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Thereby opens a route for file format implementations such as that appearing for CPC DSK that create an in-memory copy and perform a full rewrite.
169 lines
4.7 KiB
C++
169 lines
4.7 KiB
C++
//
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// OricMFMDSK.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 21/11/2016.
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// Copyright © 2016 Thomas Harte. All rights reserved.
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//
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#include "OricMFMDSK.hpp"
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#include "../../Track/PCMTrack.hpp"
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#include "../../Encodings/MFM/Constants.hpp"
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#include "../../Encodings/MFM/Shifter.hpp"
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#include "../../Encodings/MFM/Encoder.hpp"
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#include "../../Track/TrackSerialiser.hpp"
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using namespace Storage::Disk;
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OricMFMDSK::OricMFMDSK(const char *file_name) :
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file_(file_name) {
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if(!file_.check_signature("MFM_DISK"))
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throw ErrorNotOricMFMDSK;
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head_count_ = file_.get32le();
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track_count_ = file_.get32le();
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geometry_type_ = file_.get32le();
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if(geometry_type_ < 1 || geometry_type_ > 2)
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throw ErrorNotOricMFMDSK;
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}
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int OricMFMDSK::get_head_position_count() {
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return static_cast<int>(track_count_);
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}
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int OricMFMDSK::get_head_count() {
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return static_cast<int>(head_count_);
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}
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long OricMFMDSK::get_file_offset_for_position(Track::Address address) {
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int seek_offset = 0;
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switch(geometry_type_) {
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case 1:
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seek_offset = address.head * static_cast<int>(track_count_) + address.position;
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break;
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case 2:
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seek_offset = address.position * static_cast<int>(track_count_ * head_count_) + address.head;
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break;
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}
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return static_cast<long>(seek_offset) * 6400 + 256;
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}
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std::shared_ptr<Track> OricMFMDSK::get_track_at_position(Track::Address address) {
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PCMSegment segment;
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{
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std::lock_guard<std::mutex> lock_guard(file_.get_file_access_mutex());
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file_.seek(get_file_offset_for_position(address), SEEK_SET);
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// The file format omits clock bits. So it's not a genuine MFM capture.
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// A consumer must contextually guess when an FB, FC, etc is meant to be a control mark.
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size_t track_offset = 0;
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uint8_t last_header[6] = {0, 0, 0, 0, 0, 0};
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std::unique_ptr<Encodings::MFM::Encoder> encoder = Encodings::MFM::GetMFMEncoder(segment.data);
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bool did_sync = false;
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while(track_offset < 6250) {
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uint8_t next_byte = file_.get8();
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track_offset++;
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switch(next_byte) {
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default: {
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encoder->add_byte(next_byte);
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if(did_sync) {
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switch(next_byte) {
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default: break;
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case 0xfe:
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for(int byte = 0; byte < 6; byte++) {
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last_header[byte] = file_.get8();
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encoder->add_byte(last_header[byte]);
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track_offset++;
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if(track_offset == 6250) break;
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}
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break;
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case 0xfb:
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for(int byte = 0; byte < (128 << last_header[3]) + 2; byte++) {
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encoder->add_byte(file_.get8());
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track_offset++;
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if(track_offset == 6250) break;
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}
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break;
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}
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}
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did_sync = false;
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}
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break;
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case 0xa1: // a synchronisation mark that implies a sector or header coming
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encoder->output_short(Storage::Encodings::MFM::MFMSync);
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did_sync = true;
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break;
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case 0xc2: // an 'ordinary' synchronisation mark
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encoder->output_short(Storage::Encodings::MFM::MFMIndexSync);
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break;
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}
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}
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}
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segment.number_of_bits = static_cast<unsigned int>(segment.data.size() * 8);
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std::shared_ptr<PCMTrack> track(new PCMTrack(segment));
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return track;
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}
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void OricMFMDSK::set_tracks(const std::map<Track::Address, std::shared_ptr<Track>> &tracks) {
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for(auto &track : tracks) {
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PCMSegment segment = Storage::Disk::track_serialisation(*track.second, Storage::Encodings::MFM::MFMBitLength);
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Storage::Encodings::MFM::Shifter shifter;
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shifter.set_is_double_density(true);
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shifter.set_should_obey_syncs(true);
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std::vector<uint8_t> parsed_track;
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int size = 0;
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int offset = 0;
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bool capture_size = false;
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for(unsigned int bit = 0; bit < segment.number_of_bits; ++bit) {
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shifter.add_input_bit(segment.bit(bit));
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if(shifter.get_token() == Storage::Encodings::MFM::Shifter::Token::None) continue;
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parsed_track.push_back(shifter.get_byte());
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if(offset) {
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offset--;
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if(!offset) {
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shifter.set_should_obey_syncs(true);
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}
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if(capture_size && offset == 2) {
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size = parsed_track.back();
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capture_size = false;
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}
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}
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if( shifter.get_token() == Storage::Encodings::MFM::Shifter::Token::Data ||
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shifter.get_token() == Storage::Encodings::MFM::Shifter::Token::DeletedData) {
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offset = 128 << size;
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shifter.set_should_obey_syncs(false);
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}
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if(shifter.get_token() == Storage::Encodings::MFM::Shifter::Token::ID) {
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offset = 6;
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shifter.set_should_obey_syncs(false);
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capture_size = true;
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}
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}
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long file_offset = get_file_offset_for_position(track.first);
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std::lock_guard<std::mutex> lock_guard(file_.get_file_access_mutex());
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file_.seek(file_offset, SEEK_SET);
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size_t track_size = std::min(static_cast<size_t>(6400), parsed_track.size());
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file_.write(parsed_track.data(), track_size);
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}
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}
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bool OricMFMDSK::get_is_read_only() {
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return file_.get_is_known_read_only();
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}
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