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126 lines
3.6 KiB
C++
126 lines
3.6 KiB
C++
//
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// Microdisc.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 22/11/2016.
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// Copyright 2016 Thomas Harte. All rights reserved.
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//
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#include "Microdisc.hpp"
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using namespace Oric;
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namespace {
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// The number below, in cycles against an 8Mhz clock, was arrived at fairly unscientifically,
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// by comparing the amount of time this emulator took to show a directory versus a video of
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// a real Oric. It therefore assumes all other timing measurements were correct on the day
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// of the test. More work to do, I think.
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const Cycles::IntType head_load_request_counter_target = 7653333;
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}
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Microdisc::Microdisc() : DiskController(P1793, 8000000, Storage::Disk::Drive::ReadyType::ShugartRDY) {
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set_control_register(last_control_, 0xff);
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}
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void Microdisc::set_control_register(uint8_t control) {
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const uint8_t changes = last_control_ ^ control;
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last_control_ = control;
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set_control_register(control, changes);
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}
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void Microdisc::set_control_register(uint8_t control, uint8_t changes) {
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// b2: data separator clock rate select (1 = double) [TODO]
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// b65: drive select
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if((changes >> 5)&3) {
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set_drive(1 << (control >> 5)&3);
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}
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// b4: side select
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if(changes & 0x10) {
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const int head = (control & 0x10) >> 4;
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for_all_drives([head] (Storage::Disk::Drive &drive, size_t) {
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drive.set_head(head);
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});
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}
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// b3: double density select (0 = double)
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if(changes & 0x08) {
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set_is_double_density(!(control & 0x08));
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}
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// b0: IRQ enable
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if(changes & 0x01) {
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const bool had_irq = get_interrupt_request_line();
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irq_enable_ = bool(control & 0x01);
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const bool has_irq = get_interrupt_request_line();
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if(has_irq != had_irq && delegate_) {
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delegate_->wd1770_did_change_output(this);
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}
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}
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// b7: EPROM select (0 = select)
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// b1: ROM disable (0 = disable)
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if(changes & 0x82) {
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PagedItem item;
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if(control & 0x02) item = PagedItem::BASIC;
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else if(control & 0x80) {
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item = PagedItem::RAM;
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} else {
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item = PagedItem::DiskROM;
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}
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set_paged_item(item);
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}
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}
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bool Microdisc::get_interrupt_request_line() {
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return irq_enable_ && WD1770::get_interrupt_request_line();
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}
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uint8_t Microdisc::get_interrupt_request_register() {
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return 0x7f | (WD1770::get_interrupt_request_line() ? 0x00 : 0x80);
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}
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uint8_t Microdisc::get_data_request_register() {
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return 0x7f | (get_data_request_line() ? 0x00 : 0x80);
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}
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void Microdisc::set_head_load_request(bool head_load) {
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head_load_request_ = head_load;
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// The drive motors (at present: I believe **all drive motors** regardless of the selected drive) receive
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// the current head load request state.
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for_all_drives([head_load] (Storage::Disk::Drive &drive, size_t) {
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drive.set_motor_on(head_load);
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});
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// A request to load the head results in a delay until the head is confirmed loaded. This delay is handled
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// in ::run_for. A request to unload the head results in an instant answer that the head is unloaded.
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if(head_load) {
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head_load_request_counter_ = 0;
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} else {
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head_load_request_counter_ = head_load_request_counter_target;
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set_head_loaded(head_load);
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}
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if(observer_) {
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observer_->set_led_status("Microdisc", head_load);
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}
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}
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void Microdisc::run_for(const Cycles cycles) {
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if(head_load_request_counter_ < head_load_request_counter_target) {
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head_load_request_counter_ += cycles.as_integral();
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if(head_load_request_counter_ >= head_load_request_counter_target) set_head_loaded(true);
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}
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WD::WD1770::run_for(cycles);
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}
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void Microdisc::set_activity_observer(Activity::Observer *observer) {
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observer_ = observer;
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if(observer) {
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observer->register_led("Microdisc");
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observer_->set_led_status("Microdisc", head_load_request_);
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}
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}
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