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Implements PCMTrack::add_segment. Thereby completes PCMTrack::resampled_clone.

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This commit is contained in:
Thomas Harte 2018-07-01 18:28:25 -04:00
parent 2d83eeb9c4
commit b4be2cd063
3 changed files with 27 additions and 7 deletions
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4
Storage/Disk/Track/PCMSegment.cpp
View File

@ -120,3 +120,7 @@ Storage::Time PCMSegmentEventSource::seek_to(const Time &time_from_start) {
const PCMSegment &PCMSegmentEventSource::segment() const {
return *segment_;
}
PCMSegment &PCMSegmentEventSource::segment() {
return *segment_;
}

1
Storage/Disk/Track/PCMSegment.hpp
View File

@ -179,6 +179,7 @@ class PCMSegmentEventSource {
@returns a reference to the underlying segment.
*/
const PCMSegment &segment() const;
PCMSegment &segment();
private:
std::shared_ptr<PCMSegment> segment_;

29
Storage/Disk/Track/PCMTrack.cpp
View File

@ -50,7 +50,7 @@ PCMTrack::PCMTrack(unsigned int bits_per_track) : PCMTrack() {
PCMSegment segment;
segment.length_of_a_bit.length = 1;
segment.length_of_a_bit.clock_rate = bits_per_track;
segment.data.resize((bits_per_track + 7) >> 3);
segment.data.resize(bits_per_track);
segment_event_sources_.emplace_back(segment);
}
@ -59,10 +59,12 @@ Track *PCMTrack::clone() const {
}
Track *PCMTrack::resampled_clone(size_t bits_per_track) {
PCMTrack *new_track = new PCMTrack(static_cast<unsigned int>(bits_per_track));
// Create an empty track.
PCMTrack *const new_track = new PCMTrack(static_cast<unsigned int>(bits_per_track));
// Plot all segments from this track onto the destination.
Time start_time;
for(const auto &event_source : segment_event_sources_) {
for(const auto &event_source: segment_event_sources_) {
const PCMSegment &source = event_source.segment();
new_track->add_segment(start_time, source, true);
start_time += source.length();
@ -131,11 +133,24 @@ Storage::Time PCMTrack::seek_to(const Time &time_since_index_hole) {
}
void PCMTrack::add_segment(const Time &start_time, const PCMSegment &segment, bool clamp_to_index_hole) {
// Write half a bit of silence to lead up to the first possible flux point.
// Get a reference to the destination.
PCMSegment &destination = segment_event_sources_.front().segment();
// Write out the bits contained in this segment.
// Determine the range to fill on the target segment.
const Time end_time = start_time + segment.length();
const size_t start_bit = start_time.length * destination.data.size() / start_time.clock_rate;
const size_t end_bit = end_time.length * destination.data.size() / end_time.clock_rate;
// Write half a bit of silence to end the segment.
// Reset the destination.
std::fill(destination.data.begin() + static_cast<off_t>(start_bit), destination.data.begin() + static_cast<off_t>(end_bit), false);
unsigned int position = start_time.length;
// Step through the source data, and for each true map to a location in the destination and set it.
const size_t target_width = end_bit - start_bit;
const size_t half_offset = target_width / (2 * segment.data.size());
for(size_t bit = 0; bit < segment.data.size(); ++bit) {
if(segment.data[bit]) {
const size_t output_bit = start_bit + half_offset + (bit * target_width) / segment.data.size();
destination.data[output_bit] = true;
}
}
}