Atmosphere/libraries/libstratosphere/source/os/os_semaphore.cpp

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/*
* Copyright (c) 2018-2020 Atmosphère-NX
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "impl/os_waitable_object_list.hpp"
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#include "impl/os_timeout_helper.hpp"
namespace ams::os {
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void InitializeSemaphore(SemaphoreType *sema, s32 count, s32 max_count) {
AMS_ASSERT(max_count >= 1);
AMS_ASSERT(count >= 0);
/* Setup objects. */
new (GetPointer(sema->cs_sema)) impl::InternalCriticalSection;
new (GetPointer(sema->cv_not_zero)) impl::InternalConditionVariable;
/* Setup wait lists. */
new (GetPointer(sema->waitlist)) impl::WaitableObjectList;
/* Set member variables. */
sema->count = count;
sema->max_count = max_count;
/* Mark initialized. */
sema->state = SemaphoreType::State_Initialized;
}
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void FinalizeSemaphore(SemaphoreType *sema) {
AMS_ASSERT(sema->state = SemaphoreType::State_Initialized);
AMS_ASSERT(GetReference(sema->waitlist).IsEmpty());
/* Mark uninitialized. */
sema->state = SemaphoreType::State_NotInitialized;
/* Destroy wait lists. */
GetReference(sema->waitlist).~WaitableObjectList();
/* Destroy objects. */
GetReference(sema->cv_not_zero).~InternalConditionVariable();
GetReference(sema->cs_sema).~InternalCriticalSection();
}
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void AcquireSemaphore(SemaphoreType *sema) {
AMS_ASSERT(sema->state == SemaphoreType::State_Initialized);
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{
std::scoped_lock lk(GetReference(sema->cs_sema));
while (sema->count == 0) {
GetReference(sema->cv_not_zero).Wait(GetPointer(sema->cs_sema));
}
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--sema->count;
}
}
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bool TryAcquireSemaphore(SemaphoreType *sema) {
AMS_ASSERT(sema->state == SemaphoreType::State_Initialized);
{
std::scoped_lock lk(GetReference(sema->cs_sema));
if (sema->count == 0) {
return false;
}
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--sema->count;
}
return true;
}
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bool TimedAcquireSemaphore(SemaphoreType *sema, TimeSpan timeout) {
AMS_ASSERT(sema->state == SemaphoreType::State_Initialized);
AMS_ASSERT(timeout.GetNanoSeconds() >= 0);
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{
impl::TimeoutHelper timeout_helper(timeout);
std::scoped_lock lk(GetReference(sema->cs_sema));
while (sema->count == 0) {
if (timeout_helper.TimedOut()) {
return false;
}
GetReference(sema->cv_not_zero).TimedWait(GetPointer(sema->cs_sema), timeout_helper);
}
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--sema->count;
}
return true;
}
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void ReleaseSemaphore(SemaphoreType *sema) {
AMS_ASSERT(sema->state == SemaphoreType::State_Initialized);
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{
std::scoped_lock lk(GetReference(sema->cs_sema));
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AMS_ASSERT(sema->count + 1 <= sema->max_count);
++sema->count;
GetReference(sema->cv_not_zero).Signal();
GetReference(sema->waitlist).SignalAllThreads();
}
}
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void ReleaseSemaphore(SemaphoreType *sema, s32 count) {
AMS_ASSERT(sema->state == SemaphoreType::State_Initialized);
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{
std::scoped_lock lk(GetReference(sema->cs_sema));
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AMS_ASSERT(sema->count + count <= sema->max_count);
sema->count += count;
GetReference(sema->cv_not_zero).Signal();
GetReference(sema->waitlist).SignalAllThreads();
}
}
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s32 GetCurrentSemaphoreCount(const SemaphoreType *sema) {
AMS_ASSERT(sema->state == SemaphoreType::State_Initialized);
return sema->count;
}
// void InitializeWaitableHolder(WaitableHolderType *waitable_holder, SemaphoreType *sema);
}