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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 typedef          bool      atomic_flag;
  61 typedef          bool      atomic_bool;
  62 typedef          char      atomic_char;
  63 typedef   signed char      atomic_schar;
  64 typedef unsigned char      atomic_uchar;
  65 typedef          short     atomic_short;
  66 typedef unsigned short     atomic_ushort;
  67 typedef          int       atomic_int;
  68 typedef unsigned int       atomic_uint;
  69 typedef          long      atomic_long;
  70 typedef unsigned long      atomic_ulong;
  71 typedef          long long atomic_llong;
  72 typedef unsigned long long atomic_ullong;
  73 //typedef          char16_t  atomic_char16_t;
  74 //typedef          char32_t  atomic_char32_t;
  75 typedef          wchar_t   atomic_wchar_t;
  76 typedef       int_least8_t atomic_int_least8_t;
  77 typedef      uint_least8_t atomic_uint_least8_t;
  78 typedef      int_least16_t atomic_int_least16_t;
  79 typedef     uint_least16_t atomic_uint_least16_t;
  80 typedef      int_least32_t atomic_int_least32_t;
  81 typedef     uint_least32_t atomic_uint_least32_t;
  82 typedef      int_least64_t atomic_int_least64_t;
  83 typedef     uint_least64_t atomic_uint_least64_t;
  84 typedef       int_fast8_t atomic_int_fast8_t;
  85 typedef      uint_fast8_t atomic_uint_fast8_t;
  86 typedef      int_fast16_t atomic_int_fast16_t;
  87 typedef     uint_fast16_t atomic_uint_fast16_t;
  88 typedef      int_fast32_t atomic_int_fast32_t;
  89 typedef     uint_fast32_t atomic_uint_fast32_t;
  90 typedef      int_fast64_t atomic_int_fast64_t;
  91 typedef     uint_fast64_t atomic_uint_fast64_t;
  92 typedef          intptr_t atomic_intptr_t;
  93 typedef         uintptr_t atomic_uintptr_t;
  94 typedef            size_t atomic_size_t;
  95 typedef         ptrdiff_t atomic_ptrdiff_t;
  96 typedef          intmax_t atomic_intmax_t;
  97 typedef         uintmax_t atomic_uintmax_t;
  98
  99 # if defined (__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4) || (defined (__clang__) && (defined (__x86_64__) || defined (__i386__)))
 100
 101 /*** Intel/GCC atomics ***/
 102
 103 #  define atomic_store(object,desired) \
 104     do { \
 105         *(object) = (desired); \
 106         __sync_synchronize(); \
 107     } while (0)
 108
 109 #  define atomic_store_explicit(object,desired,order) \
 110     atomic_store(object,desired)
 111
 112 #  define atomic_load(object) \
 113     (__sync_synchronize(), *(object))
 114
 115 #  define atomic_load_explicit(object,order) \
 116     atomic_load(object)
 117
 118 #  define atomic_exchange(object,desired) \
 119 ({  \
 120     typeof (object) _obj = (object); \
 121     typeof (*object) _old; \
 122     do \
 123         _old = atomic_load(_obj); \
 124     while (!__sync_bool_compare_and_swap(_obj, _old, (desired))); \
 125     _old; \
 126 })
 127
 128 #  define atomic_exchange_explicit(object,desired,order) \
 129     atomic_exchange(object,desired)
 130
 131 #  define atomic_compare_exchange(object,expected,desired) \
 132 ({  \
 133     typeof (object) _exp = (expected); \
 134     typeof (*object) _old = *_exp; \
 135     *_exp = __sync_val_compare_and_swap((object), _old, (desired)); \
 136     *_exp == _old; \
 137 })
 138
 139 #  define atomic_compare_exchange_strong(object,expected,desired) \
 140     atomic_compare_exchange(object, expected, desired)
 141
 142 #  define atomic_compare_exchange_strong_explicit(object,expected,desired,order) \
 143     atomic_compare_exchange_strong(object, expected, desired)
 144
 145 #  define atomic_compare_exchange_weak(object,expected,desired) \
 146     atomic_compare_exchange(object, expected, desired)
 147
 148 #  define atomic_compare_exchange_weak_explicit(object,expected,desired,order) \
