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