Makes first attempt at 6 and 2 decoder.

Analyser/Static/DiskII/StaticAnalyser.cpp

@@ -9,14 +9,24 @@
 #include "StaticAnalyser.hpp"
 #include "../AppleII/Target.hpp"
 
+#include "../../../Storage/Disk/Track/TrackSerialiser.hpp"
+#include "../../../Storage/Disk/Encodings/AppleGCR/SegmentParser.hpp"
+
 Analyser::Static::TargetList Analyser::Static::DiskII::GetTargets(const Media &media, const std::string &file_name, TargetPlatform::IntType potential_platforms) {
+	// This analyser can comprehend disks only.
+	if(media.disks.empty()) return {};
+
+	// Grab track 0, sector 0.
+	auto track_zero = media.disks.front()->get_track_at_position(Storage::Disk::Track::Address(0, 0));
+	auto sector_map = Storage::Encodings::AppleGCR::sectors_from_segment(
+		Storage::Disk::track_serialisation(*track_zero, Storage::Time(1, 50000)));
+
 	using Target = Analyser::Static::AppleII::Target;
 	auto target = std::unique_ptr<Target>(new Target);
 	target->machine = Machine::AppleII;
 	target->media = media;
 
-	if(!target->media.disks.empty())
-		target->disk_controller = Target::DiskController::SixteenSector;
+	target->disk_controller = Target::DiskController::SixteenSector;
 
 	TargetList targets;
 	targets.push_back(std::move(target));

OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj

@@ -644,8 +644,8 @@
 		4BEE0A701D72496600532C7B /* PRG.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BEE0A6D1D72496600532C7B /* PRG.cpp */; };
 		4BEF6AAA1D35CE9E00E73575 /* DigitalPhaseLockedLoopBridge.mm in Sources */ = {isa = PBXBuildFile; fileRef = 4BEF6AA91D35CE9E00E73575 /* DigitalPhaseLockedLoopBridge.mm */; };
 		4BEF6AAC1D35D1C400E73575 /* DPLLTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4BEF6AAB1D35D1C400E73575 /* DPLLTests.swift */; };
-		4BF437EE209D0F7E008CBD6B /* TrackParser.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BF437EC209D0F7E008CBD6B /* TrackParser.cpp */; };
-		4BF437EF209D0F7E008CBD6B /* TrackParser.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BF437EC209D0F7E008CBD6B /* TrackParser.cpp */; };
+		4BF437EE209D0F7E008CBD6B /* SegmentParser.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BF437EC209D0F7E008CBD6B /* SegmentParser.cpp */; };
+		4BF437EF209D0F7E008CBD6B /* SegmentParser.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BF437EC209D0F7E008CBD6B /* SegmentParser.cpp */; };
 		4BFCA1241ECBDCB400AC40C1 /* AllRAMProcessor.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BFCA1211ECBDCAF00AC40C1 /* AllRAMProcessor.cpp */; };
 		4BFCA1271ECBE33200AC40C1 /* TestMachineZ80.mm in Sources */ = {isa = PBXBuildFile; fileRef = 4BFCA1261ECBE33200AC40C1 /* TestMachineZ80.mm */; };
 		4BFCA1291ECBE7A700AC40C1 /* zexall.com in Resources */ = {isa = PBXBuildFile; fileRef = 4BFCA1281ECBE7A700AC40C1 /* zexall.com */; };
@@ -1422,8 +1422,9 @@
 		4BEF6AA81D35CE9E00E73575 /* DigitalPhaseLockedLoopBridge.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = DigitalPhaseLockedLoopBridge.h; sourceTree = "<group>"; };
 		4BEF6AA91D35CE9E00E73575 /* DigitalPhaseLockedLoopBridge.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = DigitalPhaseLockedLoopBridge.mm; sourceTree = "<group>"; };
 		4BEF6AAB1D35D1C400E73575 /* DPLLTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = DPLLTests.swift; sourceTree = "<group>"; };
-		4BF437EC209D0F7E008CBD6B /* TrackParser.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = TrackParser.cpp; sourceTree = "<group>"; };
-		4BF437ED209D0F7E008CBD6B /* TrackParser.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = TrackParser.hpp; sourceTree = "<group>"; };
+		4BF437EC209D0F7E008CBD6B /* SegmentParser.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = SegmentParser.cpp; sourceTree = "<group>"; };
+		4BF437ED209D0F7E008CBD6B /* SegmentParser.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = SegmentParser.hpp; sourceTree = "<group>"; };
+		4BF437F0209D112F008CBD6B /* Sector.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = Sector.hpp; sourceTree = "<group>"; };
 		4BF4A2D91F534DB300B171F4 /* TargetPlatforms.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = TargetPlatforms.hpp; sourceTree = "<group>"; };
 		4BF6606A1F281573002CB053 /* ClockReceiver.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = ClockReceiver.hpp; sourceTree = "<group>"; };
 		4BF8295F1D8F3C87001BAE39 /* CRC.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; name = CRC.hpp; path = ../../NumberTheory/CRC.hpp; sourceTree = "<group>"; };
@@ -3014,9 +3015,10 @@
 			isa = PBXGroup;
 			children = (
 				4BD67DCE209BF27B00AB2146 /* Encoder.cpp */,
+				4BF437EC209D0F7E008CBD6B /* SegmentParser.cpp */,
 				4BD67DCF209BF27B00AB2146 /* Encoder.hpp */,
-				4BF437EC209D0F7E008CBD6B /* TrackParser.cpp */,
-				4BF437ED209D0F7E008CBD6B /* TrackParser.hpp */,
+				4BF437F0209D112F008CBD6B /* Sector.hpp */,
+				4BF437ED209D0F7E008CBD6B /* SegmentParser.hpp */,
 			);
 			name = AppleGCR;
 			path = Encodings/AppleGCR;
@@ -3629,7 +3631,7 @@
 				4B055AEE1FAE9BBF0060FFFF /* Keyboard.cpp in Sources */,
 				4B055AED1FAE9BA20060FFFF /* Z80Storage.cpp in Sources */,
 				4B1B88BC202E2EC100B67DFF /* MultiKeyboardMachine.cpp in Sources */,
-				4BF437EF209D0F7E008CBD6B /* TrackParser.cpp in Sources */,
+				4BF437EF209D0F7E008CBD6B /* SegmentParser.cpp in Sources */,
 				4B055AD11FAE9B030060FFFF /* Video.cpp in Sources */,
 				4B055AA21FAE85DA0060FFFF /* SSD.cpp in Sources */,
 				4BEBFB4E2002C4BF000708CC /* MSXDSK.cpp in Sources */,
@@ -3872,7 +3874,7 @@
 				4B54C0C81F8D91E50050900F /* Keyboard.cpp in Sources */,
 				4B79A5011FC913C900EEDAD5 /* MSX.cpp in Sources */,
 				4BEE0A701D72496600532C7B /* PRG.cpp in Sources */,
-				4BF437EE209D0F7E008CBD6B /* TrackParser.cpp in Sources */,
+				4BF437EE209D0F7E008CBD6B /* SegmentParser.cpp in Sources */,
 				4B8334861F5DA3780097E338 /* 6502Storage.cpp in Sources */,
 				4B8FE2271DA1DE2D0090D3CE /* NSBundle+DataResource.m in Sources */,
 				4B2A53A01D117D36003C6002 /* CSMachine.mm in Sources */,