 149     atomic_compare_exchange_weak(object, expected, desired)
 150
 151 #  define atomic_fetch_add(object,operand) \
 152     __sync_fetch_and_add(object, operand)
 153
 154 #  define atomic_fetch_add_explicit(object,operand,order) \
 155     atomic_fetch_add(object,operand)
 156
 157 #  define atomic_fetch_sub(object,operand) \
 158     __sync_fetch_and_sub(object, operand)
 159
 160 #  define atomic_fetch_sub_explicit(object,operand,order) \
 161     atomic_fetch_sub(object,operand)
 162
 163 #  define atomic_fetch_or(object,operand) \
 164     __sync_fetch_and_or(object, operand)
 165
 166 #  define atomic_fetch_or_explicit(object,operand,order) \
 167     atomic_fetch_or(object,operand)
 168
 169 #  define atomic_fetch_xor(object,operand) \
 170     __sync_fetch_and_sub(object, operand)
 171
 172 #  define atomic_fetch_xor_explicit(object,operand,order) \
 173     atomic_fetch_sub(object,operand)
 174
 175 #  define atomic_fetch_and(object,operand) \
 176     __sync_fetch_and_and(object, operand)
 177
 178 #  define atomic_fetch_and_explicit(object,operand,order) \
 179     atomic_fetch_and(object,operand)
 180
 181 #  define atomic_flag_test_and_set(object) \
 182     atomic_exchange(object, true)
 183
 184 #  define atomic_flag_test_and_set_explicit(object,order) \
 185     atomic_flag_test_and_set(object)
 186
 187 #  define atomic_flag_clear(object) \
 188     atomic_store(object, false)
 189
 190 #  define atomic_flag_clear_explicit(object,order) \
 191     atomic_flag_clear(object)
 192
 193 # elif defined (__GNUC__)
 194
 195 /*** No atomics ***/
 196
 197 #  define atomic_store(object,desired) \
 198     do { \
 199         typeof (object) _obj = (object); \
 200         typeof (*object) _des = (desired); \
 201         vlc_global_lock(VLC_ATOMIC_MUTEX); \
 202         *_obj = _des; \
 203         vlc_global_unlock(VLC_ATOMIC_MUTEX); \
 204     } while (0)
 205 #  define atomic_store_explicit(object,desired,order) \
 206     atomic_store(object,desired)
 207
 208 #  define atomic_load(object) \
 209 ({ \
 210     typeof (object) _obj = (object); \
 211     typeof (*object) _old; \
 212     vlc_global_lock(VLC_ATOMIC_MUTEX); \
 213     _old = *_obj; \
 214     vlc_global_unlock(VLC_ATOMIC_MUTEX); \
 215     _old; \
 216 })
 217 #  define atomic_load_explicit(object,order) \
 218     atomic_load(object)
 219
 220 #  define atomic_exchange(object,desired) \
 221 ({ \
 222     typeof (object) _obj = (object); \
 223     typeof (*object) _des = (desired); \
 224     typeof (*object) _old; \
 225     vlc_global_lock(VLC_ATOMIC_MUTEX); \
 226     _old = *_obj; \
 227     *_obj = _des; \
 228     vlc_global_unlock(VLC_ATOMIC_MUTEX); \
 229     _old; \
 230 })
 231 #  define atomic_exchange_explicit(object,desired,order) \
 232     atomic_exchange(object,desired)
 233
 234 #  define atomic_compare_exchange_strong(object,expected,desired) \
 235 ({ \
 236     typeof (object) _obj = (object); \
 237     typeof (object) _exp = (expected); \
 238     typeof (*object) _des = (desired); \
 239     bool ret; \
 240     vlc_global_lock(VLC_ATOMIC_MUTEX); \
 241     ret = *_obj == *_exp; \
 242     if (ret) \
 243         *_obj = _des; \
 244     else \
 245         *_exp = *_obj; \
 246     vlc_global_unlock(VLC_ATOMIC_MUTEX); \
 247     ret; \
 248 })
 249 #  define atomic_compare_exchange_strong_explicit(object,expected,desired,order) \
 250     atomic_compare_exchange_strong(object, expected, desired)
 251 #  define atomic_compare_exchange_weak(object,expected,desired) \
 252     atomic_compare_exchange_strong(object, expected, desired)
 253 #  define atomic_compare_exchange_weak_explicit(object,expected,desired,order) \
 254     atomic_compare_exchange_weak(object, expected, desired)
 255
 256 #  define atomic_fetch_OP(object,desired,op) \
 257 ({ \
 258     typeof (object) _obj = (object); \
