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Diffstat (limited to '')
-rw-r--r-- | src/core/hle/kernel/semaphore.cpp | 95 |
1 files changed, 95 insertions, 0 deletions
diff --git a/src/core/hle/kernel/semaphore.cpp b/src/core/hle/kernel/semaphore.cpp new file mode 100644 index 000000000..6bc8066a6 --- /dev/null +++ b/src/core/hle/kernel/semaphore.cpp @@ -0,0 +1,95 @@ +// 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 Object { +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::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 = !IsAvailable(); + + if (wait) { + Kernel::WaitCurrentThread(WAITTYPE_SEMA, GetHandle()); + waiting_threads.push(GetCurrentThreadHandle()); + } else { + --available_count; + } + + return MakeResult<bool>(wait); + } +}; + +//////////////////////////////////////////////////////////////////////////////////////////////////// + +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); + 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 |