2014-12-03 18:49:51 -05:00
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// Copyright 2014 Citra Emulator Project
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// Licensed under GPLv2+
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// Refer to the license.txt file included.
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2014-12-04 11:40:36 -05:00
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#include <queue>
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2014-12-03 18:49:51 -05:00
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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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u32 initial_count; ///< Number of entries reserved for other threads
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u32 max_count; ///< Maximum number of simultaneous holders the semaphore can have
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u32 current_usage; ///< Number of currently used entries 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 is at its peak capacity
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* @return Whether the semaphore is full
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*/
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bool IsFull() const {
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return current_usage == max_count;
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}
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ResultVal<bool> WaitSynchronization() override {
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bool wait = current_usage == max_count;
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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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++current_usage;
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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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/**
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* Creates a semaphore
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* @param initial_count number of slots reserved for other threads
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* @param max_count maximum number of holders the semaphore can have
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* @param name Optional name of semaphore
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* @return Handle for the newly created semaphore
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*/
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Handle CreateSemaphore(u32 initial_count,
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u32 max_count, const std::string& name) {
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Semaphore* semaphore = new Semaphore;
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Handle handle = g_object_pool.Create(semaphore);
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semaphore->initial_count = initial_count;
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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 = semaphore->current_usage = max_count;
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semaphore->current_usage -= initial_count;
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semaphore->name = name;
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return handle;
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}
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ResultCode CreateSemaphore(Handle* handle, u32 initial_count,
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u32 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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*handle = CreateSemaphore(initial_count, max_count, 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->current_usage < 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->max_count - semaphore->current_usage;
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semaphore->current_usage = semaphore->current_usage - 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->IsFull()) {
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Kernel::ResumeThreadFromWait(semaphore->waiting_threads.front());
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semaphore->waiting_threads.pop();
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semaphore->current_usage++;
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}
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return RESULT_SUCCESS;
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}
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} // namespace
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