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https://github.com/Atmosphere-NX/Atmosphere-libs.git
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121 lines
4.4 KiB
C++
121 lines
4.4 KiB
C++
/*
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* Copyright (c) Atmosphère-NX
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <stratosphere.hpp>
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namespace ams::os {
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namespace {
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ALWAYS_INLINE bool IsBarrierInitialized(const BarrierType *barrier) {
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return barrier->max_threads != 0;
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}
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ALWAYS_INLINE u64 GetBarrierBaseCounterImpl(const BarrierType *barrier) {
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/* Check pre-conditions. */
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#if defined(AMS_OS_INTERNAL_CRITICAL_SECTION_IMPL_CAN_CHECK_LOCKED_BY_CURRENT_THREAD)
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AMS_ASSERT(util::GetReference(barrier->cs_barrier).IsLockedByCurrentThread());
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#endif
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/* Convert two u32s to u64. */
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return (static_cast<u64>(barrier->base_counter_lower) << 0) | (static_cast<u64>(barrier->base_counter_upper) << BITSIZEOF(barrier->base_counter_lower));
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}
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ALWAYS_INLINE void SetBarrierBaseCounterImpl(BarrierType *barrier, u64 value) {
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/* Check pre-conditions. */
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#if defined(AMS_OS_INTERNAL_CRITICAL_SECTION_IMPL_CAN_CHECK_LOCKED_BY_CURRENT_THREAD)
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AMS_ASSERT(util::GetReference(barrier->cs_barrier).IsLockedByCurrentThread());
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#endif
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/* Store as two u32s. */
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barrier->base_counter_lower = static_cast<u32>(value >> 0);
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barrier->base_counter_upper = static_cast<u32>(value >> BITSIZEOF(barrier->base_counter_lower));
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}
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}
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void InitializeBarrier(BarrierType *barrier, int num_threads) {
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/* Check pre-conditions. */
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AMS_ASSERT(num_threads >= 1);
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/* Construct objects. */
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util::ConstructAt(barrier->cs_barrier);
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util::ConstructAt(barrier->cv_gathered);
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/* Set member variables. */
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barrier->max_threads = num_threads;
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barrier->waiting_threads = 0;
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barrier->base_counter_lower = 0;
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barrier->base_counter_upper = 0;
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}
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void FinalizeBarrier(BarrierType *barrier) {
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/* Check pre-conditions. */
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AMS_ASSERT(IsBarrierInitialized(barrier));
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AMS_ASSERT(barrier->waiting_threads == 0);
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/* Clear max threads. */
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barrier->max_threads = 0;
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/* Destroy objects. */
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util::DestroyAt(barrier->cs_barrier);
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util::DestroyAt(barrier->cv_gathered);
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}
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void AwaitBarrier(BarrierType *barrier) {
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/* Check pre-conditions. */
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AMS_ASSERT(IsBarrierInitialized(barrier));
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/* Await the barrier. */
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{
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/* Acquire exclusive access to the barrier. */
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auto &cs = util::GetReference(barrier->cs_barrier);
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std::scoped_lock lk(cs);
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/* Read barrier state. */
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const u64 base_counter = GetBarrierBaseCounterImpl(barrier);
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const auto max_threads = barrier->max_threads;
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auto waiting_threads = barrier->waiting_threads;
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/* Determine next base counter. */
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const u64 done_base_counter = base_counter + max_threads;
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/* Increment waiting threads. */
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++waiting_threads;
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/* Check if all threads have synchronized. */
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if (waiting_threads >= max_threads) {
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/* They have, so reset waiting thread count. */
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barrier->waiting_threads = 0;
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/* Set the updated base counter. */
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SetBarrierBaseCounterImpl(barrier, done_base_counter);
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/* Broadcast to our cv. */
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util::GetReference(barrier->cv_gathered).Broadcast();
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} else {
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/* More threads are needed, so update waiting thread count. */
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barrier->waiting_threads = waiting_threads;
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/* Wait for remaining threads to await. */
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while (GetBarrierBaseCounterImpl(barrier) < done_base_counter) {
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util::GetReference(barrier->cv_gathered).Wait(std::addressof(cs));
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}
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}
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}
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}
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}
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