From 90012608ce0adf9ac8a7bcf06d8bda3d385ce6c8 Mon Sep 17 00:00:00 2001
From: Cancerous <randprint@gmail.com>
Date: Sat, 25 Jan 2020 13:11:00 -0500
Subject: [PATCH] [UI] add crude fps limiter for games that are too fast

---
 src/xenia/gpu/command_processor.cc | 17 ++++++++++++++++-
 src/xenia/gpu/command_processor.h  |  2 ++
 src/xenia/ui/window.cc             | 14 ++++++++++++++
 3 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/src/xenia/gpu/command_processor.cc b/src/xenia/gpu/command_processor.cc
index 0122d4ed8..381e2b30c 100644
--- a/src/xenia/gpu/command_processor.cc
+++ b/src/xenia/gpu/command_processor.cc
@@ -26,6 +26,8 @@
 #include "xenia/kernel/kernel_state.h"
 #include "xenia/kernel/user_module.h"
 
+DECLARE_bool(fps_limit);
+
 namespace xe {
 namespace gpu {
 
@@ -806,7 +808,7 @@ bool CommandProcessor::ExecutePacketType3_XE_SWAP(RingBuffer* reader,
                                                   uint32_t count) {
   SCOPE_profile_cpu_f("gpu");
 
-  XELOGI("XE_SWAP");
+  XELOGD("XE_SWAP");
 
   Profiler::Flip();
 
@@ -828,6 +830,19 @@ bool CommandProcessor::ExecutePacketType3_XE_SWAP(RingBuffer* reader,
   }
 
   ++counter_;
+
+
+  // crude FPS limiter until one of you does a better implementation
+  if(cvars::fps_limit) {
+
+    if (xe::Clock::QueryHostSystemTime() > swap_update_time_ns_ + 16666) {
+      swap_update_time_ns_ = xe::Clock::QueryHostSystemTime();
+    } else {
+      xe::threading::MaybeYield();
+      xe::threading::Sleep(std::chrono::nanoseconds((swap_update_time_ns_ +
+		  16666) - xe::Clock::QueryHostSystemTime()));
+    }
+  }
   return true;
 }
 
diff --git a/src/xenia/gpu/command_processor.h b/src/xenia/gpu/command_processor.h
index e613d5a03..c224e4504 100644
--- a/src/xenia/gpu/command_processor.h
+++ b/src/xenia/gpu/command_processor.h
@@ -260,6 +260,8 @@ class CommandProcessor {
   std::wstring trace_stream_path_;
   std::wstring trace_frame_path_;
 
+  uint64_t swap_update_time_ns_ = 0;
+
   std::atomic<bool> worker_running_;
   kernel::object_ref<kernel::XHostThread> worker_thread_;
 
diff --git a/src/xenia/ui/window.cc b/src/xenia/ui/window.cc
index 0894f5328..2af2bf944 100644
--- a/src/xenia/ui/window.cc
+++ b/src/xenia/ui/window.cc
@@ -18,9 +18,12 @@
 #include "xenia/base/logging.h"
 #include "xenia/base/profiling.h"
 #include "xenia/ui/imgui_drawer.h"
+#include "xenia/cpu/thread.h"
 
 DEFINE_bool(fps_titlebar, true, "Show FPS in titlebar", "General");
 
+DEFINE_bool(fps_limit, false, "try to limit 2d games from being too fast", "Video");
+
 namespace xe {
 namespace ui {
 
@@ -178,6 +181,17 @@ void Window::OnPaint(UIEvent* e) {
   ++frame_count_;
   ++fps_frame_count_;
   uint64_t now_ns = xe::Clock::QueryHostSystemTime();
+
+  // crude FPS limiter until one of you does a better implementation
+  if(cvars::fps_limit) {
+    if (now_ns > fps_update_time_ns_ + 16666) {
+      // do nothing
+    } else {
+      xe::threading::Sleep(std::chrono::nanoseconds((fps_update_time_ns_ +
+		  16666) - now_ns));
+    }
+  }
+
   if (now_ns > fps_update_time_ns_ + 1000 * 10000) {
     fps_ = static_cast<uint32_t>(
         fps_frame_count_ /