CLK/Machines/Commodore/1540/C1540.cpp

//
//  Commodore1540.cpp
//  Clock Signal
//
//  Created by Thomas Harte on 05/07/2016.
//  Copyright © 2016 Thomas Harte. All rights reserved.
//

#include "C1540.hpp"
#include <string>
#include "../../../Storage/Disk/Encodings/CommodoreGCR.hpp"

using namespace Commodore::C1540;

Machine::Machine() :
	_shift_register(0),
	Storage::Disk::Drive(1000000, 4, 300)
{
	// create a serial port and a VIA to run it
	_serialPortVIA.reset(new SerialPortVIA);
	_serialPort.reset(new SerialPort);

	// attach the serial port to its VIA and vice versa
	_serialPort->set_serial_port_via(_serialPortVIA);
	_serialPortVIA->set_serial_port(_serialPort);

	// set this instance as the delegate to receive interrupt requests from both VIAs
	_serialPortVIA->set_interrupt_delegate(this);
	_driveVIA.set_interrupt_delegate(this);
	_driveVIA.set_delegate(this);

	// set a bit rate
	set_expected_bit_length(Storage::Encodings::CommodoreGCR::length_of_a_bit_in_time_zone(3));
}

void Machine::set_serial_bus(std::shared_ptr<::Commodore::Serial::Bus> serial_bus)
{
	Commodore::Serial::AttachPortAndBus(_serialPort, serial_bus);
}

unsigned int Machine::perform_bus_operation(CPU6502::BusOperation operation, uint16_t address, uint8_t *value)
{
//	static bool log = false;
//	if(operation == CPU6502::BusOperation::ReadOpcode && (address == 0xF3C0)) log = true;
//	if(operation == CPU6502::BusOperation::ReadOpcode && log) 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;

	if(operation == CPU6502::BusOperation::ReadOpcode)
	{
		log = (address >= 0xE85B && address <= 0xE907) || (address >= 0xE9C9 && address <= 0xEA2D);
		 if(log) printf("\n%04x: ", address);
	}
	if(log)  printf("[%c %04x] ", isReadOperation(operation) ? 'r' : 'w', address);*/

	/*
		Memory map (given that I'm unsure yet on any potential mirroring):

			0x0000–0x07ff	RAM
			0x1800–0x180f	the serial-port VIA
			0x1c00–0x1c0f	the drive VIA
			0xc000–0xffff	ROM
	*/
	if(address < 0x800)
	{
		if(isReadOperation(operation))
			*value = _ram[address];
		else
			_ram[address] = *value;
	}
	else if(address >= 0xc000)
	{
		if(isReadOperation(operation))
			*value = _rom[address & 0x3fff];
	}
	else if(address >= 0x1800 && address <= 0x180f)
	{
		if(isReadOperation(operation))
			*value = _serialPortVIA->get_register(address);
		else
			_serialPortVIA->set_register(address, *value);
	}
	else if(address >= 0x1c00 && address <= 0x1c0f)
	{
		if(isReadOperation(operation))
			*value = _driveVIA.get_register(address);
		else
			_driveVIA.set_register(address, *value);
	}

	_serialPortVIA->run_for_half_cycles(2);
	_driveVIA.run_for_half_cycles(2);

	return 1;
}

void Machine::set_rom(const uint8_t *rom)
{
	memcpy(_rom, rom, sizeof(_rom));
}

void Machine::run_for_cycles(int number_of_cycles)
{
	CPU6502::Processor<Machine>::run_for_cycles(number_of_cycles);
	if(_driveVIA.get_motor_enabled()) // TODO: motor speed up/down
		Storage::Disk::Drive::run_for_cycles(number_of_cycles);
}

#pragma mark - 6522 delegate

void Machine::mos6522_did_change_interrupt_status(void *mos6522)
{
	// both VIAs are connected to the IRQ line
	set_irq_line(_serialPortVIA->get_interrupt_line() || _driveVIA.get_interrupt_line());
}

#pragma mark - Disk drive

void Machine::process_input_bit(int value, unsigned int cycles_since_index_hole)
{
	_shift_register = (_shift_register << 1) | value;
	if((_shift_register & 0x3ff) == 0x3ff)
	{
		_driveVIA.set_sync_detected(true);
		_bit_window_offset = -1; // i.e. this bit isn't the first within a data window, but the next might be
	}
	else
	{
		_driveVIA.set_sync_detected(false);
	}
	_bit_window_offset++;
	if(_bit_window_offset == 8)
	{
		_driveVIA.set_data_input((uint8_t)_shift_register);
		_bit_window_offset = 0;
		if(_driveVIA.get_should_set_overflow())
		{
			set_overflow_line(true);
		}
	}
	else
		set_overflow_line(false);
}

// 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));
}