libc/include/stdatomic.h

   1 /*-
   2  * Copyright (c) 2011 Ed Schouten <ed@FreeBSD.org>
   3  *                    David Chisnall <theraven@FreeBSD.org>
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  25  * SUCH DAMAGE.
  26  *
  27  * $FreeBSD$
  28  */
  29
  30 #ifndef _STDATOMIC_H_
  31 #define _STDATOMIC_H_
  32
  33 #include <sys/cdefs.h>
  34
  35 #if defined(__cplusplus) && defined(_USING_LIBCXX) && \
  36     (__has_feature(cxx_atomic) || _GNUC_VER >= 407)
  37
  38 /* We have a usable C++ <atomic>; use it instead.  */
  39
  40 #include <atomic>
  41
  42 #undef _Atomic
  43         /* Also defined by <atomic> for gcc.  But not used in macros. */
  44         /* Also a clang intrinsic.                                    */
  45         /* Should not be used by client code before this file is      */
  46         /* included.  The definitions in <atomic> themselves see      */
  47         /* the old definition, as they should.                        */
  48         /* Client code sees the following definition.                 */
  49 #define _Atomic(t) std::atomic<t>
  50
  51 using std::atomic_is_lock_free;
  52 using std::atomic_init;
  53 using std::atomic_store;
  54 using std::atomic_store_explicit;
  55 using std::atomic_load;
  56 using std::atomic_load_explicit;
  57 using std::atomic_exchange;
  58 using std::atomic_exchange_explicit;
  59 using std::atomic_compare_exchange_strong;
  60 using std::atomic_compare_exchange_strong_explicit;
  61 using std::atomic_compare_exchange_weak;
  62 using std::atomic_compare_exchange_weak_explicit;
  63 using std::atomic_fetch_add;
  64 using std::atomic_fetch_add_explicit;
  65 using std::atomic_fetch_sub;
  66 using std::atomic_fetch_sub_explicit;
  67 using std::atomic_fetch_or;
  68 using std::atomic_fetch_or_explicit;
  69 using std::atomic_fetch_xor;
  70 using std::atomic_fetch_xor_explicit;
  71 using std::atomic_fetch_and;
  72 using std::atomic_fetch_and_explicit;
  73 using std::atomic_thread_fence;
  74 using std::atomic_signal_fence;
  75
  76 using std::memory_order;
  77 using std::memory_order_relaxed;
  78 using std::memory_order_consume;
  79 using std::memory_order_release;
  80 using std::memory_order_acq_rel;
  81 using std::memory_order_seq_cst;
  82
  83 using std::atomic_bool;
  84 using std::atomic_char;
  85 using std::atomic_schar;
  86 using std::atomic_uchar;
  87 using std::atomic_short;
  88 using std::atomic_ushort;
  89 using std::atomic_int;
  90 using std::atomic_uint;
  91 using std::atomic_long;
  92 using std::atomic_ulong;
  93 using std::atomic_llong;
  94 using std::atomic_ullong;
  95 using std::atomic_char16_t;
  96 using std::atomic_char32_t;
  97 using std::atomic_wchar_t;
  98 using std::atomic_int_least8_t;
  99 using std::atomic_uint_least8_t;
 100 using std::atomic_int_least16_t;
 101 using std::atomic_uint_least16_t;
 102 using std::atomic_int_least32_t;
 103 using std::atomic_uint_least32_t;
 104 using std::atomic_int_least64_t;
 105 using std::atomic_uint_least64_t;
 106 using std::atomic_int_fast8_t;
 107 using std::atomic_uint_fast8_t;
 108 using std::atomic_int_fast16_t;
 109 using std::atomic_uint_fast16_t;
 110 using std::atomic_int_fast32_t;
 111 using std::atomic_uint_fast32_t;
 112 using std::atomic_int_fast64_t;
 113 using std::atomic_uint_fast64_t;
 114 using std::atomic_intptr_t;
 115 using std::atomic_uintptr_t;
 116 using std::atomic_size_t;
 117 using std::atomic_ptrdiff_t;
 118 using std::atomic_intmax_t;
 119 using std::atomic_uintmax_t;
 120
 121 #else /* <atomic> unavailable, possibly because this is C, not C++ */
 122
 123 #include <sys/types.h>
 124 #include <stdbool.h>
 125
 126 /*
 127  * C: Do it ourselves.
