Merge pull request #90 from davidgiven/write

Add support for writing LDBS image files.

.hgignore

@@ -3,6 +3,10 @@ streams
 .*\.flux
 .*\.img
 .*\.raw
+.*\.orig
 .vscode
 remote
+FluxEngine.cydsn/CortexM3
+FluxEngine.cydsn/Generated_Source
+FluxEngine.cydsn/codegentemp
 

FluxEngine.cydsn/FluxEngine.cyprj

@@ -2310,13 +2310,13 @@
 <CyGuid_ebc4f06d-207f-49c2-a540-72acf4adabc0 type_name="CyDesigner.Common.ProjMgmt.Model.CyPrjMgmtFolderSerialize" version="3">
 <CyGuid_2f73275c-45bf-46ba-b3b1-00a2fe0c8dd8 type_name="CyDesigner.Common.ProjMgmt.Model.CyPrjMgmtBaseContainerSerialize" version="1">
 <CyGuid_31768f72-0253-412b-af77-e7dba74d1330 type_name="CyDesigner.Common.ProjMgmt.Model.CyPrjMgmtItemSerialize" version="2" name="DEBUG_PINS" persistent="">
-<Hidden v="True" />
+<Hidden v="False" />
 </CyGuid_31768f72-0253-412b-af77-e7dba74d1330>
 <CyGuid_0820c2e7-528d-4137-9a08-97257b946089 type_name="CyDesigner.Common.ProjMgmt.Model.CyPrjMgmtItemListSerialize" version="2">
 <dependencies>
 <CyGuid_8b8ab257-35d3-4473-b57b-36315200b38b type_name="CyDesigner.Common.ProjMgmt.Model.CyPrjMgmtFileSerialize" version="3" xml_contents_version="1">
 <CyGuid_31768f72-0253-412b-af77-e7dba74d1330 type_name="CyDesigner.Common.ProjMgmt.Model.CyPrjMgmtItemSerialize" version="2" name="DEBUG_PINS_aliases.h" persistent="Generated_Source\PSoC5\DEBUG_PINS_aliases.h">
-<Hidden v="True" />
+<Hidden v="False" />
 </CyGuid_31768f72-0253-412b-af77-e7dba74d1330>
 <build_action v="HEADER;;;;" />
 <PropertyDeltas />
@@ -3249,6 +3249,39 @@
 </CyGuid_2f73275c-45bf-46ba-b3b1-00a2fe0c8dd8>
 <filters />
 </CyGuid_ebc4f06d-207f-49c2-a540-72acf4adabc0>
+<CyGuid_ebc4f06d-207f-49c2-a540-72acf4adabc0 type_name="CyDesigner.Common.ProjMgmt.Model.CyPrjMgmtFolderSerialize" version="3">
+<CyGuid_2f73275c-45bf-46ba-b3b1-00a2fe0c8dd8 type_name="CyDesigner.Common.ProjMgmt.Model.CyPrjMgmtBaseContainerSerialize" version="1">
+<CyGuid_31768f72-0253-412b-af77-e7dba74d1330 type_name="CyDesigner.Common.ProjMgmt.Model.CyPrjMgmtItemSerialize" version="2" name="CAPTURE_CONTROL" persistent="">
+<Hidden v="False" />
+</CyGuid_31768f72-0253-412b-af77-e7dba74d1330>
+<CyGuid_0820c2e7-528d-4137-9a08-97257b946089 type_name="CyDesigner.Common.ProjMgmt.Model.CyPrjMgmtItemListSerialize" version="2">
+<dependencies>
+<CyGuid_8b8ab257-35d3-4473-b57b-36315200b38b type_name="CyDesigner.Common.ProjMgmt.Model.CyPrjMgmtFileSerialize" version="3" xml_contents_version="1">
+<CyGuid_31768f72-0253-412b-af77-e7dba74d1330 type_name="CyDesigner.Common.ProjMgmt.Model.CyPrjMgmtItemSerialize" version="2" name="CAPTURE_CONTROL.h" persistent="Generated_Source\PSoC5\CAPTURE_CONTROL.h">
+<Hidden v="False" />
+</CyGuid_31768f72-0253-412b-af77-e7dba74d1330>
+<build_action v="HEADER;;;;" />
+<PropertyDeltas />
+</CyGuid_8b8ab257-35d3-4473-b57b-36315200b38b>
+<CyGuid_8b8ab257-35d3-4473-b57b-36315200b38b type_name="CyDesigner.Common.ProjMgmt.Model.CyPrjMgmtFileSerialize" version="3" xml_contents_version="1">
+<CyGuid_31768f72-0253-412b-af77-e7dba74d1330 type_name="CyDesigner.Common.ProjMgmt.Model.CyPrjMgmtItemSerialize" version="2" name="CAPTURE_CONTROL.c" persistent="Generated_Source\PSoC5\CAPTURE_CONTROL.c">
+<Hidden v="False" />
+</CyGuid_31768f72-0253-412b-af77-e7dba74d1330>
+<build_action v="SOURCE_C;CortexM3;;;" />
+<PropertyDeltas />
+</CyGuid_8b8ab257-35d3-4473-b57b-36315200b38b>
+<CyGuid_8b8ab257-35d3-4473-b57b-36315200b38b type_name="CyDesigner.Common.ProjMgmt.Model.CyPrjMgmtFileSerialize" version="3" xml_contents_version="1">
+<CyGuid_31768f72-0253-412b-af77-e7dba74d1330 type_name="CyDesigner.Common.ProjMgmt.Model.CyPrjMgmtItemSerialize" version="2" name="CAPTURE_CONTROL_PM.c" persistent="Generated_Source\PSoC5\CAPTURE_CONTROL_PM.c">
+<Hidden v="False" />
+</CyGuid_31768f72-0253-412b-af77-e7dba74d1330>
+<build_action v="SOURCE_C;CortexM3;;;" />
+<PropertyDeltas />
+</CyGuid_8b8ab257-35d3-4473-b57b-36315200b38b>
+</dependencies>
+</CyGuid_0820c2e7-528d-4137-9a08-97257b946089>
+</CyGuid_2f73275c-45bf-46ba-b3b1-00a2fe0c8dd8>
+<filters />
+</CyGuid_ebc4f06d-207f-49c2-a540-72acf4adabc0>
 </dependencies>
 </CyGuid_0820c2e7-528d-4137-9a08-97257b946089>
 </CyGuid_2f73275c-45bf-46ba-b3b1-00a2fe0c8dd8>

