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- /* Copyright (c) 2015, Google Inc.
- *
- * Permission to use, copy, modify, and/or distribute this software for any
- * purpose with or without fee is hereby granted, provided that the above
- * copyright notice and this permission notice appear in all copies.
- *
- * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
- * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
- * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
- * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
- * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
- * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
-
- #include "internal.h"
-
-
- #if defined(OPENSSL_C11_ATOMIC)
-
- #include <assert.h>
- #include <stdalign.h>
- #include <stdatomic.h>
- #include <stdlib.h>
-
- #include <openssl/type_check.h>
-
-
- /* See comment above the typedef of CRYPTO_refcount_t about these tests. */
- static_assert(alignof(CRYPTO_refcount_t) == alignof(_Atomic CRYPTO_refcount_t),
- "_Atomic alters the needed alignment of a reference count");
- static_assert(sizeof(CRYPTO_refcount_t) == sizeof(_Atomic CRYPTO_refcount_t),
- "_Atomic alters the size of a reference count");
-
- static_assert((CRYPTO_refcount_t)-1 == CRYPTO_REFCOUNT_MAX,
- "CRYPTO_REFCOUNT_MAX is incorrect");
-
- void CRYPTO_refcount_inc(CRYPTO_refcount_t *in_count) {
- _Atomic CRYPTO_refcount_t *count = (_Atomic CRYPTO_refcount_t *) in_count;
- uint32_t expected = atomic_load(count);
-
- while (expected != CRYPTO_REFCOUNT_MAX) {
- uint32_t new_value = expected + 1;
- if (atomic_compare_exchange_weak(count, &expected, new_value)) {
- break;
- }
- }
- }
-
- int CRYPTO_refcount_dec_and_test_zero(CRYPTO_refcount_t *in_count) {
- _Atomic CRYPTO_refcount_t *count = (_Atomic CRYPTO_refcount_t *)in_count;
- uint32_t expected = atomic_load(count);
-
- for (;;) {
- if (expected == 0) {
- abort();
- } else if (expected == CRYPTO_REFCOUNT_MAX) {
- return 0;
- } else {
- const uint32_t new_value = expected - 1;
- if (atomic_compare_exchange_weak(count, &expected, new_value)) {
- return new_value == 0;
- }
- }
- }
- }
-
- #endif /* OPENSSL_C11_ATOMIC */
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