 128  * Note that the runtime representation defined here should be compatible
 129  * with the C++ one, i.e. an _Atomic(T) needs to contain the same
 130  * bits as a T.
 131  */
 132
 133 #include <stddef.h>  /* For ptrdiff_t.                          */
 134 #include <stdint.h>  /* TODO: Should pollute namespace less.    */
 135 #if __STDC_VERSION__ >= 201112L
 136 # include <uchar.h>  /* For char16_t and char32_t.              */
 137 #endif
 138
 139 #if __has_extension(c_atomic) || __has_extension(cxx_atomic)
 140 #define __CLANG_ATOMICS
 141 #elif __GNUC_PREREQ__(4, 7)
 142 #define __GNUC_ATOMICS
 143 #elif defined(__GNUC__)
 144 #define __SYNC_ATOMICS
 145 #else
 146 #error "stdatomic.h does not support your compiler"
 147 #endif
 148
 149 /*
 150  * 7.17.1 Atomic lock-free macros.
 151  */
 152
 153 #ifdef __GCC_ATOMIC_BOOL_LOCK_FREE
 154 #define ATOMIC_BOOL_LOCK_FREE           __GCC_ATOMIC_BOOL_LOCK_FREE
 155 #endif
 156 #ifdef __GCC_ATOMIC_CHAR_LOCK_FREE
 157 #define ATOMIC_CHAR_LOCK_FREE           __GCC_ATOMIC_CHAR_LOCK_FREE
 158 #endif
 159 #ifdef __GCC_ATOMIC_CHAR16_T_LOCK_FREE
 160 #define ATOMIC_CHAR16_T_LOCK_FREE       __GCC_ATOMIC_CHAR16_T_LOCK_FREE
 161 #endif
 162 #ifdef __GCC_ATOMIC_CHAR32_T_LOCK_FREE
 163 #define ATOMIC_CHAR32_T_LOCK_FREE       __GCC_ATOMIC_CHAR32_T_LOCK_FREE
 164 #endif
 165 #ifdef __GCC_ATOMIC_WCHAR_T_LOCK_FREE
 166 #define ATOMIC_WCHAR_T_LOCK_FREE        __GCC_ATOMIC_WCHAR_T_LOCK_FREE
 167 #endif
 168 #ifdef __GCC_ATOMIC_SHORT_LOCK_FREE
 169 #define ATOMIC_SHORT_LOCK_FREE          __GCC_ATOMIC_SHORT_LOCK_FREE
 170 #endif
 171 #ifdef __GCC_ATOMIC_INT_LOCK_FREE
 172 #define ATOMIC_INT_LOCK_FREE            __GCC_ATOMIC_INT_LOCK_FREE
 173 #endif
 174 #ifdef __GCC_ATOMIC_LONG_LOCK_FREE
 175 #define ATOMIC_LONG_LOCK_FREE           __GCC_ATOMIC_LONG_LOCK_FREE
 176 #endif
 177 #ifdef __GCC_ATOMIC_LLONG_LOCK_FREE
 178 #define ATOMIC_LLONG_LOCK_FREE          __GCC_ATOMIC_LLONG_LOCK_FREE
 179 #endif
 180 #ifdef __GCC_ATOMIC_POINTER_LOCK_FREE
 181 #define ATOMIC_POINTER_LOCK_FREE        __GCC_ATOMIC_POINTER_LOCK_FREE
 182 #endif
 183
 184 /*
 185  * 7.17.2 Initialization.
 186  */
 187
 188 #if defined(__CLANG_ATOMICS)
 189 #define ATOMIC_VAR_INIT(value)          (value)
 190 #define atomic_init(obj, value)         __c11_atomic_init(obj, value)
 191 #else
 192 #define ATOMIC_VAR_INIT(value)          { .__val = (value) }
 193 #define atomic_init(obj, value)         ((void)((obj)->__val = (value)))
 194 #endif
 195
 196 /*
 197  * Clang and recent GCC both provide predefined macros for the memory
 198  * orderings.  If we are using a compiler that doesn't define them, use the
 199  * clang values - these will be ignored in the fallback path.
