[GPU] Added janky(?) support for register: D1MODE_V_COUNTER

Put internal_display_resolution into graphics_system

Thanks Beeanyew for initial implementation

src/xenia/gpu/graphics_system.cc

@@ -29,6 +29,29 @@
 #include "xenia/ui/graphics_provider.h"
 #include "xenia/ui/window.h"
 #include "xenia/ui/windowed_app_context.h"
+
+DEFINE_int32(internal_display_resolution, 8,
+             "Allow game that support different resolutions to be rendered "
+             "in specific resolution.\n"
+             "   0=640x480\n"
+             "   1=640x576\n"
+             "   2=720x480\n"
+             "   3=720x576\n"
+             "   4=800x600\n"
+             "   5=848x480\n"
+             "   6=1024x768\n"
+             "   7=1152x864\n"
+             "   8=1280x720 (Default)\n"
+             "   9=1280x768\n"
+             "   10=1280x960\n"
+             "   11=1280x1024\n"
+             "   12=1360x768\n"
+             "   13=1440x900\n"
+             "   14=1680x1050\n"
+             "   15=1920x540\n"
+             "   16=1920x1080\n",
+             "Video");
+
 DEFINE_bool(
     store_shaders, true,
     "Store shaders persistently and load them when loading games to avoid "
@@ -128,6 +151,9 @@ X_STATUS GraphicsSystem::Setup(cpu::Processor* processor,
             const double duration_scalar = 0.90;
 
             while (frame_limiter_worker_running_) {
+              register_file()->values[XE_GPU_REG_D1MODE_V_COUNTER] +=
+                  GetInternalDisplayResolution().second;
+
               if (cvars::vsync) {
                 const uint64_t current_time = Clock::QueryGuestTickCount();
                 const uint64_t tick_freq = Clock::guest_tick_frequency();
@@ -246,8 +272,6 @@ uint32_t GraphicsSystem::ReadRegister(uint32_t addr) {
       return 0x08100748;
     case 0x0F01:  // RB_BC_CONTROL
       return 0x0000200E;
-    case 0x194C:  // R500_D1MODE_V_COUNTER
-      return 0x000002D0;
     case 0x1951:  // interrupt status
       return 1;   // vblank
     case 0x1961:  // AVIVO_D1MODE_VIEWPORT_SIZE
@@ -381,5 +405,14 @@ bool GraphicsSystem::Restore(ByteStream* stream) {
   return command_processor_->Restore(stream);
 }
 
+std::pair<uint16_t, uint16_t> GraphicsSystem::GetInternalDisplayResolution() {
+  if (cvars::internal_display_resolution >
+      internal_display_resolution_entries.size()) {
+    return internal_display_resolution_entries[8];
+  }
+  return internal_display_resolution_entries
+      [cvars::internal_display_resolution];
+}
+
 }  // namespace gpu
 }  // namespace xe