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(__GNUC__) && !defined(__GNUC_PREREQ)
36 /* Duplicate definition here, since the mingw sys/cdefs.h omits the */
37 /* definition, and this needs to be usable there. */
38 #define __GNUC_PREREQ(x, y) \
39 ((__GNUC__ == (x) && __GNUC_MINOR__ >= (y)) || (__GNUC__ > (x)))
40 #endif /* __GNUC__ && ... */
41
42 #if defined(__cplusplus) && __cplusplus >= 201103L && defined(_USING_LIBCXX)
43 # ifdef __clang__
44 # if __has_feature(cxx_atomic)
45 # define _STDATOMIC_HAVE_ATOMIC
46 # endif
47 # else /* gcc */
48 # if __GNUC_PREREQ(4, 7)
49 # define _STDATOMIC_HAVE_ATOMIC
50 # endif
51 # endif
52 #endif
53
54 #ifdef _STDATOMIC_HAVE_ATOMIC
55
56 /* We have a usable C++ <atomic>; use it instead. */
57
58 #include <atomic>
59
60 #undef _Atomic
61 /* Also defined by <atomic> for gcc. But not used in macros. */
62 /* Also a clang intrinsic. */
63 /* Should not be used by client code before this file is */
64 /* included. The definitions in <atomic> themselves see */
65 /* the old definition, as they should. */
66 /* Client code sees the following definition. */
67
68 #define _Atomic(t) std::atomic<t>
69
70 using std::atomic_is_lock_free;
71 using std::atomic_init;
72 using std::atomic_store;
73 using std::atomic_store_explicit;
74 using std::atomic_load;
75 using std::atomic_load_explicit;
76 using std::atomic_exchange;
77 using std::atomic_exchange_explicit;
78 using std::atomic_compare_exchange_strong;
79 using std::atomic_compare_exchange_strong_explicit;
80 using std::atomic_compare_exchange_weak;
81 using std::atomic_compare_exchange_weak_explicit;
82 using std::atomic_fetch_add;
83 using std::atomic_fetch_add_explicit;
84 using std::atomic_fetch_sub;
85 using std::atomic_fetch_sub_explicit;
86 using std::atomic_fetch_or;
87 using std::atomic_fetch_or_explicit;
88 using std::atomic_fetch_xor;
89 using std::atomic_fetch_xor_explicit;
90 using std::atomic_fetch_and;
91 using std::atomic_fetch_and_explicit;
92 using std::atomic_thread_fence;
93 using std::atomic_signal_fence;
94
95 using std::memory_order;
96 using std::memory_order_relaxed;
97 using std::memory_order_consume;
98 using std::memory_order_acquire;
99 using std::memory_order_release;
100 using std::memory_order_acq_rel;
101 using std::memory_order_seq_cst;
102
103 using std::atomic_bool;
104 using std::atomic_char;
105 using std::atomic_schar;
106 using std::atomic_uchar;
107 using std::atomic_short;
108 using std::atomic_ushort;
109 using std::atomic_int;
110 using std::atomic_uint;
111 using std::atomic_long;
112 using std::atomic_ulong;
113 using std::atomic_llong;
114 using std::atomic_ullong;
115 using std::atomic_char16_t;
116 using std::atomic_char32_t;
117 using std::atomic_wchar_t;
118 using std::atomic_int_least8_t;
119 using std::atomic_uint_least8_t;
120 using std::atomic_int_least16_t;
121 using std::atomic_uint_least16_t;
122 using std::atomic_int_least32_t;
123 using std::atomic_uint_least32_t;
124 using std::atomic_int_least64_t;
125 using std::atomic_uint_least64_t;
126 using std::atomic_int_fast8_t;
127 using std::atomic_uint_fast8_t;
128 using std::atomic_int_fast16_t;
129 using std::atomic_uint_fast16_t;
130 using std::atomic_int_fast32_t;
131 using std::atomic_uint_fast32_t;
132 using std::atomic_int_fast64_t;
133 using std::atomic_uint_fast64_t;
134 using std::atomic_intptr_t;
135 using std::atomic_uintptr_t;
136 using std::atomic_size_t;
137 using std::atomic_ptrdiff_t;
138 using std::atomic_intmax_t;
139 using std::atomic_uintmax_t;
140
141 #else /* <atomic> unavailable, possibly because this is C, not C++ */
142
143 #include <sys/types.h>
144 #include <stdbool.h>
145
146 /*
147 * C: Do it ourselves.
