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255 lines
7.0 KiB
C++
255 lines
7.0 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 "UnformattedTrack.hpp"
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#include <algorithm>
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#include <cassert>
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using namespace Storage::Disk;
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Drive::Drive(unsigned int input_clock_rate, int revolutions_per_minute, unsigned 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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}
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void Drive::set_disk(const std::shared_ptr<Disk> &disk) {
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disk_ = disk;
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has_disk_ = !!disk_;
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invalidate_track();
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update_sleep_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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bool Drive::is_sleeping() {
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return !motor_is_on_ || !has_disk_;
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}
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bool Drive::get_is_track_zero() {
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return head_position_ == 0;
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}
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void Drive::step(int direction) {
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int old_head_position = head_position_;
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head_position_ = std::max(head_position_ + direction, 0);
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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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void Drive::set_head(unsigned 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_, (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 true;
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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(!motor_is_on) {
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ready_index_count_ = 0;
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}
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update_sleep_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_ += (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 = (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 = (int)cycles_until_bits_written_.get_unsigned_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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#pragma 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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setup_track();
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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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Time interval = (current_event_.length - duration_already_passed) * rotational_multiplier_;
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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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// TODO: ready test here.
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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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#pragma 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(head_, (unsigned int)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(head_, (unsigned int)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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assert(time_found >= Time(0) && time_found < Time(1) && time_found <= track_time_now);
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offset = track_time_now - time_found;
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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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#pragma 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_segment_.number_of_bits = 0;
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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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bool needs_new_byte = !(write_segment_.number_of_bits&7);
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if(needs_new_byte) write_segment_.data.push_back(0);
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if(value) write_segment_.data[write_segment_.number_of_bits >> 3] |= 0x80 >> (write_segment_.number_of_bits & 7);
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write_segment_.number_of_bits++;
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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(!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<PCMPatchedTrack>(track_);
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if(!patched_track_) {
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patched_track_.reset(new PCMPatchedTrack(track_));
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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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