Use the FAT12 boot sector to determine geometry.

Analyser/Static/StaticAnalyser.cpp

@@ -43,9 +43,9 @@
 #include "../../Storage/Disk/DiskImage/Formats/MacintoshIMG.hpp"
 #include "../../Storage/Disk/DiskImage/Formats/G64.hpp"
 #include "../../Storage/Disk/DiskImage/Formats/DMK.hpp"
+#include "../../Storage/Disk/DiskImage/Formats/FAT12.hpp"
 #include "../../Storage/Disk/DiskImage/Formats/HFE.hpp"
 #include "../../Storage/Disk/DiskImage/Formats/MSA.hpp"
-#include "../../Storage/Disk/DiskImage/Formats/MSXDSK.hpp"
 #include "../../Storage/Disk/DiskImage/Formats/NIB.hpp"
 #include "../../Storage/Disk/DiskImage/Formats/OricMFMDSK.hpp"
 #include "../../Storage/Disk/DiskImage/Formats/SSD.hpp"
@@ -147,7 +147,7 @@ static Media GetMediaAndPlatforms(const std::string &file_name, TargetPlatform::
 	Format("dsk", result.disks, Disk::DiskImageHolder<Storage::Disk::MacintoshIMG>, TargetPlatform::Macintosh)	// DSK (Macintosh, floppy disk)
 	Format("dsk", result.mass_storage_devices, MassStorage::HFV, TargetPlatform::Macintosh)						// DSK (Macintosh, hard disk, single volume image)
 	Format("dsk", result.mass_storage_devices, MassStorage::DSK, TargetPlatform::Macintosh)						// DSK (Macintosh, hard disk, full device image)
-	Format("dsk", result.disks, Disk::DiskImageHolder<Storage::Disk::MSXDSK>, TargetPlatform::MSX)				// DSK (MSX)
+	Format("dsk", result.disks, Disk::DiskImageHolder<Storage::Disk::FAT12>, TargetPlatform::MSX)				// DSK (MSX)
 	Format("dsk", result.disks, Disk::DiskImageHolder<Storage::Disk::OricMFMDSK>, TargetPlatform::Oric)			// DSK (Oric)
 	Format("g64", result.disks, Disk::DiskImageHolder<Storage::Disk::G64>, TargetPlatform::Commodore)			// G64
 	Format(	"hfe",
@@ -157,7 +157,7 @@ static Media GetMediaAndPlatforms(const std::string &file_name, TargetPlatform::
 			// HFE (TODO: switch to AllDisk once the MSX stops being so greedy)
 	Format("img", result.disks, Disk::DiskImageHolder<Storage::Disk::MacintoshIMG>, TargetPlatform::Macintosh)		// IMG (DiskCopy 4.2)
 	Format("image", result.disks, Disk::DiskImageHolder<Storage::Disk::MacintoshIMG>, TargetPlatform::Macintosh)	// IMG (DiskCopy 4.2)
-	Format("img", result.disks, Disk::DiskImageHolder<Storage::Disk::MSXDSK>, TargetPlatform::Enterprise)		// IMG (Enterprise/MS-DOS style)
+	Format("img", result.disks, Disk::DiskImageHolder<Storage::Disk::FAT12>, TargetPlatform::Enterprise)		// IMG (Enterprise/MS-DOS style)
 	Format("msa", result.disks, Disk::DiskImageHolder<Storage::Disk::MSA>, TargetPlatform::AtariST)				// MSA
 	Format("nib", result.disks, Disk::DiskImageHolder<Storage::Disk::NIB>, TargetPlatform::DiskII)				// NIB
 	Format("o", result.tapes, Tape::ZX80O81P, TargetPlatform::ZX8081)											// O

