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363 lines
9.5 KiB
C++
363 lines
9.5 KiB
C++
//
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// MFM.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 18/09/2016.
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// Copyright © 2016 Thomas Harte. All rights reserved.
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//
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#include "MFM.hpp"
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#include "../PCMTrack.hpp"
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#include "../../../NumberTheory/CRC.hpp"
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using namespace Storage::Encodings::MFM;
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class MFMEncoder: public Encoder {
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public:
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MFMEncoder(std::vector<uint8_t> &target) : Encoder(target) {}
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void add_byte(uint8_t input) {
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uint16_t spread_value =
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(uint16_t)(
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((input & 0x01) << 0) |
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((input & 0x02) << 1) |
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((input & 0x04) << 2) |
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((input & 0x08) << 3) |
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((input & 0x10) << 4) |
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((input & 0x20) << 5) |
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((input & 0x40) << 6) |
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((input & 0x80) << 7)
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);
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uint16_t or_bits = (uint16_t)((spread_value << 1) | (spread_value >> 1) | (output_ << 15));
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output_ = spread_value | ((~or_bits) & 0xaaaa);
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output_short(output_);
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}
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void add_index_address_mark() {
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output_short(output_ = MFMIndexAddressMark);
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add_byte(MFMIndexAddressByte);
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}
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void add_ID_address_mark() {
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output_short(output_ = MFMAddressMark);
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add_byte(MFMIDAddressByte);
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}
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void add_data_address_mark() {
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output_short(output_ = MFMAddressMark);
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add_byte(MFMDataAddressByte);
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}
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void add_deleted_data_address_mark() {
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output_short(output_ = MFMAddressMark);
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add_byte(MFMDeletedDataAddressByte);
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}
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private:
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uint16_t output_;
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};
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class FMEncoder: public Encoder {
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// encodes each 16-bit part as clock, data, clock, data [...]
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public:
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FMEncoder(std::vector<uint8_t> &target) : Encoder(target) {}
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void add_byte(uint8_t input) {
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output_short(
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(uint16_t)(
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((input & 0x01) << 0) |
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((input & 0x02) << 1) |
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((input & 0x04) << 2) |
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((input & 0x08) << 3) |
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((input & 0x10) << 4) |
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((input & 0x20) << 5) |
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((input & 0x40) << 6) |
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((input & 0x80) << 7) |
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0xaaaa
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));
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}
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void add_index_address_mark() { output_short(FMIndexAddressMark); }
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void add_ID_address_mark() { output_short(FMIDAddressMark); }
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void add_data_address_mark() { output_short(FMDataAddressMark); }
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void add_deleted_data_address_mark() { output_short(FMDeletedDataAddressMark); }
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};
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static uint8_t logarithmic_size_for_size(size_t size)
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{
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switch(size)
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{
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default: return 0;
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case 256: return 1;
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case 512: return 2;
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case 1024: return 3;
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case 2048: return 4;
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case 4196: return 5;
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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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GetTrackWithSectors(
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const std::vector<Sector> §ors,
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size_t post_index_address_mark_bytes, uint8_t post_index_address_mark_value,
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size_t pre_address_mark_bytes, size_t post_address_mark_bytes,
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size_t pre_data_mark_bytes, size_t post_data_bytes,
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size_t inter_sector_gap,
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size_t expected_track_bytes)
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{
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Storage::Disk::PCMSegment segment;
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segment.data.reserve(expected_track_bytes);
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T shifter(segment.data);
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NumberTheory::CRC16 crc_generator(0x1021, 0xffff);
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// output the index mark
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shifter.add_index_address_mark();
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// add the post-index mark
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for(int 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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for(const Sector §or : sectors)
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{
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// gap
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for(int c = 0; c < pre_address_mark_bytes; c++) shifter.add_byte(0x00);
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// sector header
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shifter.add_ID_address_mark();
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shifter.add_byte(sector.track);
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shifter.add_byte(sector.side);
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shifter.add_byte(sector.sector);
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uint8_t size = logarithmic_size_for_size(sector.data.size());
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shifter.add_byte(size);
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// header CRC
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crc_generator.reset();
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crc_generator.add(sector.track);
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crc_generator.add(sector.side);
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crc_generator.add(sector.sector);
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crc_generator.add(size);
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uint16_t crc_value = crc_generator.get_value();
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shifter.add_byte(crc_value >> 8);
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shifter.add_byte(crc_value & 0xff);
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// gap
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for(int c = 0; c < post_address_mark_bytes; c++) shifter.add_byte(0x4e);
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for(int c = 0; c < pre_data_mark_bytes; c++) shifter.add_byte(0x00);
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// data
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shifter.add_data_address_mark();
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crc_generator.reset();
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for(size_t c = 0; c < sector.data.size(); c++)
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{
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shifter.add_byte(sector.data[c]);
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crc_generator.add(sector.data[c]);
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}
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// data CRC
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crc_value = crc_generator.get_value();
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shifter.add_byte(crc_value >> 8);
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shifter.add_byte(crc_value & 0xff);
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// gap
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for(int c = 0; c < post_data_bytes; c++) shifter.add_byte(0x00);
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for(int c = 0; c < inter_sector_gap; c++) shifter.add_byte(0x4e);
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}
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while(segment.data.size() < expected_track_bytes) shifter.add_byte(0x00);
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segment.number_of_bits = (unsigned int)(segment.data.size() * 8);
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return std::shared_ptr<Storage::Disk::Track>(new Storage::Disk::PCMTrack(std::move(segment)));
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}
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Encoder::Encoder(std::vector<uint8_t> &target) :
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target_(target)
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{}
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void Encoder::output_short(uint16_t value)
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{
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target_.push_back(value >> 8);
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target_.push_back(value & 0xff);
