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349 lines
10 KiB
C++
349 lines
10 KiB
C++
//
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// Drive.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 25/09/2016.
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// Copyright 2016 Thomas Harte. All rights reserved.
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//
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#include "Drive.hpp"
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#include "Track/UnformattedTrack.hpp"
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#include <algorithm>
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#include <cassert>
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#include <cmath>
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#include <chrono>
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#include <random>
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using namespace Storage::Disk;
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Drive::Drive(unsigned int input_clock_rate, int revolutions_per_minute, int number_of_heads):
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Storage::TimedEventLoop(input_clock_rate),
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rotational_multiplier_(60, revolutions_per_minute),
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available_heads_(number_of_heads) {
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rotational_multiplier_.simplify();
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const auto seed = static_cast<std::default_random_engine::result_type>(std::chrono::system_clock::now().time_since_epoch().count());
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std::default_random_engine randomiser(seed);
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// Get at least 64 bits of random information; rounding is likey to give this a slight bias.
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random_source_ = 0;
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auto half_range = (randomiser.max() - randomiser.min()) / 2;
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for(int bit = 0; bit < 64; ++bit) {
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random_source_ <<= 1;
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random_source_ |= ((randomiser() - randomiser.min()) >= half_range) ? 1 : 0;
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}
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}
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Drive::~Drive() {
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if(disk_) disk_->flush_tracks();
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}
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void Drive::set_disk(const std::shared_ptr<Disk> &disk) {
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if(disk_) disk_->flush_tracks();
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disk_ = disk;
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has_disk_ = !!disk_;
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invalidate_track();
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update_clocking_observer();
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}
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bool Drive::has_disk() {
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return has_disk_;
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}
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ClockingHint::Preference Drive::preferred_clocking() {
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return (!motor_is_on_ || !has_disk_) ? ClockingHint::Preference::None : ClockingHint::Preference::JustInTime;
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}
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bool Drive::get_is_track_zero() {
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return head_position_ == HeadPosition(0);
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}
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void Drive::step(HeadPosition offset) {
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HeadPosition old_head_position = head_position_;
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head_position_ += offset;
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if(head_position_ < HeadPosition(0)) {
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head_position_ = HeadPosition(0);
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if(observer_) observer_->announce_drive_event(drive_name_, Activity::Observer::DriveEvent::StepBelowZero);
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} else {
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if(observer_) observer_->announce_drive_event(drive_name_, Activity::Observer::DriveEvent::StepNormal);
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}
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// If the head moved, flush the old track.
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if(head_position_ != old_head_position) {
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track_ = nullptr;
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}
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}
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std::shared_ptr<Track> Drive::step_to(HeadPosition offset) {
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HeadPosition old_head_position = head_position_;
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head_position_ = std::max(offset, HeadPosition(0));
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if(head_position_ != old_head_position) {
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track_ = nullptr;
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setup_track();
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}
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return track_;
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}
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void Drive::set_head(int head) {
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head = std::min(head, available_heads_ - 1);
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if(head != head_) {
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head_ = head;
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track_ = nullptr;
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}
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}
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Storage::Time Drive::get_time_into_track() {
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// `result` will initially be amount of time since the index hole was seen as a
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// proportion of a second; convert it into proportion of a rotation, simplify and return.
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Time result(cycles_since_index_hole_, static_cast<int>(get_input_clock_rate()));
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result /= rotational_multiplier_;
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result.simplify();
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// assert(result <= Time(1));
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return result;
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}
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bool Drive::get_is_read_only() {
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if(disk_) return disk_->get_is_read_only();
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return true;
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}
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bool Drive::get_is_ready() {
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return ready_index_count_ == 2;
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}
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void Drive::set_motor_on(bool motor_is_on) {
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motor_is_on_ = motor_is_on;
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if(observer_) {
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observer_->set_drive_motor_status(drive_name_, motor_is_on_);
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if(announce_motor_led_) {
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observer_->set_led_status(drive_name_, motor_is_on_);
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}
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}
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if(!motor_is_on) {
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ready_index_count_ = 0;
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if(disk_) disk_->flush_tracks();
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}
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update_clocking_observer();
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}
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bool Drive::get_motor_on() {
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return motor_is_on_;
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}
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void Drive::set_event_delegate(Storage::Disk::Drive::EventDelegate *delegate) {
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event_delegate_ = delegate;
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}
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void Drive::advance(const Cycles cycles) {
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cycles_since_index_hole_ += static_cast<unsigned int>(cycles.as_int());
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if(event_delegate_) event_delegate_->advance(cycles);
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}
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void Drive::run_for(const Cycles cycles) {
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if(has_disk_ && motor_is_on_) {
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Time zero(0);
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int number_of_cycles = cycles.as_int();
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while(number_of_cycles) {
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int cycles_until_next_event = static_cast<int>(get_cycles_until_next_event());
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int cycles_to_run_for = std::min(cycles_until_next_event, number_of_cycles);
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if(!is_reading_ && cycles_until_bits_written_ > zero) {
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int write_cycles_target = cycles_until_bits_written_.get<int>();
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if(cycles_until_bits_written_.length % cycles_until_bits_written_.clock_rate) write_cycles_target++;
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cycles_to_run_for = std::min(cycles_to_run_for, write_cycles_target);
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}
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number_of_cycles -= cycles_to_run_for;
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if(!is_reading_) {
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if(cycles_until_bits_written_ > zero) {
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Storage::Time cycles_to_run_for_time(cycles_to_run_for);
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if(cycles_until_bits_written_ <= cycles_to_run_for_time) {
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if(event_delegate_) event_delegate_->process_write_completed();
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if(cycles_until_bits_written_ <= cycles_to_run_for_time)
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cycles_until_bits_written_.set_zero();
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else
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cycles_until_bits_written_ -= cycles_to_run_for_time;
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} else {
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cycles_until_bits_written_ -= cycles_to_run_for_time;
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}
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}
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}
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TimedEventLoop::run_for(Cycles(cycles_to_run_for));
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}
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}
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}
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// MARK: - Track timed event loop
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void Drive::get_next_event(const Time &duration_already_passed) {
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// Grab a new track if not already in possession of one. This will recursively call get_next_event,
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// supplying a proper duration_already_passed.
