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// Copyright 2008 Dolphin Emulator Project / 2017 Citra Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.
#pragma once
#include <chrono>
#include <functional>
#include <memory>
#include <mutex>
#include <optional>
#include <string>
#include <vector>
#include "common/common_types.h"
#include "common/threadsafe_queue.h"
namespace Core::Timing {
/// A callback that may be scheduled for a particular core timing event.
using TimedCallback = std::function<void(u64 userdata, s64 cycles_late)>;
/// Contains the characteristics of a particular event.
struct EventType {
EventType(TimedCallback&& callback, std::string&& name)
: callback{std::move(callback)}, name{std::move(name)} {}
/// The event's callback function.
TimedCallback callback;
/// A pointer to the name of the event.
const std::string name;
};
/**
* This is a system to schedule events into the emulated machine's future. Time is measured
* in main CPU clock cycles.
*
* To schedule an event, you first have to register its type. This is where you pass in the
* callback. You then schedule events using the type id you get back.
*
* The int cyclesLate that the callbacks get is how many cycles late it was.
* So to schedule a new event on a regular basis:
* inside callback:
* ScheduleEvent(periodInCycles - cyclesLate, callback, "whatever")
*/
class CoreTiming {
public:
CoreTiming();
~CoreTiming();
CoreTiming(const CoreTiming&) = delete;
CoreTiming(CoreTiming&&) = delete;
CoreTiming& operator=(const CoreTiming&) = delete;
CoreTiming& operator=(CoreTiming&&) = delete;
/// CoreTiming begins at the boundary of timing slice -1. An initial call to Advance() is
/// required to end slice - 1 and start slice 0 before the first cycle of code is executed.
void Initialize();
/// Tears down all timing related functionality.
void Shutdown();
/// After the first Advance, the slice lengths and the downcount will be reduced whenever an
/// event is scheduled earlier than the current values.
///
/// Scheduling from a callback will not update the downcount until the Advance() completes.
void ScheduleEvent(s64 cycles_into_future, const std::shared_ptr<EventType>& event_type,
u64 userdata = 0);
void UnscheduleEvent(const std::shared_ptr<EventType>& event_type, u64 userdata);
/// We only permit one event of each type in the queue at a time.
void RemoveEvent(const std::shared_ptr<EventType>& event_type);
void ForceExceptionCheck(s64 cycles);
/// This should only be called from the emu thread, if you are calling it any other thread,
/// you are doing something evil
u64 GetTicks() const;
u64 GetIdleTicks() const;
void AddTicks(u64 ticks);
/// Advance must be called at the beginning of dispatcher loops, not the end. Advance() ends
/// the previous timing slice and begins the next one, you must Advance from the previous
/// slice to the current one before executing any cycles. CoreTiming starts in slice -1 so an
/// Advance() is required to initialize the slice length before the first cycle of emulated
/// instructions is executed.
void Advance();
/// Pretend that the main CPU has executed enough cycles to reach the next event.
void Idle();
std::chrono::microseconds GetGlobalTimeUs() const;
void ResetRun();
s64 GetDowncount() const;
void SwitchContext(u64 new_context) {
current_context = new_context;
}
bool CanCurrentContextRun() const {
return time_slice[current_context] > 0;
}
std::optional<u64> NextAvailableCore(const s64 needed_ticks) const;
private:
struct Event;
/// Clear all pending events. This should ONLY be done on exit.
void ClearPendingEvents();
static constexpr u64 num_cpu_cores = 4;
s64 global_timer = 0;
s64 idled_cycles = 0;
s64 slice_length = 0;
u64 accumulated_ticks = 0;
std::array<s64, num_cpu_cores> downcounts{};
// Slice of time assigned to each core per run.
std::array<s64, num_cpu_cores> time_slice{};
u64 current_context = 0;
// Are we in a function that has been called from Advance()
// If events are scheduled from a function that gets called from Advance(),
// don't change slice_length and downcount.
bool is_global_timer_sane = false;
// The queue is a min-heap using std::make_heap/push_heap/pop_heap.
// We don't use std::priority_queue because we need to be able to serialize, unserialize and
// erase arbitrary events (RemoveEvent()) regardless of the queue order. These aren't
// accomodated by the standard adaptor class.
std::vector<Event> event_queue;
u64 event_fifo_id = 0;
std::shared_ptr<EventType> ev_lost;
std::mutex inner_mutex;
};
/// Creates a core timing event with the given name and callback.
///
/// @param name The name of the core timing event to create.
/// @param callback The callback to execute for the event.
///
/// @returns An EventType instance representing the created event.
///
std::shared_ptr<EventType> CreateEvent(std::string name, TimedCallback&& callback);
} // namespace Core::Timing
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