 200  */
 201
 202 #ifndef __ATOMIC_RELAXED
 203 #define __ATOMIC_RELAXED                0
 204 #endif
 205 #ifndef __ATOMIC_CONSUME
 206 #define __ATOMIC_CONSUME                1
 207 #endif
 208 #ifndef __ATOMIC_ACQUIRE
 209 #define __ATOMIC_ACQUIRE                2
 210 #endif
 211 #ifndef __ATOMIC_RELEASE
 212 #define __ATOMIC_RELEASE                3
 213 #endif
 214 #ifndef __ATOMIC_ACQ_REL
 215 #define __ATOMIC_ACQ_REL                4
 216 #endif
 217 #ifndef __ATOMIC_SEQ_CST
 218 #define __ATOMIC_SEQ_CST                5
 219 #endif
 220
 221 /*
 222  * 7.17.3 Order and consistency.
 223  *
 224  * The memory_order_* constants that denote the barrier behaviour of the
 225  * atomic operations.
 226  * The enum values must be identical to those used by the
 227  * C++ <atomic> header.
 228  */
 229
 230 typedef enum {
 231         memory_order_relaxed = __ATOMIC_RELAXED,
 232         memory_order_consume = __ATOMIC_CONSUME,
 233         memory_order_acquire = __ATOMIC_ACQUIRE,
 234         memory_order_release = __ATOMIC_RELEASE,
 235         memory_order_acq_rel = __ATOMIC_ACQ_REL,
 236         memory_order_seq_cst = __ATOMIC_SEQ_CST
 237 } memory_order;
 238
 239 /*
 240  * 7.17.4 Fences.
 241  */
 242
 243 static __inline void
 244 atomic_thread_fence(memory_order __order __attribute__((unused)))
 245 {
 246
 247 #ifdef __CLANG_ATOMICS
 248         __c11_atomic_thread_fence(__order);
 249 #elif defined(__GNUC_ATOMICS)
 250         __atomic_thread_fence(__order);
 251 #else
 252         __sync_synchronize();
 253 #endif
 254 }
 255
 256 static __inline void
 257 atomic_signal_fence(memory_order __order __attribute__((unused)))
 258 {
 259
 260 #ifdef __CLANG_ATOMICS
 261         __c11_atomic_signal_fence(__order);
 262 #elif defined(__GNUC_ATOMICS)
 263         __atomic_signal_fence(__order);
 264 #else
 265         __asm volatile ("" ::: "memory");
 266 #endif
 267 }
 268
 269 /*
 270  * 7.17.5 Lock-free property.
 271  */
 272
 273 #if defined(_KERNEL)
 274 /* Atomics in kernelspace are always lock-free. */
 275 #define atomic_is_lock_free(obj) \
 276         ((void)(obj), (_Bool)1)
 277 #elif defined(__CLANG_ATOMICS)
 278 #define atomic_is_lock_free(obj) \
 279         __c11_atomic_is_lock_free(sizeof(*(obj)))
 280 #elif defined(__GNUC_ATOMICS)
 281 #define atomic_is_lock_free(obj) \
 282         __atomic_is_lock_free(sizeof((obj)->__val), &(obj)->__val)
 283 #else
 284 #define atomic_is_lock_free(obj) \
 285         ((void)(obj), sizeof((obj)->__val) <= sizeof(void *))
 286 #endif
 287
 288 /*
 289  * 7.17.6 Atomic integer types.
 290  */
 291
 292 #if !__has_extension(c_atomic) && !__has_extension(cxx_atomic)
 293 /*
 294  * No native support for _Atomic(). Place object in structure to prevent
 295  * most forms of direct non-atomic access.
