1 /* Copyright (c) 2015, Google Inc.
2 *
3 * Permission to use, copy, modify, and/or distribute this software for any
4 * purpose with or without fee is hereby granted, provided that the above
5 * copyright notice and this permission notice appear in all copies.
6 *
7 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
8 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
9 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
10 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
11 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
12 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
13 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
14
15 #include "internal.h"
16
17 #include <assert.h>
18 #include <stdlib.h>
19
20
21 // See comment above the typedef of CRYPTO_refcount_t about these tests.
22 static_assert(alignof(CRYPTO_refcount_t) == alignof(CRYPTO_atomic_u32),
23 "CRYPTO_refcount_t does not match CRYPTO_atomic_u32 alignment");
24 static_assert(sizeof(CRYPTO_refcount_t) == sizeof(CRYPTO_atomic_u32),
25 "CRYPTO_refcount_t does not match CRYPTO_atomic_u32 size");
26
27 static_assert((CRYPTO_refcount_t)-1 == CRYPTO_REFCOUNT_MAX,
28 "CRYPTO_REFCOUNT_MAX is incorrect");
29
CRYPTO_refcount_inc(CRYPTO_refcount_t * in_count)30 void CRYPTO_refcount_inc(CRYPTO_refcount_t *in_count) {
31 CRYPTO_atomic_u32 *count = (CRYPTO_atomic_u32 *)in_count;
32 uint32_t expected = CRYPTO_atomic_load_u32(count);
33
34 while (expected != CRYPTO_REFCOUNT_MAX) {
35 uint32_t new_value = expected + 1;
36 if (CRYPTO_atomic_compare_exchange_weak_u32(count, &expected, new_value)) {
37 break;
38 }
39 }
40 }
41
CRYPTO_refcount_dec_and_test_zero(CRYPTO_refcount_t * in_count)42 int CRYPTO_refcount_dec_and_test_zero(CRYPTO_refcount_t *in_count) {
43 CRYPTO_atomic_u32 *count = (CRYPTO_atomic_u32 *)in_count;
44 uint32_t expected = CRYPTO_atomic_load_u32(count);
45
46 for (;;) {
47 if (expected == 0) {
48 abort();
49 } else if (expected == CRYPTO_REFCOUNT_MAX) {
50 return 0;
51 } else {
52 const uint32_t new_value = expected - 1;
53 if (CRYPTO_atomic_compare_exchange_weak_u32(count, &expected,
54 new_value)) {
55 return new_value == 0;
56 }
57 }
58 }
59 }
60