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}
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std::shared_ptr<Storage::Disk::Track> Storage::Encodings::MFM::GetFMTrackWithSectors(const std::vector<Sector> §ors)
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{
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return GetTrackWithSectors<FMEncoder>(
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sectors,
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16, 0x00,
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6, 0,
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17, 14,
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0,
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6250); // i.e. 250kbps (including clocks) * 60 = 15000kpm, at 300 rpm => 50 kbits/rotation => 6250 bytes/rotation
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}
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std::shared_ptr<Storage::Disk::Track> Storage::Encodings::MFM::GetMFMTrackWithSectors(const std::vector<Sector> §ors)
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{
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return GetTrackWithSectors<MFMEncoder>(
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sectors,
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50, 0x4e,
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12, 22,
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12, 18,
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32,
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12500); // unintelligently: double the single-density bytes/rotation (or: 500kps @ 300 rpm)
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}
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std::unique_ptr<Encoder> Storage::Encodings::MFM::GetMFMEncoder(std::vector<uint8_t> &target)
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{
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return std::unique_ptr<Encoder>(new MFMEncoder(target));
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}
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std::unique_ptr<Encoder> Storage::Encodings::MFM::GetFMEncoder(std::vector<uint8_t> &target)
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{
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return std::unique_ptr<Encoder>(new FMEncoder(target));
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}
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#pragma mark - Parser
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Parser::Parser(bool is_mfm, const std::shared_ptr<Storage::Disk::Disk> &disk) :
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Storage::Disk::Controller(4000000, 1, 300),
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crc_generator_(0x1021, 0xffff),
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shift_register_(0), track_(0), is_mfm_(is_mfm)
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{
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Storage::Time bit_length;
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bit_length.length = 1;
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bit_length.clock_rate = is_mfm ? 500000 : 250000; // i.e. 250 kbps (including clocks)
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set_expected_bit_length(bit_length);
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drive.reset(new Storage::Disk::Drive);
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drive->set_disk(disk);
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set_drive(drive);
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set_motor_on(true);
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}
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std::shared_ptr<Storage::Encodings::MFM::Sector> Parser::get_sector(uint8_t track, uint8_t sector)
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{
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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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{
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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++) step(direction);
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}
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return get_sector(sector);
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}
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void Parser::process_input_bit(int value, unsigned int cycles_since_index_hole)
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{
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shift_register_ = ((shift_register_ << 1) | (unsigned int)value) & 0xffff;
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bit_count_++;
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}
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void Parser::process_index_hole()
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{
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index_count_++;
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}
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uint8_t Parser::get_next_byte()
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{
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bit_count_ = 0;
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while(bit_count_ < 16) run_for_cycles(1);
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uint8_t byte = (uint8_t)(
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((shift_register_&0x0001) >> 0) |
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((shift_register_&0x0004) >> 1) |
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((shift_register_&0x0010) >> 2) |
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((shift_register_&0x0040) >> 3) |
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((shift_register_&0x0100) >> 4) |
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((shift_register_&0x0400) >> 5) |
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((shift_register_&0x1000) >> 6) |
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((shift_register_&0x4000) >> 7));
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crc_generator_.add(byte);
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return byte;
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}
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std::shared_ptr<Storage::Encodings::MFM::Sector> Parser::get_next_sector()
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{
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std::shared_ptr<Storage::Encodings::MFM::Sector> sector(new Storage::Encodings::MFM::Sector);
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index_count_ = 0;
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while(index_count_ < 2)
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{
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// look for an ID address mark
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while(1)
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{
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run_for_cycles(1);
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if(is_mfm_)
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{
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if(shift_register_ == Storage::Encodings::MFM::MFMAddressMark)
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{
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uint8_t mark = get_next_byte();
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if(mark == Storage::Encodings::MFM::MFMIDAddressByte) break;
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}
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}
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else
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{
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if(shift_register_ == Storage::Encodings::MFM::FMIDAddressMark) break;
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}
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if(index_count_ >= 2) return nullptr;
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}
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crc_generator_.reset();
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sector->track = get_next_byte();
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sector->side = get_next_byte();
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sector->sector = get_next_byte();
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uint8_t size = get_next_byte();
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uint16_t header_crc = crc_generator_.get_value();
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if((header_crc >> 8) != get_next_byte()) continue;
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if((header_crc & 0xff) != get_next_byte()) continue;
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// look for data mark
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while(1)
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{
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run_for_cycles(1);
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if(is_mfm_)
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{
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if(shift_register_ == Storage::Encodings::MFM::MFMAddressMark)
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{
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uint8_t mark = get_next_byte();
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if(mark == Storage::Encodings::MFM::MFMDataAddressByte) break;
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if(mark == Storage::Encodings::MFM::MFMIDAddressByte) return nullptr;
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}
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}
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else
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{
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if(shift_register_ == Storage::Encodings::MFM::FMDataAddressMark) break;
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if(shift_register_ == Storage::Encodings::MFM::FMIDAddressMark) return nullptr;
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}
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if(index_count_ >= 2) return nullptr;
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}
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size_t data_size = (size_t)(128 << size);
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sector->data.reserve(data_size);
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crc_generator_.reset();
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for(size_t c = 0; c < data_size; c++)
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{
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sector->data.push_back(get_next_byte());
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}
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uint16_t data_crc = crc_generator_.get_value();
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if((data_crc >> 8) != get_next_byte()) continue;
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if((data_crc & 0xff) != get_next_byte()) continue;
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return sector;
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}
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return nullptr;
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}
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std::shared_ptr<Storage::Encodings::MFM::Sector> Parser::get_sector(uint8_t sector)
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{
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std::shared_ptr<Storage::Encodings::MFM::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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{
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std::shared_ptr<Storage::Encodings::MFM::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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