148 * Note that the runtime representation defined here should be compatible
149 * with the C++ one, i.e. an _Atomic(T) needs to contain the same
150 * bits as a T.
151 */
152
153 #include <stddef.h> /* For ptrdiff_t. */
154 #include <stdint.h> /* TODO: Should pollute namespace less. */
155 #if __STDC_VERSION__ >= 201112L
156 # include <uchar.h> /* For char16_t and char32_t. */
157 #endif
158
159 #ifdef __clang__
160 # if __has_extension(c_atomic) || __has_extension(cxx_atomic)
161 # define __CLANG_ATOMICS
162 # else
163 # error "stdatomic.h does not support your compiler"
164 # endif
165 # if __has_builtin(__sync_swap)
166 # define __HAS_BUILTIN_SYNC_SWAP
167 # endif
168 #else
169 # if __GNUC_PREREQ(4, 7)
170 # define __GNUC_ATOMICS
171 # else
172 # define __SYNC_ATOMICS
173 # ifdef __cplusplus
174 # define __ATOMICS_AVOID_DOT_INIT
175 # endif
176 # endif
177 #endif
178
179 /*
180 * 7.17.1 Atomic lock-free macros.
181 */
182
183 #ifdef __GCC_ATOMIC_BOOL_LOCK_FREE
184 #define ATOMIC_BOOL_LOCK_FREE __GCC_ATOMIC_BOOL_LOCK_FREE
185 #elif defined(__SYNC_ATOMICS)
186 #define ATOMIC_BOOL_LOCK_FREE 2 /* For all modern platforms */
187 #endif
188 #ifdef __GCC_ATOMIC_CHAR_LOCK_FREE
189 #define ATOMIC_CHAR_LOCK_FREE __GCC_ATOMIC_CHAR_LOCK_FREE
190 #elif defined(__SYNC_ATOMICS)
191 #define ATOMIC_CHAR_LOCK_FREE 2
192 #endif
193 #ifdef __GCC_ATOMIC_CHAR16_T_LOCK_FREE
194 #define ATOMIC_CHAR16_T_LOCK_FREE __GCC_ATOMIC_CHAR16_T_LOCK_FREE
195 #elif defined(__SYNC_ATOMICS)
196 #define ATOMIC_CHAR16_T_LOCK_FREE 2
197 #endif
198 #ifdef __GCC_ATOMIC_CHAR32_T_LOCK_FREE
199 #define ATOMIC_CHAR32_T_LOCK_FREE __GCC_ATOMIC_CHAR32_T_LOCK_FREE
200 #elif defined(__SYNC_ATOMICS)
201 #define ATOMIC_CHAR32_T_LOCK_FREE 2
202 #endif
203 #ifdef __GCC_ATOMIC_WCHAR_T_LOCK_FREE
204 #define ATOMIC_WCHAR_T_LOCK_FREE __GCC_ATOMIC_WCHAR_T_LOCK_FREE
205 #elif defined(__SYNC_ATOMICS)
206 #define ATOMIC_WCHAR_T_LOCK_FREE 2
207 #endif
208 #ifdef __GCC_ATOMIC_SHORT_LOCK_FREE
209 #define ATOMIC_SHORT_LOCK_FREE __GCC_ATOMIC_SHORT_LOCK_FREE
210 #elif defined(__SYNC_ATOMICS)
211 #define ATOMIC_SHORT_LOCK_FREE 2
212 #endif
213 #ifdef __GCC_ATOMIC_INT_LOCK_FREE
214 #define ATOMIC_INT_LOCK_FREE __GCC_ATOMIC_INT_LOCK_FREE
215 #elif defined(__SYNC_ATOMICS)
216 #define ATOMIC_INT_LOCK_FREE 2
217 #endif
218 #ifdef __GCC_ATOMIC_LONG_LOCK_FREE
219 #define ATOMIC_LONG_LOCK_FREE __GCC_ATOMIC_LONG_LOCK_FREE
220 #elif defined(__SYNC_ATOMICS)
221 #define ATOMIC_LONG_LOCK_FREE 2
222 #endif
223 #ifdef __GCC_ATOMIC_LLONG_LOCK_FREE
224 #define ATOMIC_LLONG_LOCK_FREE __GCC_ATOMIC_LLONG_LOCK_FREE
225 #elif defined(__SYNC_ATOMICS)
226 #define ATOMIC_LLONG_LOCK_FREE 1 /* maybe */
227 #endif
228 #ifdef __GCC_ATOMIC_POINTER_LOCK_FREE
229 #define ATOMIC_POINTER_LOCK_FREE __GCC_ATOMIC_POINTER_LOCK_FREE
230 #elif defined(__SYNC_ATOMICS)
231 #define ATOMIC_POINTER_LOCK_FREE 2
232 #endif
233
234 /*
235 * 7.17.2 Initialization.