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if(!track_) {
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random_interval_.set_zero();
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setup_track();
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return;
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}
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// If gain has now been turned up so as to generate noise, generate some noise.
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if(random_interval_ > Time(0)) {
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current_event_.type = Track::Event::IndexHole;
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current_event_.length.length = 2 + (random_source_&1);
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current_event_.length.clock_rate = 1000000;
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random_source_ = (random_source_ >> 1) | (random_source_ << 63);
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if(random_interval_ < current_event_.length) {
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current_event_.length = random_interval_;
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random_interval_.set_zero();
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} else {
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random_interval_ -= current_event_.length;
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}
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set_next_event_time_interval(current_event_.length);
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return;
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}
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if(track_) {
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current_event_ = track_->get_next_event();
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} else {
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current_event_.length.length = 1;
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current_event_.length.clock_rate = 1;
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current_event_.type = Track::Event::IndexHole;
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}
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// divide interval, which is in terms of a single rotation of the disk, by rotation speed to
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// convert it into revolutions per second; this is achieved by multiplying by rotational_multiplier_
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assert(current_event_.length <= Time(1) && current_event_.length >= Time(0));
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assert(current_event_.length > duration_already_passed);
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Time interval = (current_event_.length - duration_already_passed) * rotational_multiplier_;
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// An interval greater than 15ms => adjust gain up the point where noise starts happening.
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// Seed that up and leave a 15ms gap until it starts.
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const Time safe_gain_period(15, 1000000);
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if(interval >= safe_gain_period) {
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random_interval_ = interval - safe_gain_period;
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interval = safe_gain_period;
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}
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set_next_event_time_interval(interval);
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}
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void Drive::process_next_event() {
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if(current_event_.type == Track::Event::IndexHole) {
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// assert(get_time_into_track() == Time(1) || get_time_into_track() == Time(0));
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if(ready_index_count_ < 2) ready_index_count_++;
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cycles_since_index_hole_ = 0;
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}
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if(
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event_delegate_ &&
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(current_event_.type == Track::Event::IndexHole || is_reading_)
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){
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event_delegate_->process_event(current_event_);
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}
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get_next_event(Time(0));
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}
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// MARK: - Track management
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std::shared_ptr<Track> Drive::get_track() {
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if(disk_) return disk_->get_track_at_position(Track::Address(head_, head_position_));
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return nullptr;
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}
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void Drive::set_track(const std::shared_ptr<Track> &track) {
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if(disk_) disk_->set_track_at_position(Track::Address(head_, head_position_), track);
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}
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void Drive::setup_track() {
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track_ = get_track();
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if(!track_) {
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track_.reset(new UnformattedTrack);
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}
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Time offset;
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Time track_time_now = get_time_into_track();
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assert(track_time_now >= Time(0) && current_event_.length <= Time(1));
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Time time_found = track_->seek_to(track_time_now);
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// time_found can be greater than track_time_now if limited precision caused rounding
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if(time_found <= track_time_now) {
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offset = track_time_now - time_found;
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} else {
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offset.set_zero();
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}
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get_next_event(offset);
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}
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void Drive::invalidate_track() {
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track_ = nullptr;
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if(patched_track_) {
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set_track(patched_track_);
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patched_track_ = nullptr;
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}
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}
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// MARK: - Writing
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void Drive::begin_writing(Time bit_length, bool clamp_to_index_hole) {
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is_reading_ = false;
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clamp_writing_to_index_hole_ = clamp_to_index_hole;
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cycles_per_bit_ = Storage::Time(get_input_clock_rate()) * bit_length;
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cycles_per_bit_.simplify();
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write_segment_.length_of_a_bit = bit_length / rotational_multiplier_;
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write_segment_.data.clear();
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write_start_time_ = get_time_into_track();
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}
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void Drive::write_bit(bool value) {
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write_segment_.data.push_back(value);
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cycles_until_bits_written_ += cycles_per_bit_;
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}
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void Drive::end_writing() {
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// If the user modifies a track, it's scaled up to a "high" resolution and modifications
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// are plotted on top of that.
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static const size_t high_resolution_track_rate = 500000;
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if(!is_reading_) {
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is_reading_ = true;
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if(!patched_track_) {
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// Avoid creating a new patched track if this one is already patched
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patched_track_ = std::dynamic_pointer_cast<PCMTrack>(track_);
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if(!patched_track_ || !patched_track_->is_resampled_clone()) {
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Track *tr = track_.get();
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patched_track_.reset(PCMTrack::resampled_clone(tr, high_resolution_track_rate));
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}
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}
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patched_track_->add_segment(write_start_time_, write_segment_, clamp_writing_to_index_hole_);
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cycles_since_index_hole_ %= get_input_clock_rate();
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invalidate_track();
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}
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}
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void Drive::set_activity_observer(Activity::Observer *observer, const std::string &name, bool add_motor_led) {
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observer_ = observer;
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announce_motor_led_ = add_motor_led;
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if(observer) {
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drive_name_ = name;
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observer->register_drive(drive_name_);
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observer->set_drive_motor_status(drive_name_, motor_is_on_);
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if(add_motor_led) {
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observer->register_led(drive_name_);
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observer->set_led_status(drive_name_, motor_is_on_);
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}
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}
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}
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