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   1 /*****************************************************************************
   2  * vlc_atomic.h:
   3  *****************************************************************************
   4  * Copyright (C) 2010 Rémi Denis-Courmont
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU Lesser General Public License as published by
   8  * the Free Software Foundation; either version 2.1 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  14  * GNU Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public License
  17  * along with this program; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  19  *****************************************************************************/
  20
  21 #ifndef VLC_ATOMIC_H
  22 # define VLC_ATOMIC_H
  23
  24 /**
  25  * \file
  26  * Atomic operations do not require locking, but they are not very powerful.
  27  */
  28
  29 # if !defined (__cplusplus) && (__STDC_VERSION__ >= 201112L) \
  30   && !defined (__STDC_NO_ATOMICS__)
  31
  32 /*** Native C11 atomics ***/
  33 #  include <stdatomic.h>
  34
  35 # else
  36
  37 #  define ATOMIC_FLAG_INIT false
  38
  39 #  define ATOMIC_VAR_INIT(value) (value)
  40
  41 #  define atomic_init(obj, value) \
  42     do { *(obj) = (value); } while(0)
  43
  44 #  define kill_dependency(y) \
  45     ((void)0)
  46
  47 #  define atomic_thread_fence(order) \
  48     __sync_synchronize()
  49
  50 #  define atomic_signal_fence(order) \
  51     ((void)0)
  52
  53 #  define atomic_is_lock_free(obj) \
  54     false
  55
  56 /* In principles, __sync_*() only supports int, long and long long and their
  57  * unsigned equivalents, i.e. 4-bytes and 8-bytes types, although GCC also
  58  * supports 1 and 2-bytes types. Some non-x86 architectures do not support
  59  * 8-byte atomic types (or not efficiently). */
  60 #  if defined (_MSC_VER)
  61 /* Some atomic operations of the Interlocked API are only
  62    available for desktop apps. Thus we define the atomic types to
  63    be at least 32 bits wide. */
  64 typedef      int_least32_t atomic_flag;
  65 typedef      int_least32_t atomic_bool;
  66 typedef      int_least32_t atomic_char;
  67 typedef      int_least32_t atomic_schar;
  68 typedef     uint_least32_t atomic_uchar;
  69 typedef      int_least32_t atomic_short;
  70 typedef     uint_least32_t atomic_ushort;
  71 #  else
  72 typedef          bool      atomic_flag;
  73 typedef          bool      atomic_bool;
  74 typedef          char      atomic_char;
  75 typedef   signed char      atomic_schar;
  76 typedef unsigned char      atomic_uchar;
  77 typedef          short     atomic_short;
  78 typedef unsigned short     atomic_ushort;
  79 #  endif
  80 typedef          int       atomic_int;
  81 typedef unsigned int       atomic_uint;
  82 typedef          long      atomic_long;
  83 typedef unsigned long      atomic_ulong;
  84 typedef          long long atomic_llong;
  85 typedef unsigned long long atomic_ullong;
  86 //typedef          char16_t  atomic_char16_t;
  87 //typedef          char32_t  atomic_char32_t;
  88 typedef          wchar_t   atomic_wchar_t;
  89 typedef       int_least8_t atomic_int_least8_t;
  90 typedef      uint_least8_t atomic_uint_least8_t;
  91 typedef      int_least16_t atomic_int_least16_t;
  92 typedef     uint_least16_t atomic_uint_least16_t;
  93 typedef      int_least32_t atomic_int_least32_t;
  94 typedef     uint_least32_t atomic_uint_least32_t;
  95 typedef      int_least64_t atomic_int_least64_t;
  96 typedef     uint_least64_t atomic_uint_least64_t;
  97 typedef       int_fast8_t atomic_int_fast8_t;
  98 typedef      uint_fast8_t atomic_uint_fast8_t;
  99 typedef      int_fast16_t atomic_int_fast16_t;
 100 typedef     uint_fast16_t atomic_uint_fast16_t;
 101 typedef      int_fast32_t atomic_int_fast32_t;
 102 typedef     uint_fast32_t atomic_uint_fast32_t;
 103 typedef      int_fast64_t atomic_int_fast64_t;
