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66 lines
2.1 KiB
C++
66 lines
2.1 KiB
C++
//
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// TrackSerialiser.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 26/09/2017.
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// Copyright 2017 Thomas Harte. All rights reserved.
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//
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#include "TrackSerialiser.hpp"
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#include <memory>
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// TODO: if this is a PCMTrack with only one segment and that segment's bit rate is within tolerance,
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// just return a copy of that segment.
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Storage::Disk::PCMSegment Storage::Disk::track_serialisation(const Track &track, Time length_of_a_bit) {
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unsigned int history_size = 16;
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std::unique_ptr<Track> track_copy(track.clone());
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// ResultAccumulator exists to append whatever comes out of the PLL to
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// its PCMSegment.
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struct ResultAccumulator {
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PCMSegment result;
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bool is_recording = false;
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void digital_phase_locked_loop_output_bit(int value) {
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if(is_recording) result.data.push_back(!!value);
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}
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} result_accumulator;
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result_accumulator.result.length_of_a_bit = length_of_a_bit;
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DigitalPhaseLockedLoop<ResultAccumulator> pll(100, result_accumulator);
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// Obtain a length multiplier which is 100 times the reciprocal
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// of the expected bit length. So a perfect bit length from
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// the source data will come out as 100 ticks.
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Time length_multiplier = Time(100*length_of_a_bit.clock_rate, length_of_a_bit.length);
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length_multiplier.simplify();
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// start at the index hole
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track_copy->seek_to(0.0f);
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// grab events until the next index hole
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Time time_error = Time(0);
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while(true) {
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Track::Event next_event = track_copy->get_next_event();
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Time extended_length = next_event.length * length_multiplier + time_error;
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time_error.clock_rate = extended_length.clock_rate;
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time_error.length = extended_length.length % extended_length.clock_rate;
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pll.run_for(Cycles(int(extended_length.get<int64_t>())));
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if(next_event.type == Track::Event::IndexHole) break;
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pll.add_pulse();
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// If the PLL is now sufficiently primed, restart, and start recording bits this time.
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if(history_size) {
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history_size--;
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if(!history_size) {
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track_copy->seek_to(0.0f);
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time_error.set_zero();
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result_accumulator.is_recording = true;
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}
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}
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}
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return result_accumulator.result;
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}
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