Edging towards audio output; the speaker is given appropriate input and output rates, and then updated with current divider and enabled/disabled status.

Machines/Electron/Electron.cpp

@@ -20,7 +20,9 @@ static const int crt_cycles_per_line = crt_cycles_multiplier * cycles_per_line;
 Machine::Machine() :
 	_interruptControl(0),
 	_frameCycles(0),
-	_outputPosition(0),
+	_displayOutputPosition(0),
+	_audioOutputPosition(0),
+	_audioOutputPositionError(0),
 	_currentOutputLine(0)
 {
 	memset(_keyStates, 0, sizeof(_keyStates));
@@ -29,6 +31,8 @@ Machine::Machine() :
 	_interruptStatus = 0x02;
 	for(int c = 0; c < 16; c++)
 		memset(_roms[c], 0xff, 16384);
+
+	_speaker.set_input_rate(62500);
 	setup6502();
 }
 
@@ -132,13 +136,23 @@ unsigned int Machine::perform_bus_operation(CPU6502::BusOperation operation, uin
 						}
 					break;
 					case 0x6:
-						printf("Counter\n");
+						if(!isReadOperation(operation))
+						{
+							if(_speaker.is_enabled)
+								update_audio();
+							_speaker.divider = *value;
+						}
 					break;
 					case 0x7:
 						if(!isReadOperation(operation))
 						{
-							_screenMode = ((*value) >> 3)&7;
-							if(_screenMode == 7) _screenMode = 4;
+							// update screen mode
+							uint8_t new_screen_mode = ((*value) >> 3)&7;
+							if(new_screen_mode == 7) new_screen_mode = 4;
+							if(new_screen_mode != _screenMode)
+							{
+								update_display();
+								_screenMode = new_screen_mode;
 								switch(_screenMode)
 								{
 									case 0: case 1: case 2: _screenModeBaseAddress = 0x3000; break;
@@ -146,7 +160,17 @@ unsigned int Machine::perform_bus_operation(CPU6502::BusOperation operation, uin
 									case 4: case 5: _screenModeBaseAddress = 0x5800; break;
 									case 6: _screenModeBaseAddress = 0x6000; break;
 								}
-							printf("Misc. control\n");
+							}
+
+							// update speaker mode
+							bool new_speaker_is_enabled = (*value & 6) == 2;
+							if(new_speaker_is_enabled != _speaker.is_enabled)
+							{
+								update_audio();
+								_speaker.is_enabled = new_speaker_is_enabled;
+							}
+
+							// TODO: tape mode, tape motor, caps lock LED
 						}
 					break;
 					default:
@@ -222,15 +246,36 @@ unsigned int Machine::perform_bus_operation(CPU6502::BusOperation operation, uin
 //	}
 
 	_frameCycles += cycles;
-	if(_frameCycles == cycles_per_frame)
+	switch(_frameCycles)
 	{
+		case 64*128:
+			update_audio();
+		break;
+
+		case 128*128:
+			update_audio();
+			signal_interrupt(InterruptRealTimeClock);
+		break;
+
+		case 196*128:
+			update_audio();
+		break;
+
+		case 284*128:
+			update_audio();
+			signal_interrupt(InterruptDisplayEnd);
+		break;
+
+		case cycles_per_frame:
 			update_display();
+			update_audio();
 			_frameCycles = 0;
-		_outputPosition = 0;
+			_displayOutputPosition = 0;
+			_audioOutputPosition = 0;
 			_currentOutputLine = 0;
+		break;
+
 	}
-	if(_frameCycles == 128*128) signal_interrupt(InterruptRealTimeClock);
-	if(_frameCycles == 284*128) signal_interrupt(InterruptDisplayEnd);
 
 	return cycles;
 }
@@ -266,6 +311,14 @@ inline void Machine::evaluate_interrupts()
 	set_irq_line(_interruptStatus & 1);
 }
 
+inline void Machine::update_audio()
+{
+	int difference = _frameCycles - _audioOutputPosition;
+	_audioOutputPosition = _frameCycles;
+	_speaker.run_for_cycles((_audioOutputPositionError + difference) >> 5);
+	_audioOutputPositionError = (_audioOutputPositionError + difference)&31;
+}
+
 inline void Machine::update_display()
 {
 	const int lines_of_hsync = 3;
@@ -275,26 +328,26 @@ inline void Machine::update_display()
 	if(_frameCycles >= end_of_hsync)
 	{
 		// assert sync for the first three lines of the display, with a break at the end for horizontal alignment
-		if(_outputPosition < end_of_hsync)
+		if(_displayOutputPosition < end_of_hsync)
 		{
 			for(int c = 0; c < lines_of_hsync; c++)
 			{
 				_crt->output_sync(119 * crt_cycles_multiplier);
 				_crt->output_blank(9 * crt_cycles_multiplier);
 			}
-			_outputPosition = end_of_hsync;
+			_displayOutputPosition = end_of_hsync;
 		}
 
