Atmosphere/libraries/libstratosphere/source/os/os_light_semaphore.cpp
2021-09-29 13:24:03 -07:00

180 lines
5.8 KiB
C++

/*
* 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 <stratosphere.hpp>
#include "impl/os_timeout_helper.hpp"
namespace ams::os {
void InitializeLightSemaphore(LightSemaphoreType *sema, s32 count, s32 max_count) {
/* Check pre-conditions. */
AMS_ASSERT(max_count >= 1);
AMS_ASSERT(0 <= count && count <= max_count);
/* Setup objects. */
util::ConstructAt(sema->mutex);
util::ConstructAt(sema->ev_not_zero, count > 0);
/* Set member variables. */
sema->count = count;
sema->max_count = max_count;
/* Mark initialized. */
sema->state = LightSemaphoreType::State_Initialized;
}
void FinalizeLightSemaphore(LightSemaphoreType *sema) {
/* Check pre-conditions. */
AMS_ASSERT(sema->state == LightSemaphoreType::State_Initialized);
/* Mark uninitialized. */
sema->state = LightSemaphoreType::State_NotInitialized;
/* Destroy objects. */
util::DestroyAt(sema->mutex);
util::DestroyAt(sema->ev_not_zero);
}
void AcquireLightSemaphore(LightSemaphoreType *sema) {
/* Check pre-conditions. */
AMS_ASSERT(sema->state == LightSemaphoreType::State_Initialized);
/* Repeatedly try to acquire the semaphore. */
while (true) {
/* Try to acquire the semaphore. */
{
/* Acquire exclusive access to the semaphore. */
std::scoped_lock lk(util::GetReference(sema->mutex));
/* If we can, acquire. */
if (sema->count > 0) {
--sema->count;
return;
}
/* Ensure that we can wait once we're unlocked. */
util::GetReference(sema->ev_not_zero).Clear();
}
/* Wait until we can try again. */
util::GetReference(sema->ev_not_zero).WaitWithManualClear();
}
}
bool TryAcquireLightSemaphore(LightSemaphoreType *sema) {
/* Check pre-conditions. */
AMS_ASSERT(sema->state == LightSemaphoreType::State_Initialized);
/* Acquire exclusive access to the semaphore. */
std::scoped_lock lk(util::GetReference(sema->mutex));
/* Try to acquire. */
if (sema->count > 0) {
--sema->count;
return true;
} else {
return false;
}
}
bool TimedAcquireLightSemaphore(LightSemaphoreType *sema, TimeSpan timeout) {
/* Check pre-conditions. */
AMS_ASSERT(sema->state == LightSemaphoreType::State_Initialized);
AMS_ASSERT(timeout.GetNanoSeconds() >= 0);
/* Create timeout helper. */
impl::TimeoutHelper timeout_helper(timeout);
/* Repeatedly try to acquire the semaphore. */
while (true) {
/* Try to acquire the semaphore. */
{
/* Acquire exclusive access to the semaphore. */
std::scoped_lock lk(util::GetReference(sema->mutex));
/* If we can, acquire. */
if (sema->count > 0) {
--sema->count;
return true;
}
/* Ensure that we can wait once we're unlocked. */
util::GetReference(sema->ev_not_zero).Clear();
}
/* Check if we're timed out. */
if (timeout_helper.TimedOut()) {
return false;
}
/* Wait until we can try again. */
util::GetReference(sema->ev_not_zero).TimedWaitWithManualClear(timeout_helper);
}
}
void ReleaseLightSemaphore(LightSemaphoreType *sema) {
/* Check pre-conditions. */
AMS_ASSERT(sema->state == LightSemaphoreType::State_Initialized);
/* Release the semaphore. */
{
/* Acquire exclusive access to the semaphore. */
std::scoped_lock lk(util::GetReference(sema->mutex));
/* Check that we can release. */
AMS_ASSERT(sema->count + 1 <= sema->max_count);
/* Release. */
++sema->count;
}
/* Signal that we released. */
util::GetReference(sema->ev_not_zero).SignalWithManualClear();
}
void ReleaseLightSemaphore(LightSemaphoreType *sema, s32 count) {
/* Check pre-conditions. */
AMS_ASSERT(sema->state == LightSemaphoreType::State_Initialized);
AMS_ASSERT(count >= 1);
/* Release the semaphore. */
{
/* Acquire exclusive access to the semaphore. */
std::scoped_lock lk(util::GetReference(sema->mutex));
/* Check that we can release. */
AMS_ASSERT(sema->count + count <= sema->max_count);
/* Release. */
sema->count += count;
}
/* Signal that we released. */
util::GetReference(sema->ev_not_zero).SignalWithManualClear();
}
s32 GetCurrentLightSemaphoreCount(const LightSemaphoreType *sema) {
/* Check pre-conditions. */
AMS_ASSERT(sema->state == LightSemaphoreType::State_Initialized);
/* Acquire exclusive access to the semaphore. */
std::scoped_lock lk(util::GetReference(sema->mutex));
/* Get the count. */
return sema->count;
}
}