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95 lines
3.3 KiB
C++
95 lines
3.3 KiB
C++
// Copyright 2014 Citra Emulator Project
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// Licensed under GPLv2 or any later version
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// Refer to the license.txt file included.
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#include <queue>
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#include "common/common.h"
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#include "core/hle/kernel/kernel.h"
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#include "core/hle/kernel/semaphore.h"
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#include "core/hle/kernel/thread.h"
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namespace Kernel {
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class Semaphore : public Object {
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public:
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std::string GetTypeName() const override { return "Semaphore"; }
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std::string GetName() const override { return name; }
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static Kernel::HandleType GetStaticHandleType() { return Kernel::HandleType::Semaphore; }
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Kernel::HandleType GetHandleType() const override { return Kernel::HandleType::Semaphore; }
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s32 max_count; ///< Maximum number of simultaneous holders the semaphore can have
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s32 available_count; ///< Number of free slots left in the semaphore
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std::queue<Handle> waiting_threads; ///< Threads that are waiting for the semaphore
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std::string name; ///< Name of semaphore (optional)
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/**
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* Tests whether a semaphore still has free slots
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* @return Whether the semaphore is available
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*/
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bool IsAvailable() const {
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return available_count > 0;
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}
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ResultVal<bool> WaitSynchronization() override {
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bool wait = !IsAvailable();
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if (wait) {
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Kernel::WaitCurrentThread(WAITTYPE_SEMA, GetHandle());
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waiting_threads.push(GetCurrentThreadHandle());
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} else {
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--available_count;
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}
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return MakeResult<bool>(wait);
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}
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};
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////////////////////////////////////////////////////////////////////////////////////////////////////
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ResultCode CreateSemaphore(Handle* handle, s32 initial_count,
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s32 max_count, const std::string& name) {
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if (initial_count > max_count)
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return ResultCode(ErrorDescription::InvalidCombination, ErrorModule::Kernel,
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ErrorSummary::WrongArgument, ErrorLevel::Permanent);
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Semaphore* semaphore = new Semaphore;
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*handle = g_object_pool.Create(semaphore);
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// When the semaphore is created, some slots are reserved for other threads,
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// and the rest is reserved for the caller thread
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semaphore->max_count = max_count;
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semaphore->available_count = initial_count;
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semaphore->name = name;
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return RESULT_SUCCESS;
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}
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ResultCode ReleaseSemaphore(s32* count, Handle handle, s32 release_count) {
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Semaphore* semaphore = g_object_pool.Get<Semaphore>(handle);
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if (semaphore == nullptr)
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return InvalidHandle(ErrorModule::Kernel);
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if (semaphore->max_count - semaphore->available_count < release_count)
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return ResultCode(ErrorDescription::OutOfRange, ErrorModule::Kernel,
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ErrorSummary::InvalidArgument, ErrorLevel::Permanent);
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*count = semaphore->available_count;
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semaphore->available_count += release_count;
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// Notify some of the threads that the semaphore has been released
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// stop once the semaphore is full again or there are no more waiting threads
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while (!semaphore->waiting_threads.empty() && semaphore->IsAvailable()) {
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Kernel::ResumeThreadFromWait(semaphore->waiting_threads.front());
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semaphore->waiting_threads.pop();
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--semaphore->available_count;
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}
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return RESULT_SUCCESS;
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}
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} // namespace
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