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244 lines
7.1 KiB
C++
244 lines
7.1 KiB
C++
//
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// Disk.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 13/09/2016.
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// Copyright 2016 Thomas Harte. All rights reserved.
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//
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#include "Disk.hpp"
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#include "../../../Storage/Disk/Controller/DiskController.hpp"
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#include "../../../Storage/Disk/Encodings/CommodoreGCR.hpp"
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#include "../../../Storage/Data/Commodore.hpp"
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#include <limits>
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#include <vector>
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#include <array>
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using namespace Analyser::Static::Commodore;
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class CommodoreGCRParser: public Storage::Disk::Controller {
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public:
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CommodoreGCRParser() : Storage::Disk::Controller(4000000), shift_register_(0), track_(1) {
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emplace_drive(4000000, 300, 2);
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set_drive(1);
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get_drive().set_motor_on(true);
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}
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struct Sector {
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uint8_t sector, track;
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std::array<uint8_t, 256> data;
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bool header_checksum_matched;
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bool data_checksum_matched;
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};
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/*!
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Attempts to read the sector located at @c track and @c sector.
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@returns a sector if one was found; @c nullptr otherwise.
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*/
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std::shared_ptr<Sector> get_sector(uint8_t track, uint8_t sector) {
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int difference = int(track) - int(track_);
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track_ = track;
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if(difference) {
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int direction = difference < 0 ? -1 : 1;
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difference *= direction;
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for(int c = 0; c < difference; c++) {
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get_drive().step(Storage::Disk::HeadPosition(direction));
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}
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unsigned int zone = 3;
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if(track >= 18) zone = 2;
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else if(track >= 25) zone = 1;
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else if(track >= 31) zone = 0;
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set_expected_bit_length(Storage::Encodings::CommodoreGCR::length_of_a_bit_in_time_zone(zone));
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}
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return get_sector(sector);
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}
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void set_disk(const std::shared_ptr<Storage::Disk::Disk> &disk) {
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get_drive().set_disk(disk);
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}
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private:
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unsigned int shift_register_;
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int index_count_;
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int bit_count_;
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uint8_t track_;
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std::shared_ptr<Sector> sector_cache_[65536];
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void process_input_bit(int value) {
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shift_register_ = ((shift_register_ << 1) | unsigned(value)) & 0x3ff;
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bit_count_++;
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}
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unsigned int proceed_to_next_block(int max_index_count) {
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// find GCR lead-in
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proceed_to_shift_value(0x3ff);
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if(shift_register_ != 0x3ff) return 0xff;
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// find end of lead-in
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while(shift_register_ == 0x3ff && index_count_ < max_index_count) {
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run_for(Cycles(1));
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}
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// continue for a further nine bits
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bit_count_ = 0;
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while(bit_count_ < 9 && index_count_ < max_index_count) {
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run_for(Cycles(1));
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}
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return Storage::Encodings::CommodoreGCR::decoding_from_dectet(shift_register_);
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}
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unsigned int get_next_byte() {
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bit_count_ = 0;
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while(bit_count_ < 10) run_for(Cycles(1));
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return Storage::Encodings::CommodoreGCR::decoding_from_dectet(shift_register_);
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}
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void proceed_to_shift_value(unsigned int shift_value) {
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const int max_index_count = index_count_ + 2;
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while(shift_register_ != shift_value && index_count_ < max_index_count) {
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run_for(Cycles(1));
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}
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}
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void process_index_hole() {
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index_count_++;
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}
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std::shared_ptr<Sector> get_sector(uint8_t sector) {
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const uint16_t sector_address = uint16_t((track_ << 8) | sector);
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if(sector_cache_[sector_address]) return sector_cache_[sector_address];
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const std::shared_ptr<Sector> first_sector = get_next_sector();
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if(!first_sector) return first_sector;
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if(first_sector->sector == sector) return first_sector;
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while(1) {
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const std::shared_ptr<Sector> next_sector = get_next_sector();
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if(next_sector->sector == first_sector->sector) return nullptr;
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if(next_sector->sector == sector) return next_sector;
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}