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

@@ -323,7 +323,7 @@
 		4B778F0023A5EB990000D260 /* G64.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B4518931F75FD1B00926311 /* G64.cpp */; };
 		4B778F0123A5EBA00000D260 /* MacintoshIMG.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BB4BFAE22A42F290069048D /* MacintoshIMG.cpp */; };
 		4B778F0223A5EBA40000D260 /* MFMSectorDump.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B58601C1F806AB200AEE2E3 /* MFMSectorDump.cpp */; };
-		4B778F0323A5EBB00000D260 /* MSXDSK.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BEBFB4B2002C4BF000708CC /* MSXDSK.cpp */; };
+		4B778F0323A5EBB00000D260 /* FAT12.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BEBFB4B2002C4BF000708CC /* FAT12.cpp */; };
 		4B778F0423A5EBB00000D260 /* OricMFMDSK.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B4518971F75FD1B00926311 /* OricMFMDSK.cpp */; };
 		4B778F0523A5EBB00000D260 /* ST.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BE0A3EC237BB170002AB46F /* ST.cpp */; };
 		4B778F0623A5EC150000D260 /* CAS.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B0E04E81FC9E5DA00F43484 /* CAS.cpp */; };
@@ -961,8 +961,8 @@
 		4BE9A6B11EDE293000CBCB47 /* zexdoc.com in Resources */ = {isa = PBXBuildFile; fileRef = 4BE9A6B01EDE293000CBCB47 /* zexdoc.com */; };
 		4BEA525E1DF33323007E74F2 /* Tape.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BEA525D1DF33323007E74F2 /* Tape.cpp */; };
 		4BEA52631DF339D7007E74F2 /* SoundGenerator.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BEA52611DF339D7007E74F2 /* SoundGenerator.cpp */; };
-		4BEBFB4D2002C4BF000708CC /* MSXDSK.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BEBFB4B2002C4BF000708CC /* MSXDSK.cpp */; };
+		4BEBFB4D2002C4BF000708CC /* FAT12.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BEBFB4B2002C4BF000708CC /* FAT12.cpp */; };
-		4BEBFB4E2002C4BF000708CC /* MSXDSK.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BEBFB4B2002C4BF000708CC /* MSXDSK.cpp */; };
+		4BEBFB4E2002C4BF000708CC /* FAT12.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BEBFB4B2002C4BF000708CC /* FAT12.cpp */; };
 		4BEBFB512002DB30000708CC /* DiskROM.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BEBFB4F2002DB30000708CC /* DiskROM.cpp */; };
 		4BEBFB522002DB30000708CC /* DiskROM.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BEBFB4F2002DB30000708CC /* DiskROM.cpp */; };
 		4BEDA3BA25B25563000C2DBD /* Decoder.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BEDA3B425B25563000C2DBD /* Decoder.cpp */; };
@@ -2021,8 +2021,8 @@
 		4BEA52601DF3343A007E74F2 /* Interrupts.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = Interrupts.hpp; sourceTree = "<group>"; };
 		4BEA52611DF339D7007E74F2 /* SoundGenerator.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = SoundGenerator.cpp; sourceTree = "<group>"; };
 		4BEA52621DF339D7007E74F2 /* SoundGenerator.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = SoundGenerator.hpp; sourceTree = "<group>"; };
-		4BEBFB4B2002C4BF000708CC /* MSXDSK.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = MSXDSK.cpp; sourceTree = "<group>"; };
