8 files changed, 120 insertions, 3 deletions

diff --git a/src/core/CMakeLists.txt b/src/core/CMakeLists.txt
index 5332e35a3..1adc78d8d 100644
--- a/src/core/CMakeLists.txt
+++ b/src/core/CMakeLists.txt
@@ -170,6 +170,7 @@ set(SRCS
             loader/smdh.cpp
             tracer/recorder.cpp
             memory.cpp
+            perf_stats.cpp
             settings.cpp
             )
 
@@ -357,6 +358,7 @@ set(HEADERS
             memory.h
             memory_setup.h
             mmio.h
+            perf_stats.h
             settings.h
             )
 
diff --git a/src/core/core.cpp b/src/core/core.cpp
index c9c9b7615..ca2c28ce4 100644
--- a/src/core/core.cpp
+++ b/src/core/core.cpp
@@ -109,6 +109,11 @@ void System::PrepareReschedule() {
     reschedule_pending = true;
 }
 
+PerfStats::Results System::GetAndResetPerfStats() {
+    auto perf_stats = this->perf_stats.Lock();
+    return perf_stats->GetAndResetStats(CoreTiming::GetGlobalTimeUs());
+}
+
 void System::Reschedule() {
     if (!reschedule_pending) {
         return;
@@ -140,6 +145,10 @@ System::ResultStatus System::Init(EmuWindow* emu_window, u32 system_mode) {
 
     LOG_DEBUG(Core, "Initialized OK");
 
+    // Reset counters and set time origin to current frame
+    GetAndResetPerfStats();
+    perf_stats.Lock()->BeginSystemFrame();
+
     return ResultStatus::Success;
 }
 
diff --git a/src/core/core.h b/src/core/core.h
index 17572a74f..3efc20c3d 100644
--- a/src/core/core.h
+++ b/src/core/core.h
@@ -6,9 +6,10 @@
 
 #include <memory>
 #include <string>
-
 #include "common/common_types.h"
+#include "common/synchronized_wrapper.h"
 #include "core/memory.h"
+#include "core/perf_stats.h"
 
 class EmuWindow;
 class ARM_Interface;
@@ -83,6 +84,8 @@ public:
     /// Prepare the core emulation for a reschedule
     void PrepareReschedule();
 
+    PerfStats::Results GetAndResetPerfStats();
+
     /**
      * Gets a reference to the emulated CPU.
      * @returns A reference to the emulated CPU.
@@ -91,6 +94,8 @@ public:
         return *cpu_core;
     }
 
+    Common::SynchronizedWrapper<PerfStats> perf_stats;
+
 private:
     /**
      * Initialize the emulated system.
diff --git a/src/core/hle/service/gsp_gpu.cpp b/src/core/hle/service/gsp_gpu.cpp
index 1457518d4..67bab38da 100644
--- a/src/core/hle/service/gsp_gpu.cpp
+++ b/src/core/hle/service/gsp_gpu.cpp
@@ -4,6 +4,7 @@
 
 #include "common/bit_field.h"
 #include "common/microprofile.h"
+#include "core/core.h"
 #include "core/hle/kernel/event.h"
 #include "core/hle/kernel/shared_memory.h"
 #include "core/hle/result.h"
@@ -280,6 +281,8 @@ ResultCode SetBufferSwap(u32 screen_id, const FrameBufferInfo& info) {
 
     if (screen_id == 0) {
         MicroProfileFlip();
+        auto perf_stats = Core::System::GetInstance().perf_stats.Lock();
+        perf_stats->EndGameFrame();
     }
 
     return RESULT_SUCCESS;
diff --git a/src/core/hw/gpu.cpp b/src/core/hw/gpu.cpp
index fa8c13d36..7cf081aad 100644
--- a/src/core/hw/gpu.cpp
+++ b/src/core/hw/gpu.cpp
@@ -32,7 +32,7 @@ namespace GPU {
 Regs g_regs;
 
 /// 268MHz CPU clocks / 60Hz frames per second
-const u64 frame_ticks = BASE_CLOCK_RATE_ARM11 / 60;
+const u64 frame_ticks = BASE_CLOCK_RATE_ARM11 / SCREEN_REFRESH_RATE;
 /// Event id for CoreTiming
 static int vblank_event;
 /// Total number of frames drawn
@@ -41,7 +41,7 @@ static u64 frame_count;
 static u32 time_point;
 /// Total delay caused by slow frames
 static float time_delay;
-constexpr float FIXED_FRAME_TIME = 1000.0f / 60;
+constexpr float FIXED_FRAME_TIME = 1000.0f / SCREEN_REFRESH_RATE;
 // Max lag caused by slow frames. Can be adjusted to compensate for too many slow frames. Higher
 // values increases time needed to limit frame rate after spikes
 constexpr float MAX_LAG_TIME = 18;
diff --git a/src/core/hw/gpu.h b/src/core/hw/gpu.h
index d53381216..bdd997b2a 100644
--- a/src/core/hw/gpu.h
+++ b/src/core/hw/gpu.h
@@ -13,6 +13,8 @@
 
 namespace GPU {
 
+constexpr float SCREEN_REFRESH_RATE = 60;
+
 // Returns index corresponding to the Regs member labeled by field_name
 // TODO: Due to Visual studio bug 209229, offsetof does not return constant expressions
 //       when used with array elements (e.g. GPU_REG_INDEX(memory_fill_config[0])).
diff --git a/src/core/perf_stats.cpp b/src/core/perf_stats.cpp
new file mode 100644
index 000000000..6d9e603e4
--- /dev/null
+++ b/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
diff --git a/src/core/perf_stats.h b/src/core/perf_stats.h
new file mode 100644
index 000000000..566a1419a
--- /dev/null
+++ b/src/core/perf_stats.h
@@ -0,0 +1,43 @@
+// Copyright 2017 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <chrono>
+#include "common/common_types.h"
+
+namespace Core {
+
+class PerfStats {
+public:
+    using Clock = std::chrono::high_resolution_clock;
+
+    struct Results {
+        /// System FPS (LCD VBlanks) in Hz
+        double system_fps;
+        /// Game FPS (GSP frame submissions) in Hz
+        double game_fps;
+        /// Walltime per system frame, in seconds, excluding any waits
+        double frametime;
+        /// Ratio of walltime / emulated time elapsed
+        double emulation_speed;
+    };
+
+    void BeginSystemFrame();
+    void EndSystemFrame();
+    void EndGameFrame();
+
+    Results GetAndResetStats(u64 current_system_time_us);
+
+private:
+    Clock::time_point reset_point = Clock::now();
+
+    Clock::time_point frame_begin;
+    Clock::duration accumulated_frametime = Clock::duration::zero();
+    u64 reset_point_system_us = 0;
+    u32 system_frames = 0;
+    u32 game_frames = 0;
+};
+
+} // namespace Core