-		while(_outputPosition >= end_of_hsync && _outputPosition < _frameCycles)
+		while(_displayOutputPosition >= end_of_hsync && _displayOutputPosition < _frameCycles)
 		{
-			const int current_line = _outputPosition >> 7;
-			const int line_position = _outputPosition & 127;
+			const int current_line = _displayOutputPosition >> 7;
+			const int line_position = _displayOutputPosition & 127;
 
 			// all lines then start with 9 cycles of sync
 			if(!line_position)
 			{
 				_crt->output_sync(9 * crt_cycles_multiplier);
-				_outputPosition += 9;
+				_displayOutputPosition += 9;
 			}
 			else
 			{
@@ -308,7 +361,7 @@ inline void Machine::update_display()
 					if(line_position == 9)
 					{
 						_crt->output_blank(119 * crt_cycles_multiplier);
-						_outputPosition += 119;
+						_displayOutputPosition += 119;
 					}
 				}
 				else
@@ -317,7 +370,7 @@ inline void Machine::update_display()
 					if(line_position == 9)
 					{
 						_crt->output_blank(15 * crt_cycles_multiplier);
-						_outputPosition += 15;
+						_displayOutputPosition += 15;
 
 						_crt->allocate_write_area(80 * crt_cycles_multiplier);
 						_currentLine = (uint8_t *)_crt->get_write_target_for_buffer(0);
@@ -392,7 +445,7 @@ inline void Machine::update_display()
 								break;
 							}
 						}
-						_outputPosition++;
+						_displayOutputPosition++;
 					}
 
 					if(line_position == 104)
@@ -408,7 +461,7 @@ inline void Machine::update_display()
 						_currentLine = nullptr;
 						_crt->output_data(80 * crt_cycles_multiplier);
 						_crt->output_blank(24 * crt_cycles_multiplier);
-						_outputPosition += 24;
+						_displayOutputPosition += 24;
 					}
 				}
 			}

Machines/Electron/Electron.hpp

@@ -70,6 +70,7 @@ class Machine: public CPU6502::Processor<Machine> {
 		void set_key_state(Key key, bool isPressed);
 
 		Outputs::CRT *get_crt() { return _crt; }
+		Outputs::Speaker *get_speaker() { return &_speaker; }
 		const char *get_signal_decoder();
 
 	private:
@@ -84,17 +85,22 @@ class Machine: public CPU6502::Processor<Machine> {
 
 		Outputs::CRT *_crt;
 
-		int _frameCycles, _outputPosition;
+		int _frameCycles, _displayOutputPosition, _audioOutputPosition, _audioOutputPositionError;
+
 		uint16_t _startScreenAddress, _startLineAddress, _currentScreenAddress;
 		int _currentOutputLine;
 		uint8_t *_currentLine;
 
 		inline void update_display();
+		inline void update_audio();
 		inline void signal_interrupt(Interrupt interrupt);
 		inline void evaluate_interrupts();
 
-		class Speaker: public ::Speaker::Filter<Speaker> {
-		};
+		class Speaker: public ::Outputs::Filter<Speaker> {
+			public:
+				uint8_t divider;
+				bool is_enabled;
+		} _speaker;
 };
 
 }

OSBindings/Mac/Clock Signal/Wrappers/CSElectron.mm

@@ -35,6 +35,11 @@
 	_electron.get_crt()->set_delegate(delegate);
 }
 
+- (void)setSpeakerDelegate:(Outputs::Speaker::Delegate *)delegate {
+	_electron.get_speaker()->set_output_rate(44100, 512);
+	_electron.get_speaker()->set_output_quality(15);
+}
+
 - (void)setView:(CSCathodeRayView *)view {
 	[super setView:view];
 	[view setSignalDecoder:[NSString stringWithUTF8String:_electron.get_signal_decoder()] type:CSCathodeRayViewSignalTypeRGB];

