From 902795d61c8db7f9bb3bc4217d09d40bd7471181 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Tue, 18 Aug 2015 00:17:03 -0400
Subject: [PATCH] Switched vertical sync detection method, at least for now.
 They never happen automatically (I need to fix that) and just always take
 effect if detected in the lower half of the display. PAL/NTSC is determined
 just by looking at the refresh rate.

---
 OSBindings/Mac/Clock Signal/CSAtari2600.mm | 36 ++++++++++++++++------
 Outputs/CRT.cpp                            | 16 +++++-----
 2 files changed, 34 insertions(+), 18 deletions(-)

diff --git a/OSBindings/Mac/Clock Signal/CSAtari2600.mm b/OSBindings/Mac/Clock Signal/CSAtari2600.mm
index 90f1596c0..df8059f22 100644
--- a/OSBindings/Mac/Clock Signal/CSAtari2600.mm	
+++ b/OSBindings/Mac/Clock Signal/CSAtari2600.mm	
@@ -24,23 +24,39 @@ struct Atari2600CRTDelegate: public Outputs::CRT::CRTDelegate {
 
 	dispatch_queue_t _serialDispatchQueue;
 
-	int _failedVSyncCount;
+	int _frameCount;
+	NSTimeInterval _startTimeInterval;
+	BOOL _didDecideRegion;
 }
 
 - (void)crtDidEndFrame:(CRTFrame *)frame didDetectVSync:(BOOL)didDetectVSync {
 
-	if(!didDetectVSync)
+	if(!_didDecideRegion)
 	{
-		_failedVSyncCount+=2;
-
-		if(_failedVSyncCount == 60)
+		if(_startTimeInterval < 1.0)
 		{
-			_atari2600.switch_region();
+			_startTimeInterval = [NSDate timeIntervalSinceReferenceDate];
+		}
+		else
+		{
+			_frameCount++;
+
+			if(_frameCount > 30)
+			{
+				float fps = (float)_frameCount / (float)([NSDate timeIntervalSinceReferenceDate] - _startTimeInterval);
+
+				if(fabsf(fps - 50.0f) < 5.0f)
+				{
+					_atari2600.switch_region();
+					_didDecideRegion = YES;
+				}
+
+				if(fabsf(fps - 60.0f) < 5.0f)
+				{
+					_didDecideRegion = YES;
+				}
+			}
 		}
-	}
-	else
-	{
-		_failedVSyncCount = MAX(_failedVSyncCount - 1, 0);
 	}
 
 	BOOL hasReturn = [self.view pushFrame:frame];
diff --git a/Outputs/CRT.cpp b/Outputs/CRT.cpp
index 7a77a90f2..9bd2a50fd 100644
--- a/Outputs/CRT.cpp
+++ b/Outputs/CRT.cpp
@@ -28,7 +28,7 @@ void CRT::set_new_timing(unsigned int cycles_per_line, unsigned int height_of_di
 	height_of_display += (height_of_display / 20);  // this is the overrun area we'll use to
 
 	// store fundamental display configuration properties
-	_height_of_display = height_of_display + 10;
+	_height_of_display = height_of_display;
 	_cycles_per_line = cycles_per_line * _time_multiplier;
 
 	// generate timing values implied by the given arbuments
@@ -103,7 +103,7 @@ CRT::SyncEvent CRT::get_next_vertical_sync_event(bool vsync_is_requested, unsign
 
 	// will an acceptable vertical sync be triggered?
 	if (vsync_is_requested && !_is_in_vsync) {
-		if (_sync_capacitor_charge_level >= _sync_capacitor_charge_threshold){// && _rasterPosition.y >= (kCRTFixedPointRange * 7) >> 3) {
+		if (_sync_capacitor_charge_level >= _sync_capacitor_charge_threshold && _rasterPosition.y >= (kCRTFixedPointRange >> 1)) {
 			proposedSyncTime = 0;
 			proposedEvent = SyncEvent::StartVSync;
 			_did_detect_vsync = true;
@@ -112,12 +112,12 @@ CRT::SyncEvent CRT::get_next_vertical_sync_event(bool vsync_is_requested, unsign
 
 	// have we overrun the maximum permitted number of horizontal syncs for this frame?
 	if (!_is_in_vsync) {
-		unsigned int time_until_end_of_frame = (kCRTFixedPointRange - _rasterPosition.y) / _scanSpeed[0].y;
-
-		if(time_until_end_of_frame < proposedSyncTime) {
-			proposedSyncTime = time_until_end_of_frame;
-			proposedEvent = SyncEvent::StartVSync;
-		}
+//		unsigned int time_until_end_of_frame = (kCRTFixedPointRange - _rasterPosition.y) / _scanSpeed[0].y;
+//
+//		if(time_until_end_of_frame < proposedSyncTime) {
+//			proposedSyncTime = time_until_end_of_frame;
+//			proposedEvent = SyncEvent::StartVSync;
+//		}
 	} else {
 		unsigned int time_until_start_of_frame = _rasterPosition.y / (uint32_t)(-_scanSpeed[kRetraceYMask].y);