 259     typeof (*object) _des = (desired); \
 260     typeof (*object) _old; \
 261     vlc_global_lock(VLC_ATOMIC_MUTEX); \
 262     _old = *_obj; \
 263     *_obj = (*_obj) op (_des); \
 264     vlc_global_unlock(VLC_ATOMIC_MUTEX); \
 265     _old; \
 266 })
 267
 268 #  define atomic_fetch_add(object,operand) \
 269     atomic_fetch_OP(object,operand,+)
 270 #  define atomic_fetch_add_explicit(object,operand,order) \
 271     atomic_fetch_add(object,operand)
 272
 273 #  define atomic_fetch_sub(object,operand) \
 274     atomic_fetch_OP(object,operand,-)
 275 #  define atomic_fetch_sub_explicit(object,operand,order) \
 276     atomic_fetch_sub(object,operand)
 277
 278 #  define atomic_fetch_or(object,operand) \
 279     atomic_fetch_OP(object,operand,|)
 280 #  define atomic_fetch_or_explicit(object,operand,order) \
 281     atomic_fetch_or(object,operand)
 282
 283 #  define atomic_fetch_xor(object,operand) \
 284     atomic_fetch_OP(object,operand,^)
 285 #  define atomic_fetch_xor_explicit(object,operand,order) \
 286     atomic_fetch_sub(object,operand)
 287
 288 #  define atomic_fetch_and(object,operand) \
 289     atomic_fetch_OP(object,operand,&)
 290 #  define atomic_fetch_and_explicit(object,operand,order) \
 291     atomic_fetch_and(object,operand)
 292
 293 #  define atomic_flag_test_and_set(object) \
 294     atomic_exchange(object, true)
 295
 296 #  define atomic_flag_test_and_set_explicit(object,order) \
 297     atomic_flag_test_and_set(object)
 298
 299 #  define atomic_flag_clear(object) \
 300     atomic_store(object, false)
 301
 302 #  define atomic_flag_clear_explicit(object,order) \
 303     atomic_flag_clear(object)
 304
 305 # else
 306 #  error FIXME: implement atomic operations for this compiler.
 307 # endif
 308 # endif
 309
 310 /**
 311  * Memory storage space for an atom. Never access it directly.
 312  */
 313 typedef union
 314 {
 315     atomic_uintptr_t u;
 316 } vlc_atomic_t;
 317
 318 /** Static initializer for \ref vlc_atomic_t */
 319 # define VLC_ATOMIC_INIT(val) { (val) }
 320
 321 /* All functions return the atom value _after_ the operation. */
 322 static inline uintptr_t vlc_atomic_get(vlc_atomic_t *atom)
 323 {
 324     return atomic_load(&atom->u);
 325 }
 326
 327 static inline uintptr_t vlc_atomic_set(vlc_atomic_t *atom, uintptr_t v)
 328 {
 329     atomic_store(&atom->u, v);
 330     return v;
 331 }
 332
 333 static inline uintptr_t vlc_atomic_add(vlc_atomic_t *atom, uintptr_t v)
 334 {
 335     return atomic_fetch_add(&atom->u, v) + v;
 336 }
 337
 338 static inline uintptr_t vlc_atomic_sub (vlc_atomic_t *atom, uintptr_t v)
 339 {
 340     return atomic_fetch_sub (&atom->u, v) - v;
 341 }
 342
 343 static inline uintptr_t vlc_atomic_inc (vlc_atomic_t *atom)
 344 {
 345     return vlc_atomic_add (atom, 1);
 346 }
 347
 348 static inline uintptr_t vlc_atomic_dec (vlc_atomic_t *atom)
 349 {
 350     return vlc_atomic_sub (atom, 1);
 351 }
 352
 353 static inline uintptr_t vlc_atomic_swap(vlc_atomic_t *atom, uintptr_t v)
 354 {
 355     return atomic_exchange(&atom->u, v);
 356 }
 357
 358 static inline uintptr_t vlc_atomic_compare_swap(vlc_atomic_t *atom,
 359                                                 uintptr_t u, uintptr_t v)
 360 {
 361     atomic_compare_exchange_strong(&atom->u, &u, v);
 362     return u;
 363 }
 364
 365 /** Helper to retrieve a single precision from an atom. */
 366 static inline float vlc_atomic_getf(vlc_atomic_t *atom)
 367 {
 368     union { float f; uintptr_t i; } u;
 369     u.i = vlc_atomic_get(atom);
 370     return u.f;
 371 }
 372
 373 /** Helper to store a single precision into an atom. */
 374 static inline float vlc_atomic_setf(vlc_atomic_t *atom, float f)
 375 {
 376     union { float f; uintptr_t i; } u;
 377     u.f = f;
 378     vlc_atomic_set(atom, u.i);
 379     return f;
 380 }
 381
 382 #endif