Fixed framing and first-byte-after-sync signalling. Hacked together as parts of it are, loading now appears to work!

Components/6522/6522.hpp

@@ -364,7 +364,7 @@ class MOS6522IRQDelegate {
 				virtual void mos6522_did_change_interrupt_status(void *mos6522) = 0;
 		};
 
-		void set_delegate(Delegate *delegate)
+		void set_interrupt_delegate(Delegate *delegate)
 		{
 			_delegate = delegate;
 		}

Machines/Commodore/1540/C1540.cpp

@@ -25,7 +25,8 @@ Machine::Machine() :
 	_serialPortVIA->set_serial_port(_serialPort);
 
 	// set this instance as the delegate to receive interrupt requests from both VIAs
-	_serialPortVIA->set_delegate(this);
+	_serialPortVIA->set_interrupt_delegate(this);
+	_driveVIA.set_interrupt_delegate(this);
 	_driveVIA.set_delegate(this);
 
 	// set a bit rate
@@ -40,10 +41,10 @@ void Machine::set_serial_bus(std::shared_ptr<::Commodore::Serial::Bus> serial_bu
 unsigned int Machine::perform_bus_operation(CPU6502::BusOperation operation, uint16_t address, uint8_t *value)
 {
 //	static bool log = false;
-//	if(operation == CPU6502::BusOperation::ReadOpcode) printf("%04x\n", address);
+//	if(operation == CPU6502::BusOperation::ReadOpcode && (address == 0xF3C0)) log = true;
-//	if(operation == CPU6502::BusOperation::ReadOpcode && (address == 0xf3be)) log = true;
 //	if(operation == CPU6502::BusOperation::ReadOpcode && log) printf("%04x\n", address);
-//	if(operation == CPU6502::BusOperation::ReadOpcode && (address >= 0xF556 && address <= 0xF56D)) printf("%04x\n", address);
+//	if(operation == CPU6502::BusOperation::ReadOpcode) printf("%04x\n", address);
+//	if(operation == CPU6502::BusOperation::ReadOpcode && (address >= 0xF510 && address <= 0xF553)) printf("%04x\n", address);
 //	if(operation == CPU6502::BusOperation::ReadOpcode && (address == 0xE887)) printf("A: %02x\n", get_value_of_register(CPU6502::Register::A));
 
 /*	static bool log = false;
@@ -121,8 +122,15 @@ void Machine::mos6522_did_change_interrupt_status(void *mos6522)
 void Machine::process_input_bit(int value, unsigned int cycles_since_index_hole)
 {
 	_shift_register = (_shift_register << 1) | value;
-	_driveVIA.set_sync_detected((_shift_register & 0x3ff) == 0x3ff);
+	if((_shift_register & 0x3ff) == 0x3ff)
-	if((_shift_register & 0x7ff) == 0x7fe) _bit_window_offset = 0;
+	{
+		_driveVIA.set_sync_detected(true);
+		_bit_window_offset = -1;
+	}
+	else
+	{
+		_driveVIA.set_sync_detected(false);
+	}
 	_bit_window_offset++;
 	if(_bit_window_offset == 8)
 	{
@@ -139,3 +147,15 @@ void Machine::process_input_bit(int value, unsigned int cycles_since_index_hole)
 
 // the 1540 does not recognise index holes
 void Machine::process_index_hole()	{}
+
+#pragma mak - Drive VIA delegate
+
+void Machine::drive_via_did_step_head(void *driveVIA, int direction)
+{
+	step(direction);
+}
+
+void Machine::drive_via_did_set_data_density(void *driveVIA, int density)
+{
+	set_expected_bit_length(Storage::Encodings::CommodoreGCR::length_of_a_bit_in_time_zone((unsigned int)density));
+}

Machines/Commodore/1540/C1540.hpp

@@ -115,10 +115,20 @@ class SerialPortVIA: public MOS::MOS6522<SerialPortVIA>, public MOS::MOS6522IRQD
 */
 class DriveVIA: public MOS::MOS6522<DriveVIA>, public MOS::MOS6522IRQDelegate {
 	public:
+		class Delegate {
+			public:
+				virtual void drive_via_did_step_head(void *driveVIA, int direction) = 0;
+				virtual void drive_via_did_set_data_density(void *driveVIA, int density) = 0;
+		};
+		void set_delegate(Delegate *delegate)
+		{
+			_delegate = delegate;
+		}
+
 		using MOS6522IRQDelegate::set_interrupt_status;
 
 		// write protect tab uncovered
-		DriveVIA() : _port_b(0xff), _port_a(0xff) {}
+		DriveVIA() : _port_b(0xff), _port_a(0xff), _delegate(nullptr) {}
 
 		uint8_t get_port_input(Port port) {
 			return port ? _port_b : _port_a;
@@ -152,10 +162,23 @@ class DriveVIA: public MOS::MOS6522<DriveVIA>, public MOS::MOS6522IRQDelegate {
 				_drive_motor = !!(value&4);
 //				if(value&4)
 //				{
-					printf("Head step: %d\n", value&3);
+
+				int step_difference = ((value&3) - (_previous_port_b_output&3))&3;
+				if(step_difference)
+				{
+					if(_delegate) _delegate->drive_via_did_step_head(this, (step_difference == 1) ? 1 : -1);
+				}
+
+				int density_difference = (_previous_port_b_output^value) & (3 << 5);
+				if(density_difference && _delegate)
+				{
+					_delegate->drive_via_did_set_data_density(this, (value >> 5)&3);
+				}
 //					printf("LED: %s\n", value&8 ? "On" : "Off");
 //					printf("Density: %d\n", (value >> 5)&3);
 //				}
+
+				_previous_port_b_output = value;
 			}
 		}
 
@@ -163,6 +186,8 @@ class DriveVIA: public MOS::MOS6522<DriveVIA>, public MOS::MOS6522IRQDelegate {
 		uint8_t _port_b, _port_a;
 		bool _should_set_overflow;
 		bool _drive_motor;
+		uint8_t _previous_port_b_output;
+		Delegate *_delegate;
 };
 
 /*!
@@ -189,6 +214,7 @@ class SerialPort : public ::Commodore::Serial::Port {
 class Machine:
 	public CPU6502::Processor<Machine>,
 	public MOS::MOS6522IRQDelegate::Delegate,
+	public DriveVIA::Delegate,
 	public Storage::DiskDrive {
 
 	public:
@@ -217,6 +243,10 @@ class Machine:
 		// to satisfy MOS::MOS6522::Delegate
 		virtual void mos6522_did_change_interrupt_status(void *mos6522);
 
+		// to satisfy DriveVIA::Delegate
+		void drive_via_did_step_head(void *driveVIA, int direction);
+		void drive_via_did_set_data_density(void *driveVIA, int density);
+
 	private:
 		uint8_t _ram[0x800];
 		uint8_t _rom[0x4000];

Machines/Commodore/Vic-20/Vic20.cpp

@@ -30,8 +30,8 @@ Machine::Machine() :
 	_serialPort->set_user_port_via(_userPortVIA);
 
 	// wire up the 6522s, tape and machine
-	_userPortVIA->set_delegate(this);
+	_userPortVIA->set_interrupt_delegate(this);
-	_keyboardVIA->set_delegate(this);
+	_keyboardVIA->set_interrupt_delegate(this);
 	_tape.set_delegate(this);
 
 	// establish the memory maps