Various variable scope optimisations, split up PAPU code and added "enable sound" button.

8 files changed, 859 insertions, 912 deletions

diff --git a/channels.js b/channels.js
new file mode 100644
index 0000000..afcb3d7
--- /dev/null
+++ b/channels.js
@@ -0,0 +1,685 @@
+function ChannelDM(papu) {
+	this.papu = papu;
+	
+	this.MODE_NORMAL = 0;
+	this.MODE_LOOP = 1;
+	this.MODE_IRQ = 2;
+	
+	this.isEnabled = null;
+	this.hasSample = null;
+	this.irqGenerated=false;
+	
+	this.playMode = null;
+	this.dmaFrequency = null;
+	this.dmaCounter = null;
+	this.deltaCounter = null;
+	this.playStartAddress = null;
+	this.playAddress = null;
+	this.playLength = null;
+	this.playLengthCounter = null;
+	this.shiftCounter = null;
+	this.reg4012 = null;
+	this.reg4013 = null;
+	this.sample = null;
+	this.dacLsb = null;
+	this.data = null;
+	
+	this.reset();
+}	
+	
+ChannelDM.prototype.clockDmc = function(){
+	
+	// Only alter DAC value if the sample buffer has data:
+	if(this.hasSample){
+		
+		if((this.data&1)===0){
+			
+			// Decrement delta:
+			if(this.deltaCounter>0) {
+			    this.deltaCounter--;
+		    }
+			
+		}else{
+			
+			// Increment delta:
+			if(this.deltaCounter<63) {
+			    this.deltaCounter++;
+		    }
+			
+		}
+		
+		// Update sample value:
+		this.sample = this.isEnabled ? (this.deltaCounter<<1)+this.dacLsb : 0;
+		
+		// Update shift register:
+		this.data>>=1;
+		
+	}
+	
+	this.dmaCounter--;
+	if(this.dmaCounter <= 0){
+		
+		// No more sample bits.
+		this.hasSample = false;
+		this.endOfSample();
+		this.dmaCounter = 8;
+		
+	}
+	
+	if(this.irqGenerated){
+		this.papu.nes.cpu.requestIrq(this.papu.nes.cpu.IRQ_NORMAL);
+	}
+	
+};
+
+ChannelDM.prototype.endOfSample = function(){
+	
+	
+	if(this.playLengthCounter===0 && this.playMode==this.MODE_LOOP){
+		
+		// Start from beginning of sample:
+		this.playAddress = this.playStartAddress;
+		this.playLengthCounter = this.playLength;
+		
+	}
+	
+	if(this.playLengthCounter > 0){
+		
+		// Fetch next sample:
+		this.nextSample();
+		
+		if(this.playLengthCounter == 0){
+		
+			// Last byte of sample fetched, generate IRQ:
+			if(this.playMode == this.MODE_IRQ){
+				
+				// Generate IRQ:
+				this.irqGenerated = true;
+				
+			}
+			
+		}
+		
+	}
+	
+};
+
+ChannelDM.prototype.nextSample = function(){
+	
+	// Fetch byte:
+	this.data = this.papu.nes.memMapper.load(this.playAddress);
+	this.papu.nes.cpu.haltCycles(4);
+	
+	this.playLengthCounter--;
+	this.playAddress++;
+	if(this.playAddress>0xFFFF){
+		this.playAddress = 0x8000;
+	}
+	
+	this.hasSample = true;
+	
+};
+
+ChannelDM.prototype.writeReg = function(address, value){
+	
+	if(address == 0x4010){
+		
+		// Play mode, DMA Frequency
+		if((value>>6)==0){
+			this.playMode = this.MODE_NORMAL;
+		}else if(((value>>6)&1)==1){
+			this.playMode = this.MODE_LOOP;
+		}else if((value>>6)==2){
+			this.playMode = this.MODE_IRQ;
+		}
+		
+		if((value&0x80)==0){
+			this.irqGenerated = false;
+		}
+		
+		this.dmaFrequency = this.papu.getDmcFrequency(value&0xF);
+		
+	}else if(address == 0x4011){
+		
+		// Delta counter load register:
+		this.deltaCounter = (value>>1)&63;
+		this.dacLsb = value&1;
+		this.sample = ((this.deltaCounter<<1)+this.dacLsb); // update sample value
+		
+	}else if(address == 0x4012){
+		
+		// DMA address load register
+		this.playStartAddress = (value<<6)|0x0C000;
+		this.playAddress = this.playStartAddress;
+		this.reg4012 = value;
+		
+	}else if(address == 0x4013){
+		
+		// Length of play code
+		this.playLength = (value<<4)+1;
+		this.playLengthCounter = this.playLength;
+		this.reg4013 = value;
+		
+	}else if(address == 0x4015){
+		
+		// DMC/IRQ Status
+		if(((value>>4)&1)==0){
+			// Disable:
+			this.playLengthCounter = 0;
+		}else{
+			// Restart:
+			this.playAddress = this.playStartAddress;
+			this.playLengthCounter = this.playLength;
+		}
+		this.irqGenerated = false;
+	}
+	
+};
+
+ChannelDM.prototype.setEnabled = function(value){
+	
+	if((!this.isEnabled) && value){
+		this.playLengthCounter = this.playLength;
+	}
+	this.isEnabled = value;
+	
+};
+
+ChannelDM.prototype.getLengthStatus = function(){
+	return ((this.playLengthCounter==0 || !this.isEnabled)?0:1);
+};
+
+ChannelDM.prototype.getIrqStatus = function(){
+	return (this.irqGenerated?1:0);
+};
+
+ChannelDM.prototype.reset = function(){
+
+	this.isEnabled = false;
+	this.irqGenerated = false;
+	this.playMode = this.MODE_NORMAL;
+	this.dmaFrequency = 0;
+	this.dmaCounter = 0;
+	this.deltaCounter = 0;
+	this.playStartAddress = 0;
+	this.playAddress = 0;
+	this.playLength = 0;
+	this.playLengthCounter = 0;
+	this.sample = 0;
+	this.dacLsb = 0;
+	this.shiftCounter = 0;
+	this.reg4012 = 0;
+	this.reg4013 = 0;
+	this.data = 0;
+	
+};
+
+
+function ChannelNoise(papu) {
+	this.papu = papu;
+	
+	this.isEnabled = null;
+	this.envDecayDisable = null;
+	this.envDecayLoopEnable = null;
+	this.lengthCounterEnable = null;
+	this.envReset = null;
+	this.shiftNow = null;
+	
+	this.lengthCounter = null;
+	this.progTimerCount = null;
+	this.progTimerMax = null;
+	this.envDecayRate = null;
+	this.envDecayCounter = null;
+	this.envVolume = null;
+	this.masterVolume = null;
+	this.shiftReg = 1<<14;
+	this.randomBit = null;
+	this.randomMode = null;
+	this.sampleValue = null;
+	this.accValue=0;
+	this.accCount=1;
+	this.tmp = null;
+	
+	this.reset();
+}
+
+ChannelNoise.prototype.reset = function(){
+	this.progTimerCount = 0;
+	this.progTimerMax = 0;
+	this.isEnabled = false;
+	this.lengthCounter = 0;
+	this.lengthCounterEnable = false;
+	this.envDecayDisable = false;
+	this.envDecayLoopEnable = false;
+	this.shiftNow = false;
+	this.envDecayRate = 0;
+	this.envDecayCounter = 0;
+	this.envVolume = 0;
+	this.masterVolume = 0;
+	this.shiftReg = 1;
+	this.randomBit = 0;
+	this.randomMode = 0;
+	this.sampleValue = 0;
+	this.tmp = 0;
+};
+
+ChannelNoise.prototype.clockLengthCounter = function(){
+	if(this.lengthCounterEnable && this.lengthCounter>0){
+		this.lengthCounter--;
+		if(this.lengthCounter == 0) this.updateSampleValue();
+	}
+};
+
+ChannelNoise.prototype.clockEnvDecay = function(){
+	
+	if(this.envReset){
+	    
+		// Reset envelope:
+		this.envReset = false;
+		this.envDecayCounter = this.envDecayRate + 1;
+		this.envVolume = 0xF;
+	}else if(--this.envDecayCounter <= 0){
+		
+		// Normal handling:
+		this.envDecayCounter = this.envDecayRate + 1;
+		if(this.envVolume>0){
+			this.envVolume--;
+		}else{
+			this.envVolume = this.envDecayLoopEnable ? 0xF : 0;
+		}	
+	}
+	this.masterVolume = this.envDecayDisable ? this.envDecayRate : this.envVolume;
+	this.updateSampleValue();
+};
+
+ChannelNoise.prototype.updateSampleValue = function(){
+	if(this.isEnabled && this.lengthCounter>0){
+		this.sampleValue = this.randomBit * this.masterVolume;
+	}
+};
+
+ChannelNoise.prototype.writeReg = function(address, value){
+	
+	if(address == 0x400C){
+		
+		// Volume/Envelope decay:
+		this.envDecayDisable = ((value&0x10)!=0);
+		this.envDecayRate = value&0xF;
+		this.envDecayLoopEnable = ((value&0x20)!=0);
+		this.lengthCounterEnable = ((value&0x20)==0);
+		this.masterVolume = this.envDecayDisable?this.envDecayRate:this.envVolume;
+		
+	}else if(address == 0x400E){
+		
+		// Programmable timer:
+		this.progTimerMax = this.papu.getNoiseWaveLength(value&0xF);
+		this.randomMode = value>>7;
+		
+	}else if(address == 0x400F){
+		
+		// Length counter
+		this.lengthCounter = this.papu.getLengthMax(value&248);
+		this.envReset = true;
+		
+	}
+	
+	// Update:
+	//updateSampleValue();
+	
+};
+
+ChannelNoise.prototype.setEnabled = function(value){
+	this.isEnabled = value;
+	if(!value) this.lengthCounter = 0;
+	this.updateSampleValue();
+};
+
+ChannelNoise.prototype.getLengthStatus = function(){
+	return ((this.lengthCounter==0 || !this.isEnabled)?0:1);
+};
+
+
+function ChannelSquare(papu, square1){
+	this.papu = papu;
+	
+	this.dutyLookup = [
+		 0, 1, 0, 0, 0, 0, 0, 0,
+		 0, 1, 1, 0, 0, 0, 0, 0,
+		 0, 1, 1, 1, 1, 0, 0, 0,
+		 1, 0, 0, 1, 1, 1, 1, 1
+	];
+	this.impLookup = [
+		 1,-1, 0, 0, 0, 0, 0, 0,
+		 1, 0,-1, 0, 0, 0, 0, 0,
+		 1, 0, 0, 0,-1, 0, 0, 0,
+		-1, 0, 1, 0, 0, 0, 0, 0
+	];
+	
+	this.sqr1 = square1;
+	this.isEnabled = null;
+	this.lengthCounterEnable = null;
+	this.sweepActive = null;
+	this.envDecayDisable = null;
+	this.envDecayLoopEnable = null;
+	this.envReset = null;
+	this.sweepCarry = null;