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}
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std::shared_ptr<Sector> get_next_sector() {
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auto sector = std::make_shared<Sector>();
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const int max_index_count = index_count_ + 2;
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while(index_count_ < max_index_count) {
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// look for a sector header
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while(1) {
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if(proceed_to_next_block(max_index_count) == 0x08) break;
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if(index_count_ >= max_index_count) return nullptr;
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}
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// get sector details, skip if this looks malformed
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uint8_t checksum = uint8_t(get_next_byte());
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sector->sector = uint8_t(get_next_byte());
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sector->track = uint8_t(get_next_byte());
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uint8_t disk_id[2];
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disk_id[0] = uint8_t(get_next_byte());
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disk_id[1] = uint8_t(get_next_byte());
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if(checksum != (sector->sector ^ sector->track ^ disk_id[0] ^ disk_id[1])) continue;
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// look for the following data
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while(1) {
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if(proceed_to_next_block(max_index_count) == 0x07) break;
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if(index_count_ >= max_index_count) return nullptr;
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}
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checksum = 0;
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for(std::size_t c = 0; c < 256; c++) {
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sector->data[c] = uint8_t(get_next_byte());
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checksum ^= sector->data[c];
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}
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if(checksum == get_next_byte()) {
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uint16_t sector_address = uint16_t((sector->track << 8) | sector->sector);
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sector_cache_[sector_address] = sector;
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return sector;
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}
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}
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return nullptr;
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}
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};
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std::vector<File> Analyser::Static::Commodore::GetFiles(const std::shared_ptr<Storage::Disk::Disk> &disk) {
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std::vector<File> files;
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CommodoreGCRParser parser;
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parser.set_disk(disk);
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// find any sector whatsoever to establish the current track
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std::shared_ptr<CommodoreGCRParser::Sector> sector;
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// assemble directory
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std::vector<uint8_t> directory;
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uint8_t next_track = 18;
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uint8_t next_sector = 1;
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while(1) {
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sector = parser.get_sector(next_track, next_sector);
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if(!sector) break;
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directory.insert(directory.end(), sector->data.begin(), sector->data.end());
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next_track = sector->data[0];
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next_sector = sector->data[1];
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if(!next_track) break;
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}
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// parse directory
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std::size_t header_pointer = size_t(-32);
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while(header_pointer+32+31 < directory.size()) {
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header_pointer += 32;
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File new_file;
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switch(directory[header_pointer + 2] & 7) {
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case 0: // DEL files
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default: continue; // Unknown file types
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case 1: new_file.type = File::DataSequence; break;
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case 2: new_file.type = File::RelocatableProgram; break; // TODO: need a "don't know about relocatable" program?
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case 3: new_file.type = File::User; break;
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// case 4: new_file.type = File::Relative; break; // Can't handle REL files yet
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}
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next_track = directory[header_pointer + 3];
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next_sector = directory[header_pointer + 4];
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new_file.raw_name.reserve(16);
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for(std::size_t c = 0; c < 16; c++) {
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new_file.raw_name.push_back(directory[header_pointer + 5 + c]);
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}
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new_file.name = Storage::Data::Commodore::petscii_from_bytes(&new_file.raw_name[0], 16, false);
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std::size_t number_of_sectors = size_t(directory[header_pointer + 0x1e]) + (size_t(directory[header_pointer + 0x1f]) << 8);
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new_file.data.reserve((number_of_sectors - 1) * 254 + 252);
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bool is_first_sector = true;
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while(next_track) {
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sector = parser.get_sector(next_track, next_sector);
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if(!sector) break;
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next_track = sector->data[0];
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next_sector = sector->data[1];
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if(is_first_sector) new_file.starting_address = uint16_t(sector->data[2]) | uint16_t(sector->data[3] << 8);
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if(next_track)
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new_file.data.insert(new_file.data.end(), sector->data.begin() + (is_first_sector ? 4 : 2), sector->data.end());
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else
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new_file.data.insert(new_file.data.end(), sector->data.begin() + 2, sector->data.begin() + next_sector);
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is_first_sector = false;
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}
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if(!next_track) files.push_back(new_file);
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}
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return files;
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}
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