Rewired the existing cause-an-update route from the OpenGLView through the best-effort updater.

OSBindings/Mac/Clock Signal/ClockSignal-Bridging-Header.h

@@ -11,3 +11,4 @@
 
 #import	"CSOpenGLView.h"
 #import "CSAudioQueue.h"
+#import "CSBestEffortUpdater.h"

OSBindings/Mac/Clock Signal/Documents/Atari2600Document.swift

@@ -18,7 +18,7 @@ class Atari2600Document: MachineDocument {
 	// MARK: NSDocument overrides
 	override init() {
 		super.init()
-		self.intendedCyclesPerSecond = 1194720
+		self.bestEffortUpdater.clockRate = 1194720
 	}
 
 	override class func autosavesInPlace() -> Bool {

OSBindings/Mac/Clock Signal/Documents/ElectronDocument.swift

@@ -27,7 +27,7 @@ class ElectronDocument: MachineDocument {
 	override func windowControllerDidLoadNib(aController: NSWindowController) {
 		super.windowControllerDidLoadNib(aController)
 
-		self.intendedCyclesPerSecond = 2000000
+		self.bestEffortUpdater.clockRate = 2000000
 
 		if let os = rom("os"), basic = rom("basic") {
 			self.electron.setOSROM(os)

OSBindings/Mac/Clock Signal/Documents/MachineDocument.swift

@@ -9,7 +9,7 @@
 import Cocoa
 import AudioToolbox
 
-class MachineDocument: NSDocument, CSOpenGLViewDelegate, CSOpenGLViewResponderDelegate, NSWindowDelegate {
+class MachineDocument: NSDocument, CSOpenGLViewDelegate, CSOpenGLViewResponderDelegate, CSBestEffortUpdaterDelegate, NSWindowDelegate {
 
 	lazy var actionLock = NSLock()
 	lazy var drawLock = NSLock()
@@ -34,6 +34,11 @@ class MachineDocument: NSDocument, CSOpenGLViewDelegate, CSOpenGLViewResponderDe
 	}
 
 	var audioQueue: CSAudioQueue! = nil
+	lazy var bestEffortUpdater: CSBestEffortUpdater = {
+		let updater = CSBestEffortUpdater()
+		updater.delegate = self
+		return updater
+	}()
 
 	override func windowControllerDidLoadNib(aController: NSWindowController) {
 		super.windowControllerDidLoadNib(aController)
@@ -66,36 +71,39 @@ class MachineDocument: NSDocument, CSOpenGLViewDelegate, CSOpenGLViewResponderDe
 		super.close()
 	}
 
-	var intendedCyclesPerSecond: Int64 = 0
+	final func bestEffortUpdater(bestEffortUpdater: CSBestEffortUpdater!, runForCycles cycles: UInt, didSkipPreviousUpdate: Bool) {
-	private var cycleCountError: Int64 = 0
+		runForNumberOfCycles(Int32(cycles))
-	private var lastTime: CVTimeStamp?
-	private var skippedFrames = 0
-	final func openGLView(view: CSOpenGLView, didUpdateToTime time: CVTimeStamp, didSkipPreviousUpdate : Bool, frequency : Double) {
-		if let lastTime = lastTime {
-			// perform (time passed in seconds) * (intended cycles per second), converting and
-			// maintaining an error count to deal with underflow
-			let videoTimeScale64 = Int64(time.videoTimeScale)
-			let videoTimeCount = ((time.videoTime - lastTime.videoTime) * intendedCyclesPerSecond) + cycleCountError
-			cycleCountError = videoTimeCount % videoTimeScale64
-			var numberOfCycles = videoTimeCount / videoTimeScale64
-
-			// if the emulation has fallen behind then silently limit the request;
-			// some actions — e.g. the host computer waking after sleep — may give us a
-			// prohibitive backlog
-			if didSkipPreviousUpdate {
-				skippedFrames++
-			} else {
-				skippedFrames = 0
-			}
-
-			// run for at most three frames up to and until that causes overshoots in the
-			// permitted processing window for at least four consecutive frames, in which
-			// case limit to one
-			numberOfCycles = min(numberOfCycles, Int64(Double(intendedCyclesPerSecond) * frequency * ((skippedFrames > 4) ? 3.0 : 1.0)))
-			runForNumberOfCycles(Int32(numberOfCycles))
-		}
-		lastTime = time
 	}
+//	var intendedCyclesPerSecond: Int64 = 0
+//	private var cycleCountError: Int64 = 0
+//	private var lastTime: CVTimeStamp?
+//	private var skippedFrames = 0
+//	final func openGLView(view: CSOpenGLView, didUpdateToTime time: CVTimeStamp, didSkipPreviousUpdate : Bool, frequency : Double) {
+//		if let lastTime = lastTime {
+//			// perform (time passed in seconds) * (intended cycles per second), converting and
+//			// maintaining an error count to deal with underflow
+//			let videoTimeScale64 = Int64(time.videoTimeScale)
+//			let videoTimeCount = ((time.videoTime - lastTime.videoTime) * intendedCyclesPerSecond) + cycleCountError
+//			cycleCountError = videoTimeCount % videoTimeScale64
+//			var numberOfCycles = videoTimeCount / videoTimeScale64
+//
+//			// if the emulation has fallen behind then silently limit the request;
+//			// some actions — e.g. the host computer waking after sleep — may give us a
+//			// prohibitive backlog
+//			if didSkipPreviousUpdate {
+//				skippedFrames++
+//			} else {
+//				skippedFrames = 0
+//			}
+//
+//			// run for at most three frames up to and until that causes overshoots in the
+//			// permitted processing window for at least four consecutive frames, in which
+//			// case limit to one
+//			numberOfCycles = min(numberOfCycles, Int64(Double(intendedCyclesPerSecond) * frequency * ((skippedFrames > 4) ? 3.0 : 1.0)))
+//			runForNumberOfCycles(Int32(numberOfCycles))
+//		}
+//		lastTime = time
+//	}
 