+	this.updateSweepPeriod = null;
+	
+	this.progTimerCount = null;
+	this.progTimerMax = null;
+	this.lengthCounter = null;
+	this.squareCounter = null;
+	this.sweepCounter = null;
+	this.sweepCounterMax = null;
+	this.sweepMode = null;
+	this.sweepShiftAmount = null;
+	this.envDecayRate = null;
+	this.envDecayCounter = null;
+	this.envVolume = null;
+	this.masterVolume = null;
+	this.dutyMode = null;
+	this.sweepResult = null;
+	this.sampleValue = null;
+	this.vol = null;
+	
+	this.reset();
+}
+
+
+ChannelSquare.prototype.reset = function() {
+	this.progTimerCount = 0;
+	this.progTimerMax = 0;
+	this.lengthCounter = 0;
+	this.squareCounter = 0;
+	this.sweepCounter = 0;
+	this.sweepCounterMax = 0;
+	this.sweepMode = 0;
+	this.sweepShiftAmount = 0;
+	this.envDecayRate = 0;
+	this.envDecayCounter = 0;
+	this.envVolume = 0;
+	this.masterVolume = 0;
+	this.dutyMode = 0;
+	this.vol = 0;
+	
+	this.isEnabled = false;
+	this.lengthCounterEnable = false;
+	this.sweepActive = false;
+	this.sweepCarry = false;
+	this.envDecayDisable = false;
+	this.envDecayLoopEnable = false;
+};
+
+ChannelSquare.prototype.clockLengthCounter = function(){
+	
+	if(this.lengthCounterEnable && this.lengthCounter>0){
+		this.lengthCounter--;
+		if(this.lengthCounter==0) this.updateSampleValue();
+	}
+	
+};
+
+ChannelSquare.prototype.clockEnvDecay = function() {
+	
+	if(this.envReset){
+		
+		// Reset envelope:
+		this.envReset = false;
+		this.envDecayCounter = this.envDecayRate + 1;
+		this.envVolume = 0xF;
+		
+	}else if((--this.envDecayCounter) <= 0){
+		
+		// Normal handling:
+		this.envDecayCounter = this.envDecayRate + 1;
+		if(this.envVolume>0){
+			this.envVolume--;
+		}else{
+			this.envVolume = this.envDecayLoopEnable ? 0xF : 0;
+		}
+		
+	}
+	
+	this.masterVolume = this.envDecayDisable ? this.envDecayRate : this.envVolume;
+	this.updateSampleValue();
+
+};
+
+ChannelSquare.prototype.clockSweep = function() {
+	
+	if(--this.sweepCounter<=0){
+		
+		this.sweepCounter = this.sweepCounterMax + 1;
+		if(this.sweepActive && this.sweepShiftAmount>0 && this.progTimerMax>7){
+			
+			// Calculate result from shifter:
+			this.sweepCarry = false;
+			if(this.sweepMode==0){
+				this.progTimerMax += (this.progTimerMax>>this.sweepShiftAmount);
+				if(this.progTimerMax > 4095){
+					this.progTimerMax = 4095;
+					this.sweepCarry = true;
+				}
+			}else{
+				this.progTimerMax = this.progTimerMax - ((this.progTimerMax>>this.sweepShiftAmount)-(this.sqr1?1:0));
+			}
+			
+		}
+			
+	}
+	
+	if(this.updateSweepPeriod){
+		this.updateSweepPeriod = false;
+		this.sweepCounter = this.sweepCounterMax + 1;
+	}
+	
+};
+
+ChannelSquare.prototype.updateSampleValue = function() {
+	
+	if(this.isEnabled && this.lengthCounter>0 && this.progTimerMax>7){
+		
+		if(this.sweepMode==0 && (this.progTimerMax + (this.progTimerMax>>this.sweepShiftAmount)) > 4095){
+		//if(this.sweepCarry){
+			this.sampleValue = 0;
+		}else{
+			this.sampleValue = this.masterVolume*this.dutyLookup[(this.dutyMode<<3)+this.squareCounter];	
+		}
+	}else{
+		this.sampleValue = 0;
+	}
+	
+};
+
+ChannelSquare.prototype.writeReg = function(address, value){
+	
+	var addrAdd = (this.sqr1?0:4);
+	if(address == 0x4000+addrAdd){
+		
+		// Volume/Envelope decay:
+		this.envDecayDisable = ((value&0x10)!=0);
+		this.envDecayRate = value & 0xF;
+		this.envDecayLoopEnable = ((value&0x20)!=0);
+		this.dutyMode = (value>>6)&0x3;
+		this.lengthCounterEnable = ((value&0x20)==0);
+		this.masterVolume = this.envDecayDisable?this.envDecayRate:this.envVolume;
+		this.updateSampleValue();
+		
+	}else if(address == 0x4001+addrAdd){
+		
+		// Sweep:
+		this.sweepActive = ((value&0x80)!=0);
+		this.sweepCounterMax = ((value>>4)&7);
+		this.sweepMode = (value>>3)&1;
+		this.sweepShiftAmount = value&7;
+		this.updateSweepPeriod = true;
+		
+	}else if(address == 0x4002+addrAdd){
+		
+		// Programmable timer:
+		this.progTimerMax &= 0x700;
+		this.progTimerMax |= value;
+		
+	}else if(address == 0x4003+addrAdd){
+		
+		// Programmable timer, length counter
+		this.progTimerMax &= 0xFF;
+		this.progTimerMax |= ((value&0x7)<<8);
+		
+		if(this.isEnabled){
+			this.lengthCounter = this.papu.getLengthMax(value&0xF8);
+		}
+		
+		this.envReset  = true;
+		
+	}
+	
+};
+
+ChannelSquare.prototype.setEnabled = function(value){
+	this.isEnabled = value;
+	if(!value) this.lengthCounter = 0;
+	this.updateSampleValue();
+};
+
+ChannelSquare.prototype.getLengthStatus = function() {
+	return ((this.lengthCounter==0 || !this.isEnabled)?0:1);
+};
+
+
+function ChannelTriangle(papu) {
+	this.papu = papu;
+	
+	this.isEnabled = null;
+	this.sampleCondition = null;
+	this.lengthCounterEnable = null;
+	this.lcHalt = null;
+	this.lcControl = null;
+	
+	this.progTimerCount = null;
+	this.progTimerMax = null;
+	this.triangleCounter = null;
+	this.lengthCounter = null;
+	this.linearCounter = null;
+	this.lcLoadValue = null;
+	this.sampleValue = null;
+	this.tmp = null;
+    
+    this.reset();
+}
+
+ChannelTriangle.prototype.reset = function(){
+	this.progTimerCount = 0;
+	this.progTimerMax = 0;
+	this.triangleCounter = 0;
+	this.isEnabled = false;
+	this.sampleCondition = false;
+	this.lengthCounter = 0;
+	this.lengthCounterEnable = false;
+	this.linearCounter = 0;
+	this.lcLoadValue = 0;
+	this.lcHalt = true;
+	this.lcControl = false;
+	this.tmp = 0;
+	this.sampleValue = 0xF;
+};
+
+ChannelTriangle.prototype.clockLengthCounter = function(){
+	if(this.lengthCounterEnable && this.lengthCounter>0){
+		this.lengthCounter--;
+		if(this.lengthCounter==0){
+			this.updateSampleCondition();
+		}
+	}
+};
+
+ChannelTriangle.prototype.clockLinearCounter = function(){
+	if(this.lcHalt){
+		// Load:
+		this.linearCounter = this.lcLoadValue;
+		this.updateSampleCondition();
+	}else if(this.linearCounter > 0){
+		// Decrement:
+		this.linearCounter--;
+		this.updateSampleCondition();
+	}
+	if(!this.lcControl){
+		// Clear halt flag:
+		this.lcHalt = false;
+	}
+};
+
+ChannelTriangle.prototype.getLengthStatus = function(){
+	return ((this.lengthCounter === 0 || !this.isEnabled)?0:1);
+};
+
+ChannelTriangle.prototype.readReg = function(address){
+	return 0;
+};
+
+ChannelTriangle.prototype.writeReg = function(address, value){
+	
+	if(address == 0x4008){
+		
+		// New values for linear counter:
+		this.lcControl 	= (value&0x80)!==0;
+		this.lcLoadValue =  value&0x7F;
+		
+		// Length counter enable:
+		this.lengthCounterEnable = !this.lcControl;
+		
+	}else if(address == 0x400A){
+		
+		// Programmable timer:
+		this.progTimerMax &= 0x700;
+		this.progTimerMax |= value;
+		
+	}else if(address == 0x400B){
+		
+		// Programmable timer, length counter
+		this.progTimerMax &= 0xFF;
+		this.progTimerMax |= ((value&0x07)<<8);
+		this.lengthCounter = this.papu.getLengthMax(value&0xF8);
+		this.lcHalt = true;
+		
+	}
+	
+	this.updateSampleCondition();
+	
+};
+
+ChannelTriangle.prototype.clockProgrammableTimer = function(nCycles){
+	
+	if(this.progTimerMax>0){
+		this.progTimerCount += nCycles;
+		while(this.progTimerMax > 0 && this.progTimerCount >= this.progTimerMax){
+			this.progTimerCount-=this.progTimerMax;
+			if(this.isEnabled && this.lengthCounter>0 && this.linearCounter>0){
+				this.clockTriangleGenerator();
+			}
+		}
+	}
+	
+};
+
+ChannelTriangle.prototype.clockTriangleGenerator = function(){
+	this.triangleCounter++;
+	this.triangleCounter &= 0x1F;
+};
+
+ChannelTriangle.prototype.setEnabled = function(value){
+	this.isEnabled = value;
+	if(!value) this.lengthCounter = 0;
+	this.updateSampleCondition();
+};
+
+ChannelTriangle.prototype.updateSampleCondition = function(){
+	this.sampleCondition = 
+		this.isEnabled 		&& 
+		this.progTimerMax>7 	&&
+		this.linearCounter>0 && 
+		this.lengthCounter>0
+	;
+};
+
+
diff --git a/cpu.js b/cpu.js
index f6cb793..df15c5c 100644
--- a/cpu.js
+++ b/cpu.js
@@ -100,7 +100,7 @@ function CPU(nes) {
         if(this.irqRequested){
             temp =
                 (this.F_CARRY)|
-                ((this.F_ZERO==0?1:0)<<1)|
+                ((this.F_ZERO===0?1:0)<<1)|
                 (this.F_INTERRUPT<<2)|
                 (this.F_DECIMAL<<3)|
                 (this.F_BRK<<4)|
diff --git a/globals.js b/globals.js
index 5d786de..ecba551 100644
--- a/globals.js
+++ b/globals.js
@@ -8,7 +8,7 @@ var Globals = {
 	nes: null,
 	fpsInterval: 500, // Time between updating FPS in ms
 	