 296  */
 297 #define _Atomic(T)              struct { T volatile __val; }
 298 #endif
 299
 300 typedef _Atomic(bool)                   atomic_bool;
 301 typedef _Atomic(char)                   atomic_char;
 302 typedef _Atomic(signed char)            atomic_schar;
 303 typedef _Atomic(unsigned char)          atomic_uchar;
 304 typedef _Atomic(short)                  atomic_short;
 305 typedef _Atomic(unsigned short)         atomic_ushort;
 306 typedef _Atomic(int)                    atomic_int;
 307 typedef _Atomic(unsigned int)           atomic_uint;
 308 typedef _Atomic(long)                   atomic_long;
 309 typedef _Atomic(unsigned long)          atomic_ulong;
 310 typedef _Atomic(long long)              atomic_llong;
 311 typedef _Atomic(unsigned long long)     atomic_ullong;
 312 #if __STDC_VERSION__ >= 201112L || __cplusplus >= 201103L
 313   typedef _Atomic(char16_t)             atomic_char16_t;
 314   typedef _Atomic(char32_t)             atomic_char32_t;
 315 #endif
 316 typedef _Atomic(wchar_t)                atomic_wchar_t;
 317 typedef _Atomic(int_least8_t)           atomic_int_least8_t;
 318 typedef _Atomic(uint_least8_t)  atomic_uint_least8_t;
 319 typedef _Atomic(int_least16_t)  atomic_int_least16_t;
 320 typedef _Atomic(uint_least16_t) atomic_uint_least16_t;
 321 typedef _Atomic(int_least32_t)  atomic_int_least32_t;
 322 typedef _Atomic(uint_least32_t) atomic_uint_least32_t;
 323 typedef _Atomic(int_least64_t)  atomic_int_least64_t;
 324 typedef _Atomic(uint_least64_t) atomic_uint_least64_t;
 325 typedef _Atomic(int_fast8_t)            atomic_int_fast8_t;
 326 typedef _Atomic(uint_fast8_t)           atomic_uint_fast8_t;
 327 typedef _Atomic(int_fast16_t)           atomic_int_fast16_t;
 328 typedef _Atomic(uint_fast16_t)  atomic_uint_fast16_t;
 329 typedef _Atomic(int_fast32_t)           atomic_int_fast32_t;
 330 typedef _Atomic(uint_fast32_t)  atomic_uint_fast32_t;
 331 typedef _Atomic(int_fast64_t)           atomic_int_fast64_t;
 332 typedef _Atomic(uint_fast64_t)  atomic_uint_fast64_t;
 333 typedef _Atomic(intptr_t)               atomic_intptr_t;
 334 typedef _Atomic(uintptr_t)              atomic_uintptr_t;
 335 typedef _Atomic(size_t)         atomic_size_t;
 336 typedef _Atomic(ptrdiff_t)              atomic_ptrdiff_t;
 337 typedef _Atomic(intmax_t)               atomic_intmax_t;
 338 typedef _Atomic(uintmax_t)              atomic_uintmax_t;
 339
 340 /*
 341  * 7.17.7 Operations on atomic types.
 342  */
 343
 344 /*
 345  * Compiler-specific operations.
 346  */
 347
 348 #if defined(__CLANG_ATOMICS)
 349 #define atomic_compare_exchange_strong_explicit(object, expected,       \
 350     desired, success, failure)                                          \
 351         __c11_atomic_compare_exchange_strong(object, expected, desired, \
 352             success, failure)
 353 #define atomic_compare_exchange_weak_explicit(object, expected,         \
 354     desired, success, failure)                                          \
 355         __c11_atomic_compare_exchange_weak(object, expected, desired,   \
 356             success, failure)
 357 #define atomic_exchange_explicit(object, desired, order)                \
 358         __c11_atomic_exchange(object, desired, order)
 359 #define atomic_fetch_add_explicit(object, operand, order)               \
 360         __c11_atomic_fetch_add(object, operand, order)
 361 #define atomic_fetch_and_explicit(object, operand, order)               \
 362         __c11_atomic_fetch_and(object, operand, order)
 363 #define atomic_fetch_or_explicit(object, operand, order)                \
 364         __c11_atomic_fetch_or(object, operand, order)
 365 #define atomic_fetch_sub_explicit(object, operand, order)               \
 366         __c11_atomic_fetch_sub(object, operand, order)
 367 #define atomic_fetch_xor_explicit(object, operand, order)               \
 368         __c11_atomic_fetch_xor(object, operand, order)
 369 #define atomic_load_explicit(object, order)                             \
 370         __c11_atomic_load(object, order)
 371 #define atomic_store_explicit(object, desired, order)                   \
 372         __c11_atomic_store(object, desired, order)
 373 #elif defined(__GNUC_ATOMICS)
 374 #define atomic_compare_exchange_strong_explicit(object, expected,       \
 375     desired, success, failure)                                          \
 376         __atomic_compare_exchange_n(&(object)->__val, expected,         \
 377             desired, 0, success, failure)
 378 #define atomic_compare_exchange_weak_explicit(object, expected,         \