 	// MARK: Utilities for children
 	func dataForResource(name : String, ofType type: String, inDirectory directory: String) -> NSData? {
@@ -115,6 +123,7 @@ class MachineDocument: NSDocument, CSOpenGLViewDelegate, CSOpenGLViewResponderDe
 	}
 
 	func openGLView(view: CSOpenGLView, drawViewOnlyIfDirty onlyIfDirty: Bool) {
+		bestEffortUpdater.update()
 		if drawLock.tryLock() {
 			self.machine().drawViewForPixelSize(view.backingSize, onlyIfDirty: onlyIfDirty)
 			drawLock.unlock()

OSBindings/Mac/Clock Signal/Documents/Vic20Document.swift

@@ -18,7 +18,7 @@ class Vic20Document: MachineDocument {
 	// MARK: NSDocument overrides
 	override init() {
 		super.init()
-		self.intendedCyclesPerSecond = 1022727
+		self.bestEffortUpdater.clockRate = 1022727
 		// TODO: or 1108405 for PAL; see http://www.antimon.org/dl/c64/code/stable.txt
 
 		if let kernel = rom("kernel-ntsc"), basic = rom("basic"), characters = rom("characters-english") {

OSBindings/Mac/Clock Signal/Views/CSOpenGLView.h

@@ -12,14 +12,6 @@
 @class CSOpenGLView;
 
 @protocol CSOpenGLViewDelegate
-/*!
-	Tells the delegate that time has advanced.
-	@param view The view sending the message.
-	@param time The time to which time has advanced.
-	@param didSkipPreviousUpdate @c YES if the previous update that would have occurred was skipped because a didUpdateToTime: call prior to that was still ongoing; @c NO otherwise.
-*/
-- (void)openGLView:(nonnull CSOpenGLView *)view didUpdateToTime:(CVTimeStamp)time didSkipPreviousUpdate:(BOOL)didSkipPreviousUpdate frequency:(double)frequency;
-
 /*!
 	Requests that the delegate produce an image of its current output state. May be called on
 	any queue or thread.

OSBindings/Mac/Clock Signal/Views/CSOpenGLView.m

@@ -12,9 +12,6 @@
 
 @implementation CSOpenGLView {
 	CVDisplayLinkRef _displayLink;
-	uint32_t _updateIsOngoing;
-	BOOL _hasSkipped;
-	dispatch_queue_t _serialDispatchQueue;
 }
 
 - (void)prepareOpenGL
@@ -34,10 +31,6 @@
 	CGLPixelFormatObj cglPixelFormat = [[self pixelFormat] CGLPixelFormatObj];
 	CVDisplayLinkSetCurrentCGDisplayFromOpenGLContext(_displayLink, cglContext, cglPixelFormat);
 
-	// create a serial dispatch queue
-	_serialDispatchQueue = dispatch_queue_create("OpenGLView", DISPATCH_QUEUE_SERIAL);
-//	dispatch_set_target_queue(_serialDispatchQueue, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0));
-
 	// set the clear colour
 	[self.openGLContext makeCurrentContext];
 	glClearColor(0.0, 0.0, 0.0, 1.0);
@@ -55,24 +48,6 @@ static CVReturn DisplayLinkCallback(CVDisplayLinkRef displayLink, const CVTimeSt
 
 - (void)drawAtTime:(const CVTimeStamp *)now frequency:(double)frequency
 {
-	const uint32_t processingMask = 0x01;
-
-	// Always post an -openGLView:didUpdateToTime: if a previous one isn't still ongoing. This is the hook upon which the substantial processing occurs.
-	if(!OSAtomicTestAndSet(processingMask, &_updateIsOngoing))
-	{
-		CVTimeStamp time = *now;
-		BOOL didSkip = _hasSkipped;
-		dispatch_async(_serialDispatchQueue, ^{
-			[self.delegate openGLView:self didUpdateToTime:time didSkipPreviousUpdate:didSkip frequency:frequency];
-			OSAtomicTestAndClear(processingMask, &_updateIsOngoing);
-		});
-		_hasSkipped = NO;
-	}
-	else
-	{
-		_hasSkipped = YES;
-	}
-
 	// Draw the display now regardless of other activity.
 	[self drawViewOnlyIfDirty:YES];
 }