 104 typedef     uint_fast64_t atomic_uint_fast64_t;
 105 typedef          intptr_t atomic_intptr_t;
 106 typedef         uintptr_t atomic_uintptr_t;
 107 typedef            size_t atomic_size_t;
 108 typedef         ptrdiff_t atomic_ptrdiff_t;
 109 typedef          intmax_t atomic_intmax_t;
 110 typedef         uintmax_t atomic_uintmax_t;
 111
 112 # if defined (__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4) || (defined (__clang__) && (defined (__x86_64__) || defined (__i386__)))
 113
 114 /*** Intel/GCC atomics ***/
 115
 116 #  define atomic_store(object,desired) \
 117     do { \
 118         *(object) = (desired); \
 119         __sync_synchronize(); \
 120     } while (0)
 121
 122 #  define atomic_store_explicit(object,desired,order) \
 123     atomic_store(object,desired)
 124
 125 #  define atomic_load(object) \
 126     (__sync_synchronize(), *(object))
 127
 128 #  define atomic_load_explicit(object,order) \
 129     atomic_load(object)
 130
 131 #  define atomic_exchange(object,desired) \
 132 ({  \
 133     typeof (object) _obj = (object); \
 134     typeof (*object) _old; \
 135     do \
 136         _old = atomic_load(_obj); \
 137     while (!__sync_bool_compare_and_swap(_obj, _old, (desired))); \
 138     _old; \
 139 })
 140
 141 #  define atomic_exchange_explicit(object,desired,order) \
 142     atomic_exchange(object,desired)
 143
 144 #  define atomic_compare_exchange(object,expected,desired) \
 145 ({  \
 146     typeof (object) _exp = (expected); \
 147     typeof (*object) _old = *_exp; \
 148     *_exp = __sync_val_compare_and_swap((object), _old, (desired)); \
 149     *_exp == _old; \
 150 })
 151
 152 #  define atomic_compare_exchange_strong(object,expected,desired) \
 153     atomic_compare_exchange(object, expected, desired)
 154
 155 #  define atomic_compare_exchange_strong_explicit(object,expected,desired,order) \
 156     atomic_compare_exchange_strong(object, expected, desired)
 157
 158 #  define atomic_compare_exchange_weak(object,expected,desired) \
 159     atomic_compare_exchange(object, expected, desired)
 160
 161 #  define atomic_compare_exchange_weak_explicit(object,expected,desired,order) \
 162     atomic_compare_exchange_weak(object, expected, desired)
 163
 164 #  define atomic_fetch_add(object,operand) \
 165     __sync_fetch_and_add(object, operand)
 166
 167 #  define atomic_fetch_add_explicit(object,operand,order) \
 168     atomic_fetch_add(object,operand)
 169
 170 #  define atomic_fetch_sub(object,operand) \
 171     __sync_fetch_and_sub(object, operand)
 172
 173 #  define atomic_fetch_sub_explicit(object,operand,order) \
 174     atomic_fetch_sub(object,operand)
 175
 176 #  define atomic_fetch_or(object,operand) \
 177     __sync_fetch_and_or(object, operand)
 178
 179 #  define atomic_fetch_or_explicit(object,operand,order) \
 180     atomic_fetch_or(object,operand)
 181
 182 #  define atomic_fetch_xor(object,operand) \
 183     __sync_fetch_and_sub(object, operand)
 184
 185 #  define atomic_fetch_xor_explicit(object,operand,order) \
 186     atomic_fetch_sub(object,operand)
 187
 188 #  define atomic_fetch_and(object,operand) \
 189     __sync_fetch_and_and(object, operand)
 190
 191 #  define atomic_fetch_and_explicit(object,operand,order) \
 192     atomic_fetch_and(object,operand)
 193
 194 #  define atomic_flag_test_and_set(object) \
 195     atomic_exchange(object, true)
 196
 197 #  define atomic_flag_test_and_set_explicit(object,order) \
 198     atomic_flag_test_and_set(object)
 199
 200 #  define atomic_flag_clear(object) \
 201     atomic_store(object, false)
 202
 203 #  define atomic_flag_clear_explicit(object,order) \
 204     atomic_flag_clear(object)
 205
 206 # elif defined (__GNUC__)
 207
 208 /*** No atomics ***/
 209
 210 #  define atomic_store(object,desired) \
 211     do { \
 212         typeof (object) _obj = (object); \
 213         typeof (*object) _des = (desired); \
 214         vlc_global_lock(VLC_ATOMIC_MUTEX); \
