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// Copyright 2014 Citra Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.
#include <queue>
#include "common/common.h"
#include "core/hle/kernel/kernel.h"
#include "core/hle/kernel/semaphore.h"
#include "core/hle/kernel/thread.h"
namespace Kernel {
class Semaphore : public Object {
public:
std::string GetTypeName() const override { return "Semaphore"; }
std::string GetName() const override { return name; }
static Kernel::HandleType GetStaticHandleType() { return Kernel::HandleType::Semaphore; }
Kernel::HandleType GetHandleType() const override { return Kernel::HandleType::Semaphore; }
u32 max_count; ///< Maximum number of simultaneous holders the semaphore can have
u32 available_count; ///< Number of free slots left in the semaphore
std::queue<Handle> waiting_threads; ///< Threads that are waiting for the semaphore
std::string name; ///< Name of semaphore (optional)
/**
* Tests whether a semaphore still has free slots
* @return Whether the semaphore is available
*/
bool IsAvailable() const {
return available_count > 0;
}
ResultVal<bool> WaitSynchronization() override {
bool wait = available_count == 0;
if (wait) {
Kernel::WaitCurrentThread(WAITTYPE_SEMA, GetHandle());
waiting_threads.push(GetCurrentThreadHandle());
} else {
--available_count;
}
return MakeResult<bool>(wait);
}
};
////////////////////////////////////////////////////////////////////////////////////////////////////
ResultCode CreateSemaphore(Handle* handle, u32 initial_count,
u32 max_count, const std::string& name) {
if (initial_count > max_count)
return ResultCode(ErrorDescription::InvalidCombination, ErrorModule::Kernel,
ErrorSummary::WrongArgument, ErrorLevel::Permanent);
Semaphore* semaphore = new Semaphore;
*handle = g_object_pool.Create(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 = name;
return RESULT_SUCCESS;
}
ResultCode ReleaseSemaphore(s32* count, Handle handle, s32 release_count) {
Semaphore* semaphore = g_object_pool.Get<Semaphore>(handle);
if (semaphore == nullptr)
return InvalidHandle(ErrorModule::Kernel);
if (semaphore->max_count - semaphore->available_count < release_count)
return ResultCode(ErrorDescription::OutOfRange, ErrorModule::Kernel,
ErrorSummary::InvalidArgument, ErrorLevel::Permanent);
*count = semaphore->available_count;
semaphore->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 (!semaphore->waiting_threads.empty() && semaphore->IsAvailable()) {
Kernel::ResumeThreadFromWait(semaphore->waiting_threads.front());
semaphore->waiting_threads.pop();
--semaphore->available_count;
}
return RESULT_SUCCESS;
}
} // namespace
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