mirror of
https://github.com/TomHarte/CLK.git
synced 2024-12-26 09:29:45 +00:00
111 lines
3.9 KiB
C++
111 lines
3.9 KiB
C++
//
|
|
// PCMTrack.cpp
|
|
// Clock Signal
|
|
//
|
|
// Created by Thomas Harte on 10/07/2016.
|
|
// Copyright © 2016 Thomas Harte. All rights reserved.
|
|
//
|
|
|
|
#include "PCMTrack.hpp"
|
|
#include "../../NumberTheory/Factors.hpp"
|
|
|
|
using namespace Storage::Disk;
|
|
|
|
PCMTrack::PCMTrack() : segment_pointer_(0) {}
|
|
|
|
PCMTrack::PCMTrack(const std::vector<PCMSegment> &segments) : PCMTrack() {
|
|
// sum total length of all segments
|
|
Time total_length;
|
|
for(auto segment : segments) {
|
|
total_length += segment.length_of_a_bit * segment.number_of_bits;
|
|
}
|
|
total_length.simplify();
|
|
|
|
// each segment is then some proportion of the total; for them all to sum to 1 they'll
|
|
// need to be adjusted to be
|
|
for(auto segment : segments) {
|
|
Time original_length_of_segment = segment.length_of_a_bit * segment.number_of_bits;
|
|
Time proportion_of_whole = original_length_of_segment / total_length;
|
|
proportion_of_whole.simplify();
|
|
PCMSegment length_adjusted_segment = segment;
|
|
length_adjusted_segment.length_of_a_bit = proportion_of_whole / segment.number_of_bits;
|
|
length_adjusted_segment.length_of_a_bit.simplify();
|
|
segment_event_sources_.emplace_back(length_adjusted_segment);
|
|
}
|
|
}
|
|
|
|
PCMTrack::PCMTrack(const PCMSegment &segment) : PCMTrack() {
|
|
// a single segment necessarily fills the track
|
|
PCMSegment length_adjusted_segment = segment;
|
|
length_adjusted_segment.length_of_a_bit.length = 1;
|
|
length_adjusted_segment.length_of_a_bit.clock_rate = segment.number_of_bits;
|
|
segment_event_sources_.emplace_back(length_adjusted_segment);
|
|
}
|
|
|
|
PCMTrack::PCMTrack(const PCMTrack &original) : PCMTrack() {
|
|
segment_event_sources_ = original.segment_event_sources_;
|
|
}
|
|
|
|
Track *PCMTrack::clone() {
|
|
return new PCMTrack(*this);
|
|
}
|
|
|
|
Track::Event PCMTrack::get_next_event() {
|
|
// ask the current segment for a new event
|
|
Track::Event event = segment_event_sources_[segment_pointer_].get_next_event();
|
|
|
|
// if it was a flux transition, that's code for end-of-segment, so dig deeper
|
|
if(event.type == Track::Event::IndexHole) {
|
|
// multiple segments may be crossed, so start summing lengths in case the net
|
|
// effect is an index hole
|
|
Time total_length = event.length;
|
|
|
|
// continue until somewhere no returning an index hole
|
|
while(event.type == Track::Event::IndexHole) {
|
|
// advance to the [start of] the next segment
|
|
segment_pointer_ = (segment_pointer_ + 1) % segment_event_sources_.size();
|
|
segment_event_sources_[segment_pointer_].reset();
|
|
|
|
// if this is all the way back to the start, that's a genuine index hole,
|
|
// so set the summed length and return
|
|
if(!segment_pointer_) {
|
|
return event;
|
|
}
|
|
|
|
// otherwise get the next event (if it's not another index hole, the loop will end momentarily),
|
|
// summing in any prior accumulated time
|
|
event = segment_event_sources_[segment_pointer_].get_next_event();
|
|
total_length += event.length;
|
|
event.length = total_length;
|
|
}
|
|
}
|
|
|
|
return event;
|
|
}
|
|
|
|
Storage::Time PCMTrack::seek_to(const Time &time_since_index_hole) {
|
|
// initial condition: no time yet accumulated, the whole thing requested yet to navigate
|
|
Storage::Time accumulated_time;
|
|
Storage::Time time_left_to_seek = time_since_index_hole;
|
|
|
|
// search from the first segment
|
|
segment_pointer_ = 0;
|
|
do {
|
|
// if this segment extends beyond the amount of time left to seek, trust it to complete
|
|
// the seek
|
|
Storage::Time segment_time = segment_event_sources_[segment_pointer_].get_length();
|
|
if(segment_time > time_left_to_seek) {
|
|
return accumulated_time + segment_event_sources_[segment_pointer_].seek_to(time_left_to_seek);
|
|
}
|
|
|
|
// otherwise swallow this segment, updating the time left to seek and time so far accumulated
|
|
time_left_to_seek -= segment_time;
|
|
accumulated_time += segment_time;
|
|
segment_pointer_ = (segment_pointer_ + 1) % segment_event_sources_.size();
|
|
} while(segment_pointer_);
|
|
|
|
// if all segments have now been swallowed, the closest we can get is the very end of
|
|
// the list of segments
|
|
return accumulated_time;
|
|
}
|