 379     desired, success, failure)                                          \
 380         __atomic_compare_exchange_n(&(object)->__val, expected,         \
 381             desired, 1, success, failure)
 382 #define atomic_exchange_explicit(object, desired, order)                \
 383         __atomic_exchange_n(&(object)->__val, desired, order)
 384 #define atomic_fetch_add_explicit(object, operand, order)               \
 385         __atomic_fetch_add(&(object)->__val, operand, order)
 386 #define atomic_fetch_and_explicit(object, operand, order)               \
 387         __atomic_fetch_and(&(object)->__val, operand, order)
 388 #define atomic_fetch_or_explicit(object, operand, order)                \
 389         __atomic_fetch_or(&(object)->__val, operand, order)
 390 #define atomic_fetch_sub_explicit(object, operand, order)               \
 391         __atomic_fetch_sub(&(object)->__val, operand, order)
 392 #define atomic_fetch_xor_explicit(object, operand, order)               \
 393         __atomic_fetch_xor(&(object)->__val, operand, order)
 394 #define atomic_load_explicit(object, order)                             \
 395         __atomic_load_n(&(object)->__val, order)
 396 #define atomic_store_explicit(object, desired, order)                   \
 397         __atomic_store_n(&(object)->__val, desired, order)
 398 #else
 399 #define __atomic_apply_stride(object, operand) \
 400         (((__typeof__((object)->__val))0) + (operand))
 401 #define atomic_compare_exchange_strong_explicit(object, expected,       \
 402     desired, success, failure)  __extension__ ({                        \
 403         __typeof__(expected) __ep = (expected);                         \
 404         __typeof__(*__ep) __e = *__ep;                                  \
 405         (void)(success); (void)(failure);                               \
 406         (bool)((*__ep = __sync_val_compare_and_swap(&(object)->__val,   \
 407             __e, desired)) == __e);                                     \
 408 })
 409 #define atomic_compare_exchange_weak_explicit(object, expected,         \
 410     desired, success, failure)                                          \
 411         atomic_compare_exchange_strong_explicit(object, expected,       \
 412                 desired, success, failure)
 413 #if __has_builtin(__sync_swap)
 414 /* Clang provides a full-barrier atomic exchange - use it if available. */
 415 #define atomic_exchange_explicit(object, desired, order)                \
 416         ((void)(order), __sync_swap(&(object)->__val, desired))
 417 #else
 418 /*
 419  * __sync_lock_test_and_set() is only an acquire barrier in theory (although in
 420  * practice it is usually a full barrier) so we need an explicit barrier before
 421  * it.
 422  */
 423 #define atomic_exchange_explicit(object, desired, order)                \
 424 __extension__ ({                                                        \
 425         __typeof__(object) __o = (object);                              \
 426         __typeof__(desired) __d = (desired);                            \
 427         (void)(order);                                                  \
 428         __sync_synchronize();                                           \
 429         __sync_lock_test_and_set(&(__o)->__val, __d);                   \
 430 })
 431 #endif
 432 #define atomic_fetch_add_explicit(object, operand, order)               \
 433         ((void)(order), __sync_fetch_and_add(&(object)->__val,          \
 434             __atomic_apply_stride(object, operand)))
 435 #define atomic_fetch_and_explicit(object, operand, order)               \
 436         ((void)(order), __sync_fetch_and_and(&(object)->__val, operand))
 437 #define atomic_fetch_or_explicit(object, operand, order)                \
 438         ((void)(order), __sync_fetch_and_or(&(object)->__val, operand))
 439 #define atomic_fetch_sub_explicit(object, operand, order)               \
 440         ((void)(order), __sync_fetch_and_sub(&(object)->__val,          \
 441             __atomic_apply_stride(object, operand)))
 442 #define atomic_fetch_xor_explicit(object, operand, order)               \
 443         ((void)(order), __sync_fetch_and_xor(&(object)->__val, operand))
 444 #define atomic_load_explicit(object, order)                             \
 445         ((void)(order), __sync_fetch_and_add(&(object)->__val, 0))
 446 #define atomic_store_explicit(object, desired, order)                   \
 447         ((void)atomic_exchange_explicit(object, desired, order))
 448 #endif
 449
 450 /*
 451  * Convenience functions.
