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285 lines
7.5 KiB
C++
285 lines
7.5 KiB
C++
//
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// Commodore1540.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 05/07/2016.
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// Copyright © 2016 Thomas Harte. All rights reserved.
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//
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#include "C1540.hpp"
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#include <string>
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#include "../../../Storage/Disk/Encodings/CommodoreGCR.hpp"
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using namespace Commodore::C1540;
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Machine::Machine() :
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shift_register_(0),
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Storage::Disk::Controller(1000000, 4, 300),
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serial_port_(new SerialPort),
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serial_port_VIA_(new SerialPortVIA)
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{
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// attach the serial port to its VIA and vice versa
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serial_port_->set_serial_port_via(serial_port_VIA_);
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serial_port_VIA_->set_serial_port(serial_port_);
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// set this instance as the delegate to receive interrupt requests from both VIAs
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serial_port_VIA_->set_interrupt_delegate(this);
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drive_VIA_.set_interrupt_delegate(this);
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drive_VIA_.set_delegate(this);
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// set a bit rate
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set_expected_bit_length(Storage::Encodings::CommodoreGCR::length_of_a_bit_in_time_zone(3));
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}
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void Machine::set_serial_bus(std::shared_ptr<::Commodore::Serial::Bus> serial_bus)
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{
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Commodore::Serial::AttachPortAndBus(serial_port_, serial_bus);
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}
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unsigned int Machine::perform_bus_operation(CPU6502::BusOperation operation, uint16_t address, uint8_t *value)
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{
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/*
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Memory map (given that I'm unsure yet on any potential mirroring):
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0x0000–0x07ff RAM
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0x1800–0x180f the serial-port VIA
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0x1c00–0x1c0f the drive VIA
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0xc000–0xffff ROM
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*/
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if(address < 0x800)
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{
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if(isReadOperation(operation))
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*value = ram_[address];
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else
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ram_[address] = *value;
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}
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else if(address >= 0xc000)
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{
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if(isReadOperation(operation))
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*value = rom_[address & 0x3fff];
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}
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else if(address >= 0x1800 && address <= 0x180f)
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{
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if(isReadOperation(operation))
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*value = serial_port_VIA_->get_register(address);
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else
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serial_port_VIA_->set_register(address, *value);
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}
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else if(address >= 0x1c00 && address <= 0x1c0f)
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{
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if(isReadOperation(operation))
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*value = drive_VIA_.get_register(address);
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else
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drive_VIA_.set_register(address, *value);
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}
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serial_port_VIA_->run_for_cycles(1);
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drive_VIA_.run_for_cycles(1);
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return 1;
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}
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void Machine::set_rom(const uint8_t *rom)
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{
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memcpy(rom_, rom, sizeof(rom_));
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}
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void Machine::set_disk(std::shared_ptr<Storage::Disk::Disk> disk)
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{
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std::shared_ptr<Storage::Disk::Drive> drive(new Storage::Disk::Drive);
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drive->set_disk(disk);
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set_drive(drive);
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}
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void Machine::run_for_cycles(int number_of_cycles)
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{
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CPU6502::Processor<Machine>::run_for_cycles(number_of_cycles);
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set_motor_on(drive_VIA_.get_motor_enabled());
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if(drive_VIA_.get_motor_enabled()) // TODO: motor speed up/down
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Storage::Disk::Controller::run_for_cycles(number_of_cycles);
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}
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#pragma mark - 6522 delegate
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void Machine::mos6522_did_change_interrupt_status(void *mos6522)
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{
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// both VIAs are connected to the IRQ line
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set_irq_line(serial_port_VIA_->get_interrupt_line() || drive_VIA_.get_interrupt_line());
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}
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#pragma mark - Disk drive
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void Machine::process_input_bit(int value, unsigned int cycles_since_index_hole)
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{
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shift_register_ = (shift_register_ << 1) | value;
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if((shift_register_ & 0x3ff) == 0x3ff)
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{
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drive_VIA_.set_sync_detected(true);
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bit_window_offset_ = -1; // i.e. this bit isn't the first within a data window, but the next might be
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}
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else
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{
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drive_VIA_.set_sync_detected(false);
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}
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bit_window_offset_++;
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if(bit_window_offset_ == 8)
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{
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drive_VIA_.set_data_input((uint8_t)shift_register_);
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bit_window_offset_ = 0;
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if(drive_VIA_.get_should_set_overflow())
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{
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set_overflow_line(true);
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}
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}
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else
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set_overflow_line(false);
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}
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// the 1540 does not recognise index holes
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void Machine::process_index_hole() {}
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#pragma mak - Drive VIA delegate
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void Machine::drive_via_did_step_head(void *driveVIA, int direction)