-	emulateSound: true,
+	emulateSound: false,
 	sampleRate: 44100, // Sound sample rate in hz
 }
 Globals.frameTime = 1000/Globals.preferredFrameRate;
diff --git a/index.html b/index.html
index b824be9..f872f90 100644
--- a/index.html
+++ b/index.html
@@ -12,6 +12,7 @@ charset="utf-8">
     <script src="jquery-1.2.6.min.js" type="text/javascript" charset="utf-8"></script>
     <script src="jquery.dimensions.min.js" type="text/javascript" charset="utf-8"></script>
     <script src="utils.js" type="text/javascript" charset="utf-8"></script>
+    <script src="channels.js" type="text/javascript" charset="utf-8"></script>
     <script src="cpu.js" type="text/javascript" charset="utf-8"></script>
     <script src="cpuinfo.js" type="text/javascript" charset="utf-8"></script>
     <script src="globals.js" type="text/javascript" charset="utf-8"></script>
@@ -55,6 +56,7 @@ charset="utf-8">
             <select id="roms"></select>
             <input type="button" value="pause" id="pause" disabled="disabled">
             <input type="button" value="restart" id="restart" disabled="disabled">
+            <input type="button" value="enable sound" id="enablesound" disabled="disabled">
         </div>
         <p id="status">Loading...</p>
 <script type="text/javascript">
@@ -144,6 +146,13 @@ digg_url = 'http://digg.com/playable_web_games/JSNES_A_NES_emulator_written_enti
     function resetButtons() {
         $("#pause").attr("disabled", null).attr("value", "pause");
         $("#restart").attr("disabled", null);
+        $("#enablesound").attr("disabled", null);
+        if (Globals.emulateSound) {
+            $("#enablesound").attr("value", "disable sound");
+        }
+        else {
+            $("#enablesound").attr("value", "enable sound");
+        }
     }
     
     $("#roms").change(function() {
@@ -169,13 +178,25 @@ digg_url = 'http://digg.com/playable_web_games/JSNES_A_NES_emulator_written_enti
         }
     });
     
+    $("#enablesound").click(function() {
+        b = $("#enablesound");
+        if (b.attr("value") == "enable sound") {
+            Globals.emulateSound = true;
+            b.attr("value", "disable sound");
+        }
+        else {
+            Globals.emulateSound = false;
+            b.attr("value", "enable sound");
+        }
+    });
+    
     $("#restart").click(function() {
         nes.reloadRom();
         nes.start();
     });
     
     function readJSSoundBuffer() {
-        return nes.papu.readBuffer();
+        return JSON.stringify(nes.papu.readBuffer());
     }
     
     var gaJsHost = (("https:" == document.location.protocol) ? "https://ssl." : "http://www.");
diff --git a/jssound.swf b/jssound.swf
index cde545f..f2c6a18 100644
--- a/jssound.swf
+++ b/jssound.swf
diff --git a/nes.js b/nes.js
index c606368..5ef45bd 100644
--- a/nes.js
+++ b/nes.js
@@ -66,54 +66,57 @@ function NES() {
         this.ppu.startFrame();
         var cycles = 0;
         var emulateSound = Globals.emulateSound;
+        var cpu = this.cpu;
+        var ppu = this.ppu;
+        var papu = this.papu;
         FRAMELOOP: for (;;) {
-            if (this.cpu.cyclesToHalt == 0) {
+            if (cpu.cyclesToHalt == 0) {
                 // Execute a CPU instruction
-                cycles = this.cpu.emulate();
-                if(emulateSound) {
-    				this.papu.clockFrameCounter(cycles);
+                cycles = cpu.emulate();
+                if (emulateSound) {
+    				papu.clockFrameCounter(cycles);
     			}
                 cycles *= 3;
             }
             else {
-                if (this.cpu.cyclesToHalt > 8) {
+                if (cpu.cyclesToHalt > 8) {
                     cycles = 24;
                     if (emulateSound) {
-                        this.papu.clockFrameCounter(8);
+                        papu.clockFrameCounter(8);
                     }
-                    this.cpu.cyclesToHalt -= 8;
+                    cpu.cyclesToHalt -= 8;
                 }
                 else {
-                    cycles = this.cpu.cyclesToHalt * 3;
+                    cycles = cpu.cyclesToHalt * 3;
                     if (emulateSound) {
-                        this.papu.clockFrameCounter(this.cpu.cyclesToHalt);
+                        papu.clockFrameCounter(cpu.cyclesToHalt);
                     }
-                    this.cpu.cyclesToHalt = 0;
+                    cpu.cyclesToHalt = 0;
                 }
             }
             
             for(;cycles>0;cycles--){
 
-                if(this.ppu.curX == this.ppu.spr0HitX 
-                        && this.ppu.f_spVisibility==1 
-                        && this.ppu.scanline-21 == this.ppu.spr0HitY){
+                if(ppu.curX == ppu.spr0HitX 
+                        && ppu.f_spVisibility==1 
+                        && ppu.scanline-21 == ppu.spr0HitY){
                     // Set sprite 0 hit flag:
-                    this.ppu.setStatusFlag(this.ppu.STATUS_SPRITE0HIT,true);
+                    ppu.setStatusFlag(ppu.STATUS_SPRITE0HIT,true);
                 }
 
-                if(this.ppu.requestEndFrame){
-                    this.ppu.nmiCounter--;
-                    if(this.ppu.nmiCounter == 0){
-                        this.ppu.requestEndFrame = false;
-                        this.ppu.startVBlank();
+                if(ppu.requestEndFrame){
+                    ppu.nmiCounter--;
+                    if(ppu.nmiCounter == 0){
+                        ppu.requestEndFrame = false;
+                        ppu.startVBlank();
                         break FRAMELOOP;
                     }
                 }
 
-                this.ppu.curX++;
-                if(this.ppu.curX==341){
-                    this.ppu.curX = 0;
-                    this.ppu.endScanline();
+                ppu.curX++;
+                if(ppu.curX==341){
+                    ppu.curX = 0;
+                    ppu.endScanline();
                 }
 
