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264 lines
8.0 KiB
C++
264 lines
8.0 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 "Encoder.hpp"
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#include "Constants.hpp"
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#include "../../Track/PCMTrack.hpp"
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#include "../../../../NumberTheory/CRC.hpp"
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#include <set>
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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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crc_generator_.add(input);
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uint16_t spread_value =
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static_cast<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 = static_cast<uint16_t>((spread_value << 1) | (spread_value >> 1) | (last_output_ << 15));
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uint16_t 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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for(int c = 0; c < 3; c++) output_short(MFMIndexSync);
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add_byte(IndexAddressByte);
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}
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void add_ID_address_mark() {
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output_sync();
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add_byte(IDAddressByte);
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}
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void add_data_address_mark() {
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output_sync();
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add_byte(DataAddressByte);
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}
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void add_deleted_data_address_mark() {
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output_sync();
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add_byte(DeletedDataAddressByte);
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}
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private:
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uint16_t last_output_;
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void output_short(uint16_t value) {
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last_output_ = value;
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Encoder::output_short(value);
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}
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void output_sync() {
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for(int c = 0; c < 3; c++) output_short(MFMSync);
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crc_generator_.set_value(MFMPostSyncCRCValue);
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}
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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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crc_generator_.add(input);
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output_short(
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static_cast<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() {
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crc_generator_.reset();
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crc_generator_.add(IndexAddressByte);
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output_short(FMIndexAddressMark);
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}
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void add_ID_address_mark() {
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crc_generator_.reset();
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crc_generator_.add(IDAddressByte);
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output_short(FMIDAddressMark);
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}
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void add_data_address_mark() {
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crc_generator_.reset();
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crc_generator_.add(DataAddressByte);
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output_short(FMDataAddressMark);
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}
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void add_deleted_data_address_mark() {
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crc_generator_.reset();
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crc_generator_.add(DeletedDataAddressByte);
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output_short(FMDeletedDataAddressMark);
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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<const Sector *> §ors,
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std::size_t post_index_address_mark_bytes, uint8_t post_index_address_mark_value,
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std::size_t pre_address_mark_bytes,
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std::size_t post_address_mark_bytes, uint8_t post_address_mark_value,
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std::size_t pre_data_mark_bytes,
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std::size_t post_data_bytes, uint8_t post_data_value,
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std::size_t expected_track_bytes) {
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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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// 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(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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for(const Sector *sector : sectors) {
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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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// sector header
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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.side);
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shifter.add_byte(sector->address.sector);
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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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// 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 < pre_data_mark_bytes; c++) shifter.add_byte(0x00);
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// data, if attached
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// TODO: allow for weak/fuzzy data.
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if(!sector->samples.empty()) {
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if(sector->is_deleted)
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shifter.add_deleted_data_address_mark();
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else
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shifter.add_data_address_mark();
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std::size_t c = 0;
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std::size_t declared_length = static_cast<std::size_t>(128 << sector->size);
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for(c = 0; c < sector->samples[0].size() && c < declared_length; c++) {
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shifter.add_byte(sector->samples[0][c]);
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}
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for(; c < declared_length; c++) {
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shifter.add_byte(0x00);
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}
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shifter.add_crc(sector->has_data_crc_error);
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}
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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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}
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while(segment.data.size() < expected_track_bytes) 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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std::size_t max_size = expected_track_bytes + (expected_track_bytes / 10);
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if(segment.data.size() > max_size) segment.data.resize(max_size);
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segment.number_of_bits = static_cast<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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void Encoder::output_short(uint16_t value) {
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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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void Encoder::add_crc(bool incorrectly) {
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uint16_t crc_value = crc_generator_.get_value();
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add_byte(crc_value >> 8);
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add_byte((crc_value & 0xff) ^ (incorrectly ? 1 : 0));
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}
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const std::size_t Storage::Encodings::MFM::DefaultSectorGapLength = std::numeric_limits<std::size_t>::max();
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static std::vector<const Sector *> sector_pointers(const std::vector<Sector> §ors) {
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std::vector<const Sector *> pointers;
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for(const Sector §or: sectors) {
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pointers.push_back(§or);
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}
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return pointers;
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}
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std::shared_ptr<Storage::Disk::Track> Storage::Encodings::MFM::GetFMTrackWithSectors(const std::vector<Sector> §ors, std::size_t sector_gap_length, uint8_t sector_gap_filler_byte) {
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return GetTrackWithSectors<FMEncoder>(
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sector_pointers(sectors),
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26, 0xff,
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6,
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11, 0xff,
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6,
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(sector_gap_length != DefaultSectorGapLength) ? sector_gap_length : 27, 0xff,
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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::GetFMTrackWithSectors(const std::vector<const Sector *> §ors, std::size_t sector_gap_length, uint8_t sector_gap_filler_byte) {
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return GetTrackWithSectors<FMEncoder>(
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sectors,
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26, 0xff,
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6,
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11, 0xff,
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6,
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(sector_gap_length != DefaultSectorGapLength) ? sector_gap_length : 27, 0xff,
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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, std::size_t sector_gap_length, uint8_t sector_gap_filler_byte) {
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return GetTrackWithSectors<MFMEncoder>(
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sector_pointers(sectors),
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50, 0x4e,
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12,
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22, 0x4e,
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12,
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(sector_gap_length != DefaultSectorGapLength) ? sector_gap_length : 54, 0xff,
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12500); // unintelligently: double the single-density bytes/rotation (or: 500kbps @ 300 rpm)
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}
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std::shared_ptr<Storage::Disk::Track> Storage::Encodings::MFM::GetMFMTrackWithSectors(const std::vector<const Sector *> §ors, std::size_t sector_gap_length, uint8_t sector_gap_filler_byte) {
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return GetTrackWithSectors<MFMEncoder>(
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sectors,
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50, 0x4e,
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12,
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22, 0x4e,
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12,
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(sector_gap_length != DefaultSectorGapLength) ? sector_gap_length : 54, 0xff,
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12500); // unintelligently: double the single-density bytes/rotation (or: 500kbps @ 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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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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return std::unique_ptr<Encoder>(new FMEncoder(target));
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}
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