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Compacts gaps when necessary to fit more sectors.
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d802e8aee3
commit
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@ -16,6 +16,11 @@
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using namespace Storage::Encodings::MFM;
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using namespace Storage::Encodings::MFM;
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enum class SurfaceItem {
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Mark,
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Data
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};
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class MFMEncoder: public Encoder {
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class MFMEncoder: public Encoder {
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public:
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public:
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MFMEncoder(std::vector<bool> &target) : Encoder(target) {}
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MFMEncoder(std::vector<bool> &target) : Encoder(target) {}
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@ -59,6 +64,14 @@ class MFMEncoder: public Encoder {
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add_byte(DeletedDataAddressByte);
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add_byte(DeletedDataAddressByte);
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}
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}
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size_t item_size(SurfaceItem item) {
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switch(item) {
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case SurfaceItem::Mark: return 8; // Three syncs plus the mark type.
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case SurfaceItem::Data: return 2; // Just a single encoded byte.
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default: assert(false);
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}
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}
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private:
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private:
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uint16_t last_output_;
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uint16_t last_output_;
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void output_short(uint16_t value) {
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void output_short(uint16_t value) {
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@ -116,6 +129,11 @@ class FMEncoder: public Encoder {
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crc_generator_.add(DeletedDataAddressByte);
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crc_generator_.add(DeletedDataAddressByte);
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output_short(FMDeletedDataAddressMark);
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output_short(FMDeletedDataAddressMark);
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}
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}
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size_t item_size(SurfaceItem item) {
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// Marks are just slightly-invalid bytes, so everything is the same length.
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return 2;
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}
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};
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};
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template<class T> std::shared_ptr<Storage::Disk::Track>
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template<class T> std::shared_ptr<Storage::Disk::Track>
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@ -131,18 +149,53 @@ template<class T> std::shared_ptr<Storage::Disk::Track>
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segment.data.reserve(expected_track_bytes * 8);
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segment.data.reserve(expected_track_bytes * 8);
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T shifter(segment.data);
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T shifter(segment.data);
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// output the index mark
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// Make a pre-estimate of output size, in case any of the idealised gaps
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// provided need to be shortened.
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const size_t data_size = shifter.item_size(SurfaceItem::Data);
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const size_t mark_size = shifter.item_size(SurfaceItem::Mark);
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const size_t max_size = (expected_track_bytes + (expected_track_bytes / 10)) * 8;
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size_t total_sector_bytes = 0;
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for(const auto sector : sectors) {
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total_sector_bytes += size_t(128 << sector->size) + 2;
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}
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while(true) {
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const size_t size =
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mark_size +
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post_index_address_mark_bytes * data_size +
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total_sector_bytes * data_size +
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sectors.size() * (
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(pre_address_mark_bytes + 6 + post_address_mark_bytes + pre_data_mark_bytes + post_data_bytes) * data_size + 2 * mark_size
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);
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// If this track already fits, do nothing.
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if(size*8 < max_size) break;
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// If all gaps are already zero, do nothing.
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if(!post_index_address_mark_bytes && !pre_address_mark_bytes && !post_address_mark_bytes && !pre_data_mark_bytes && !post_data_bytes)
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break;
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// Very simple solution: try halving all gaps.
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post_index_address_mark_bytes >>= 1;
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pre_address_mark_bytes >>= 1;
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post_address_mark_bytes >>= 1;
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pre_data_mark_bytes >>= 1;
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post_data_bytes >>= 1;
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}
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// Output the index mark.
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shifter.add_index_address_mark();
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shifter.add_index_address_mark();
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// add the post-index mark
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// Add the post-index mark.
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for(std::size_t c = 0; c < post_index_address_mark_bytes; c++) shifter.add_byte(post_index_address_mark_value);
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for(std::size_t c = 0; c < post_index_address_mark_bytes; c++) shifter.add_byte(post_index_address_mark_value);
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// add sectors
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// Add sectors.
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for(const Sector *sector : sectors) {
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for(const Sector *sector : sectors) {
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// gap
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// Gap.
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for(std::size_t c = 0; c < pre_address_mark_bytes; c++) shifter.add_byte(0x00);
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for(std::size_t c = 0; c < pre_address_mark_bytes; c++) shifter.add_byte(0x00);
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// sector header
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// Sector header.
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shifter.add_ID_address_mark();
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shifter.add_ID_address_mark();
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shifter.add_byte(sector->address.track);
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shifter.add_byte(sector->address.track);
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shifter.add_byte(sector->address.side);
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shifter.add_byte(sector->address.side);
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@ -150,11 +203,11 @@ template<class T> std::shared_ptr<Storage::Disk::Track>
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shifter.add_byte(sector->size);
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shifter.add_byte(sector->size);
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shifter.add_crc(sector->has_header_crc_error);
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shifter.add_crc(sector->has_header_crc_error);
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// gap
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// Gap.
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for(std::size_t c = 0; c < post_address_mark_bytes; c++) shifter.add_byte(post_address_mark_value);
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for(std::size_t c = 0; c < post_address_mark_bytes; c++) shifter.add_byte(post_address_mark_value);
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for(std::size_t c = 0; c < pre_data_mark_bytes; c++) shifter.add_byte(0x00);
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for(std::size_t c = 0; c < pre_data_mark_bytes; c++) shifter.add_byte(0x00);
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// data, if attached
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// Data, if attached.
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// TODO: allow for weak/fuzzy data.
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// TODO: allow for weak/fuzzy data.
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if(!sector->samples.empty()) {
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if(!sector->samples.empty()) {
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if(sector->is_deleted)
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if(sector->is_deleted)
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@ -173,14 +226,13 @@ template<class T> std::shared_ptr<Storage::Disk::Track>
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shifter.add_crc(sector->has_data_crc_error);
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shifter.add_crc(sector->has_data_crc_error);
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}
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}
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// gap
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// Gap.
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for(std::size_t c = 0; c < post_data_bytes; c++) shifter.add_byte(post_data_value);
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for(std::size_t c = 0; c < post_data_bytes; c++) shifter.add_byte(post_data_value);
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}
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}
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while(segment.data.size() < expected_track_bytes*8) shifter.add_byte(0x00);
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while(segment.data.size() < expected_track_bytes*8) shifter.add_byte(0x00);
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// Allow the amount of data written to be up to 10% more than the expected size. Which is generous.
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// Allow the amount of data written to be up to 10% more than the expected size. Which is generous.
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const std::size_t max_size = (expected_track_bytes + (expected_track_bytes / 10)) * 8;
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if(segment.data.size() > max_size) segment.data.resize(max_size);
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if(segment.data.size() > max_size) segment.data.resize(max_size);
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return std::shared_ptr<Storage::Disk::Track>(new Storage::Disk::PCMTrack(std::move(segment)));
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return std::shared_ptr<Storage::Disk::Track>(new Storage::Disk::PCMTrack(std::move(segment)));
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