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137 lines
3.7 KiB
C++
137 lines
3.7 KiB
C++
//
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// DiskController.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 14/07/2016.
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// Copyright 2016 Thomas Harte. All rights reserved.
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//
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#include "DiskController.hpp"
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using namespace Storage::Disk;
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Controller::Controller(Cycles clock_rate) :
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clock_rate_multiplier_(128000000 / clock_rate.as_integral()),
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clock_rate_(clock_rate.as_integral() * clock_rate_multiplier_),
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pll_(100, *this),
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empty_drive_(int(clock_rate.as_integral()), 1, 1),
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drive_(&empty_drive_) {
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empty_drive_.set_clocking_hint_observer(this);
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set_expected_bit_length(Time(1));
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}
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void Controller::set_component_prefers_clocking(ClockingHint::Source *, ClockingHint::Preference) {
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update_clocking_observer();
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}
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ClockingHint::Preference Controller::preferred_clocking() const {
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// Nominate RealTime clocking if any drive currently wants any clocking whatsoever.
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// Otherwise, ::None will do.
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for(auto &drive: drives_) {
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if(drive.preferred_clocking() != ClockingHint::Preference::None) {
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return ClockingHint::Preference::RealTime;
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}
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}
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if(empty_drive_.preferred_clocking() != ClockingHint::Preference::None) {
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return ClockingHint::Preference::RealTime;
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}
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return ClockingHint::Preference::None;
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}
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void Controller::run_for(const Cycles cycles) {
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for(auto &drive: drives_) {
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drive.run_for(cycles);
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}
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empty_drive_.run_for(cycles);
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}
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Drive &Controller::get_drive() {
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return *drive_;
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}
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// MARK: - Drive::EventDelegate
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void Controller::process_event(const Drive::Event &event) {
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switch(event.type) {
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case Track::Event::FluxTransition: pll_.add_pulse(); break;
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case Track::Event::IndexHole: process_index_hole(); break;
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}
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}
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void Controller::advance(const Cycles cycles) {
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if(is_reading_) pll_.run_for(Cycles(cycles.as_integral() * clock_rate_multiplier_));
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}
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void Controller::process_write_completed() {
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// Provided for subclasses to override.
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}
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// MARK: - PLL control and delegate
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void Controller::set_expected_bit_length(Time bit_length) {
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bit_length_ = bit_length;
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bit_length_.simplify();
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Time cycles_per_bit = Storage::Time(int(clock_rate_)) * bit_length;
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cycles_per_bit.simplify();
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// this conversion doesn't need to be exact because there's a lot of variation to be taken
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// account of in rotation speed, air turbulence, etc, so a direct conversion will do
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const int clocks_per_bit = cycles_per_bit.get<int>();
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pll_.set_clocks_per_bit(clocks_per_bit);
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}
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void Controller::digital_phase_locked_loop_output_bit(int value) {
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if(is_reading_) process_input_bit(value);
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}
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void Controller::set_drive(int index_mask) {
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if(drive_selection_mask_ == index_mask) {
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return;
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}
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const ClockingHint::Preference former_preference = preferred_clocking();
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// Stop receiving events from the current drive.
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get_drive().set_event_delegate(nullptr);
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// TODO: a transfer of writing state, if writing?
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if(!index_mask) {
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drive_ = &empty_drive_;
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} else {
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// TEMPORARY FIX: connect up only the first selected drive.
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// TODO: at least merge events if multiple drives are selected. Some computers have
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// controllers that allow this, with usually meaningless results as far as I can
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// imagine. But the limit of an emulator shouldn't be the author's imagination.
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size_t index = 0;
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while(!(index_mask&1)) {
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index_mask >>= 1;
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++index;
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}
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drive_ = &drives_[index];
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}
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get_drive().set_event_delegate(this);
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if(preferred_clocking() != former_preference) {
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update_clocking_observer();
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}
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}
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void Controller::begin_writing(bool clamp_to_index_hole) {
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is_reading_ = false;
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get_drive().begin_writing(bit_length_, clamp_to_index_hole);
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}
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void Controller::end_writing() {
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if(!is_reading_) {
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is_reading_ = true;
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get_drive().end_writing();
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}
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}
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bool Controller::is_reading() {
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return is_reading_;
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}
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