FluxEngine.cydsn/main.c

@@ -306,6 +306,7 @@ static void cmd_read(struct read_frame* f)
     dma_underrun = false;
     int count = 0;
     SAMPLER_CONTROL_Write(0); /* !reset */
+    CAPTURE_CONTROL_Write(1);
     CyDmaChSetInitialTd(dma_channel, td[dma_writing_to_td]);
     CyDmaClearPendingDrq(dma_channel);
     CyDmaChEnable(dma_channel, 1);
@@ -364,7 +365,8 @@ static void cmd_read(struct read_frame* f)
         }
         dma_reading_from_td = NEXT_BUFFER(dma_reading_from_td);
     }
-abort:
+abort:;
+    CAPTURE_CONTROL_Write(0);
     CyDmaChSetRequest(dma_channel, CY_DMA_CPU_TERM_CHAIN);
     while (CyDmaChGetRequest(dma_channel))
         ;

Makefile

@@ -22,7 +22,7 @@ export LIBS = $(shell pkg-config --libs $(PACKAGES))
 export EXTENSION =
 endif
 
-CFLAGS += -Ilib -Idep/fmt
+CFLAGS += -Ilib -Idep/fmt -Iarch
 
 export OBJDIR = .obj
 

arch/amiga/decoder.cc

@@ -92,6 +92,8 @@ void AmigaDecoder::decodeSectorRecord()
 
     uint32_t wanteddatachecksum = deinterleave(ptr, 4).reader().read_be32();
     uint32_t gotdatachecksum = checksum(rawbytes.slice(62, 1024));
-    _sector->data = deinterleave(ptr, 512);
+
+    _sector->data.clear();
+    _sector->data.writer().append(deinterleave(ptr, 512)).append(recoveryinfo);
     _sector->status = (gotdatachecksum == wanteddatachecksum) ? Sector::OK : Sector::BAD_CHECKSUM;
 }

arch/brother/brother.h

@@ -9,6 +9,9 @@
 #define BROTHER_DATA_RECORD_CHECKSUM     3
 #define BROTHER_DATA_RECORD_ENCODED_SIZE 415
 
+#define BROTHER_TRACKS_PER_DISK          78
+#define BROTHER_SECTORS_PER_TRACK        12
+
 class Sector;
 class Fluxmap;
 