Storage/Disk/Encodings/AppleGCR/Encoder.cpp

@@ -139,24 +139,24 @@ Storage::Disk::PCMSegment AppleGCR::six_and_two_data(const uint8_t *source) {
 	// and combined copies of the bottom two bits of the sector
 	// contents; the 256 bytes afterwards are the remaining
 	// six bits.
-	const uint8_t bit_shuffle[] = {0, 2, 1, 3};
+	const uint8_t bit_reverse[] = {0, 2, 1, 3};
 	for(std::size_t c = 0; c < 84; ++c) {
 		segment.data[3 + c] =
 			static_cast<uint8_t>(
-				bit_shuffle[source[c]&3] |
-				(bit_shuffle[source[c + 86]&3] << 2) |
-				(bit_shuffle[source[c + 172]&3] << 4)
+				bit_reverse[source[c]&3] |
+				(bit_reverse[source[c + 86]&3] << 2) |
+				(bit_reverse[source[c + 172]&3] << 4)
 			);
 	}
 	segment.data[87] =
 			static_cast<uint8_t>(
-				(bit_shuffle[source[84]&3] << 0) |
-				(bit_shuffle[source[170]&3] << 2)
+				(bit_reverse[source[84]&3] << 0) |
+				(bit_reverse[source[170]&3] << 2)
 			);
 	segment.data[88] =
 			static_cast<uint8_t>(
-				(bit_shuffle[source[85]&3] << 0) |
-				(bit_shuffle[source[171]&3] << 2)
+				(bit_reverse[source[85]&3] << 0) |
+				(bit_reverse[source[171]&3] << 2)
 			);
 
