timing: added support for PAL timing

src/device/gpu/gpu.cpp

@@ -786,6 +786,20 @@ void GPU::writeGP1(uint32_t data) {
     }
 }
 
+float GPU::cyclesPerLine() const {
+    if (isNtsc())
+        return timing::CYCLES_PER_LINE_NTSC;
+    else
+        return timing::CYCLES_PER_LINE_PAL;
+}
+
+int GPU::linesPerFrame() const {
+    if (isNtsc())
+        return timing::LINES_TOTAL_NTSC;
+    else
+        return timing::LINES_TOTAL_PAL;
+}
+
 bool GPU::emulateGpuCycles(int cycles) {
     gpuDot += cycles;
 
@@ -794,7 +808,7 @@ bool GPU::emulateGpuCycles(int cycles) {
     gpuDot %= 3413;
     gpuLine += newLines;
 
-    if (gpuLine < timing::LINE_VBLANK_START_NTSC - 1) {
+    if (gpuLine < linesPerFrame() - 20 - 1) {
         if (gp1_08.verticalResolution == GP1_08::VerticalResolution::r480 && gp1_08.interlace) {
             odd = (frames % 2) != 0;
         } else {
@@ -804,7 +818,7 @@ bool GPU::emulateGpuCycles(int cycles) {
         odd = false;
     }
 
-    if (gpuLine == timing::LINES_TOTAL_NTSC - 1) {
+    if (gpuLine == linesPerFrame() - 1) {
         gpuLine = 0;
         frames++;
         return true;
@@ -825,7 +839,7 @@ bool GPU::insideDrawingArea(int x, int y) const {
            && (y < VRAM_HEIGHT);
 }
 
-bool GPU::isNtsc() { return forceNtsc || gp1_08.videoMode == GP1_08::VideoMode::ntsc; }
+bool GPU::isNtsc() const { return forceNtsc || gp1_08.videoMode == GP1_08::VideoMode::ntsc; }
 
 void GPU::dumpVram() {
     const char* dumpName = "vram.png";

src/device/gpu/gpu.h

@@ -132,6 +132,9 @@ class GPU {
     uint32_t readVramData();
     uint32_t getStat();
 
+    float cyclesPerLine() const;
+    int linesPerFrame() const;
+
    public:
     GPU(System* sys);
     ~GPU();
@@ -139,7 +142,7 @@ class GPU {
     bool emulateGpuCycles(int cycles);
     uint32_t read(uint32_t address);
     void write(uint32_t address, uint32_t data);
-    bool isNtsc();
+    bool isNtsc() const;
 
     int minDrawingX(int x) const;
     int minDrawingY(int y) const;

src/platform/windows/main.cpp

@@ -41,7 +41,7 @@ double limitFramerate(bool framelimiter, bool ntsc) {
     double currentTime = SDL_GetPerformanceCounter() / counterFrequency;
     double deltaTime = currentTime - startTime;
 
-    double frameTime = ntsc ? (1.0 / timing::NTSC_FRAMERATE) : (1.0 / 50.0);
+    double frameTime = ntsc ? (1.0 / timing::NTSC_FRAMERATE) : (1.0 / timing::PAL_FRAMERATE);
 
     if (framelimiter && deltaTime < frameTime) {
         // If deltaTime was shorter than frameTime - spin

src/system.cpp

@@ -409,7 +409,7 @@ void System::emulateFrame() {
         }
 
         // TODO: Move this code to Timer class
-        if (gpu->gpuLine > timing::LINE_VBLANK_START_NTSC) {
+        if (gpu->gpuLine > gpu->linesPerFrame() - 20) {
             auto& t = *timer[1];
             if (t.mode.syncEnabled) {
                 using modes = device::timer::CounterMode::SyncMode1;

src/utils/timing.h

@@ -6,11 +6,21 @@ constexpr uint64_t US_IN_SECOND = 1'000'000;
 constexpr uint64_t CPU_CLOCK = 33'868'800;  // 44100 * 768
 constexpr uint64_t GPU_CLOCK = 53'222'400;
 
-// NTSC
-const float DOTS_TOTAL = 3413.6f;
-const int LINE_VBLANK_START_NTSC = 243;
+//#define USE_EXACT_FPS
+#ifdef USE_EXACT_FPS
+const float CYCLES_PER_LINE_NTSC = 3413.6f;
+const float CYCLES_PER_LINE_PAL = 3406.1f;
 const int LINES_TOTAL_NTSC = 263;
-const float NTSC_FRAMERATE = (float)GPU_CLOCK / (DOTS_TOTAL * LINES_TOTAL_NTSC);
+const int LINES_TOTAL_PAL = 314;
+#else
+const float CYCLES_PER_LINE_NTSC = 3372;
+const float CYCLES_PER_LINE_PAL = 3389;
+const int LINES_TOTAL_NTSC = 263;
+const int LINES_TOTAL_PAL = 314;
+#endif
+
+const float NTSC_FRAMERATE = (float)GPU_CLOCK / (CYCLES_PER_LINE_NTSC * LINES_TOTAL_NTSC);
+const float PAL_FRAMERATE = (float)GPU_CLOCK / (CYCLES_PER_LINE_PAL * LINES_TOTAL_PAL);
 
 constexpr uint64_t usToCpuCycles(uint64_t us) { return us * CPU_CLOCK / US_IN_SECOND; }
 }  // namespace timing