@@ -22,9 +25,15 @@ public:
     void decodeDataRecord();
 };
 
-extern void writeBrotherSectorHeader(std::vector<bool>& bits, unsigned& cursor,
-		int track, int sector);
-extern void writeBrotherSectorData(std::vector<bool>& bits, unsigned& cursor,
-		const Bytes& data);
+class BrotherEncoder : public AbstractEncoder
+{
+public:
+	virtual ~BrotherEncoder() {}
+
+public:
+    std::unique_ptr<Fluxmap> encode(int physicalTrack, int physicalSide, const SectorSet& allSectors);
+};
+
+extern FlagGroup brotherEncoderFlags;
 
 #endif

arch/brother/decoder.cc

@@ -3,6 +3,7 @@
 #include "fluxmap.h"
 #include "decoders/fluxmapreader.h"
 #include "decoders/decoders.h"
+#include "encoders/encoders.h"
 #include "record.h"
 #include "brother.h"
 #include "sector.h"

arch/brother/encoder.cc

@@ -0,0 +1,167 @@
+#include "globals.h"
+#include "record.h"
+#include "decoders/decoders.h"
+#include "encoders/encoders.h"
+#include "brother.h"
+#include "crc.h"
+#include "sectorset.h"
+#include "writer.h"
+
+FlagGroup brotherEncoderFlags;
+
+static DoubleFlag clockRateUs(
+	{ "--clock-rate" },
+	"Encoded data clock rate (microseconds).",
+	3.83);
+
+static DoubleFlag postIndexGapMs(
+	{ "--post-index-gap" },
+	"Post-index gap before first sector header (milliseconds).",
+	1.0);
+
+static DoubleFlag sectorSpacingMs(
+	{ "--sector-spacing" },
+	"Time between successive sector headers (milliseconds).",
+	16.2);
+
+static DoubleFlag postHeaderSpacingMs(
+	{ "--post-header-spacing" },
+	"Time between a sector's header and data records (milliseconds).",
+	0.69);
+
+static StringFlag sectorSkew(
+	{ "--sector-skew" },
+	"Order in which to write sectors.",
+	"05a3816b4927");
+
+static int encode_header_gcr(uint16_t word)
+{
+	switch (word)
+	{
+		#define GCR_ENTRY(gcr, data) \
+			case data: return gcr;
+		#include "header_gcr.h"
+		#undef GCR_ENTRY
+	}                       
+	return -1;             
+};
+
+static int encode_data_gcr(uint8_t data)
+{
+	switch (data)
+	{
+		#define GCR_ENTRY(gcr, data) \
+			case data: return gcr;
+		#include "data_gcr.h"
+		#undef GCR_ENTRY
+	}                       
+	return -1;             
+};
+
+static void write_bits(std::vector<bool>& bits, unsigned& cursor, uint32_t data, int width)
+{
+	cursor += width;
+	for (int i=0; i<width; i++)
+	{
+		unsigned pos = cursor - i - 1;
+		if (pos < bits.size())
+			bits[pos] = data & 1;
+		data >>= 1;
+	}
+}
+
+static void write_sector_header(std::vector<bool>& bits, unsigned& cursor,
+		int track, int sector)
+{
+	write_bits(bits, cursor, 0xffffffff, 31);
+	write_bits(bits, cursor, BROTHER_SECTOR_RECORD, 32);
+	write_bits(bits, cursor, encode_header_gcr(track), 16);
+	write_bits(bits, cursor, encode_header_gcr(sector), 16);
+	write_bits(bits, cursor, encode_header_gcr(0x2f), 16);
+}
+
+static void write_sector_data(std::vector<bool>& bits, unsigned& cursor, const Bytes& data)
+{
+	write_bits(bits, cursor, 0xffffffff, 32);
+	write_bits(bits, cursor, BROTHER_DATA_RECORD, 32);
+
+	uint16_t fifo = 0;
+	int width = 0;
+
+	if (data.size() != BROTHER_DATA_RECORD_PAYLOAD)
+		Error() << "unsupported sector size";
+
+	auto write_byte = [&](uint8_t byte)
