CLK/Storage/Disk/DiskController.cpp

//
//  DiskController.cpp
//  Clock Signal
//
//  Created by Thomas Harte on 14/07/2016.
//  Copyright © 2016 Thomas Harte. All rights reserved.
//

#include "DiskController.hpp"

using namespace Storage::Disk;

Controller::Controller(unsigned int clock_rate, unsigned int clock_rate_multiplier, unsigned int revolutions_per_minute) :
	clock_rate_(clock_rate * clock_rate_multiplier),
	clock_rate_multiplier_(clock_rate_multiplier),
	rotational_multiplier_(60u, revolutions_per_minute),

	cycles_since_index_hole_(0),
	motor_is_on_(false),

	is_reading_(true),
	track_is_dirty_(false),

	TimedEventLoop(clock_rate * clock_rate_multiplier)
{
	// seed this class with a PLL, any PLL, so that it's safe to assume non-nullptr later
	Time one(1);
	set_expected_bit_length(one);
}

void Controller::setup_track()
{
	if(patched_track_)
	{
		drive_->set_track(patched_track_);
	}

	track_ = drive_->get_track();
	track_is_dirty_ = false;

	Time offset;
	Time track_time_now = get_time_into_track();
	if(track_ && track_time_now > Time(0))
	{
		Time time_found = track_->seek_to(track_time_now);
		offset = track_time_now - time_found;
	}
	else
	{
		offset = track_time_now;
	}

	get_next_event(offset);
}

void Controller::run_for_cycles(int number_of_cycles)
{
	if(drive_ && drive_->has_disk() && motor_is_on_)
	{
		if(!track_) setup_track();

		number_of_cycles *= clock_rate_multiplier_;
		while(number_of_cycles)
		{
			int cycles_until_next_event = (int)get_cycles_until_next_event();
			int cycles_to_run_for = std::min(cycles_until_next_event, number_of_cycles);

			cycles_since_index_hole_ += (unsigned int)cycles_to_run_for;

			number_of_cycles -= cycles_to_run_for;
			pll_->run_for_cycles(cycles_to_run_for);
			TimedEventLoop::run_for_cycles(cycles_to_run_for);
		}
	}
}

#pragma mark - Track timed event loop

void Controller::get_next_event(const Time &duration_already_passed)
{
	if(track_)
		current_event_ = track_->get_next_event();
	else
	{
		current_event_.length.length = 1;
		current_event_.length.clock_rate = 1;
		current_event_.type = Track::Event::IndexHole;
	}

	// divide interval, which is in terms of a single rotation of the disk, by rotation speed to
	// convert it into revolutions per second; this is achieved by multiplying by rotational_multiplier_
	set_next_event_time_interval((current_event_.length - duration_already_passed) * rotational_multiplier_);
}

void Controller::process_next_event()
{
	switch(current_event_.type)
	{
		case Track::Event::FluxTransition:
			pll_->add_pulse();
		break;
		case Track::Event::IndexHole:
			printf("%p %d [/%d = %d]\n", this, cycles_since_index_hole_, clock_rate_multiplier_, cycles_since_index_hole_ / clock_rate_multiplier_);
			cycles_since_index_hole_ = 0;
			process_index_hole();
		break;
	}
	get_next_event(Time(0));
}

Storage::Time Controller::get_time_into_track()
{
	// this is proportion of a second
	Time result(cycles_since_index_hole_, 8000000 * clock_rate_multiplier_);
	result /= rotational_multiplier_;
	result.simplify();
	return result;
}

#pragma mark - Writing

void Controller::begin_writing()
{
	is_reading_ = false;

	write_segment_.length_of_a_bit = bit_length_ * rotational_multiplier_;
	write_segment_.data.clear();
	write_segment_.number_of_bits = 0;

	write_start_time_ = get_time_into_track();
}

void Controller::write_bit(bool value)
{
	bool needs_new_byte = !(write_segment_.number_of_bits&7);
	if(needs_new_byte) write_segment_.data.push_back(0);
	if(value) write_segment_.data[write_segment_.number_of_bits >> 3] |= 0x80 >> (write_segment_.number_of_bits & 7);
	write_segment_.number_of_bits++;
}

void Controller::end_writing()
{
	is_reading_ = true;

	if(!patched_track_)
	{
		patched_track_.reset(new PCMPatchedTrack(track_));
	}
	patched_track_->add_segment(write_start_time_, write_segment_);
}

#pragma mark - PLL control and delegate

void Controller::set_expected_bit_length(Time bit_length)
{
	bit_length_ = bit_length;

	// this conversion doesn't need to be exact because there's a lot of variation to be taken
	// account of in rotation speed, air turbulence, etc, so a direct conversion will do
	int clocks_per_bit = (int)((bit_length.length * clock_rate_) / bit_length.clock_rate);
	pll_.reset(new DigitalPhaseLockedLoop(clocks_per_bit, clocks_per_bit / 5, 3));
	pll_->set_delegate(this);
}

void Controller::digital_phase_locked_loop_output_bit(int value)
{
	process_input_bit(value, cycles_since_index_hole_);
}

#pragma mark - Drive actions

bool Controller::get_is_track_zero()
{
	if(!drive_) return false;
	return drive_->get_is_track_zero();
}

bool Controller::get_drive_is_ready()
{
	if(!drive_) return false;
	return drive_->has_disk();
}

void Controller::step(int direction)
{
	if(drive_) drive_->step(direction);
	invalidate_track();
}

void Controller::set_motor_on(bool motor_on)
{
	motor_is_on_ = motor_on;
}

bool Controller::get_motor_on()
{
	return motor_is_on_;
}

void Controller::set_drive(std::shared_ptr<Drive> drive)
{
	drive_ = drive;
	invalidate_track();
}

void Controller::invalidate_track()
{
	track_ = nullptr;
}