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https://github.com/TomHarte/CLK.git
synced 2024-12-26 09:29:45 +00:00
Put sufficiently much of PCMTrack
into place to get to a stored list of segments, having determined a common clock rate between them and therefore a complete track length.
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@ -80,8 +80,8 @@ std::shared_ptr<Track> G64::get_track_at_position(unsigned int position)
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track_length |= (uint16_t)fgetc(_file) << 8;
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// grab the byte contents of this track
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uint8_t track_contents[track_length];
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fread(track_contents, 1, track_length, _file);
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std::unique_ptr<uint8_t> track_contents(new uint8_t[track_length]);
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fread(track_contents.get(), 1, track_length, _file);
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// seek to this track's entry in the speed zone table
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fseek(_file, (long)((position * 4) + 0x15c), SEEK_SET);
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@ -104,10 +104,83 @@ std::shared_ptr<Track> G64::get_track_at_position(unsigned int position)
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// read the speed zone bytes
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uint8_t speed_zone_contents[speed_zone_length];
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fread(speed_zone_contents, 1, speed_zone_length, _file);
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// TODO: divide into individual PCMSegments (per byte, if necessary), shove into a PCMTrack
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}
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else
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{
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PCMSegment segment;
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segment.duration.length = track_length * 8;
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segment.duration.clock_rate = track_length * 8;
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segment.data = std::move(track_contents);
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resulting_track.reset(new PCMTrack(std::move(segment)));
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}
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return resulting_track;
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}
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#pragma mark - PCMTrack
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unsigned int greatest_common_divisor(unsigned int a, unsigned int b)
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{
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if(a < b)
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{
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unsigned int swap = b;
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b = a;
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a = swap;
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}
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while(1) {
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if(!a) return b;
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if(!b) return a;
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unsigned int remainder = a%b;
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a = b;
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b = remainder;
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}
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}
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unsigned int least_common_multiple(unsigned int a, unsigned int b)
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{
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unsigned int gcd = greatest_common_divisor(a, b);
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return (a*b) / gcd;
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}
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PCMTrack::PCMTrack(std::vector<PCMSegment> segments)
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{
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_segments = std::move(segments);
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fix_length();
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}
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PCMTrack::PCMTrack(PCMSegment segment)
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{
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_segments.push_back(std::move(segment));
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fix_length();
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}
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PCMTrack::Event PCMTrack::get_next_event()
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{
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PCMTrack::Event new_event;
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return new_event;
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}
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void PCMTrack::fix_length()
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{
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// find the least common multiple of all segment clock rates
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_track_clock_rate = _segments[0].duration.clock_rate;
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for(size_t c = 1; c < _segments.size(); c++)
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{
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_track_clock_rate = least_common_multiple(_track_clock_rate, _segments[c].duration.clock_rate);
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}
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// therby determine the total length, storing it to next_event as the divisor
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_next_event.length.clock_rate = 0;
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for(size_t c = 0; c < _segments.size(); c++)
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{
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unsigned int multiplier = _track_clock_rate / _segments[c].duration.clock_rate;
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_next_event.length.clock_rate += _segments[c].duration.length * multiplier;
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}
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_segment_pointer = _bit_pointer = 0;
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}
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@ -10,10 +10,39 @@
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#define G64_hpp
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#include "../Disk.hpp"
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#include <vector>
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namespace Storage {
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struct PCMSegment {
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Time duration;
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std::unique_ptr<uint8_t> data;
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};
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class PCMTrack: public Track {
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public:
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PCMTrack(std::vector<PCMSegment> segments);
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PCMTrack(PCMSegment segment);
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virtual Event get_next_event();
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private:
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// storage for the segments that describe this track
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std::vector<PCMSegment> _segments;
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// a helper to determine the overall track clock rate and it's length
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void fix_length();
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// the event perpetually returned; impliedly contains the length of the entire track
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// as its clock rate, per the need for everything on a Track to sum to a length of 1
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PCMTrack::Event _next_event;
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// contains the master clock rate
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unsigned int _track_clock_rate;
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// a pointer to the first bit to consider as the next event
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size_t _segment_pointer;
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size_t _bit_pointer;
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};
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class G64: public Disk {
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