OSBindings/Mac/Clock Signal/Wrappers/CSMachine+Subclassing.h

@@ -7,14 +7,17 @@
 //
 
 #import "CSMachine.h"
-#include "../../../../Outputs/CRT.hpp"
+#include "CRT.hpp"
+#include "Speaker.hpp"
 
 @interface CSMachine (Subclassing)
 
+- (void)setSpeakerDelegate:(Outputs::Speaker::Delegate *)delegate;
 - (void)setCRTDelegate:(Outputs::CRT::Delegate *)delegate;
-- (void)doRunForNumberOfCycles:(int)numberOfCycles;
-- (void)crt:(Outputs::CRT *)crt didEndFrame:(CRTFrame *)frame didDetectVSync:(BOOL)didDetectVSync;
 
+- (void)doRunForNumberOfCycles:(int)numberOfCycles;
 - (void)perform:(dispatch_block_t)action;
 
+- (void)crt:(Outputs::CRT *)crt didEndFrame:(CRTFrame *)frame didDetectVSync:(BOOL)didDetectVSync;
+
 @end

OSBindings/Mac/Clock Signal/Wrappers/CSMachine.mm

@@ -53,6 +53,7 @@ typedef NS_ENUM(NSInteger, CSAtari2600RunningState) {
 	if (self) {
 		_crtDelegate.machine = self;
 		[self setCRTDelegate:&_crtDelegate];
+		[self setSpeakerDelegate:nil];
 		_serialDispatchQueue = dispatch_queue_create("Machine queue", DISPATCH_QUEUE_SERIAL);
 		_runningLock = [[NSConditionLock alloc] initWithCondition:CSMachineRunningStateStopped];
 	}
@@ -61,6 +62,7 @@ typedef NS_ENUM(NSInteger, CSAtari2600RunningState) {
 }
 
 - (void)setCRTDelegate:(Outputs::CRT::Delegate *)delegate {}
+- (void)setSpeakerDelegate:(Outputs::Speaker::Delegate *)delegate {}
 - (void)doRunForNumberOfCycles:(int)numberOfCycles {}
 
 @end

Outputs/Speaker.cpp

@@ -8,5 +8,5 @@
 
 #include "Speaker.hpp"
 
-using namespace Speaker;
+using namespace Outputs;
 

Outputs/Speaker.hpp

@@ -10,17 +10,18 @@
 #define Speaker_hpp
 
 #include <stdint.h>
+#include <stdio.h>
 #include "../SignalProcessing/Stepper.hpp"
 
-namespace Speaker {
+namespace Outputs {
 
+class Speaker {
+	public:
 		class Delegate {
 			public:
 				virtual void speaker_did_complete_samples(uint8_t *buffer);
 		};
 
-template <class T> class Filter {
-	public:
 		void set_output_rate(int cycles_per_second, int buffer_size)
 		{
 			_output_cycles_per_second = cycles_per_second;
@@ -50,18 +51,7 @@ template <class T> class Filter {
 			set_needs_updated_filter_coefficients();
 		}
 
-		void run_for_cycles(int input_cycles)
-		{
-			if(_coefficients_are_dirty) update_filter_coefficients();
-
-			// point sample for now, as a temporary measure
-			while(input_cycles--)
-			{
-				static_cast<T *>(this)->perform_bus_operation();
-			}
-		}
-
-	private:
+	protected:
 		uint16_t *_buffer_in_progress;
 		int _buffer_size;
 		int _buffer_in_progress_pointer;
@@ -76,14 +66,31 @@ template <class T> class Filter {
 		{
 			_coefficients_are_dirty = true;
 		}
+};
+
+template <class T> class Filter: public Speaker {
+	public:
+		void run_for_cycles(int input_cycles)
+		{
+			if(_coefficients_are_dirty) update_filter_coefficients();
+
+			// point sample for now, as a temporary measure
+			while(input_cycles--)
+			{
+//				static_cast<T *>(this)->perform_bus_operation();
+			}
+		}
+
+	private:
+		SignalProcessing::Stepper *_stepper;
 
 		void update_filter_coefficients()
 		{
 			_coefficients_are_dirty = false;
 			_buffer_in_progress_pointer = 0;
 
-			delete[] _stepper;
-			_stepper = Stepper(_input_cycles_per_second, _output_cycles_per_second);
+			delete _stepper;
+			_stepper = new SignalProcessing::Stepper((uint64_t)_input_cycles_per_second, (uint64_t)_output_cycles_per_second);
 		}
 };