 215         *_obj = _des; \
 216         vlc_global_unlock(VLC_ATOMIC_MUTEX); \
 217     } while (0)
 218 #  define atomic_store_explicit(object,desired,order) \
 219     atomic_store(object,desired)
 220
 221 #  define atomic_load(object) \
 222 ({ \
 223     typeof (object) _obj = (object); \
 224     typeof (*object) _old; \
 225     vlc_global_lock(VLC_ATOMIC_MUTEX); \
 226     _old = *_obj; \
 227     vlc_global_unlock(VLC_ATOMIC_MUTEX); \
 228     _old; \
 229 })
 230 #  define atomic_load_explicit(object,order) \
 231     atomic_load(object)
 232
 233 #  define atomic_exchange(object,desired) \
 234 ({ \
 235     typeof (object) _obj = (object); \
 236     typeof (*object) _des = (desired); \
 237     typeof (*object) _old; \
 238     vlc_global_lock(VLC_ATOMIC_MUTEX); \
 239     _old = *_obj; \
 240     *_obj = _des; \
 241     vlc_global_unlock(VLC_ATOMIC_MUTEX); \
 242     _old; \
 243 })
 244 #  define atomic_exchange_explicit(object,desired,order) \
 245     atomic_exchange(object,desired)
 246
 247 #  define atomic_compare_exchange_strong(object,expected,desired) \
 248 ({ \
 249     typeof (object) _obj = (object); \
 250     typeof (object) _exp = (expected); \
 251     typeof (*object) _des = (desired); \
 252     bool ret; \
 253     vlc_global_lock(VLC_ATOMIC_MUTEX); \
 254     ret = *_obj == *_exp; \
 255     if (ret) \
 256         *_obj = _des; \
 257     else \
 258         *_exp = *_obj; \
 259     vlc_global_unlock(VLC_ATOMIC_MUTEX); \
 260     ret; \
 261 })
 262 #  define atomic_compare_exchange_strong_explicit(object,expected,desired,order) \
 263     atomic_compare_exchange_strong(object, expected, desired)
 264 #  define atomic_compare_exchange_weak(object,expected,desired) \
 265     atomic_compare_exchange_strong(object, expected, desired)
 266 #  define atomic_compare_exchange_weak_explicit(object,expected,desired,order) \
 267     atomic_compare_exchange_weak(object, expected, desired)
 268
 269 #  define atomic_fetch_OP(object,desired,op) \
 270 ({ \
 271     typeof (object) _obj = (object); \
 272     typeof (*object) _des = (desired); \
 273     typeof (*object) _old; \
 274     vlc_global_lock(VLC_ATOMIC_MUTEX); \
 275     _old = *_obj; \
 276     *_obj = (*_obj) op (_des); \
 277     vlc_global_unlock(VLC_ATOMIC_MUTEX); \
 278     _old; \
 279 })
 280
 281 #  define atomic_fetch_add(object,operand) \
 282     atomic_fetch_OP(object,operand,+)
 283 #  define atomic_fetch_add_explicit(object,operand,order) \
 284     atomic_fetch_add(object,operand)
 285
 286 #  define atomic_fetch_sub(object,operand) \
 287     atomic_fetch_OP(object,operand,-)
 288 #  define atomic_fetch_sub_explicit(object,operand,order) \
 289     atomic_fetch_sub(object,operand)
 290
 291 #  define atomic_fetch_or(object,operand) \
 292     atomic_fetch_OP(object,operand,|)
 293 #  define atomic_fetch_or_explicit(object,operand,order) \
 294     atomic_fetch_or(object,operand)
 295
 296 #  define atomic_fetch_xor(object,operand) \
 297     atomic_fetch_OP(object,operand,^)
 298 #  define atomic_fetch_xor_explicit(object,operand,order) \
 299     atomic_fetch_sub(object,operand)
 300
 301 #  define atomic_fetch_and(object,operand) \
 302     atomic_fetch_OP(object,operand,&)
 303 #  define atomic_fetch_and_explicit(object,operand,order) \
 304     atomic_fetch_and(object,operand)
 305
 306 #  define atomic_flag_test_and_set(object) \
 307     atomic_exchange(object, true)
 308
 309 #  define atomic_flag_test_and_set_explicit(object,order) \
 310     atomic_flag_test_and_set(object)
 311
 312 #  define atomic_flag_clear(object) \
 313     atomic_store(object, false)
 314
 315 #  define atomic_flag_clear_explicit(object,order) \
 316     atomic_flag_clear(object)
 317
 318 # elif defined (_MSC_VER)
 319
 320 # include <windows.h>
 321
 322 /*** Use the Interlocked API. ***/
 323
 324 /* Define macros in order to dispatch to the correct function depending on the type.
