ts);              \
 365                 __v |= _bt_unsigned_cast(typeof(__v), cmask);           \
 366         } else {                                                        \
 367                 __v = _bt_piecewise_lshift(__v, ts);                    \
 368                 __v |= _bt_unsigned_cast(typeof(__v), __ptr[this_unit]);\
 369         }                                                               \
 370         *__vptr = __v;                                                  \
 371 } while (0)
 372
 373 /*
 374  * bt_bitfield_read - read integer from a bitfield in native endianness
 375  * bt_bitfield_read_le - read integer from a bitfield in little endian
 376  * bt_bitfield_read_be - read integer from a bitfield in big endian
 377  */
 378
 379 #if (BYTE_ORDER == LITTLE_ENDIAN)
 380
 381 #define bt_bitfield_read(_ptr, type, _start, _length, _vptr)            \
 382         _bt_bitfield_read_le(_ptr, type, _start, _length, _vptr)
 383
 384 #define bt_bitfield_read_le(_ptr, type, _start, _length, _vptr)         \
 385         _bt_bitfield_read_le(_ptr, type, _start, _length, _vptr)
 386
 387 #define bt_bitfield_read_be(_ptr, type, _start, _length, _vptr)         \
 388         _bt_bitfield_read_be(_ptr, unsigned char, _start, _length, _vptr)
 389
 390 #elif (BYTE_ORDER == BIG_ENDIAN)
 391
 392 #define bt_bitfield_read(_ptr, type, _start, _length, _vptr)            \
 393         _bt_bitfield_read_be(_ptr, type, _start, _length, _vptr)
 394
 395 #define bt_bitfield_read_le(_ptr, type, _start, _length, _vptr)         \
 396         _bt_bitfield_read_le(_ptr, unsigned char, _start, _length, _vptr)
 397
 398 #define bt_bitfield_read_be(_ptr, type, _start, _length, _vptr)         \
 399         _bt_bitfield_read_be(_ptr, type, _start, _length, _vptr)
 400
 401 #else /* (BYTE_ORDER == PDP_ENDIAN) */
 402
 403 #error "Byte order not supported"
 404
 405 #endif
 406
 407 #endif /* _BABELTRACE_BITFIELD_H */