 	for(std::size_t c = 0; c < 256; ++c) {

Storage/Disk/Encodings/AppleGCR/Sector.hpp

@@ -0,0 +1,47 @@
+//
+//  Sector.hpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 04/05/2018.
+//  Copyright © 2018 Thomas Harte. All rights reserved.
+//
+
+#ifndef Sector_h
+#define Sector_h
+
+#include <cstdint>
+#include <vector>
+
+namespace Storage {
+namespace Encodings {
+namespace AppleGCR {
+
+struct Sector {
+	/*!
+		Describes the location of a sector, implementing < to allow for use as a set key.
+	*/
+	struct Address {
+		uint_fast8_t volume = 0, track = 0, sector = 0;
+
+		bool operator < (const Address &rhs) const {
+			return ((volume << 16) | (track << 8) | sector) < ((rhs.volume << 16) | (rhs.track << 8) | rhs.sector);
+		}
+	};
+
+	Address address;
+	std::vector<uint8_t> data;
+
+	bool has_data_checksum_error = false;
+	bool has_header_checksum_error = false;
+
+	enum class Encoding {
+		FiveAndThree, SixAndTwo
+	};
+	Encoding encoding = Encoding::SixAndTwo;
+};
+
+}
+}
+}
+
+#endif /* Sector_h */

Storage/Disk/Encodings/AppleGCR/SegmentParser.cpp

@@ -0,0 +1,166 @@
+//
+//  SegmentParser.cpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 04/05/2018.
+//  Copyright © 2018 Thomas Harte. All rights reserved.
+//
+
+#include "SegmentParser.hpp"
+
+#include "Encoder.hpp"
+
+#include <array>
+
+namespace {
+
+const uint8_t six_and_two_unmapping[] = {
+	0x00, 0x01, 0xff, 0xff,
+	0x02, 0x03, 0xff, 0x04, 0x05, 0x06, 0xff, 0xff,
+	0xff, 0xff, 0xff, 0xff, 0x07, 0x08, 0xff, 0xff,
+	0xff, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0xff, 0xff,
+	0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0xff, 0x14,
+	0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0xff, 0xff,
+	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+	0xff, 0x1b, 0xff, 0x1c, 0x1d, 0x1e, 0xff, 0xff,
+	0xff, 0x1f, 0xff, 0xff, 0x20, 0x21, 0xff, 0x22,
+	0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0xff, 0xff,
+	0xff, 0xff, 0xff, 0x29, 0x2a, 0x2b, 0xff, 0x2c,
+	0x2d, 0x2e, 0x2f, 0x30, 0x31, 0x32, 0xff, 0xff,
+	0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0xff, 0x39,
+	0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f, 0xff, 0xff
+};
+
+}
+
+using namespace Storage::Encodings::AppleGCR;
+
+std::map<std::size_t, Sector> Storage::Encodings::AppleGCR::sectors_from_segment(const Disk::PCMSegment &&segment) {
+	std::map<std::size_t, Sector> result;
+
+	uint_fast8_t shift_register = 0;
+
+	const std::size_t scanning_sentinel = std::numeric_limits<std::size_t>::max();
+	std::unique_ptr<Sector> new_sector;
+	std::size_t pointer = scanning_sentinel;
+	std::array<uint_fast8_t, 8> header{{0, 0, 0, 0, 0, 0, 0, 0}};
+	std::array<uint_fast8_t, 3> scanner;
+
+	for(unsigned int bit = 0; bit < segment.number_of_bits; ++bit) {
+		// Apple GCR parsing: bytes always have the top bit set.
+		shift_register = static_cast<uint_fast8_t>((shift_register << 1) | segment.bit(bit));
+		if(!(shift_register&0x80)) continue;
+
+		// Grab the byte.
+		const uint_fast8_t value = shift_register;
+		shift_register = 0;
+
+		if(pointer == scanning_sentinel) {
+			scanner[0] = scanner[1];
+			scanner[1] = scanner[2];
+			scanner[2] = value;
+
+			if(
+				scanner[0] == header_prologue[0] &&
+				scanner[1] == header_prologue[1] &&
+				(
+					scanner[2] == header_prologue[2] ||
+					scanner[2] == data_prologue[2]
+				)) {
+				pointer = 0;
+
+				// If this is the start of a data section, and at least
+				// one header has been witnessed, start a sector.
+				if(scanner[2] == data_prologue[2]) {
+					new_sector.reset(new Sector);
+					new_sector->data.reserve(412);
+				}
+			}
+		} else {
+			if(new_sector) {
+				// If this is an epilogue, make sense of this whole sector;
+				// otherwise just keep the byte for later.
+				if(value == epilogue[1]) {
+					std::unique_ptr<Sector> sector = std::move(new_sector);
+					new_sector.reset();
+					pointer = scanning_sentinel;
+
+					// Check for an expected size; the first byte of the epilogue has been stored, so
+					// these numbers are one bigger than usual.
+					if(sector->data.size() != 412 && sector->data.size() != 344) continue;
+					sector->data.resize(sector->data.size() - 1);
+
+					// Check for apparent four and four encoding.
+					uint_fast8_t header_mask = 0xff;
+					for(auto c : header) header_mask &= c;
+					header_mask &= 0xaa;
+					if(header_mask != 0xaa) continue;
+
+					sector->address.volume = ((header[0] << 1) | 1) & header[1];
+					sector->address.track = ((header[2] << 1) | 1) & header[3];
+					sector->address.sector = ((header[4] << 1) | 1) & header[5];
+
+					// Check the header checksum.
+					uint_fast8_t checksum = ((header[6] << 1) | 1) & header[7];
+					if(checksum != (sector->address.volume^sector->address.track^sector->address.sector)) continue;
+
+					if(sector->data.size() == 343) {
+						// Unmap the sector contents as 6 and 2 data.
+						bool out_of_bounds = false;
+						for(auto &c : sector->data) {
+							if(c < 0x96 || six_and_two_unmapping[c - 0x96] == 0xff) {
+								out_of_bounds = true;
+								break;
+							}
+							c = six_and_two_unmapping[c - 0x96];
+						}
+						if(out_of_bounds) continue;
+
+						// Undo the XOR step on sector contents and check that checksum.
+						for(std::size_t c = 1; c < sector->data.size(); ++c) {
+							sector->data[c] ^= sector->data[c-1];
+						}
+						if(sector->data.back()) continue;
+
+						// Having checked the checksum, remove it.
+						sector->data.resize(sector->data.size() - 1);
+
+						// Undo the 6 and 2 mapping.
+						const uint8_t bit_reverse[] = {0, 2, 1, 3};
+						#define unmap(byte, nibble, shift)	\
+							sector->data[86 + byte] = static_cast<uint8_t>(\
+								(sector->data[86 + byte] << 2) | bit_reverse[(sector->data[nibble] >> shift)&3]);
+
+						for(std::size_t c = 0; c < 84; ++c) {
+							unmap(c, c, 0);
+							unmap(c+86, c, 2);
+							unmap(c+172, c, 4);
+						}
+
+						unmap(84, 84, 0);
+						unmap(170, 84, 2);
+						unmap(85, 85, 0);
+						unmap(171, 85, 2);
+
+						#undef unmap
+					}
+
+					// Throw away the collection of two-bit chunks.
+					sector->data.erase(sector->data.begin(), sector->data.end() - 256);
+				} else {
+					new_sector->data.push_back(value);
+				}
+			} else {
+				// Just capture the header in place; it'll be decoded
+				// once a whole sector has been read.
+				header[pointer] = value;
+				++pointer;
+				if(pointer == 8) {
+					pointer = scanning_sentinel;
+				}
+			}
+		}
+	}
+
+	return result;
+}

