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https://github.com/TomHarte/CLK.git
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Calling it 'number theory' probably isn't accurate but extracted the CRC stuff and started using it for [M]FM encoding.
This commit is contained in:
Thomas Harte
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commit
180c3df2d4
11
NumberTheory/CRC.cpp
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11
NumberTheory/CRC.cpp
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@ -0,0 +1,11 @@
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//
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// CRC.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 "CRC.hpp"
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using namespace NumberTheory;
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40
NumberTheory/CRC.hpp
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40
NumberTheory/CRC.hpp
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//
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// CRC.hpp
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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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#ifndef CRC_hpp
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#define CRC_hpp
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#include <cstdint>
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namespace NumberTheory {
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class CRC16 {
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public:
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CRC16(uint16_t polynomial, uint16_t reset_value) :
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reset_value_(reset_value), value_(reset_value), polynomial_(polynomial) {}
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inline void reset() { value_ = reset_value_; }
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inline void add(uint8_t value) {
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// TODO: go table based
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value_ ^= (uint16_t)value << 8;
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for(int c = 0; c < 8; c++)
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{
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uint16_t exclusive_or = (value_&0x8000) ? polynomial_ : 0x0000;
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value_ = (uint16_t)(value_ << 1) ^ exclusive_or;
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}
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}
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inline uint16_t get_value() { return value_; }
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private:
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uint16_t reset_value_, polynomial_;
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uint16_t value_;
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};
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}
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#endif /* CRC_hpp */
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@ -356,6 +356,7 @@
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4BEF6AAC1D35D1C400E73575 /* DPLLTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4BEF6AAB1D35D1C400E73575 /* DPLLTests.swift */; };
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4BF1354C1D6D2C300054B2EA /* StaticAnalyser.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BF1354A1D6D2C300054B2EA /* StaticAnalyser.cpp */; };
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4BF8295D1D8F048B001BAE39 /* MFM.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BF8295B1D8F048B001BAE39 /* MFM.cpp */; };
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4BF829601D8F3C87001BAE39 /* CRC.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BF8295E1D8F3C87001BAE39 /* CRC.cpp */; };
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/* End PBXBuildFile section */
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/* Begin PBXContainerItemProxy section */
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@ -808,6 +809,8 @@
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4BF1354B1D6D2C300054B2EA /* StaticAnalyser.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; name = StaticAnalyser.hpp; path = ../../StaticAnalyser/StaticAnalyser.hpp; sourceTree = "<group>"; };
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4BF8295B1D8F048B001BAE39 /* MFM.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = MFM.cpp; path = Encodings/MFM.cpp; sourceTree = "<group>"; };
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4BF8295C1D8F048B001BAE39 /* MFM.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; name = MFM.hpp; path = Encodings/MFM.hpp; sourceTree = "<group>"; };
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4BF8295E1D8F3C87001BAE39 /* CRC.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = CRC.cpp; path = ../../NumberTheory/CRC.cpp; sourceTree = "<group>"; };
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4BF8295F1D8F3C87001BAE39 /* CRC.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; name = CRC.hpp; path = ../../NumberTheory/CRC.hpp; sourceTree = "<group>"; };
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/* End PBXFileReference section */
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/* Begin PBXFrameworksBuildPhase section */
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@ -1394,6 +1397,8 @@
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isa = PBXGroup;
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children = (
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4BB697C61D4B558F00248BDF /* Factors.hpp */,
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4BF8295E1D8F3C87001BAE39 /* CRC.cpp */,
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4BF8295F1D8F3C87001BAE39 /* CRC.hpp */,
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);
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name = NumberTheory;
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sourceTree = "<group>";
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@ -2079,6 +2084,7 @@
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4B0CCC451C62D0B3001CAC5F /* CRT.cpp in Sources */,
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4B643F3F1D77B88000D431D6 /* DocumentController.swift in Sources */,
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4BA799951D8B656E0045123D /* StaticAnalyser.cpp in Sources */,
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4BF829601D8F3C87001BAE39 /* CRC.cpp in Sources */,
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4B55CE591C3B7D360093A61B /* ElectronDocument.swift in Sources */,
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4B4DC82B1D2C27A4003C5BF8 /* SerialBus.cpp in Sources */,
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4BC3B74F1CD194CC00F86E85 /* Shader.cpp in Sources */,
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@ -9,6 +9,7 @@
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#include "MFM.hpp"
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#import "../PCMTrack.hpp"
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#import "../../../NumberTheory/CRC.hpp"
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using namespace Storage::Encodings::MFM;
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@ -106,6 +107,19 @@ template <class T> class FMShifter: public Shifter<T> {
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}
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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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@ -115,6 +129,7 @@ template<class T> std::shared_ptr<Storage::Disk::Track>
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size_t inter_sector_gap)
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{
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T shifter;
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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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@ -125,30 +140,46 @@ template<class T> std::shared_ptr<Storage::Disk::Track>
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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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switch(sector.data.size())
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{
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default: shifter.add_byte(0); break;
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case 256: shifter.add_byte(1); break;
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case 512: shifter.add_byte(2); break;
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case 1024: shifter.add_byte(3); break;
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case 2048: shifter.add_byte(4); break;
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case 4196: shifter.add_byte(5); break;
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}
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// TODO: CRC of bytes since the track number
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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 & 0xff);
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shifter.add_byte(crc_value >> 8);
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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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for(size_t c = 0; c < sector.data.size(); c++) shifter.add_byte(sector.data[c]);
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// TODO: CRC of data
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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 & 0xff);
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shifter.add_byte(crc_value >> 8);
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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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@ -159,17 +190,19 @@ template<class T> std::shared_ptr<Storage::Disk::Track>
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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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struct VectorReceiver {
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void output_short(uint16_t value) {
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data.push_back(value & 0xff);
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data.push_back(value >> 8);
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}
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std::vector<uint8_t> data;
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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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struct VectorShifter: public FMShifter<VectorShifter> {
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void output_short(uint16_t value) {
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data.push_back(value & 0xff);
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data.push_back(value >> 8);
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}
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std::vector<uint8_t> data;
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struct VectorShifter: public FMShifter<VectorShifter>, VectorReceiver {
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using VectorReceiver::output_short;
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};
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return GetTrackWithSectors<VectorShifter>(
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sectors,
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16, 0x00,
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@ -180,14 +213,9 @@ std::shared_ptr<Storage::Disk::Track> Storage::Encodings::MFM::GetFMTrackWithSec
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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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struct VectorShifter: public MFMShifter<VectorShifter> {
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void output_short(uint16_t value) {
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data.push_back(value & 0xff);
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data.push_back(value >> 8);
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}
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std::vector<uint8_t> data;
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struct VectorShifter: public MFMShifter<VectorShifter>, VectorReceiver {
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using VectorReceiver::output_short;
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};
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return GetTrackWithSectors<VectorShifter>(
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sectors,
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50, 0x4e,
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