+	{
+		fifo |= (byte << (8 - width));
+		width += 8;
+
+		while (width >= 5)
+		{
+			uint8_t quintet = fifo >> 11;
+			fifo <<= 5;
+			width -= 5;
+
+			write_bits(bits, cursor, encode_data_gcr(quintet), 8);
+		}
+	};
+
+	for (uint8_t byte : data)
+		write_byte(byte);
+
+	uint32_t realCrc = crcbrother(data);
+	write_byte(realCrc>>16);
+	write_byte(realCrc>>8);
+	write_byte(realCrc);
+	write_byte(0x58); /* magic */
+    write_byte(0xd4);
+    while (width != 0)
+        write_byte(0);
+}
+
+static int charToInt(char c)
+{
+	if (isdigit(c))
+		return c - '0';
+	return 10 + tolower(c) - 'a';
+}
+
+std::unique_ptr<Fluxmap> BrotherEncoder::encode(
+	int physicalTrack, int physicalSide, const SectorSet& allSectors)
+{
+	if ((physicalTrack < 0) || (physicalTrack >= BROTHER_TRACKS_PER_DISK)
+        || (physicalSide != 0))
+		return std::unique_ptr<Fluxmap>();
+
+	int bitsPerRevolution = 200000.0 / clockRateUs;
+	const std::string& skew = sectorSkew.get();
+	std::vector<bool> bits(bitsPerRevolution);
+	unsigned cursor = 0;
+
+	for (int sectorCount=0; sectorCount<BROTHER_SECTORS_PER_TRACK; sectorCount++)
+	{
+		int sectorId = charToInt(skew.at(sectorCount));
+		double headerMs = postIndexGapMs + sectorCount*sectorSpacingMs;
+		unsigned headerCursor = headerMs*1e3 / clockRateUs;
+		double dataMs = headerMs + postHeaderSpacingMs;
+		unsigned dataCursor = dataMs*1e3 / clockRateUs;
+
+		const auto& sectorData = allSectors.get(physicalTrack, 0, sectorId);
+
+		fillBitmapTo(bits, cursor, headerCursor, { true, false });
+		write_sector_header(bits, cursor, physicalTrack, sectorId);
+		fillBitmapTo(bits, cursor, dataCursor, { true, false });
+		write_sector_data(bits, cursor, sectorData->data);
+	}
+
+	if (cursor > bits.size())
+		Error() << "track data overrun";
+	fillBitmapTo(bits, cursor, bits.size(), { true, false });
+
+	// The pre-index gap is not normally reported.
+	// std::cerr << "pre-index gap " << 200.0 - (double)cursor*clockRateUs/1e3 << std::endl;
+	
+	std::unique_ptr<Fluxmap> fluxmap(new Fluxmap);
+	fluxmap->appendBits(bits, clockRateUs*1e3);
+	return fluxmap;
+}

arch/macintosh/decoder.cc

@@ -153,6 +153,9 @@ void MacintoshDecoder::decodeSectorRecord()
     uint8_t formatByte = decode_data_gcr(header[3]);
     uint8_t wantedsum = decode_data_gcr(header[4]);
 
+    if (encodedSector > 11)
+        return;
+
     _sector->logicalTrack = _track->physicalTrack;
     _sector->logicalSide = decode_side(encodedSide);
     _sector->logicalSector = encodedSector;
@@ -177,5 +180,7 @@ void MacintoshDecoder::decodeDataRecord()
         inputbuffer[i] = decode_data_gcr(inputbuffer[i]);
         
     _sector->status = Sector::BAD_CHECKSUM;
-    _sector->data = decode_crazy_data(inputbuffer, _sector->status);
+    Bytes userData = decode_crazy_data(inputbuffer, _sector->status);
+    _sector->data.clear();
+    _sector->data.writer().append(userData.slice(12, 512)).append(userData.slice(0, 12));
 }

doc/disk-amiga.md

@@ -23,6 +23,17 @@ You should end up with an `amiga.adf` which is 901120 bytes long (for a
 normal DD disk) --- it ought to be a perfectly normal ADF file which you can
 use in an emulator.
 