236 */
237
238 #if defined(__CLANG_ATOMICS)
239 #define ATOMIC_VAR_INIT(value) (value)
240 #define atomic_init(obj, value) __c11_atomic_init(obj, value)
241 #else
242 #ifdef __ATOMICS_AVOID_DOT_INIT
243 #define ATOMIC_VAR_INIT(value) { value }
244 #else
245 #define ATOMIC_VAR_INIT(value) { .__val = (value) }
246 #endif
247 #define atomic_init(obj, value) ((void)((obj)->__val = (value)))
248 #endif
249
250 /*
251 * Clang and recent GCC both provide predefined macros for the memory
252 * orderings. If we are using a compiler that doesn't define them, use the
253 * clang values - these will be ignored in the fallback path.
254 */
255
256 #ifndef __ATOMIC_RELAXED
257 #define __ATOMIC_RELAXED 0
258 #endif
259 #ifndef __ATOMIC_CONSUME
260 #define __ATOMIC_CONSUME 1
261 #endif
262 #ifndef __ATOMIC_ACQUIRE
263 #define __ATOMIC_ACQUIRE 2
264 #endif
265 #ifndef __ATOMIC_RELEASE
266 #define __ATOMIC_RELEASE 3
267 #endif
268 #ifndef __ATOMIC_ACQ_REL
269 #define __ATOMIC_ACQ_REL 4
270 #endif
271 #ifndef __ATOMIC_SEQ_CST
272 #define __ATOMIC_SEQ_CST 5
273 #endif
274
275 /*
276 * 7.17.3 Order and consistency.
277 *
278 * The memory_order_* constants that denote the barrier behaviour of the
279 * atomic operations.
280 * The enum values must be identical to those used by the
281 * C++ <atomic> header.
282 */
283
284 typedef enum {
285 memory_order_relaxed = __ATOMIC_RELAXED,
286 memory_order_consume = __ATOMIC_CONSUME,
287 memory_order_acquire = __ATOMIC_ACQUIRE,
288 memory_order_release = __ATOMIC_RELEASE,
289 memory_order_acq_rel = __ATOMIC_ACQ_REL,
290 memory_order_seq_cst = __ATOMIC_SEQ_CST
291 } memory_order;
292
293 /*
294 * 7.17.4 Fences.
295 */
296
297 static __inline void
atomic_thread_fence(memory_order __order)298 atomic_thread_fence(memory_order __order __attribute__((unused)))
299 {
300
301 #ifdef __CLANG_ATOMICS
302 __c11_atomic_thread_fence(__order);
303 #elif defined(__GNUC_ATOMICS)
304 __atomic_thread_fence(__order);
305 #else
306 __sync_synchronize();
307 #endif
308 }
309
310 static __inline void
atomic_signal_fence(memory_order __order)311 atomic_signal_fence(memory_order __order __attribute__((unused)))
312 {
313
314 #ifdef __CLANG_ATOMICS
315 __c11_atomic_signal_fence(__order);
316 #elif defined(__GNUC_ATOMICS)
317 __atomic_signal_fence(__order);
318 #else
319 __asm volatile ("" ::: "memory");
320 #endif
321 }
322
323 /*
324 * 7.17.5 Lock-free property.