             }
diff --git a/papu.js b/papu.js
index a897b7c..1ec475e 100644
--- a/papu.js
+++ b/papu.js
@@ -1,691 +1,6 @@
 
-function ChannelDM(papu) {
-	this.papu = papu;
-	
-	this.MODE_NORMAL = 0;
-	this.MODE_LOOP = 1;
-	this.MODE_IRQ = 2;
-	
-	this.isEnabled = null;
-	this.hasSample = null;
-	this.irqGenerated=false;
-	
-	this.playMode = null;
-	this.dmaFrequency = null;
-	this.dmaCounter = null;
-	this.deltaCounter = null;
-	this.playStartAddress = null;
-	this.playAddress = null;
-	this.playLength = null;
-	this.playLengthCounter = null;
-	this.shiftCounter = null;
-	this.reg4012,reg4013 = null;
-	this.status = null;
-	this.sample = null;
-	this.dacLsb = null;
-	this.data = null;
-	
-	this.reset();
-}	
-	
-ChannelDM.prototype.clockDmc = function(){
-	
-	// Only alter DAC value if the sample buffer has data:
-	if(this.hasSample){
-		
-		if((this.data&1)==0){
-			
-			// Decrement delta:
-			if(this.deltaCounter>0) this.deltaCounter--;
-			
-		}else{
-			
-			// Increment delta:
-			if(this.deltaCounter<63) this.deltaCounter++;
-			
-		}
-		
-		// Update sample value:
-		this.sample = this.isEnabled ? (this.deltaCounter<<1)+this.dacLsb : 0;
-		
-		// Update shift register:
-		this.data>>=1;
-		
-	}
-	
-	this.dmaCounter--;
-	if(this.dmaCounter <= 0){
-		
-		// No more sample bits.
-		this.hasSample = false;
-		this.endOfSample();
-		this.dmaCounter = 8;
-		
-	}
-	
-	if(this.irqGenerated){
-		this.papu.nes.cpu.requestIrq(this.papu.nes.cpu.IRQ_NORMAL);
-	}
-	
-}
-
-ChannelDM.prototype.endOfSample = function(){
-	
-	
-	if(this.playLengthCounter==0 && this.playMode==this.MODE_LOOP){
-		
-		// Start from beginning of sample:
-		this.playAddress = this.playStartAddress;
-		this.playLengthCounter = this.playLength;
-		
-	}
-	
-	if(this.playLengthCounter > 0){
-		
-		// Fetch next sample:
-		this.nextSample();
-		
-		if(this.playLengthCounter == 0){
-		
-			// Last byte of sample fetched, generate IRQ:
-			if(this.playMode == this.MODE_IRQ){
-				
-				// Generate IRQ:
-				this.irqGenerated = true;
-				
-			}
-			
-		}
-		
-	}
-	
-}
-
-ChannelDM.prototype.nextSample = function(){
-	
-	// Fetch byte:
-	this.data = this.papu.nes.memMapper.load(this.playAddress);
-	this.papu.nes.cpu.haltCycles(4);
-	
-	this.playLengthCounter--;
-	this.playAddress++;
-	if(this.playAddress>0xFFFF){
-		this.playAddress = 0x8000;
-	}
-	
-	this.hasSample = true;
-	
-}
-
-ChannelDM.prototype.writeReg = function(address, value){
-	
-	if(address == 0x4010){
-		
-		// Play mode, DMA Frequency
-		if((value>>6)==0){
-			this.playMode = this.MODE_NORMAL;
-		}else if(((value>>6)&1)==1){
-			this.playMode = this.MODE_LOOP;
-		}else if((value>>6)==2){
-			this.playMode = this.MODE_IRQ;
-		}
-		
-		if((value&0x80)==0){
-			this.irqGenerated = false;
-		}
-		
-		this.dmaFrequency = this.papu.getDmcFrequency(value&0xF);
-		
-	}else if(address == 0x4011){
-		
-		// Delta counter load register:
-		this.deltaCounter = (value>>1)&63;
-		this.dacLsb = value&1;
-		this.sample = ((this.deltaCounter<<1)+this.dacLsb); // update sample value
-		
-	}else if(address == 0x4012){
-		
-		// DMA address load register
-		this.playStartAddress = (value<<6)|0x0C000;
-		this.playAddress = this.playStartAddress;
-		this.reg4012 = value;
-		
-	}else if(address == 0x4013){
-		
-		// Length of play code
-		this.playLength = (value<<4)+1;
-		this.playLengthCounter = this.playLength;
-		this.reg4013 = value;
-		
-	}else if(address == 0x4015){
-		
-		// DMC/IRQ Status
-		if(((value>>4)&1)==0){
-			// Disable:
-			this.playLengthCounter = 0;
-		}else{
-			// Restart:
-			this.playAddress = this.playStartAddress;
-			this.playLengthCounter = this.playLength;
-		}
-		this.irqGenerated = false;
-	}
-	
-}
-
-ChannelDM.prototype.setEnabled = function(value){
-	
-	if((!this.isEnabled) && value){
-		this.playLengthCounter = this.playLength;
-	}
-	this.isEnabled = value;
-	
-}
-
-ChannelDM.prototype.getLengthStatus = function(){
-	return ((this.playLengthCounter==0 || !this.isEnabled)?0:1);
-}
-
-ChannelDM.prototype.getIrqStatus = function(){
-	return (this.irqGenerated?1:0);
-}
-
-ChannelDM.prototype.reset = function(){
-
-	this.isEnabled = false;
-	this.irqGenerated = false;
-	this.playMode = this.MODE_NORMAL;
-	this.dmaFrequency = 0;
-	this.dmaCounter = 0;
-	this.deltaCounter = 0;
-	this.playStartAddress = 0;
-	this.playAddress = 0;
-	this.playLength = 0;
-	this.playLengthCounter = 0;
-	this.status = 0;
-	this.sample = 0;
-	this.dacLsb = 0;
-	this.shiftCounter = 0;
-	this.reg4012 = 0;
-	this.reg4013 = 0;
-	this.data = 0;
-	
-}
-
-
-function ChannelNoise(papu) {
-	this.papu = papu;
-	
-	this.isEnabled = null;
-	this.envDecayDisable = null;
-	this.envDecayLoopEnable = null;
-	this.lengthCounterEnable = null;
-	this.envReset = null;
-	this.shiftNow = null;
-	
-	this.lengthCounter = null;
-	this.progTimerCount = null;
-	this.progTimerMax = null;
-	this.envDecayRate = null;
-	this.envDecayCounter = null;
-	this.envVolume = null;
-	this.masterVolume = null;
-	this.shiftReg = 1<<14;
-	this.randomBit = null;
-	this.randomMode = null;
-	this.sampleValue = null;
-	this.accValue=0;
-	this.accCount=1;
-	this.tmp = null;
-	
-	this.reset();
-}
-
-ChannelNoise.prototype.reset = function(){
-	this.progTimerCount = 0;
-	this.progTimerMax = 0;
-	this.isEnabled = false;
-	this.lengthCounter = 0;
-	this.lengthCounterEnable = false;
-	this.envDecayDisable = false;
-	this.envDecayLoopEnable = false;
-	this.shiftNow = false;
-	this.envDecayRate = 0;
-	this.envDecayCounter = 0;
-	this.envVolume = 0;
-	this.masterVolume = 0;
-	this.shiftReg = 1;
-	this.randomBit = 0;
-	this.randomMode = 0;
-	this.sampleValue = 0;
-	this.tmp = 0;
-}
-
-ChannelNoise.prototype.clockLengthCounter = function(){
-	if(this.lengthCounterEnable && this.lengthCounter>0){
-		this.lengthCounter--;
-		if(this.lengthCounter == 0) this.updateSampleValue();
-	}
-}
-
-ChannelNoise.prototype.clockEnvDecay = function(){
-	
-	if(this.envReset){
-	    
-		// Reset envelope:
-		this.envReset = false;
-		this.envDecayCounter = this.envDecayRate + 1;
-		this.envVolume = 0xF;
-	}else if(--this.envDecayCounter <= 0){
-		
-		// Normal handling:
-		this.envDecayCounter = this.envDecayRate + 1;
-		if(this.envVolume>0){
-			this.envVolume--;
-		}else{
-			this.envVolume = this.envDecayLoopEnable ? 0xF : 0;
-		}	
-	}
-	this.masterVolume = this.envDecayDisable ? this.envDecayRate : this.envVolume;
-	this.updateSampleValue();
-}
-
-ChannelNoise.prototype.updateSampleValue = function(){
-	if(this.isEnabled && this.lengthCounter>0){
-		this.sampleValue = this.randomBit * this.masterVolume;
-	}
-}
-
-ChannelNoise.prototype.writeReg = function(address, value){
-	
-	if(address == 0x400C){
-		
-		// Volume/Envelope decay:
-		this.envDecayDisable = ((value&0x10)!=0);
-		this.envDecayRate = value&0xF;
-		this.envDecayLoopEnable = ((value&0x20)!=0);
-		this.lengthCounterEnable = ((value&0x20)==0);
-		this.masterVolume = this.envDecayDisable?this.envDecayRate:this.envVolume;
-		
-	}else if(address == 0x400E){
-		
-		// Programmable timer:
-		this.progTimerMax = this.papu.getNoiseWaveLength(value&0xF);
-		this.randomMode = value>>7;
-		
-	}else if(address == 0x400F){
-		
-		// Length counter
-		this.lengthCounter = this.papu.getLengthMax(value&248);
-		this.envReset = true;
-		
-	}
-	
-	// Update:
-	//updateSampleValue();
-	
-}
-
-ChannelNoise.prototype.setEnabled = function(value){
-	this.isEnabled = value;
-	if(!value) this.lengthCounter = 0;
-	this.updateSampleValue();
-}
-
-ChannelNoise.prototype.getLengthStatus = function(){
-	return ((this.lengthCounter==0 || !this.isEnabled)?0:1);
-}
-
-
-function ChannelSquare(papu, square1){
-	this.papu = papu;
-	
-	this.dutyLookup = new Array(
-		 0, 1, 0, 0, 0, 0, 0, 0,
-		 0, 1, 1, 0, 0, 0, 0, 0,
-		 0, 1, 1, 1, 1, 0, 0, 0,
-		 1, 0, 0, 1, 1, 1, 1, 1
-	);
-	this.impLookup = new Array(
-		 1,-1, 0, 0, 0, 0, 0, 0,
-		 1, 0,-1, 0, 0, 0, 0, 0,
-		 1, 0, 0, 0,-1, 0, 0, 0,
-		-1, 0, 1, 0, 0, 0, 0, 0
-	);
-	
-	this.sqr1 = square1;
