openmv/common/mutex.c
iabdalkader 6d28ea730e common/mutex: Return true, if unlocked.
Signed-off-by: iabdalkader <i.abdalkader@gmail.com>
2025-09-18 18:06:44 +02:00

63 lines
2.3 KiB
C

/*
* SPDX-License-Identifier: MIT
*
* Copyright (C) 2013-2025 OpenMV, LLC.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*
* Mutex implementation.
*/
#include "common/mutex.h"
void mutex_init0(mutex_t *m) {
atomic_store_explicit(&m->tid, 0, memory_order_relaxed);
atomic_flag_clear_explicit(&m->lock, memory_order_relaxed);
}
void mutex_lock(mutex_t *m, size_t tid) {
while (atomic_flag_test_and_set_explicit(&m->lock, memory_order_acquire));
atomic_store_explicit(&m->tid, tid, memory_order_release);
}
bool mutex_try_lock(mutex_t *m, size_t tid) {
if (!atomic_flag_test_and_set_explicit(&m->lock, memory_order_acquire)) {
atomic_store_explicit(&m->tid, tid, memory_order_release);
return true;
}
return false;
}
bool mutex_try_lock_fair(mutex_t *m, size_t tid) {
if (atomic_load_explicit(&m->tid, memory_order_acquire) != tid) {
if (!atomic_flag_test_and_set_explicit(&m->lock, memory_order_acquire)) {
atomic_store_explicit(&m->tid, tid, memory_order_release);
return true;
}
}
return false;
}
bool mutex_unlock(mutex_t *m, size_t tid) {
if (atomic_load_explicit(&m->tid, memory_order_acquire) == tid) {
atomic_flag_clear_explicit(&m->lock, memory_order_release);
return true;
}
return false;
}