 452  *
 453  * Don't provide these in kernel space. In kernel space, we should be
 454  * disciplined enough to always provide explicit barriers.
 455  */
 456
 457 #ifndef _KERNEL
 458 #define atomic_compare_exchange_strong(object, expected, desired)       \
 459         atomic_compare_exchange_strong_explicit(object, expected,       \
 460             desired, memory_order_seq_cst, memory_order_seq_cst)
 461 #define atomic_compare_exchange_weak(object, expected, desired)         \
 462         atomic_compare_exchange_weak_explicit(object, expected,         \
 463             desired, memory_order_seq_cst, memory_order_seq_cst)
 464 #define atomic_exchange(object, desired)                                \
 465         atomic_exchange_explicit(object, desired, memory_order_seq_cst)
 466 #define atomic_fetch_add(object, operand)                               \
 467         atomic_fetch_add_explicit(object, operand, memory_order_seq_cst)
 468 #define atomic_fetch_and(object, operand)                               \
 469         atomic_fetch_and_explicit(object, operand, memory_order_seq_cst)
 470 #define atomic_fetch_or(object, operand)                                \
 471         atomic_fetch_or_explicit(object, operand, memory_order_seq_cst)
 472 #define atomic_fetch_sub(object, operand)                               \
 473         atomic_fetch_sub_explicit(object, operand, memory_order_seq_cst)
 474 #define atomic_fetch_xor(object, operand)                               \
 475         atomic_fetch_xor_explicit(object, operand, memory_order_seq_cst)
 476 #define atomic_load(object)                                             \
 477         atomic_load_explicit(object, memory_order_seq_cst)
 478 #define atomic_store(object, desired)                                   \
 479         atomic_store_explicit(object, desired, memory_order_seq_cst)
 480 #endif /* !_KERNEL */
 481
 482 /*
 483  * 7.17.8 Atomic flag type and operations.
 484  *
 485  * XXX: Assume atomic_bool can be used as an atomic_flag. Is there some
 486  * kind of compiler built-in type we could use?
 487  */
 488
 489 typedef struct {
 490         atomic_bool     __flag;
 491 } atomic_flag;
 492
 493 #define ATOMIC_FLAG_INIT                { ATOMIC_VAR_INIT(false) }
 494
 495 static __inline bool
 496 atomic_flag_test_and_set_explicit(volatile atomic_flag *__object,
 497     memory_order __order)
 498 {
 499         return (atomic_exchange_explicit(&__object->__flag, 1, __order));
 500 }
 501
 502 static __inline void
 503 atomic_flag_clear_explicit(volatile atomic_flag *__object, memory_order __order)
 504 {
 505
 506         atomic_store_explicit(&__object->__flag, 0, __order);
 507 }
 508
 509 #ifndef _KERNEL
 510 static __inline bool
 511 atomic_flag_test_and_set(volatile atomic_flag *__object)
 512 {
 513
 514         return (atomic_flag_test_and_set_explicit(__object,
 515             memory_order_seq_cst));
 516 }
 517
 518 static __inline void
 519 atomic_flag_clear(volatile atomic_flag *__object)
 520 {
 521
 522         atomic_flag_clear_explicit(__object, memory_order_seq_cst);
 523 }
 524 #endif /* !_KERNEL */
 525
 526 #endif /* <atomic> unavailable */
 527
 528 #endif /* !_STDATOMIC_H_ */