-	this.isEnabled = null;
-	this.lengthCounterEnable = null;
-	this.sweepActive = null;
-	this.envDecayDisable = null;
-	this.envDecayLoopEnable = null;
-	this.envReset = null;
-	this.sweepCarry = null;
-	this.updateSweepPeriod = null;
-	
-	this.progTimerCount = null;
-	this.progTimerMax = null;
-	this.lengthCounter = null;
-	this.squareCounter = null;
-	this.sweepCounter = null;
-	this.sweepCounterMax = null;
-	this.sweepMode = null;
-	this.sweepShiftAmount = null;
-	this.envDecayRate = null;
-	this.envDecayCounter = null;
-	this.envVolume = null;
-	this.masterVolume = null;
-	this.dutyMode = null;
-	this.sweepResult = null;
-	this.sampleValue = null;
-	this.vol = null;
-	
-	this.reset();
-}
-
-
-ChannelSquare.prototype.reset = function() {
-	this.progTimerCount = 0;
-	this.progTimerMax = 0;
-	this.lengthCounter = 0;
-	this.squareCounter = 0;
-	this.sweepCounter = 0;
-	this.sweepCounterMax = 0;
-	this.sweepMode = 0;
-	this.sweepShiftAmount = 0;
-	this.envDecayRate = 0;
-	this.envDecayCounter = 0;
-	this.envVolume = 0;
-	this.masterVolume = 0;
-	this.dutyMode = 0;
-	this.vol = 0;
-	
-	this.isEnabled = false;
-	this.lengthCounterEnable = false;
-	this.sweepActive = false;
-	this.sweepCarry = false;
-	this.envDecayDisable = false;
-	this.envDecayLoopEnable = false;
-}
-
-ChannelSquare.prototype.clockLengthCounter = function(){
-	
-	if(this.lengthCounterEnable && this.lengthCounter>0){
-		this.lengthCounter--;
-		if(this.lengthCounter==0) this.updateSampleValue();
-	}
-	
-}
-
-ChannelSquare.prototype.clockEnvDecay = function() {
-	
-	if(this.envReset){
-		
-		// Reset envelope:
-		this.envReset = false;
-		this.envDecayCounter = this.envDecayRate + 1;
-		this.envVolume = 0xF;
-		
-	}else if((--this.envDecayCounter) <= 0){
-		
-		// Normal handling:
-		this.envDecayCounter = this.envDecayRate + 1;
-		if(this.envVolume>0){
-			this.envVolume--;
-		}else{
-			this.envVolume = this.envDecayLoopEnable ? 0xF : 0;
-		}
-		
-	}
-	
-	this.masterVolume = this.envDecayDisable ? this.envDecayRate : this.envVolume;
-	this.updateSampleValue();
-
-}
-
-ChannelSquare.prototype.clockSweep = function() {
-	
-	if(--this.sweepCounter<=0){
-		
-		this.sweepCounter = this.sweepCounterMax + 1;
-		if(this.sweepActive && this.sweepShiftAmount>0 && this.progTimerMax>7){
-			
-			// Calculate result from shifter:
-			this.sweepCarry = false;
-			if(this.sweepMode==0){
-				this.progTimerMax += (this.progTimerMax>>this.sweepShiftAmount);
-				if(this.progTimerMax > 4095){
-					this.progTimerMax = 4095;
-					this.sweepCarry = true;
-				}
-			}else{
-				this.progTimerMax = this.progTimerMax - ((this.progTimerMax>>this.sweepShiftAmount)-(this.sqr1?1:0));
-			}
-			
-		}
-			
-	}
-	
-	if(this.updateSweepPeriod){
-		this.updateSweepPeriod = false;
-		this.sweepCounter = this.sweepCounterMax + 1;
-	}
-	
-}
-
-ChannelSquare.prototype.updateSampleValue = function() {
-	
-	if(this.isEnabled && this.lengthCounter>0 && this.progTimerMax>7){
-		
-		if(this.sweepMode==0 && (this.progTimerMax + (this.progTimerMax>>this.sweepShiftAmount)) > 4095){
-		//if(this.sweepCarry){
-			this.sampleValue = 0;
-		}else{
-			this.sampleValue = this.masterVolume*this.dutyLookup[(this.dutyMode<<3)+this.squareCounter];	
-		}
-	}else{
-		this.sampleValue = 0;
-	}
-	
-}
-
-ChannelSquare.prototype.writeReg = function(address, value){
-	
-	var addrAdd = (this.sqr1?0:4);
-	if(address == 0x4000+addrAdd){
-		
-		// Volume/Envelope decay:
-		this.envDecayDisable = ((value&0x10)!=0);
-		this.envDecayRate = value & 0xF;
-		this.envDecayLoopEnable = ((value&0x20)!=0);
-		this.dutyMode = (value>>6)&0x3;
-		this.lengthCounterEnable = ((value&0x20)==0);
-		this.masterVolume = this.envDecayDisable?this.envDecayRate:this.envVolume;
-		this.updateSampleValue();
-		
-	}else if(address == 0x4001+addrAdd){
-		
-		// Sweep:
-		this.sweepActive = ((value&0x80)!=0);
-		this.sweepCounterMax = ((value>>4)&7);
-		this.sweepMode = (value>>3)&1;
-		this.sweepShiftAmount = value&7;
-		this.updateSweepPeriod = true;
-		
-	}else if(address == 0x4002+addrAdd){
-		
-		// Programmable timer:
-		this.progTimerMax &= 0x700;
-		this.progTimerMax |= value;
-		
-	}else if(address == 0x4003+addrAdd){
-		
-		// Programmable timer, length counter
-		this.progTimerMax &= 0xFF;
-		this.progTimerMax |= ((value&0x7)<<8);
-		
-		if(this.isEnabled){
-			this.lengthCounter = this.papu.getLengthMax(value&0xF8);
-		}
-		
-		this.envReset  = true;
-		
-	}
-	
-}
-
-ChannelSquare.prototype.setEnabled = function(value){
-	this.isEnabled = value;
-	if(!value) this.lengthCounter = 0;
-	this.updateSampleValue();
-}
-
-ChannelSquare.prototype.getLengthStatus = function() {
-	return ((this.lengthCounter==0 || !this.isEnabled)?0:1);
-}
-
-
-function ChannelTriangle(papu) {
-	this.papu = papu;
-	
-	this.isEnabled = null;
-	this.sampleCondition = null;
-	this.lengthCounterEnable = null;
-	this.lcHalt = null;
-	this.lcControl = null;
-	
-	this.progTimerCount = null;
-	this.progTimerMax = null;
-	this.triangleCounter = null;
-	this.lengthCounter = null;
-	this.linearCounter = null;
-	this.lcLoadValue = null;
-	this.sampleValue = null;
-	this.tmp = null;
-    
-    this.reset();
-}
-
-ChannelTriangle.prototype.reset = function(){
-	this.progTimerCount = 0;
-	this.progTimerMax = 0;
-	this.triangleCounter = 0;
-	this.isEnabled = false;
-	this.sampleCondition = false;
-	this.lengthCounter = 0;
-	this.lengthCounterEnable = false;
-	this.linearCounter = 0;
-	this.lcLoadValue = 0;
-	this.lcHalt = true;
-	this.lcControl = false;
-	this.tmp = 0;
-	this.sampleValue = 0xF;
-}
-
-ChannelTriangle.prototype.clockLengthCounter = function(){
-	if(this.lengthCounterEnable && this.lengthCounter>0){
-		this.lengthCounter--;
-		if(this.lengthCounter==0){
-			this.updateSampleCondition();
-		}
-	}
-}
-
-ChannelTriangle.prototype.clockLinearCounter = function(){
-	if(this.lcHalt){
-		// Load:
-		this.linearCounter = this.lcLoadValue;
-		this.updateSampleCondition();
-	}else if(this.linearCounter > 0){
-		// Decrement:
-		this.linearCounter--;
-		this.updateSampleCondition();
-	}
-	if(!this.lcControl){
-		// Clear halt flag:
-		this.lcHalt = false;
-	}
-}
-
-ChannelTriangle.prototype.getLengthStatus = function(){
-	return ((this.lengthCounter==0 || !this.isEnabled)?0:1);
-}
-
-ChannelTriangle.prototype.readReg = function(address){
-	return 0;
-}
-
-ChannelTriangle.prototype.writeReg = function(address, value){
-	
-	if(address == 0x4008){
-		
-		// New values for linear counter:
-		this.lcControl 	= (value&0x80)!=0;
-		this.lcLoadValue =  value&0x7F;
-		
-		// Length counter enable:
-		this.lengthCounterEnable = !this.lcControl;
-		
-	}else if(address == 0x400A){
-		
-		// Programmable timer:
-		this.progTimerMax &= 0x700;
-		this.progTimerMax |= value;
-		
-	}else if(address == 0x400B){
-		
-		// Programmable timer, length counter
-		this.progTimerMax &= 0xFF;
-		this.progTimerMax |= ((value&0x07)<<8);
-		this.lengthCounter = this.papu.getLengthMax(value&0xF8);
-		this.lcHalt = true;
-		
-	}
-	
-	this.updateSampleCondition();
-	
-}
-
-ChannelTriangle.prototype.clockProgrammableTimer = function(nCycles){
-	
-	if(this.progTimerMax>0){
-		this.progTimerCount += nCycles;
-		while(this.progTimerMax > 0 && this.progTimerCount >= this.progTimerMax){
-			this.progTimerCount-=this.progTimerMax;
-			if(this.isEnabled && this.lengthCounter>0 && this.linearCounter>0){
-				this.clockTriangleGenerator();
-			}
-		}
-	}
-	
-}
-
-ChannelTriangle.prototype.clockTriangleGenerator = function(){
-	this.triangleCounter++;
-	this.triangleCounter &= 0x1F;
-}
-
-ChannelTriangle.prototype.setEnabled = function(value){
-	this.isEnabled = value;
-	if(!value) this.lengthCounter = 0;
-	this.updateSampleCondition();
-}
-
-ChannelTriangle.prototype.updateSampleCondition = function(){
-	this.sampleCondition = 
-		this.isEnabled 		&& 
-		this.progTimerMax>7 	&&
-		this.linearCounter>0 && 
-		this.lengthCounter>0
-	;
-}
-
-
-
 function PAPU(nes) {
 	this.nes = nes;
-
-    this.buffer = nes;
 	
