From 5799025ac4dc8bf211bce254b87938b42880029d Mon Sep 17 00:00:00 2001
From: bunnei <bunneidev@gmail.com>
Date: Wed, 24 Dec 2014 02:49:09 -0500
Subject: [PATCH] GPU: Further improve synchronization.

---
 src/core/hw/gpu.cpp | 42 ++++++++++++++++++++----------------------
 1 file changed, 20 insertions(+), 22 deletions(-)

diff --git a/src/core/hw/gpu.cpp b/src/core/hw/gpu.cpp
index 67a8bc324e..7e70b34c18 100644
--- a/src/core/hw/gpu.cpp
+++ b/src/core/hw/gpu.cpp
@@ -21,12 +21,10 @@ namespace GPU {
 
 Regs g_regs;
 
-u32 g_cur_line = 0;         ///< Current vertical screen line
-u64 g_last_line_ticks = 0;  ///< CPU tick count from last vertical screen line
-u64 g_last_frame_ticks = 0; ///< CPU tick count from last frame
-
-static u32 kFrameCycles = 0; ///< 268MHz / 60 frames per second
-static u32 kFrameTicks  = 0; ///< Approximate number of instructions/frame
+static u64 frame_ticks      = 0;    ///< 268MHz / 60 frames per second
+static u32 cur_line         = 0;    ///< Current vertical screen line
+static u64 last_frame_ticks = 0;    ///< CPU tick count from last frame
+static u64 last_update_tick = 0;    ///< CPU ticl count from last GPU update
 
 template <typename T>
 inline void Read(T &var, const u32 raw_addr) {
@@ -34,7 +32,7 @@ inline void Read(T &var, const u32 raw_addr) {
     u32 index = addr / 4;
 
     // Reads other than u32 are untested, so I'd rather have them abort than silently fail
-    if (index >= Regs::NumIds() || !std::is_same<T,u32>::value) {
+    if (index >= Regs::NumIds() || !std::is_same<T, u32>::value) {
         LOG_ERROR(HW_GPU, "unknown Read%lu @ 0x%08X", sizeof(var) * 8, addr);
         return;
     }
@@ -48,7 +46,7 @@ inline void Write(u32 addr, const T data) {
     u32 index = addr / 4;
 
     // Writes other than u32 are untested, so I'd rather have them abort than silently fail
-    if (index >= Regs::NumIds() || !std::is_same<T,u32>::value) {
+    if (index >= Regs::NumIds() || !std::is_same<T, u32>::value) {
         LOG_ERROR(HW_GPU, "unknown Write%lu 0x%08X @ 0x%08X", sizeof(data) * 8, (u32)data, addr);
         return;
     }
@@ -179,7 +177,6 @@ template void Write<u8>(u32 addr, const u8 data);
 /// Update hardware
 void Update() {
     auto& framebuffer_top = g_regs.framebuffer_config[0];
-    u64 current_ticks = Core::g_app_core->GetTicks();
 
     // Update the frame after a certain number of CPU ticks have elapsed. This assumes that the
     // active frame in memory is always complete to render. There also may be issues with this
@@ -189,9 +186,9 @@ void Update() {
     // primitive homebrew relies on a vertical blank interrupt to happen inevitably (regardless of a
     // threading reschedule).
 
-    if ((current_ticks - g_last_frame_ticks) > GPU::kFrameTicks) {
+    if ((Core::g_app_core->GetTicks() - last_frame_ticks) > (GPU::frame_ticks)) {
         VideoCore::g_renderer->SwapBuffers();
-        g_last_frame_ticks = current_ticks;
+        last_frame_ticks = Core::g_app_core->GetTicks();
     }
 
     // Synchronize GPU on a thread reschedule: Because we cannot accurately predict a vertical
@@ -199,17 +196,20 @@ void Update() {
     // accurately when this is signalled between thread switches.
 
     if (HLE::g_reschedule) {
+        u64 current_ticks = Core::g_app_core->GetTicks();
+        u64 line_ticks = (GPU::frame_ticks / framebuffer_top.height) * 16;
 
-        // Synchronize line...
-        if ((current_ticks - g_last_line_ticks) >= GPU::kFrameTicks / framebuffer_top.height) {
+        //// Synchronize line...
+        if ((current_ticks - last_update_tick) >= line_ticks) {
             GSP_GPU::SignalInterrupt(GSP_GPU::InterruptId::PDC0);
-            g_cur_line++;
-            g_last_line_ticks = current_ticks;
+            cur_line++;
+            last_update_tick += line_ticks;
         }
 
         // Synchronize frame...
-        if (g_cur_line >= framebuffer_top.height) {
-            g_cur_line = 0;
+        if (cur_line >= framebuffer_top.height) {
+            cur_line = 0;
+            VideoCore::g_renderer->SwapBuffers();
             GSP_GPU::SignalInterrupt(GSP_GPU::InterruptId::PDC1);
         }
     }
@@ -217,11 +217,9 @@ void Update() {
 
 /// Initialize hardware
 void Init() {
-    kFrameCycles = 268123480 / Settings::values.gpu_refresh_rate;
-    kFrameTicks  = kFrameCycles / 3;
-
-    g_cur_line = 0;
-    g_last_frame_ticks = g_last_line_ticks = Core::g_app_core->GetTicks();
+    frame_ticks = 268123480 / Settings::values.gpu_refresh_rate;
+    cur_line = 0;
+    last_update_tick = last_frame_ticks = Core::g_app_core->GetTicks();
 
     auto& framebuffer_top = g_regs.framebuffer_config[0];
     auto& framebuffer_sub = g_regs.framebuffer_config[1];