325 */
326
327 #if defined(_KERNEL)
328 /* Atomics in kernelspace are always lock-free. */
329 #define atomic_is_lock_free(obj) \
330 ((void)(obj), (_Bool)1)
331 #elif defined(__CLANG_ATOMICS)
332 #define atomic_is_lock_free(obj) \
333 __c11_atomic_is_lock_free(sizeof(*(obj)))
334 #elif defined(__GNUC_ATOMICS)
335 #define atomic_is_lock_free(obj) \
336 __atomic_is_lock_free(sizeof((obj)->__val), &(obj)->__val)
337 #else
338 #define atomic_is_lock_free(obj) \
339 ((void)(obj), sizeof((obj)->__val) <= sizeof(void *))
340 #endif
341
342 /*
343 * 7.17.6 Atomic integer types.
344 */
345
346 #ifndef __CLANG_ATOMICS
347 /*
348 * No native support for _Atomic(). Place object in structure to prevent
349 * most forms of direct non-atomic access.
350 */
351 #define _Atomic(T) struct { T volatile __val; }
352 #endif
353
354 typedef _Atomic(bool) atomic_bool;
355 typedef _Atomic(char) atomic_char;
356 typedef _Atomic(signed char) atomic_schar;
357 typedef _Atomic(unsigned char) atomic_uchar;
358 typedef _Atomic(short) atomic_short;
359 typedef _Atomic(unsigned short) atomic_ushort;
360 typedef _Atomic(int) atomic_int;
361 typedef _Atomic(unsigned int) atomic_uint;
362 typedef _Atomic(long) atomic_long;
363 typedef _Atomic(unsigned long) atomic_ulong;
364 typedef _Atomic(long long) atomic_llong;
365 typedef _Atomic(unsigned long long) atomic_ullong;
366 #if __STDC_VERSION__ >= 201112L || __cplusplus >= 201103L
367 typedef _Atomic(char16_t) atomic_char16_t;
368 typedef _Atomic(char32_t) atomic_char32_t;
369 #endif
370 typedef _Atomic(wchar_t) atomic_wchar_t;
371 typedef _Atomic(int_least8_t) atomic_int_least8_t;
372 typedef _Atomic(uint_least8_t) atomic_uint_least8_t;
373 typedef _Atomic(int_least16_t) atomic_int_least16_t;
374 typedef _Atomic(uint_least16_t) atomic_uint_least16_t;
375 typedef _Atomic(int_least32_t) atomic_int_least32_t;
376 typedef _Atomic(uint_least32_t) atomic_uint_least32_t;
377 typedef _Atomic(int_least64_t) atomic_int_least64_t;
378 typedef _Atomic(uint_least64_t) atomic_uint_least64_t;
379 typedef _Atomic(int_fast8_t) atomic_int_fast8_t;
380 typedef _Atomic(uint_fast8_t) atomic_uint_fast8_t;
381 typedef _Atomic(int_fast16_t) atomic_int_fast16_t;
382 typedef _Atomic(uint_fast16_t) atomic_uint_fast16_t;
383 typedef _Atomic(int_fast32_t) atomic_int_fast32_t;
384 typedef _Atomic(uint_fast32_t) atomic_uint_fast32_t;
385 typedef _Atomic(int_fast64_t) atomic_int_fast64_t;
386 typedef _Atomic(uint_fast64_t) atomic_uint_fast64_t;
387 typedef _Atomic(intptr_t) atomic_intptr_t;
388 typedef _Atomic(uintptr_t) atomic_uintptr_t;
389 typedef _Atomic(size_t) atomic_size_t;
390 typedef _Atomic(ptrdiff_t) atomic_ptrdiff_t;
391 typedef _Atomic(intmax_t) atomic_intmax_t;
392 typedef _Atomic(uintmax_t) atomic_uintmax_t;
393
394 /*
395 * 7.17.7 Operations on atomic types.
396 */
397
398 /*
399 * Compiler-specific operations.
