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+// Copyright 2020 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <functional>
+#include <memory>
+
+#include "common/common_types.h"
+#include "common/spin_lock.h"
+
+#if !defined(_WIN32) && !defined(WIN32)
+namespace boost::context::detail {
+struct transfer_t;
+}
+#endif
+
+namespace Common {
+
+/**
+ * Fiber class
+ * a fiber is a userspace thread with it's own context. They can be used to
+ * implement coroutines, emulated threading systems and certain asynchronous
+ * patterns.
+ *
+ * This class implements fibers at a low level, thus allowing greater freedom
+ * to implement such patterns. This fiber class is 'threadsafe' only one fiber
+ * can be running at a time and threads will be locked while trying to yield to
+ * a running fiber until it yields. WARNING exchanging two running fibers between
+ * threads will cause a deadlock. In order to prevent a deadlock, each thread should
+ * have an intermediary fiber, you switch to the intermediary fiber of the current
+ * thread and then from it switch to the expected fiber. This way you can exchange
+ * 2 fibers within 2 different threads.
+ */
+class Fiber {
+public:
+ Fiber(std::function<void(void*)>&& entry_point_func, void* start_parameter);
+ ~Fiber();
+
+ Fiber(const Fiber&) = delete;
+ Fiber& operator=(const Fiber&) = delete;
+
+ Fiber(Fiber&&) = default;
+ Fiber& operator=(Fiber&&) = default;
+
+ /// Yields control from Fiber 'from' to Fiber 'to'
+ /// Fiber 'from' must be the currently running fiber.
+ static void YieldTo(std::shared_ptr<Fiber>& from, std::shared_ptr<Fiber>& to);
+ static std::shared_ptr<Fiber> ThreadToFiber();
+
+ void SetRewindPoint(std::function<void(void*)>&& rewind_func, void* start_parameter);
+
+ void Rewind();
+
+ /// Only call from main thread's fiber
+ void Exit();
+
+ /// Changes the start parameter of the fiber. Has no effect if the fiber already started
+ void SetStartParameter(void* new_parameter) {
+ start_parameter = new_parameter;
+ }
+
+private:
+ Fiber();
+
+#if defined(_WIN32) || defined(WIN32)
+ void OnRewind();
+ void Start();
+ static void FiberStartFunc(void* fiber_parameter);
+ static void RewindStartFunc(void* fiber_parameter);
+#else
+ void OnRewind(boost::context::detail::transfer_t& transfer);
+ void Start(boost::context::detail::transfer_t& transfer);
+ static void FiberStartFunc(boost::context::detail::transfer_t transfer);
+ static void RewindStartFunc(boost::context::detail::transfer_t transfer);
+#endif
+
+ struct FiberImpl;
+
+ SpinLock guard{};
+ std::function<void(void*)> entry_point;
+ std::function<void(void*)> rewind_point;
+ void* rewind_parameter{};
+ void* start_parameter{};
+ std::shared_ptr<Fiber> previous_fiber;
+ std::unique_ptr<FiberImpl> impl;
+ bool is_thread_fiber{};
+ bool released{};
+};
+
+} // namespace Common