From ba8ff096fdc9f7ab101851c4cd06c3244a7d84c3 Mon Sep 17 00:00:00 2001
From: fearlessTobi <thm.frey@gmail.com>
Date: Tue, 21 Aug 2018 01:14:06 +0200
Subject: Port #3353 from Citra

---
 src/core/perf_stats.cpp        | 17 +++++++++++++----
 src/core/settings.h            |  3 ++-
 src/core/telemetry_session.cpp |  5 +++--
 3 files changed, 18 insertions(+), 7 deletions(-)

(limited to 'src/core')

diff --git a/src/core/perf_stats.cpp b/src/core/perf_stats.cpp
index 8e09b9b63..c6022c02a 100644
--- a/src/core/perf_stats.cpp
+++ b/src/core/perf_stats.cpp
@@ -78,20 +78,29 @@ void FrameLimiter::DoFrameLimiting(microseconds current_system_time_us) {
     // values increase the time needed to recover and limit framerate again after spikes.
     constexpr microseconds MAX_LAG_TIME_US = 25us;
 
-    if (!Settings::values.toggle_framelimit) {
+    if (!Settings::values.use_frame_limit) {
         return;
     }
 
     auto now = Clock::now();
 
-    frame_limiting_delta_err += current_system_time_us - previous_system_time_us;
+    const double sleep_scale = Settings::values.frame_limit / 100.0;
+
+    // Max lag caused by slow frames. Shouldn't be more than the length of a frame at the current
+    // speed percent or it will clamp too much and prevent this from properly limiting to that
+    // percent. High values means it'll take longer after a slow frame to recover and start
+    // limiting
+    const microseconds max_lag_time_us = duration_cast<microseconds>(
+        std::chrono::duration<double, std::chrono::microseconds::period>(25ms / sleep_scale));
+    frame_limiting_delta_err += duration_cast<microseconds>(
+        std::chrono::duration<double, std::chrono::microseconds::period>(
+            (current_system_time_us - previous_system_time_us) / sleep_scale));
     frame_limiting_delta_err -= duration_cast<microseconds>(now - previous_walltime);
     frame_limiting_delta_err =
-        std::clamp(frame_limiting_delta_err, -MAX_LAG_TIME_US, MAX_LAG_TIME_US);
+        std::clamp(frame_limiting_delta_err, -max_lag_time_us, max_lag_time_us);
 
     if (frame_limiting_delta_err > microseconds::zero()) {
         std::this_thread::sleep_for(frame_limiting_delta_err);
-
         auto now_after_sleep = Clock::now();
         frame_limiting_delta_err -= duration_cast<microseconds>(now_after_sleep - now);
         now = now_after_sleep;
diff --git a/src/core/settings.h b/src/core/settings.h
index 73dc3061f..ed6f42471 100644
--- a/src/core/settings.h
+++ b/src/core/settings.h
@@ -130,7 +130,8 @@ struct Values {
 
     // Renderer
     float resolution_factor;
-    bool toggle_framelimit;
+    bool use_frame_limit;
+    u16 frame_limit;
     bool use_accurate_framebuffers;
 
     float bg_red;
diff --git a/src/core/telemetry_session.cpp b/src/core/telemetry_session.cpp
index 69aa7a7be..5bd64f10e 100644
--- a/src/core/telemetry_session.cpp
+++ b/src/core/telemetry_session.cpp
@@ -161,8 +161,9 @@ TelemetrySession::TelemetrySession() {
              Settings::values.use_multi_core);
     AddField(Telemetry::FieldType::UserConfig, "Renderer_ResolutionFactor",
              Settings::values.resolution_factor);
-    AddField(Telemetry::FieldType::UserConfig, "Renderer_ToggleFramelimit",
-             Settings::values.toggle_framelimit);
+    AddField(Telemetry::FieldType::UserConfig, "Renderer_UseFrameLimit",
+             Settings::values.use_frame_limit);
+    AddField(Telemetry::FieldType::UserConfig, "Renderer_FrameLimit", Settings::values.frame_limit);
     AddField(Telemetry::FieldType::UserConfig, "Renderer_UseAccurateFramebuffers",
              Settings::values.use_accurate_framebuffers);
     AddField(Telemetry::FieldType::UserConfig, "System_UseDockedMode",
-- 
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