 	this.square1 = new ChannelSquare(this,true);
 	this.square2 = new ChannelSquare(this,false);
@@ -698,7 +13,7 @@ function PAPU(nes) {
 	this.initCounter = 2048;
 	this.channelEnableValue = null;
 
-	this.bufferSize = 4096;
+	this.bufferSize = 8192;
 	this.bufferIndex = 0;
 	this.sampleRate = 44100;
 
@@ -707,7 +22,7 @@ function PAPU(nes) {
 	this.noiseWavelengthLookup = null;
 	this.square_table = null;
 	this.tnd_table = null;
-	this.sampleBuffer = new Array(this.bufferSize*4);
+	this.sampleBuffer = new Array(this.bufferSize*2);
 
 	this.frameIrqEnabled = false;
 	this.frameIrqActive;
@@ -723,7 +38,6 @@ function PAPU(nes) {
 	this.frameTime = null;
 	this.sampleTimerMax = null;
 	this.sampleCount = null;
-	this.triValue = 0;
 
 	this.smpSquare1 = null;
 	this.smpSquare2 = null;
@@ -758,7 +72,6 @@ function PAPU(nes) {
 	this.stereoPosRDMC = null;
 
 	this.extraCycles = null;
-	this.maxCycles = null;
     
     // Panning:
 	this.panning = new Array(
@@ -969,7 +282,7 @@ PAPU.prototype.clockFrameCounter = function(nCycles){
 
 	if(this.initCounter > 0){
 		if(this.initingHardware){
-			this.initCounter-=nCycles;
+			this.initCounter -= nCycles;
 			if(this.initCounter<=0) this.initingHardware = false;
 			return;
 		}
@@ -977,10 +290,10 @@ PAPU.prototype.clockFrameCounter = function(nCycles){
 
 	// Don't process ticks beyond next sampling:
 	nCycles += this.extraCycles;
-	this.maxCycles = this.sampleTimerMax-this.sampleTimer;
-	if((nCycles<<10) > this.maxCycles){
+	var maxCycles = this.sampleTimerMax-this.sampleTimer;
+	if((nCycles<<10) > maxCycles){
 
-		this.extraCycles = ((nCycles<<10) - this.maxCycles)>>10;
+		this.extraCycles = ((nCycles<<10) - maxCycles)>>10;
 		nCycles -= this.extraCycles;
 
 	}else{
@@ -989,38 +302,44 @@ PAPU.prototype.clockFrameCounter = function(nCycles){
 		
 	}
 	
+	var dmc = this.dmc;
+	var triangle = this.triangle;
+	var square1 = this.square1;
+	var square2 = this.square2;
+	var noise = this.noise;
+	
 	// Clock DMC:
-	if(this.dmc.isEnabled){
+	if(dmc.isEnabled){
 		
-		this.dmc.shiftCounter-=(nCycles<<3);
-		while(this.dmc.shiftCounter<=0 && this.dmc.dmaFrequency>0){
-			this.dmc.shiftCounter += this.dmc.dmaFrequency;
-			this.dmc.clockDmc();
+		dmc.shiftCounter-=(nCycles<<3);
+		while(dmc.shiftCounter<=0 && dmc.dmaFrequency>0){
+			dmc.shiftCounter += dmc.dmaFrequency;
+			dmc.clockDmc();
 		}
 
 	}
 
 	// Clock Triangle channel Prog timer:
-	if(this.triangle.progTimerMax>0){
+	if(triangle.progTimerMax>0){
 		
-		this.triangle.progTimerCount -= nCycles;
-		while(this.triangle.progTimerCount <= 0){
+		triangle.progTimerCount -= nCycles;
+		while(triangle.progTimerCount <= 0){
 			
-			this.triangle.progTimerCount += this.triangle.progTimerMax+1;
-			if(this.triangle.linearCounter>0 && this.triangle.lengthCounter>0){
+			triangle.progTimerCount += triangle.progTimerMax+1;
+			if(triangle.linearCounter>0 && triangle.lengthCounter>0){
 
-				this.triangle.triangleCounter++;
-				this.triangle.triangleCounter &= 0x1F;
+				triangle.triangleCounter++;
+				triangle.triangleCounter &= 0x1F;
 
-				if(this.triangle.isEnabled){
-					if(this.triangle.triangleCounter>=0x10){
+				if(triangle.isEnabled){
+					if(triangle.triangleCounter>=0x10){
 						// Normal value.
-						this.triangle.sampleValue = (this.triangle.triangleCounter&0xF);
+						triangle.sampleValue = (triangle.triangleCounter&0xF);
 					}else{
 						// Inverted value.
-						this.triangle.sampleValue = (0xF - (this.triangle.triangleCounter&0xF));
+						triangle.sampleValue = (0xF - (triangle.triangleCounter&0xF));
 					}
-					this.triangle.sampleValue <<= 4;
+					triangle.sampleValue <<= 4;
 				}
 
 			}
@@ -1029,124 +348,117 @@ PAPU.prototype.clockFrameCounter = function(nCycles){
 	}
 
 	// Clock Square channel 1 Prog timer:
-	this.square1.progTimerCount -= nCycles;
-	if(this.square1.progTimerCount <= 0){
+	square1.progTimerCount -= nCycles;
+	if(square1.progTimerCount <= 0){
 
-		this.square1.progTimerCount += (this.square1.progTimerMax+1)<<1;
+		square1.progTimerCount += (square1.progTimerMax+1)<<1;
 
-		this.square1.squareCounter++;
-		this.square1.squareCounter&=0x7;
-		this.square1.updateSampleValue();
+		square1.squareCounter++;
+		square1.squareCounter&=0x7;
+		square1.updateSampleValue();
 			
 	}
 
 	// Clock Square channel 2 Prog timer:
-	this.square2.progTimerCount -= nCycles;
-	if(this.square2.progTimerCount <= 0){
+	square2.progTimerCount -= nCycles;
+	if(square2.progTimerCount <= 0){
 
-		this.square2.progTimerCount += (this.square2.progTimerMax+1)<<1;
+		square2.progTimerCount += (square2.progTimerMax+1)<<1;
 
-		this.square2.squareCounter++;
-		this.square2.squareCounter&=0x7;
-		this.square2.updateSampleValue();
+		square2.squareCounter++;
+		square2.squareCounter&=0x7;
+		square2.updateSampleValue();
 		
 	}
 
 	// Clock noise channel Prog timer:
 	var acc_c = nCycles;
-	if(this.noise.progTimerCount-acc_c > 0){
+	if(noise.progTimerCount-acc_c > 0){
 		
 		// Do all cycles at once:
-		this.noise.progTimerCount -= acc_c;
-		this.noise.accCount       += acc_c;
-		this.noise.accValue       += acc_c * this.noise.sampleValue;
+		noise.progTimerCount -= acc_c;
+		noise.accCount       += acc_c;
+		noise.accValue       += acc_c * noise.sampleValue;
 		
