Add performance statistics to status bar

src/core/perf_stats.cpp

@@ -0,0 +1,53 @@
+// Copyright 2017 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include <chrono>
+#include "core/hw/gpu.h"
+#include "core/perf_stats.h"
+
+namespace Core {
+
+void PerfStats::BeginSystemFrame() {
+    frame_begin = Clock::now();
+}
+
+void PerfStats::EndSystemFrame() {
+    auto frame_end = Clock::now();
+    accumulated_frametime += frame_end - frame_begin;
+    system_frames += 1;
+}
+
+void PerfStats::EndGameFrame() {
+    game_frames += 1;
+}
+
+PerfStats::Results PerfStats::GetAndResetStats(u64 current_system_time_us) {
+    using DoubleSecs = std::chrono::duration<double, std::chrono::seconds::period>;
+    using std::chrono::duration_cast;
+
+    auto now = Clock::now();
+    // Walltime elapsed since stats were reset
+    auto interval = duration_cast<DoubleSecs>(now - reset_point).count();
+
+    auto system_us_per_second =
+        static_cast<double>(current_system_time_us - reset_point_system_us) / interval;
+
+    Results results{};
+    results.system_fps = static_cast<double>(system_frames) / interval;
+    results.game_fps = static_cast<double>(game_frames) / interval;
+    results.frametime = duration_cast<DoubleSecs>(accumulated_frametime).count() /
+                        static_cast<double>(system_frames);
+    results.emulation_speed = system_us_per_second / 1'000'000.0;
+
+    // Reset counters
+    reset_point = now;
+    reset_point_system_us = current_system_time_us;
+    accumulated_frametime = Clock::duration::zero();
+    system_frames = 0;
+    game_frames = 0;
+
+    return results;
+}
+
+} // namespace Core