+		4BEBFB4B2002C4BF000708CC /* FAT12.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = FAT12.cpp; sourceTree = "<group>"; };
-		4BEBFB4C2002C4BF000708CC /* MSXDSK.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = MSXDSK.hpp; sourceTree = "<group>"; };
+		4BEBFB4C2002C4BF000708CC /* FAT12.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = FAT12.hpp; sourceTree = "<group>"; };
 		4BEBFB4F2002DB30000708CC /* DiskROM.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = DiskROM.cpp; sourceTree = "<group>"; };
 		4BEBFB502002DB30000708CC /* DiskROM.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = DiskROM.hpp; sourceTree = "<group>"; };
 		4BEDA3B425B25563000C2DBD /* Decoder.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = Decoder.cpp; sourceTree = "<group>"; };
@@ -2713,7 +2713,7 @@
 				4BB4BFAE22A42F290069048D /* MacintoshIMG.cpp */,
 				4B58601C1F806AB200AEE2E3 /* MFMSectorDump.cpp */,
 				4BC131782346DF2B00E4FF3D /* MSA.cpp */,
-				4BEBFB4B2002C4BF000708CC /* MSXDSK.cpp */,
+				4BEBFB4B2002C4BF000708CC /* FAT12.cpp */,
 				4B0F94FC208C1A1600FE41D9 /* NIB.cpp */,
 				4B4518971F75FD1B00926311 /* OricMFMDSK.cpp */,
 				4B4518991F75FD1B00926311 /* SSD.cpp */,
@@ -2730,7 +2730,7 @@
 				4BB4BFAF22A42F290069048D /* MacintoshIMG.hpp */,
 				4B58601D1F806AB200AEE2E3 /* MFMSectorDump.hpp */,
 				4BC131792346DF2B00E4FF3D /* MSA.hpp */,
-				4BEBFB4C2002C4BF000708CC /* MSXDSK.hpp */,
+				4BEBFB4C2002C4BF000708CC /* FAT12.hpp */,
 				4B0F94FD208C1A1600FE41D9 /* NIB.hpp */,
 				4B4518981F75FD1B00926311 /* OricMFMDSK.hpp */,
 				4B45189A1F75FD1B00926311 /* SSD.hpp */,
@@ -5283,7 +5283,7 @@
 				4BB4BFBA22A4372F0069048D /* StaticAnalyser.cpp in Sources */,
 				4B055AA21FAE85DA0060FFFF /* SSD.cpp in Sources */,
 				4B2E86E325DC95150024F1E9 /* Joystick.cpp in Sources */,
-				4BEBFB4E2002C4BF000708CC /* MSXDSK.cpp in Sources */,
+				4BEBFB4E2002C4BF000708CC /* FAT12.cpp in Sources */,
 				4B055ADD1FAE9B460060FFFF /* i8272.cpp in Sources */,
 				4B055A9C1FAE85DA0060FFFF /* CPCDSK.cpp in Sources */,
 				4B2BF19223DCC6A800C3AD60 /* STX.cpp in Sources */,
@@ -5597,7 +5597,7 @@
 				4B894536201967B4007DE474 /* Z80.cpp in Sources */,
 				4BCA6CC81D9DD9F000C2D7B2 /* CommodoreROM.cpp in Sources */,
 				4BC1317A2346DF2B00E4FF3D /* MSA.cpp in Sources */,
-				4BEBFB4D2002C4BF000708CC /* MSXDSK.cpp in Sources */,
+				4BEBFB4D2002C4BF000708CC /* FAT12.cpp in Sources */,
 				4BBFBB6C1EE8401E00C01E7A /* ZX8081.cpp in Sources */,
 				4B83348A1F5DB94B0097E338 /* IRQDelegatePortHandler.cpp in Sources */,
 				4B8DD3862634D37E00B3C866 /* SNA.cpp in Sources */,
@@ -5745,7 +5745,7 @@
 				4B3BA0CF1D318B44005DD7A7 /* MOS6522Bridge.mm in Sources */,
 				4B778F6023A5F3460000D260 /* Disk.cpp in Sources */,
 				4B778F5C23A5F3070000D260 /* MSX.cpp in Sources */,
-				4B778F0323A5EBB00000D260 /* MSXDSK.cpp in Sources */,
+				4B778F0323A5EBB00000D260 /* FAT12.cpp in Sources */,
 				4B778F4023A5F1910000D260 /* z8530.cpp in Sources */,
 				4B778EFD23A5EB8E0000D260 /* AppleDSK.cpp in Sources */,
 				4B778EFB23A5EB7E0000D260 /* HFE.cpp in Sources */,