400 */
401
402 #if defined(__CLANG_ATOMICS)
403 #define atomic_compare_exchange_strong_explicit(object, expected, \
404 desired, success, failure) \
405 __c11_atomic_compare_exchange_strong(object, expected, desired, \
406 success, failure)
407 #define atomic_compare_exchange_weak_explicit(object, expected, \
408 desired, success, failure) \
409 __c11_atomic_compare_exchange_weak(object, expected, desired, \
410 success, failure)
411 #define atomic_exchange_explicit(object, desired, order) \
412 __c11_atomic_exchange(object, desired, order)
413 #define atomic_fetch_add_explicit(object, operand, order) \
414 __c11_atomic_fetch_add(object, operand, order)
415 #define atomic_fetch_and_explicit(object, operand, order) \
416 __c11_atomic_fetch_and(object, operand, order)
417 #define atomic_fetch_or_explicit(object, operand, order) \
418 __c11_atomic_fetch_or(object, operand, order)
419 #define atomic_fetch_sub_explicit(object, operand, order) \
420 __c11_atomic_fetch_sub(object, operand, order)
421 #define atomic_fetch_xor_explicit(object, operand, order) \
422 __c11_atomic_fetch_xor(object, operand, order)
423 #define atomic_load_explicit(object, order) \
424 __c11_atomic_load(object, order)
425 #define atomic_store_explicit(object, desired, order) \
426 __c11_atomic_store(object, desired, order)
427 #elif defined(__GNUC_ATOMICS)
428 #define atomic_compare_exchange_strong_explicit(object, expected, \
429 desired, success, failure) \
430 __atomic_compare_exchange_n(&(object)->__val, expected, \
431 desired, 0, success, failure)
432 #define atomic_compare_exchange_weak_explicit(object, expected, \
433 desired, success, failure) \
434 __atomic_compare_exchange_n(&(object)->__val, expected, \
435 desired, 1, success, failure)
436 #define atomic_exchange_explicit(object, desired, order) \
437 __atomic_exchange_n(&(object)->__val, desired, order)
438 #define atomic_fetch_add_explicit(object, operand, order) \
439 __atomic_fetch_add(&(object)->__val, operand, order)
440 #define atomic_fetch_and_explicit(object, operand, order) \
441 __atomic_fetch_and(&(object)->__val, operand, order)
442 #define atomic_fetch_or_explicit(object, operand, order) \
443 __atomic_fetch_or(&(object)->__val, operand, order)
444 #define atomic_fetch_sub_explicit(object, operand, order) \
445 __atomic_fetch_sub(&(object)->__val, operand, order)
446 #define atomic_fetch_xor_explicit(object, operand, order) \
447 __atomic_fetch_xor(&(object)->__val, operand, order)
448 #define atomic_load_explicit(object, order) \
449 __atomic_load_n(&(object)->__val, order)
450 #define atomic_store_explicit(object, desired, order) \
451 __atomic_store_n(&(object)->__val, desired, order)
452 #else
453 #define __atomic_apply_stride(object, operand) \
454 (((__typeof__((object)->__val))0) + (operand))
455 #define atomic_compare_exchange_strong_explicit(object, expected, \
456 desired, success, failure) __extension__ ({ \
457 __typeof__(expected) __ep = (expected); \
458 __typeof__(*__ep) __e = *__ep; \
459 (void)(success); (void)(failure); \
460 (bool)((*__ep = __sync_val_compare_and_swap(&(object)->__val, \
461 __e, desired)) == __e); \
462 })
463 #define atomic_compare_exchange_weak_explicit(object, expected, \
464 desired, success, failure) \
465 atomic_compare_exchange_strong_explicit(object, expected, \
466 desired, success, failure)
467 #ifdef __HAS_BUILTIN_SYNC_SWAP
468 /* Clang provides a full-barrier atomic exchange - use it if available. */
469 #define atomic_exchange_explicit(object, desired, order) \
470 ((void)(order), __sync_swap(&(object)->__val, desired))
471 #else
472 /*
473 * __sync_lock_test_and_set() is only an acquire barrier in theory (although in
474 * practice it is usually a full barrier) so we need an explicit barrier before
475 * it.
