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// Copyright 2014 Citra Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#include "common/assert.h"
#include "core/hle/kernel/kernel.h"
#include "core/hle/kernel/semaphore.h"
#include "core/hle/kernel/thread.h"
namespace Kernel {
Semaphore::Semaphore() {}
Semaphore::~Semaphore() {}
ResultVal<SharedPtr<Semaphore>> Semaphore::Create(s32 initial_count, s32 max_count,
std::string name) {
if (initial_count > max_count)
return ResultCode(ErrorDescription::InvalidCombination, ErrorModule::Kernel,
ErrorSummary::WrongArgument, ErrorLevel::Permanent);
SharedPtr<Semaphore> semaphore(new Semaphore);
// When the semaphore is created, some slots are reserved for other threads,
// and the rest is reserved for the caller thread
semaphore->max_count = max_count;
semaphore->available_count = initial_count;
semaphore->name = std::move(name);
return MakeResult<SharedPtr<Semaphore>>(std::move(semaphore));
}
bool Semaphore::ShouldWait() {
return available_count <= 0;
}
void Semaphore::Acquire() {
ASSERT_MSG(!ShouldWait(), "object unavailable!");
--available_count;
}
ResultVal<s32> Semaphore::Release(s32 release_count) {
if (max_count - available_count < release_count)
return ResultCode(ErrorDescription::OutOfRange, ErrorModule::Kernel,
ErrorSummary::InvalidArgument, ErrorLevel::Permanent);
s32 previous_count = available_count;
available_count += release_count;
// Notify some of the threads that the semaphore has been released
// stop once the semaphore is full again or there are no more waiting threads
while (!ShouldWait() && WakeupNextThread() != nullptr) {
Acquire();
}
HLE::Reschedule(__func__);
return MakeResult<s32>(previous_count);
}
} // namespace
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