+If you want the metadata as well, specify a 528 byte sector size for the
+output image:
+
+```
+fluxengine read amiga -o amiga.adf:b=528
+```
+
+You will end up with a 929280 byte long image which you probably _can't_ use
+in an emulator; each sector will contain the 512 bytes of user payload
+followed by the 16 bytes of metadata.
+
 Useful references
 -----------------
 

doc/disk-macintosh.md

@@ -50,6 +50,10 @@ with holes where missing sectors should be. This was easiest. If anyone can
 suggest a better way, please [get in
 touch](https://github.com/davidgiven/fluxengine/issues/new).
 
+The 12 bytes of metadata _follow_ the 512 bytes of user payload in the sector
+image. If you don't want it, specify a geometry in the output file with a
+512-byte sectore size like `-o mac.img:c=80:h=1:s=12:b=512`.
+
 Useful references
 -----------------
 

doc/using.md

@@ -112,6 +112,42 @@ sensible for the command you're using.
 **Important note:** FluxEngine _always_ uses zero-based units (even if the
 *disk format says otherwise).
 
+### Input and output specifiers
+
+These use a very similar syntax to the source and destination specifiers
+(because they're based on the same microformat library!) but are used for
+input and output _images_: i.e. nicely lined up arrays of sectors which you
+can actually do something with.
+
+Use `--input` (`-i`) or `--output` (`-o`) as appropriate to tell FluxEngine
+where you want to read from or write to. The actual format is autodetected
+based on the extension:
+
+  - `.img` or `.adf`: raw sector images in CHS order. Append
+    `:c=80:h=2:s=9:b=512` to set the geometry; that specifies 80 cylinders, 2
+    heads, 9 sectors, 512 bytes per sector. For output files (`--output`) the
+    geometry will be autodetected if left unspecified. For input files you
+    normally have to specify it.
+
+  - `.ldbs`: John Elliott's [LDBS disk image
+    format](http://www.seasip.info/Unix/LibDsk/ldbs.html), which is
+    consumable by the [libdsk](http://www.seasip.info/Unix/LibDsk/) suite of
+    tools. This allows things like variable numbers of sectors per track
+    (e.g. Macintosh or Commodore 64) and also provides information about
+    whether sectors were read correctly. You can use libdsk to convert this
+    to other formats, using a command like this:
+
+    ```
+    $ dsktrans out.ldbs -otype tele out.td0
+    ```
+
+    ...to convert to TeleDisk format. (Note you have to use dsktrans rather
+    than dskconv due to a minor bug in the geometry hadnling.)
+
+    FluxEngine's LDBS support is currently limited to write only, and
+    it doesn't store a lot of the more esoteric LDBS features like format
+    types, timings, and data rates.
+
 ### High density disks
 
