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Use C11 atomic operations to implement the mutex instead of hard-coded intrinsics. This generates more efficient assembly on newer ARM architectures by taking advantage of the new LDA/STL instructions (and their exclusive variants), which avoid full memory barriers while still providing memory ordering guarantees. Signed-off-by: iabdalkader <i.abdalkader@gmail.com>
61 lines
2.3 KiB
C
61 lines
2.3 KiB
C
/*
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* SPDX-License-Identifier: MIT
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*
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* Copyright (C) 2013-2025 OpenMV, LLC.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*
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* Mutex implementation.
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*/
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#include "common/mutex.h"
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void mutex_init0(mutex_t *m) {
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atomic_store_explicit(&m->tid, 0, memory_order_relaxed);
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atomic_flag_clear_explicit(&m->lock, memory_order_relaxed);
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}
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void mutex_lock(mutex_t *m, size_t tid) {
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while (atomic_flag_test_and_set_explicit(&m->lock, memory_order_acquire));
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atomic_store_explicit(&m->tid, tid, memory_order_release);
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}
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bool mutex_try_lock(mutex_t *m, size_t tid) {
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if (!atomic_flag_test_and_set_explicit(&m->lock, memory_order_acquire)) {
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atomic_store_explicit(&m->tid, tid, memory_order_release);
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return true;
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}
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return false;
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}
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bool mutex_try_lock_fair(mutex_t *m, size_t tid) {
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if (atomic_load_explicit(&m->tid, memory_order_acquire) != tid) {
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if (!atomic_flag_test_and_set_explicit(&m->lock, memory_order_acquire)) {
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atomic_store_explicit(&m->tid, tid, memory_order_release);
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return true;
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}
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}
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return false;
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}
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void mutex_unlock(mutex_t *m, size_t tid) {
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if (atomic_load_explicit(&m->tid, memory_order_acquire) == tid) {
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atomic_flag_clear_explicit(&m->lock, memory_order_release);
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}
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}
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