59 lines
1.9 KiB
C++
59 lines
1.9 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 "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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ResultVal<SharedPtr<Semaphore>> Semaphore::Create(s32 initial_count, s32 max_count,
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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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SharedPtr<Semaphore> semaphore(new Semaphore);
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// TOOD(yuriks): Don't create Handle (see Thread::Create())
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CASCADE_RESULT(auto unused, Kernel::g_handle_table.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 = std::move(name);
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return MakeResult<SharedPtr<Semaphore>>(std::move(semaphore));
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}
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bool Semaphore::ShouldWait() {
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return available_count <= 0;
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}
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void Semaphore::Acquire() {
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_assert_msg_(Kernel, !ShouldWait(), "object unavailable!");
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--available_count;
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}
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ResultVal<s32> Semaphore::Release(s32 release_count) {
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if (max_count - 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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s32 previous_count = available_count;
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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 (!ShouldWait() && WakeupNextThread() != nullptr) {
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Acquire();
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}
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return MakeResult<s32>(previous_count);
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}
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} // namespace
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