476 */
477 #define atomic_exchange_explicit(object, desired, order) \
478 __extension__ ({ \
479 __typeof__(object) __o = (object); \
480 __typeof__(desired) __d = (desired); \
481 (void)(order); \
482 __sync_synchronize(); \
483 __sync_lock_test_and_set(&(__o)->__val, __d); \
484 })
485 #endif
486 #define atomic_fetch_add_explicit(object, operand, order) \
487 ((void)(order), __sync_fetch_and_add(&(object)->__val, \
488 __atomic_apply_stride(object, operand)))
489 #define atomic_fetch_and_explicit(object, operand, order) \
490 ((void)(order), __sync_fetch_and_and(&(object)->__val, operand))
491 #define atomic_fetch_or_explicit(object, operand, order) \
492 ((void)(order), __sync_fetch_and_or(&(object)->__val, operand))
493 #define atomic_fetch_sub_explicit(object, operand, order) \
494 ((void)(order), __sync_fetch_and_sub(&(object)->__val, \
495 __atomic_apply_stride(object, operand)))
496 #define atomic_fetch_xor_explicit(object, operand, order) \
497 ((void)(order), __sync_fetch_and_xor(&(object)->__val, operand))
498 #define atomic_load_explicit(object, order) \
499 ((void)(order), __sync_fetch_and_add(&(object)->__val, 0))
500 #define atomic_store_explicit(object, desired, order) \
501 ((void)atomic_exchange_explicit(object, desired, order))
502 #endif
503
504 /*
505 * Convenience functions.
506 *
507 * Don't provide these in kernel space. In kernel space, we should be
508 * disciplined enough to always provide explicit barriers.
509 */
510
511 #ifndef _KERNEL
512 #define atomic_compare_exchange_strong(object, expected, desired) \
513 atomic_compare_exchange_strong_explicit(object, expected, \
514 desired, memory_order_seq_cst, memory_order_seq_cst)
515 #define atomic_compare_exchange_weak(object, expected, desired) \
516 atomic_compare_exchange_weak_explicit(object, expected, \
517 desired, memory_order_seq_cst, memory_order_seq_cst)
518 #define atomic_exchange(object, desired) \
519 atomic_exchange_explicit(object, desired, memory_order_seq_cst)
520 #define atomic_fetch_add(object, operand) \
521 atomic_fetch_add_explicit(object, operand, memory_order_seq_cst)
522 #define atomic_fetch_and(object, operand) \
523 atomic_fetch_and_explicit(object, operand, memory_order_seq_cst)
524 #define atomic_fetch_or(object, operand) \
525 atomic_fetch_or_explicit(object, operand, memory_order_seq_cst)
526 #define atomic_fetch_sub(object, operand) \
527 atomic_fetch_sub_explicit(object, operand, memory_order_seq_cst)
528 #define atomic_fetch_xor(object, operand) \
529 atomic_fetch_xor_explicit(object, operand, memory_order_seq_cst)
530 #define atomic_load(object) \
531 atomic_load_explicit(object, memory_order_seq_cst)
532 #define atomic_store(object, desired) \
533 atomic_store_explicit(object, desired, memory_order_seq_cst)
534 #endif /* !_KERNEL */
535
536 /*
537 * 7.17.8 Atomic flag type and operations.
538 *
539 * XXX: Assume atomic_bool can be used as an atomic_flag. Is there some
540 * kind of compiler built-in type we could use?
541 */
542
543 typedef struct {
544 atomic_bool __flag;
545 } atomic_flag;
546
547 #define ATOMIC_FLAG_INIT { ATOMIC_VAR_INIT(false) }
548
549 static __inline bool
atomic_flag_test_and_set_explicit(volatile atomic_flag * __object,memory_order __order)550 atomic_flag_test_and_set_explicit(volatile atomic_flag *__object,
551 memory_order __order)
552 {
553 return (atomic_exchange_explicit(&__object->__flag, 1, __order));
554 }
555
556 static __inline void
atomic_flag_clear_explicit(volatile atomic_flag * __object,memory_order __order)557 atomic_flag_clear_explicit(volatile atomic_flag *__object, memory_order __order)
558 {
559
560 atomic_store_explicit(&__object->__flag, 0, __order);
561 }
562
563 #ifndef _KERNEL
564 static __inline bool
atomic_flag_test_and_set(volatile atomic_flag * __object)565 atomic_flag_test_and_set(volatile atomic_flag *__object)
566 {
567
568 return (atomic_flag_test_and_set_explicit(__object,
569 memory_order_seq_cst));
570 }
571
572 static __inline void
atomic_flag_clear(volatile atomic_flag * __object)573 atomic_flag_clear(volatile atomic_flag *__object)
574 {
575
576 atomic_flag_clear_explicit(__object, memory_order_seq_cst);
577 }
578 #endif /* !_KERNEL */
579
580 #endif /* <atomic> unavailable */
581
582 #endif /* !_STDATOMIC_H_ */
583