From 92c8bd4b1f650438274e50303a6d3f668924d071 Mon Sep 17 00:00:00 2001
From: Yuri Kunde Schlesner <yuriks@yuriks.net>
Date: Sun, 19 Feb 2017 18:18:26 -0800
Subject: PerfStats: Add method to get the instantaneous time ratio

---
 src/core/perf_stats.cpp | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

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

diff --git a/src/core/perf_stats.cpp b/src/core/perf_stats.cpp
index 6d9e603e4..8d9e521a3 100644
--- a/src/core/perf_stats.cpp
+++ b/src/core/perf_stats.cpp
@@ -6,6 +6,9 @@
 #include "core/hw/gpu.h"
 #include "core/perf_stats.h"
 
+using DoubleSecs = std::chrono::duration<double, std::chrono::seconds::period>;
+using std::chrono::duration_cast;
+
 namespace Core {
 
 void PerfStats::BeginSystemFrame() {
@@ -16,6 +19,9 @@ void PerfStats::EndSystemFrame() {
     auto frame_end = Clock::now();
     accumulated_frametime += frame_end - frame_begin;
     system_frames += 1;
+
+    previous_frame_length = frame_end - previous_frame_end;
+    previous_frame_end = frame_end;
 }
 
 void PerfStats::EndGameFrame() {
@@ -23,9 +29,6 @@ void PerfStats::EndGameFrame() {
 }
 
 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();
@@ -50,4 +53,9 @@ PerfStats::Results PerfStats::GetAndResetStats(u64 current_system_time_us) {
     return results;
 }
 
+double PerfStats::GetLastFrameTimeScale() {
+    constexpr double FRAME_LENGTH = 1.0 / GPU::SCREEN_REFRESH_RATE;
+    return duration_cast<DoubleSecs>(previous_frame_length).count() / FRAME_LENGTH;
+}
+
 } // namespace Core
-- 
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