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{
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step(direction);
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}
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void Machine::drive_via_did_set_data_density(void *driveVIA, int density)
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{
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set_expected_bit_length(Storage::Encodings::CommodoreGCR::length_of_a_bit_in_time_zone((unsigned int)density));
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}
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#pragma mark - SerialPortVIA
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SerialPortVIA::SerialPortVIA() :
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port_b_(0x00), attention_acknowledge_level_(false), attention_level_input_(true), data_level_output_(false)
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{}
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uint8_t SerialPortVIA::get_port_input(Port port)
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{
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if(port) return port_b_;
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return 0xff;
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}
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void SerialPortVIA::set_port_output(Port port, uint8_t value, uint8_t mask)
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{
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if(port)
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{
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std::shared_ptr<::Commodore::Serial::Port> serialPort = serial_port_.lock();
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if(serialPort) {
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attention_acknowledge_level_ = !(value&0x10);
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data_level_output_ = (value&0x02);
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serialPort->set_output(::Commodore::Serial::Line::Clock, (::Commodore::Serial::LineLevel)!(value&0x08));
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update_data_line();
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}
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}
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}
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void SerialPortVIA::set_serial_line_state(::Commodore::Serial::Line line, bool value)
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{
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switch(line)
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{
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default: break;
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case ::Commodore::Serial::Line::Data: port_b_ = (port_b_ & ~0x01) | (value ? 0x00 : 0x01); break;
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case ::Commodore::Serial::Line::Clock: port_b_ = (port_b_ & ~0x04) | (value ? 0x00 : 0x04); break;
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case ::Commodore::Serial::Line::Attention:
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attention_level_input_ = !value;
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port_b_ = (port_b_ & ~0x80) | (value ? 0x00 : 0x80);
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set_control_line_input(Port::A, Line::One, !value);
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update_data_line();
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break;
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}
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}
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void SerialPortVIA::set_serial_port(const std::shared_ptr<::Commodore::Serial::Port> &serialPort)
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{
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serial_port_ = serialPort;
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}
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void SerialPortVIA::update_data_line()
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{
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std::shared_ptr<::Commodore::Serial::Port> serialPort = serial_port_.lock();
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if(serialPort)
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{
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// "ATN (Attention) is an input on pin 3 of P2 and P3 that is sensed at PB7 and CA1 of UC3 after being inverted by UA1"
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serialPort->set_output(::Commodore::Serial::Line::Data,
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(::Commodore::Serial::LineLevel)(!data_level_output_ && (attention_level_input_ != attention_acknowledge_level_)));
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}
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}
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#pragma mark - DriveVIA
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void DriveVIA::set_delegate(Delegate *delegate)
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{
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delegate_ = delegate;
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}
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// write protect tab uncovered
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DriveVIA::DriveVIA() : port_b_(0xff), port_a_(0xff), delegate_(nullptr) {}
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uint8_t DriveVIA::get_port_input(Port port) {
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return port ? port_b_ : port_a_;
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}
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void DriveVIA::set_sync_detected(bool sync_detected) {
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port_b_ = (port_b_ & 0x7f) | (sync_detected ? 0x00 : 0x80);
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}
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void DriveVIA::set_data_input(uint8_t value) {
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port_a_ = value;
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}
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bool DriveVIA::get_should_set_overflow() {
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return should_set_overflow_;
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}
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bool DriveVIA::get_motor_enabled() {
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return drive_motor_;
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}
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void DriveVIA::set_control_line_output(Port port, Line line, bool value) {
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if(port == Port::A && line == Line::Two) {
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should_set_overflow_ = value;
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}
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}
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void DriveVIA::set_port_output(Port port, uint8_t value, uint8_t direction_mask) {
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if(port)
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{
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// record drive motor state
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drive_motor_ = !!(value&4);
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// check for a head step
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int step_difference = ((value&3) - (previous_port_b_output_&3))&3;
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if(step_difference)
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{
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if(delegate_) delegate_->drive_via_did_step_head(this, (step_difference == 1) ? 1 : -1);
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}
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// check for a change in density
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int density_difference = (previous_port_b_output_^value) & (3 << 5);
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if(density_difference && delegate_)
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{
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delegate_->drive_via_did_set_data_density(this, (value >> 5)&3);
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}
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// TODO: something with the drive LED
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// printf("LED: %s\n", value&8 ? "On" : "Off");
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previous_port_b_output_ = value;
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}
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}
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#pragma mark - SerialPort
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void SerialPort::set_input(::Commodore::Serial::Line line, ::Commodore::Serial::LineLevel level) {
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std::shared_ptr<SerialPortVIA> serialPortVIA = serial_port_VIA_.lock();
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if(serialPortVIA) serialPortVIA->set_serial_line_state(line, (bool)level);
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}
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void SerialPort::set_serial_port_via(const std::shared_ptr<SerialPortVIA> &serialPortVIA) {
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serial_port_VIA_ = serialPortVIA;
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}
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