 325    Several ranges are need because some operations are not implemented for all types. */
 326 #  define atomic_type_dispatch_32_64(operation, object, ...) \
 327     (sizeof(*object) == 4 ? operation((LONG *)object, __VA_ARGS__) : \
 328     sizeof(*object) == 8 ? operation##64((LONGLONG *)object, __VA_ARGS__) : \
 329     (abort(), 0))
 330
 331 #  define atomic_type_dispatch_16_64(operation, object, ...) \
 332     (sizeof(*object) == 2 ? operation##16((short *)object, __VA_ARGS__) : \
 333     atomic_type_dispatch_32_64(operation, object, __VA_ARGS__))
 334
 335 #  define atomic_type_dispatch_8_64(operation, object, ...) \
 336     (sizeof(*object) == 1 ? operation##8((char *)object, __VA_ARGS__) : \
 337     atomic_type_dispatch_16_64(operation, object, __VA_ARGS__))
 338
 339 #  define atomic_store(object,desired) \
 340     atomic_type_dispatch_16_64(InterlockedExchange, object, desired)
 341 #  define atomic_store_explicit(object,desired,order) \
 342     atomic_store(object, desired)
 343
 344 #  define atomic_load(object) \
 345     atomic_type_dispatch_16_64(InterlockedCompareExchange, object, 0, 0)
 346 #  define atomic_load_explicit(object,order) \
 347     atomic_load(object)
 348
 349 #  define atomic_exchange(object,desired) \
 350     atomic_type_dispatch_16_64(InterlockedExchange, object, desired)
 351 #  define atomic_exchange_explicit(object,desired,order) \
 352     atomic_exchange(object, desired)
 353
 354 #  define atomic_compare_exchange_strong(object,expected,desired) \
 355     atomic_type_dispatch_16_64(InterlockedCompareExchange, object, *expected, desired) == *expected
 356 #  define atomic_compare_exchange_strong_explicit(object,expected,desired,order) \
 357     atomic_compare_exchange_strong(object, expected, desired)
 358 #  define atomic_compare_exchange_weak(object,expected,desired) \
 359     atomic_compare_exchange_strong(object, expected, desired)
 360 #  define atomic_compare_exchange_weak_explicit(object,expected,desired,order) \
 361     atomic_compare_exchange_weak(object, expected, desired)
 362
 363 #  define atomic_fetch_add(object,operand) \
 364     atomic_type_dispatch_32_64(InterlockedExchangeAdd, object, operand)
 365 #  define atomic_fetch_add_explicit(object,operand,order) \
 366     atomic_fetch_add(object, operand)
 367
 368 #  define atomic_fetch_sub(object,operand) \
 369     atomic_type_dispatch_32_64(InterlockedExchangeAdd, object, -(LONGLONG)operand)
 370 #  define atomic_fetch_sub_explicit(object,operand,order) \
 371     atomic_fetch_sub(object, operand)
 372
 373 #  define atomic_fetch_or(object,operand) \
 374     atomic_type_dispatch_8_64(InterlockedOr, object, operand)
 375 #  define atomic_fetch_or_explicit(object,operand,order) \
 376     atomic_fetch_or(object, operand)
 377
 378 #  define atomic_fetch_xor(object,operand) \
 379     atomic_type_dispatch_8_64(InterlockedXor, object, operand)
 380 #  define atomic_fetch_xor_explicit(object,operand,order) \
 381     atomic_fetch_sub(object, operand)
 382
 383 #  define atomic_fetch_and(object,operand) \
 384     atomic_type_dispatch_8_64(InterlockedAnd, object, operand)
 385 #  define atomic_fetch_and_explicit(object,operand,order) \
 386     atomic_fetch_and(object, operand)
 387
 388 #  define atomic_flag_test_and_set(object) \
 389     atomic_exchange(object, true)
 390
 391 #  define atomic_flag_test_and_set_explicit(object,order) \
 392     atomic_flag_test_and_set(object)
 393
 394 #  define atomic_flag_clear(object) \
 395     atomic_store(object, false)
 396
 397 #  define atomic_flag_clear_explicit(object,order) \
 398     atomic_flag_clear(object)
 399
 400 # else
 401 #  error FIXME: implement atomic operations for this compiler.
 402 # endif
 403 # endif
 404
 405 typedef atomic_uint_least32_t vlc_atomic_float;
 406
 407 static inline void vlc_atomic_init_float(vlc_atomic_float *var, float f)
 408 {
 409     union { float f; uint32_t i; } u;
 410     u.f = f;
 411     atomic_init(var, u.i);
 412 }
 413
 414 /** Helper to retrieve a single precision from an atom. */
 415 static inline float vlc_atomic_load_float(vlc_atomic_float *atom)
 416 {
 417     union { float f; uint32_t i; } u;
 418     u.i = atomic_load(atom);
 419     return u.f;
 420 }
 421
 422 /** Helper to store a single precision into an atom. */
 423 static inline void vlc_atomic_store_float(vlc_atomic_float *atom, float f)
 424 {
 425     union { float f; uint32_t i; } u;
 426     u.f = f;
 427     atomic_store(atom, u.i);
 428 }
 429
 430 #endif