Storage/Disk/DiskImage/Formats/FAT12.cpp

@@ -0,0 +1,57 @@
+//
+//  FAT12.cpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 07/01/2018.
+//  Copyright 2018 Thomas Harte. All rights reserved.
+//
+
+#include "FAT12.hpp"
+
+#include "Utility/ImplicitSectors.hpp"
+
+using namespace Storage::Disk;
+
+FAT12::FAT12(const std::string &file_name) :
+	MFMSectorDump(file_name) {
+	// The only sanity check here is whether a sensible
+	// geometry is encoded in the first sector, or can be guessed.
+	off_t file_size = file_.stats().st_size;
+
+	if(file_size < 512) throw Error::InvalidFormat;
+
+	// Inspect the FAT.
+	file_.seek(11, SEEK_SET);
+	sector_size_ = file_.get16le();
+	file_.seek(19, SEEK_SET);
+	const uint16_t total_sectors = file_.get16le();
+	file_.seek(24, SEEK_SET);
+	sector_count_ = file_.get16le();
+	head_count_ = file_.get16le();
+
+	// Throw if there would seemingly be an incomplete track.
+	if(file_size != total_sectors*sector_size_) throw Error::InvalidFormat;
+	if(total_sectors % (head_count_ * sector_count_)) throw Error::InvalidFormat;
+	track_count_ = int(total_sectors / (head_count_ * sector_count_));
+
+	// Check that there is a valid power-of-two sector size.
+	uint8_t log_sector_size = 2;
+	while(log_sector_size < 5 && (1 << (7+log_sector_size)) != sector_size_) {
+		++log_sector_size;
+	}
+	if(log_sector_size >= 5) throw Error::InvalidFormat;
+
+	set_geometry(sector_count_, log_sector_size, 1, true);
+}
+
+HeadPosition FAT12::get_maximum_head_position() {
+	return HeadPosition(track_count_);
+}
+
+int FAT12::get_head_count() {
+	return head_count_;
+}
+
+long FAT12::get_file_offset_for_position(Track::Address address) {
+	return (address.position.as_int()*head_count_ + address.head) * sector_size_ * sector_count_;
+}

Storage/Disk/DiskImage/Formats/FAT12.hpp

@@ -1,5 +1,5 @@
 //
-//  MSXDSK.hpp
+//  FAT12.hpp
 //  Clock Signal
 //
 //  Created by Thomas Harte on 07/01/2018.
@@ -17,12 +17,12 @@ namespace Storage {
 namespace Disk {
 
 /*!
-	Provides a @c DiskImage describing an MSDOS-style disk image:
+	Provides a @c DiskImage holding an MSDOS-style FAT12 disk image:
 	a sector dump of appropriate proportions.
 */
-class MSXDSK: public MFMSectorDump {
+class FAT12: public MFMSectorDump {
 	public:
-		MSXDSK(const std::string &file_name);
+		FAT12(const std::string &file_name);
 		HeadPosition get_maximum_head_position() final;
 		int get_head_count() final;
 
@@ -31,6 +31,8 @@ class MSXDSK: public MFMSectorDump {
 
 		int head_count_;
 		int track_count_;
+		int sector_count_;
+		int sector_size_;
 };
 
 }

Storage/Disk/DiskImage/Formats/MSXDSK.cpp

@@ -1,59 +0,0 @@
-//
-//  MSXDSK.cpp
-//  Clock Signal
-//
-//  Created by Thomas Harte on 07/01/2018.
-//  Copyright 2018 Thomas Harte. All rights reserved.
-//
-
-#include "MSXDSK.hpp"
-
-#include "Utility/ImplicitSectors.hpp"
-
-namespace {
-	constexpr int sectors_per_track = 9;
-	constexpr int sector_size = 2;
-	constexpr off_t track_size = (128 << sector_size)*sectors_per_track;
-}
-
-using namespace Storage::Disk;
-
-MSXDSK::MSXDSK(const std::string &file_name) :
-	MFMSectorDump(file_name) {
-	// The only sanity check here is whether a sensible
-	// geometry can be guessed.
-	off_t file_size = file_.stats().st_size;
-
-	// Throw if there would seemingly be an incomplete track.
-	if(file_size % track_size) throw Error::InvalidFormat;
-
-	track_count_ = int(file_size / track_size);
-	head_count_ = 1;
-
-	// Throw if too large or too small or too large for single sided and
-	// clearly not double sided.
-	if(track_count_ < 40) throw Error::InvalidFormat;
-	if(track_count_ > 82*2) throw Error::InvalidFormat;
-	if(track_count_ > 82 && track_count_&1) throw Error::InvalidFormat;
-
-	// The below effectively prefers the idea of a single-sided 80-track disk
-	// to a double-sided 40-track disk. Emulators have to guess.
-	if(track_count_ > 82) {
-		track_count_ /= 2;
-		head_count_ = 2;
-	}
-
-	set_geometry(sectors_per_track, sector_size, 1, true);
-}
-
-HeadPosition MSXDSK::get_maximum_head_position() {
-	return HeadPosition(track_count_);
-}
-
-int MSXDSK::get_head_count() {
-	return head_count_;
-}
-
-long MSXDSK::get_file_offset_for_position(Track::Address address) {
-	return (address.position.as_int()*head_count_ + address.head) * 512 * 9;
-}