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103 lines
2.3 KiB
C++
103 lines
2.3 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 "../PCMTrack.hpp"
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#include "../Encodings/MFM.hpp"
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using namespace Storage::Disk;
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OricMFMDSK::OricMFMDSK(const char *file_name) :
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Storage::FileHolder(file_name)
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{
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if(!check_signature("MFM_DISK", 8))
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throw ErrorNotOricMFMDSK;
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head_count_ = fgetc32le();
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track_count_ = fgetc32le();
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geometry_type_ = fgetc32le();
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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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unsigned int OricMFMDSK::get_head_position_count()
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{
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return track_count_;
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}
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unsigned int OricMFMDSK::get_head_count()
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{
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return head_count_;
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}
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std::shared_ptr<Track> OricMFMDSK::get_uncached_track_at_position(unsigned int head, unsigned int position)
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{
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long seek_offset = 0;
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switch(geometry_type_)
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{
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case 1:
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seek_offset = (head * track_count_) + position;
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break;
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case 2:
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seek_offset = (position * track_count_ * head_count_) + head;
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break;
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}
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fseek(file_, (seek_offset * 6400) + 256, SEEK_SET);
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PCMSegment segment;
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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];
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std::unique_ptr<Encodings::MFM::Encoder> encoder = Encodings::MFM::GetMFMEncoder(segment.data);
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while(track_offset < 6250)
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{
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uint8_t next_byte = (uint8_t)fgetc(file_);
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track_offset++;
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switch(next_byte)
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{
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default:
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encoder->add_byte(next_byte);
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break;
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case 0xfe: // an ID synchronisation
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{
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encoder->add_ID_address_mark();
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for(int byte = 0; byte < 6; byte++)
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{
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last_header[byte] = (uint8_t)fgetc(file_);
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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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}
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break;
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case 0xfb: // a data synchronisation
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encoder->add_data_address_mark();
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for(int byte = 0; byte < (128 << last_header[3]) + 2; byte++)
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{
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encoder->add_byte((uint8_t)fgetc(file_));
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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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segment.number_of_bits = (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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