Storage/Disk/Encodings/AppleGCR/SegmentParser.hpp

@@ -0,0 +1,30 @@
+//
+//  SegmentParser.hpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 04/05/2018.
+//  Copyright © 2018 Thomas Harte. All rights reserved.
+//
+
+#ifndef TrackParser_hpp
+#define TrackParser_hpp
+
+#include "Sector.hpp"
+#include "../../Track/PCMSegment.hpp"
+#include <map>
+
+namespace Storage {
+namespace Encodings {
+namespace AppleGCR {
+
+/*!
+	Scans @c segment for all included sectors, returning a set that maps from location within
+	the segment (counted in bits from the beginning) to sector.
+*/
+std::map<std::size_t, Sector> sectors_from_segment(const Disk::PCMSegment &&segment);
+
+}
+}
+}
+
+#endif /* TrackParser_hpp */

Storage/Disk/Encodings/AppleGCR/TrackParser.cpp

@@ -1,9 +0,0 @@
-//
-//  TrackParser.cpp
-//  Clock Signal
-//
-//  Created by Thomas Harte on 04/05/2018.
-//  Copyright © 2018 Thomas Harte. All rights reserved.
-//
-
-#include "TrackParser.hpp"

Storage/Disk/Encodings/AppleGCR/TrackParser.hpp

@@ -1,14 +0,0 @@
-//
-//  TrackParser.hpp
-//  Clock Signal
-//
-//  Created by Thomas Harte on 04/05/2018.
-//  Copyright © 2018 Thomas Harte. All rights reserved.
-//
-
-#ifndef TrackParser_hpp
-#define TrackParser_hpp
-
-#include <stdio.h>
-
-#endif /* TrackParser_hpp */

Storage/Disk/Encodings/MFM/SegmentParser.hpp

@@ -19,7 +19,8 @@ namespace MFM {
 
 /*!
 	Scans @c segment for all included sectors, returning a set that maps from location within
-	the segment (counted in bits from the beginning) to sector.
+	the segment (counted in bits from the beginning and pointing to the location the disk
+	had reached upon detection of the ID mark) to sector.
 */
 std::map<std::size_t, Sector> sectors_from_segment(const Disk::PCMSegment &&segment, bool is_double_density);