 	}else{
 		
 		// Slow-step:
 		while((acc_c--) > 0){
 			
-			if(--this.noise.progTimerCount <= 0 && this.noise.progTimerMax>0){
+			if(--noise.progTimerCount <= 0 && noise.progTimerMax>0){
 	
 				// Update noise shift register:
-				this.noise.shiftReg <<= 1;
-				this.noise.tmp = (((this.noise.shiftReg << (this.noise.randomMode==0?1:6)) ^ this.noise.shiftReg) & 0x8000 );
-				if(this.noise.tmp!=0){
+				noise.shiftReg <<= 1;
+				noise.tmp = (((noise.shiftReg << (noise.randomMode==0?1:6)) ^ noise.shiftReg) & 0x8000 );
+				if(noise.tmp!=0){
 					
 					// Sample value must be 0.
-					this.noise.shiftReg |= 0x01;
-					this.noise.randomBit = 0;
-					this.noise.sampleValue = 0;
+					noise.shiftReg |= 0x01;
+					noise.randomBit = 0;
+					noise.sampleValue = 0;
 					
 				}else{
 					
 					// Find sample value:
-					this.noise.randomBit = 1;
-					if(this.noise.isEnabled && this.noise.lengthCounter>0){
-						this.noise.sampleValue = this.noise.masterVolume;
+					noise.randomBit = 1;
+					if(noise.isEnabled && noise.lengthCounter>0){
+						noise.sampleValue = noise.masterVolume;
 					}else{
-						this.noise.sampleValue = 0;
+						noise.sampleValue = 0;
 					}
 					
 				}
 				
-				this.noise.progTimerCount += this.noise.progTimerMax;
+				noise.progTimerCount += noise.progTimerMax;
 					
 			}
 		
-			this.noise.accValue += this.noise.sampleValue;
-			this.noise.accCount++;
+			noise.accValue += noise.sampleValue;
+			noise.accCount++;
 		
 		}
 	}
 	
 
 	// Frame IRQ handling:
-	if(this.frameIrqEnabled && this.frameIrqActive){
+	if (this.frameIrqEnabled && this.frameIrqActive){
 		this.nes.cpu.requestIrq(this.nes.cpu.IRQ_NORMAL);
 	}
 
 	// Clock frame counter at double CPU speed:
-	this.masterFrameCounter+=(nCycles<<1);
-	if(this.masterFrameCounter>=this.frameTime){
-
+	this.masterFrameCounter += (nCycles<<1);
+	if (this.masterFrameCounter >= this.frameTime) {
 		// 240Hz tick:
 		this.masterFrameCounter -= this.frameTime;
 		this.frameCounterTick();
-		
-
 	}
 	
-	
 	// Accumulate sample value:
 	this.accSample(nCycles);
 
-
 	// Clock sample timer:
 	this.sampleTimer += nCycles<<10;
 	if(this.sampleTimer>=this.sampleTimerMax){
-
 		// Sample channels:
 		this.sample();
 		this.sampleTimer -= this.sampleTimerMax;
-
 	}
-
 }
 
 PAPU.prototype.accSample = function(cycles){
+	var triangle = this.triangle;
 	
 	// Special treatment for triangle channel - need to interpolate.
-	if(this.triangle.sampleCondition){
+	if(triangle.sampleCondition){
 
-		this.triValue = parseInt((this.triangle.progTimerCount<<4) / (this.triangle.progTimerMax+1));
-		if(this.triValue>16) this.triValue = 16;
-		if(this.triangle.triangleCounter >= 16){
-			this.triValue = 16-this.triValue;
+		var triValue = parseInt((triangle.progTimerCount<<4) / (triangle.progTimerMax+1));
+		if(triValue>16) triValue = 16;
+		if(triangle.triangleCounter >= 16){
+			triValue = 16-triValue;
 		}
 		
 		// Add non-interpolated sample value:
-		this.triValue += this.triangle.sampleValue;
+		triValue += triangle.sampleValue;
 		
 	}
 	
@@ -1154,7 +466,7 @@ PAPU.prototype.accSample = function(cycles){
 	// Now sample normally:
 	if(cycles == 2){
 		
-		this.smpTriangle += this.triValue				<< 1;
+		this.smpTriangle += triValue				<< 1;
 		this.smpDmc      += this.dmc.sample			<< 1;
 		this.smpSquare1  += this.square1.sampleValue	<< 1;
 		this.smpSquare2  += this.square2.sampleValue	<< 1;
@@ -1162,7 +474,7 @@ PAPU.prototype.accSample = function(cycles){
 		
 	}else if(cycles == 4){
 		
-		this.smpTriangle += this.triValue				<< 2;
+		this.smpTriangle += triValue				<< 2;
 		this.smpDmc      += this.dmc.sample			<< 2;
 		this.smpSquare1  += this.square1.sampleValue	<< 2;
 		this.smpSquare2  += this.square2.sampleValue	<< 2;
@@ -1170,7 +482,7 @@ PAPU.prototype.accSample = function(cycles){
 		
 	}else{
 		
-		this.smpTriangle += cycles * this.triValue;
+		this.smpTriangle += cycles * triValue;
 		this.smpDmc      += cycles * this.dmc.sample;
 		this.smpSquare1  += cycles * this.square1.sampleValue;
 		this.smpSquare2  += cycles * this.square2.sampleValue;
@@ -1284,7 +596,7 @@ PAPU.prototype.sample = function(){
 	sampleValueR = this.smpAccumR;
 
 	// Write:
-	if(this.bufferIndex+4 < this.sampleBuffer.length){
+	if(this.bufferIndex+2 < this.sampleBuffer.length){
 	    if (sampleValueL > this.maxSample) this.maxSample = sampleValueL;
 	    if (sampleValueL < this.minSample) this.minSample = sampleValueL;
 		this.sampleBuffer[this.bufferIndex++] = (sampleValueL );
@@ -1301,12 +613,15 @@ PAPU.prototype.sample = function(){
 
 PAPU.prototype.readBuffer = function() {
     //console.debug(this.bufferIndex);
-    if (this.bufferIndex+4 >= this.sampleBuffer.length) {
+    if (this.bufferIndex >= 2048) {
         var b = this.sampleBuffer;
-        this.sampleBuffer = new Array(this.bufferSize*4);
+        this.sampleBuffer = new Array(this.bufferSize*2);
         this.bufferIndex = 0;
         return b
     }
+    else {
+        console.debug("Insufficient buffer: "+this.bufferIndex);
+    }
 }
 
 PAPU.prototype.getLengthMax = function(value){
diff --git a/ppu.js b/ppu.js
index e60ff20..f0c9a8d 100644
--- a/ppu.js
+++ b/ppu.js
@@ -43,7 +43,6 @@ function PPU(nes) {
     
     
     this.vramMirrorTable = null;            // Mirroring Lookup Table.
-    this.i = null;
     
     // SPR-RAM I/O:
     this.sramAddress = null; // 8-bit only.
@@ -89,13 +88,12 @@ function PPU(nes) {
     // Name table data:
     this.ntable1 = new Array(4);
     this.nameTable = null;
-    this.currentMirroring=-1;
+    this.currentMirroring = -1;
     
     // Palette data:
     this.sprPalette = new Array(16);
     this.imgPalette = new Array(16);
     
-    
     // Misc:
     this.scanlineAlreadyRendered = null;
     this.requestEndFrame = null;
@@ -104,14 +102,6 @@ function PPU(nes) {
     this.tmp = null;
     this.dummyCycleToggle = null;
     
-    // Vars used when updating regs/address:
-    this.address = null;
-    this.b1 = null;
-    this.b2 = null;
-    
-    
-    
-    
     // Variables used when rendering:
     this.attrib = new Array(32);
     this.buffer = new Array(256*240);
@@ -120,38 +110,15 @@ function PPU(nes) {
     this.pixrendered = new Array(256*240);
     this.spr0dummybuffer = new Array(256*240);
     this.dummyPixPriTable = new Array(256*240);
-    this.oldFrame = new Array(256*240);
-    this.tpix = null;
     
-    this.scanlineChanged = Array(240);
-    this.requestRenderAll=false;
     this.validTileData = null;
-    this.att = null;
     
     this.scantile = new Array(32);
-    this.t = null;
-    
-    
-    
     
     // These are temporary variables used in rendering and sound procedures.
     // Their states outside of those procedures can be ignored.
+    // TODO: the use of this is a bit weird, investigate
     this.curNt = null;
-    this.destIndex = null;
-    this.x = null;
-    this.y = null;
-    this.sx = null;
-    this.si = null;
-    this.ei = null;
-    this.tile = null;
-    this.col = null;
-    this.baseTile = null;
-    this.tscanoffset = null;
-    this.srcy1 = null;
-    this.srcy2 = null;
-    this.bufferSize = null;
-    this.available = null;
-    this.scale = null;
     
     this.init = function() {
         // Get the memory:
@@ -196,10 +163,6 @@ function PPU(nes) {
         this.lastRenderedScanline = -1;
         this.curX = 0;
         
-        // Initialize old frame buffer:
-        for(var i=0;i<this.oldFrame.length;i++){
-            this.oldFrame[i]=-1;
-        }
     }
     
     
@@ -813,59 +776,59 @@ function PPU(nes) {
     // Updates the scroll registers from a new VRAM address.
     this.regsFromAddress = function(){
         
