From 62e35ffc0effddfacb73ebc766735148436d7331 Mon Sep 17 00:00:00 2001
From: Fernando Sahmkow <fsahmkow27@gmail.com>
Date: Wed, 5 Feb 2020 19:12:27 -0400
Subject: Core: Implement a Host Timer.

---
 src/core/host_timing.cpp | 161 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 161 insertions(+)
 create mode 100644 src/core/host_timing.cpp

(limited to 'src/core/host_timing.cpp')

diff --git a/src/core/host_timing.cpp b/src/core/host_timing.cpp
new file mode 100644
index 000000000..c02f571c6
--- /dev/null
+++ b/src/core/host_timing.cpp
@@ -0,0 +1,161 @@
+// Copyright 2020 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include "core/host_timing.h"
+
+#include <algorithm>
+#include <mutex>
+#include <string>
+#include <tuple>
+
+#include "common/assert.h"
+#include "common/thread.h"
+#include "core/core_timing_util.h"
+
+namespace Core::HostTiming {
+
+std::shared_ptr<EventType> CreateEvent(std::string name, TimedCallback&& callback) {
+    return std::make_shared<EventType>(std::move(callback), std::move(name));
+}
+
+struct CoreTiming::Event {
+    u64 time;
+    u64 fifo_order;
+    u64 userdata;
+    std::weak_ptr<EventType> type;
+
+    // Sort by time, unless the times are the same, in which case sort by
+    // the order added to the queue
+    friend bool operator>(const Event& left, const Event& right) {
+        return std::tie(left.time, left.fifo_order) > std::tie(right.time, right.fifo_order);
+    }
+
+    friend bool operator<(const Event& left, const Event& right) {
+        return std::tie(left.time, left.fifo_order) < std::tie(right.time, right.fifo_order);
+    }
+};
+
+CoreTiming::CoreTiming() = default;
+CoreTiming::~CoreTiming() = default;
+
+void CoreTiming::ThreadEntry(CoreTiming& instance) {
+    instance.Advance();
+}
+
+void CoreTiming::Initialize() {
+    event_fifo_id = 0;
+    const auto empty_timed_callback = [](u64, s64) {};
+    ev_lost = CreateEvent("_lost_event", empty_timed_callback);
+    start_time = std::chrono::system_clock::now();
+    timer_thread = std::make_unique<std::thread>(ThreadEntry, std::ref(*this));
+}
+
+void CoreTiming::Shutdown() {
+    std::unique_lock<std::mutex> guard(inner_mutex);
+    shutting_down = true;
+    if (!is_set) {
+        is_set = true;
+        condvar.notify_one();
+    }
+    inner_mutex.unlock();
+    timer_thread->join();
+    ClearPendingEvents();
+}
+
+void CoreTiming::ScheduleEvent(s64 ns_into_future, const std::shared_ptr<EventType>& event_type,
+                               u64 userdata) {
+    std::lock_guard guard{inner_mutex};
+    const u64 timeout = static_cast<u64>(GetGlobalTimeNs().count() + ns_into_future);
+
+    event_queue.emplace_back(Event{timeout, event_fifo_id++, userdata, event_type});
+
+    std::push_heap(event_queue.begin(), event_queue.end(), std::greater<>());
+    if (!is_set) {
+        is_set = true;
+        condvar.notify_one();
+    }
+}
+
+void CoreTiming::UnscheduleEvent(const std::shared_ptr<EventType>& event_type, u64 userdata) {
+    std::lock_guard guard{inner_mutex};
+
+    const auto itr = std::remove_if(event_queue.begin(), event_queue.end(), [&](const Event& e) {
+        return e.type.lock().get() == event_type.get() && e.userdata == userdata;
+    });
+
+    // Removing random items breaks the invariant so we have to re-establish it.
+    if (itr != event_queue.end()) {
+        event_queue.erase(itr, event_queue.end());
+        std::make_heap(event_queue.begin(), event_queue.end(), std::greater<>());
+    }
+}
+
+u64 CoreTiming::GetCPUTicks() const {
+    std::chrono::nanoseconds time_now = GetGlobalTimeNs();
+    return Core::Timing::nsToCycles(time_now);
+}
+
+u64 CoreTiming::GetClockTicks() const {
+    std::chrono::nanoseconds time_now = GetGlobalTimeNs();
+    return Core::Timing::nsToClockCycles(time_now);
+}
+
+void CoreTiming::ClearPendingEvents() {
+    event_queue.clear();
+}
+
+void CoreTiming::RemoveEvent(const std::shared_ptr<EventType>& event_type) {
+    std::lock_guard guard{inner_mutex};
+
+    const auto itr = std::remove_if(event_queue.begin(), event_queue.end(), [&](const Event& e) {
+        return e.type.lock().get() == event_type.get();
+    });
+
+    // Removing random items breaks the invariant so we have to re-establish it.
+    if (itr != event_queue.end()) {
+        event_queue.erase(itr, event_queue.end());
+        std::make_heap(event_queue.begin(), event_queue.end(), std::greater<>());
+    }
+}
+
+void CoreTiming::Advance() {
+    while (true) {
+        std::unique_lock<std::mutex> guard(inner_mutex);
+
+        global_timer = GetGlobalTimeNs().count();
+
+        while (!event_queue.empty() && event_queue.front().time <= global_timer) {
+            Event evt = std::move(event_queue.front());
+            std::pop_heap(event_queue.begin(), event_queue.end(), std::greater<>());
+            event_queue.pop_back();
+            inner_mutex.unlock();
+
+            if (auto event_type{evt.type.lock()}) {
+                event_type->callback(evt.userdata, global_timer - evt.time);
+            }
+
+            inner_mutex.lock();
+        }
+        auto next_time = std::chrono::nanoseconds(event_queue.front().time - global_timer);
+        condvar.wait_for(guard, next_time, [this] { return is_set; });
+        is_set = false;
+        if (shutting_down) {
+            break;
+        }
+    }
+}
+
+std::chrono::nanoseconds CoreTiming::GetGlobalTimeNs() const {
+    sys_time_point current = std::chrono::system_clock::now();
+    auto elapsed = current - start_time;
+    return std::chrono::duration_cast<std::chrono::nanoseconds>(elapsed);
+}
+
+std::chrono::microseconds CoreTiming::GetGlobalTimeUs() const {
+    sys_time_point current = std::chrono::system_clock::now();
+    auto elapsed = current - start_time;
+    return std::chrono::duration_cast<std::chrono::microseconds>(elapsed);
+}
+
+} // namespace Core::Timing
-- 
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