From d67bcd654c11d49a9e0e2a88c471da049d96be29 Mon Sep 17 00:00:00 2001
From: Connor McLaughlin <stenzek@gmail.com>
Date: Fri, 20 Mar 2020 01:12:41 +1000
Subject: [PATCH] GPU: Prevent emulator locking up when switching between
 PAL/NTSC mode

---
 src/core/gpu.cpp | 12 ++++++++----
 src/core/gpu.h   |  6 +++++-
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/src/core/gpu.cpp b/src/core/gpu.cpp
index 28529a0a3..80523ed07 100644
--- a/src/core/gpu.cpp
+++ b/src/core/gpu.cpp
@@ -321,13 +321,17 @@ void GPU::UpdateCRTCConfig()
 
   if (m_GPUSTAT.pal_mode)
   {
-    cs.vertical_total = 314;
-    cs.horizontal_total = 3406;
+    cs.vertical_total = PAL_TOTAL_LINES;
+    cs.current_scanline %= PAL_TOTAL_LINES;
+    cs.horizontal_total = PAL_TICKS_PER_LINE;
+    cs.current_tick_in_scanline %= PAL_TICKS_PER_LINE;
   }
   else
   {
-    cs.vertical_total = 263;
-    cs.horizontal_total = 3413;
+    cs.vertical_total = NTSC_TOTAL_LINES;
+    cs.current_scanline %= NTSC_TOTAL_LINES;
+    cs.horizontal_total = NTSC_TICKS_PER_LINE;
+    cs.current_tick_in_scanline %= NTSC_TICKS_PER_LINE;
   }
 
   const TickCount ticks_per_frame = cs.horizontal_total * cs.vertical_total;
diff --git a/src/core/gpu.h b/src/core/gpu.h
index 0d97806c9..713cfe219 100644
--- a/src/core/gpu.h
+++ b/src/core/gpu.h
@@ -94,7 +94,11 @@ public:
     MAX_PRIMITIVE_HEIGHT = 512,
     DOT_TIMER_INDEX = 0,
     HBLANK_TIMER_INDEX = 1,
-    MAX_RESOLUTION_SCALE = 16
+    MAX_RESOLUTION_SCALE = 16,
+    NTSC_TICKS_PER_LINE = 3413,
+    NTSC_TOTAL_LINES = 263,
+    PAL_TICKS_PER_LINE = 3406,
+    PAL_TOTAL_LINES = 314,
   };
 
   // 4x4 dither matrix.