-        this.address = (this.vramTmpAddress>>8)&0xFF;
-        this.regFV = (this.address>>4)&7;
-        this.regV = (this.address>>3)&1;
-        this.regH = (this.address>>2)&1;
-        this.regVT = (this.regVT&7) | ((this.address&3)<<3);
+        var address = (this.vramTmpAddress>>8)&0xFF;
+        this.regFV = (address>>4)&7;
+        this.regV = (address>>3)&1;
+        this.regH = (address>>2)&1;
+        this.regVT = (this.regVT&7) | ((address&3)<<3);
         
-        this.address = this.vramTmpAddress&0xFF;
-        this.regVT = (this.regVT&24) | ((this.address>>5)&7);
-        this.regHT = this.address&31;
+        address = this.vramTmpAddress&0xFF;
+        this.regVT = (this.regVT&24) | ((address>>5)&7);
+        this.regHT = address&31;
     }
     
     // Updates the scroll registers from a new VRAM address.
     this.cntsFromAddress = function(){
         
-        this.address = (this.vramAddress>>8)&0xFF;
-        this.cntFV = (this.address>>4)&3;
-        this.cntV = (this.address>>3)&1;
-        this.cntH = (this.address>>2)&1;
-        this.cntVT = (this.cntVT&7) | ((this.address&3)<<3);        
+        var address = (this.vramAddress>>8)&0xFF;
+        this.cntFV = (address>>4)&3;
+        this.cntV = (address>>3)&1;
+        this.cntH = (address>>2)&1;
+        this.cntVT = (this.cntVT&7) | ((address&3)<<3);        
         
-        this.address = this.vramAddress&0xFF;
-        this.cntVT = (this.cntVT&24) | ((this.address>>5)&7);
-        this.cntHT = this.address&31;
+        address = this.vramAddress&0xFF;
+        this.cntVT = (this.cntVT&24) | ((address>>5)&7);
+        this.cntHT = address&31;
         
     }
     
     this.regsToAddress = function(){
-        this.b1  = (this.regFV&7)<<4;
-        this.b1 |= (this.regV&1)<<3;
-        this.b1 |= (this.regH&1)<<2;
-        this.b1 |= (this.regVT>>3)&3;
+        var b1  = (this.regFV&7)<<4;
+        b1 |= (this.regV&1)<<3;
+        b1 |= (this.regH&1)<<2;
+        b1 |= (this.regVT>>3)&3;
         
-        this.b2  = (this.regVT&7)<<5;
-        this.b2 |= this.regHT&31;
+        var b2  = (this.regVT&7)<<5;
+        b2 |= this.regHT&31;
         
-        this.vramTmpAddress = ((this.b1<<8) | this.b2)&0x7FFF;
+        this.vramTmpAddress = ((b1<<8) | b2)&0x7FFF;
     }
     
     this.cntsToAddress = function(){
-        this.b1  = (this.cntFV&7)<<4;
-        this.b1 |= (this.cntV&1)<<3;
-        this.b1 |= (this.cntH&1)<<2;
-        this.b1 |= (this.cntVT>>3)&3;
+        var b1  = (this.cntFV&7)<<4;
+        b1 |= (this.cntV&1)<<3;
+        b1 |= (this.cntH&1)<<2;
+        b1 |= (this.cntVT>>3)&3;
         
-        this.b2  = (this.cntVT&7)<<5;
-        this.b2 |= this.cntHT&31;
+        var b2  = (this.cntVT&7)<<5;
+        b2 |= this.cntHT&31;
         
-        this.vramAddress = ((this.b1<<8) | this.b2)&0x7FFF;
+        this.vramAddress = ((b1<<8) | b2)&0x7FFF;
     }
     
     this.incTileCounter = function(count){
         
-        for(this.i=count;this.i!=0;this.i--){
+        for(var i=count; i!=0; i--){
             this.cntHT++;
             if(this.cntHT==32){
                 this.cntHT=0;
@@ -967,7 +930,6 @@ function PPU(nes) {
             var pixrendered = this.pixrendered;
             for(var destIndex=si;destIndex<ei;destIndex++){
                 if(pixrendered[destIndex]>0xFF){
-                    //console.log("Writing "+this.imgPalette[this.col+this.att].toString(16)+" to buffer at "+this.destIndex.toString(16));
                     buffer[destIndex] = bgbuffer[destIndex];
                 }
             }
@@ -977,28 +939,6 @@ function PPU(nes) {
             this.renderSpritesPartially(startScan,scanCount,false);
         }
         
-        /*BufferView screen = nes.getGui().getScreenView();
-        if(screen.scalingEnabled() && !screen.useHWScaling() && !requestRenderAll){
-            
-            // Check which scanlines have changed, to try to
-            // speed up scaling:
-            int j,jmax;
-            if(startScan+scanCount>240)scanCount=240-startScan;
-            for(int i=startScan;i<startScan+scanCount;i++){
-                scanlineChanged[i]=false;
-                si = i<<8;
-                jmax = si+256;
-                for(j=si;j<jmax;j++){
-                    if(buffer[j]!=oldFrame[j]){
-                        scanlineChanged[i]=true;
-                        break;
-                    }
-                    oldFrame[j]=buffer[j];
-                }
-                System.arraycopy(buffer,j,oldFrame,j,jmax-j);
-            }
-            
-        }*/
         
         this.validTileData = false;
         
@@ -1067,7 +1007,6 @@ function PPU(nes) {
                             for(;sx<8;sx++){
                                 col = tpix[tscanoffset+sx];
                                 if(col != 0){
-                                    //console.log("Writing "+this.imgPalette[this.col+this.att].toString(16)+" to buffer at "+this.destIndex.toString(16));
                                     var pix = imgPalette[col+att];
                                     targetBuffer[destIndex] = pix;
                                     pixrendered[destIndex] |= 256;
@@ -1132,7 +1071,7 @@ function PPU(nes) {
                         this.srcy2 = 8;
                         
                         if(this.sprY[i]<startscan){
-                            srcy1 = startscan - this.sprY[i]-1;
+                            this.srcy1 = startscan - this.sprY[i]-1;
                         }
                         
                         if(this.sprY[i]+8 > startscan+scancount){
@@ -1151,21 +1090,21 @@ function PPU(nes) {
                             top = this.sprTile[i]-1+256;
                         }
                         
-                        this.srcy1 = 0;
-                        this.srcy2 = 8;
+                        var srcy1 = 0;
+                        var srcy2 = 8;
                         
                         if(this.sprY[i]<startscan){
-                            this.srcy1 = startscan - this.sprY[i]-1;
+                            srcy1 = startscan - this.sprY[i]-1;
                         }
                         
                         if(this.sprY[i]+8 > startscan+scancount){
-                            this.srcy2 = startscan+scancount-this.sprY[i];
+                            srcy2 = startscan+scancount-this.sprY[i];
                         }
                         
                         this.ptTile[top+(this.vertFlip[i]?1:0)].render(0,
-                            this.srcy1,
+                            srcy1,
                             8,
-                            this.srcy2,
+                            srcy2,
                             this.sprX[i],
                             this.sprY[i]+1,
                             this.sprCol[i],
@@ -1176,22 +1115,22 @@ function PPU(nes) {
                             this.pixrendered
                         );
                         
-                        this.srcy1 = 0;
-                        this.srcy2 = 8;
+                        var srcy1 = 0;
+                        var srcy2 = 8;
                         
                         if(this.sprY[i]+8<startscan){
-                            this.srcy1 = startscan - (this.sprY[i]+8+1);
+                            srcy1 = startscan - (this.sprY[i]+8+1);
                         }
                         
                         if(this.sprY[i]+16 > startscan+scancount){
-                            this.srcy2 = startscan+scancount-(this.sprY[i]+8);
+                            srcy2 = startscan+scancount-(this.sprY[i]+8);
                         }
                         
                         this.ptTile[top+(this.vertFlip[i]?0:1)].render(
                             0,
-                            this.srcy1,
+                            srcy1,
                             8,
-                            this.srcy2,
+                            srcy2,
                             this.sprX[i],
                             this.sprY[i]+1+8,
                             this.sprCol[i],
@@ -1443,16 +1382,6 @@ function PPU(nes) {
                 leftOver-8, this.ppuMem[address-8], value);
         }
     }
-    
-    this.invalidateFrameCache = function(){
-        
-        // Clear the no-update scanline buffer:
-        for(var i=0;i<240;i++) this.scanlineChanged[i]=true;
-        
-        for(var i=0;i<this.oldFrame.length;i++) this.oldFrame[i]=-1;
-        this.requestRenderAll = true;
-        
-    }
 
     // Updates the internal name table buffers
     // with this new byte.
@@ -1533,8 +1462,6 @@ function PPU(nes) {
         this.validTileData = false;
         this.nmiCounter = 0;
         this.tmp = 0;
-        this.att = 0;
-        this.i = 0;
         
         // Control Flags Register 1:
         this.f_nmiOnVblank = 0;    // NMI on VBlank. 0=disable, 1=enable
@@ -1566,10 +1493,6 @@ function PPU(nes) {
         this.regFH = 0;
         this.regS = 0;
         
-        for (var i=0; i<this.scanlineChanged.length;i++)
-            this.scanlineChanged[i] = true;
-        for (var i=0; i<this.oldFrame.length;i++)
-            this.oldFrame[i] = -1;
         
         // Initialize stuff:
         this.init();