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// Copyright 2014 Citra Emulator Project
// Licensed under GPLv2 or any later version
// 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 WaitObject {
public:
std::string GetTypeName() const override { return "Semaphore"; }
std::string GetName() const override { return name; }
static const HandleType HANDLE_TYPE = HandleType::Semaphore;
HandleType GetHandleType() const override { return HANDLE_TYPE; }
s32 max_count; ///< Maximum number of simultaneous holders the semaphore can have
s32 available_count; ///< Number of free slots left in the semaphore
std::string name; ///< Name of semaphore (optional)
bool ShouldWait() override {
return available_count <= 0;
}
void Acquire() override {
_assert_msg_(Kernel, !ShouldWait(), "object unavailable!");
--available_count;
}
};
////////////////////////////////////////////////////////////////////////////////////////////////////
ResultCode CreateSemaphore(Handle* handle, s32 initial_count,
s32 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;
// TOOD(yuriks): Fix error reporting
*handle = g_handle_table.Create(semaphore).ValueOr(INVALID_HANDLE);
// 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_handle_table.Get<Semaphore>(handle).get();
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->ShouldWait() && semaphore->WakeupNextThread() != nullptr) {
semaphore->Acquire();
}
return RESULT_SUCCESS;
}
} // namespace
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