 High density disks use a different magnetic medium to low and double density

lib/brother/encoder.cc

@@ -1,92 +0,0 @@
-#include "globals.h"
-#include "record.h"
-#include "decoders/decoders.h"
-#include "brother.h"
-#include "crc.h"
-
-static int encode_header_gcr(uint16_t word)
-{
-	switch (word)
-	{
-		#define GCR_ENTRY(gcr, data) \
-			case data: return gcr;
-		#include "header_gcr.h"
-		#undef GCR_ENTRY
-	}                       
-	return -1;             
-};
-
-static int encode_data_gcr(uint8_t data)
-{
-	switch (data)
-	{
-		#define GCR_ENTRY(gcr, data) \
-			case data: return gcr;
-		#include "data_gcr.h"
-		#undef GCR_ENTRY
-	}                       
-	return -1;             
-};
-
-static void write_bits(std::vector<bool>& bits, unsigned& cursor, uint32_t data, int width)
-{
-	cursor += width;
-	for (int i=0; i<width; i++)
-	{
-		unsigned pos = cursor - i - 1;
-		if (pos < bits.size())
-			bits[pos] = data & 1;
-		data >>= 1;
-	}
-}
-
-void writeBrotherSectorHeader(std::vector<bool>& bits, unsigned& cursor,
-		int track, int sector)
-{
-	write_bits(bits, cursor, 0xffffffff, 31);
-	write_bits(bits, cursor, BROTHER_SECTOR_RECORD, 32);
-	write_bits(bits, cursor, encode_header_gcr(track), 16);
-	write_bits(bits, cursor, encode_header_gcr(sector), 16);
-	write_bits(bits, cursor, encode_header_gcr(0x2f), 16);
-}
-
-void writeBrotherSectorData(std::vector<bool>& bits, unsigned& cursor, const Bytes& data)
-{
-	write_bits(bits, cursor, 0xffffffff, 32);
-	write_bits(bits, cursor, BROTHER_DATA_RECORD, 32);
-
-	uint16_t fifo = 0;
-	int width = 0;
-
-	if (data.size() != BROTHER_DATA_RECORD_PAYLOAD)
-		Error() << "unsupported sector size";
-
-	auto write_byte = [&](uint8_t byte)
-	{
-		fifo |= (byte << (8 - width));
-		width += 8;
-
-		while (width >= 5)
-		{
-			uint8_t quintet = fifo >> 11;
-			fifo <<= 5;
-			width -= 5;
-
-			write_bits(bits, cursor, encode_data_gcr(quintet), 8);
-		}
-	};
-
-	for (uint8_t byte : data)
-		write_byte(byte);
-
-	uint32_t realCrc = crcbrother(data);
-	write_byte(realCrc>>16);
-	write_byte(realCrc>>8);
-	write_byte(realCrc);
-	write_byte(0x58); /* magic */
-    write_byte(0xd4);
-    while (width != 0)
-        write_byte(0);
-}
-
-

lib/bytes.cc

@@ -2,6 +2,7 @@
 #include "bytes.h"
 #include "fmt/format.h"
 #include "common/crunch.h"
+#include <fstream>
 #include <zlib.h>
 
 static std::shared_ptr<std::vector<uint8_t>> createVector(unsigned size)
@@ -280,6 +281,16 @@ Bytes Bytes::uncrunch() const
     return output;
 }
 
+void Bytes::writeToFile(const std::string& filename) const
+{
+    std::ofstream f(filename, std::ios::out | std::ios::binary);
+    if (!f.is_open())
+        Error() << fmt::format("cannot open output file '{}'", filename);
+
+    f.write((const char*) cbegin(), size());
+    f.close();
+}
+
 ByteReader Bytes::reader() const
 {
     return ByteReader(*this);

lib/bytes.h

@@ -56,6 +56,8 @@ public:
     ByteReader reader() const;
     ByteWriter writer();
 
+    void writeToFile(const std::string& filename) const;
+
 private:
     std::shared_ptr<std::vector<uint8_t>> _data;
     unsigned _low;

lib/dataspec.cc

@@ -5,6 +5,11 @@
 #include <regex>
 #include <sstream>
 
+MissingModifierException::MissingModifierException(const std::string& mod):
+    mod(mod),
+    std::runtime_error(fmt::format("missing mandatory modifier '{}'", mod))
+{}
+
 std::vector<std::string> DataSpec::split(
         const std::string& s, const std::string& delimiter)
 {
@@ -74,31 +79,108 @@ void DataSpec::set(const std::string& spec)
     filename = words[0];
     if (words.size() > 1)
     {
-        locations.clear();
-
         for (size_t i = 1; i < words.size(); i++)
         {
             auto mod = parseMod(words[i]);
-            if ((mod.name != "t") && (mod.name != "s") && (mod.name != "d"))
-                Error() << fmt::format("unknown data modifier '{}'", mod.name);
             modifiers[mod.name] = mod;
         }
+    }
+}
 
-        const auto& drives = modifiers["d"].data;
+const DataSpec::Modifier& DataSpec::at(const std::string& mod) const
+{
+    try
+    {
+        return modifiers.at(mod);
+    }
+    catch (const std::out_of_range& e)
+    {
+        throw MissingModifierException(mod);
+    }
+}
+
+bool DataSpec::has(const std::string& mod) const
+{
+    return modifiers.find(mod) != modifiers.end();
+}
+
+FluxSpec::FluxSpec(const DataSpec& spec)
+{
+    try 
+    {
+        filename = spec.filename;
+
+        locations.clear();
+
+        const auto& drives = spec.at("d").data;
         if (drives.size() != 1)
             Error() << "you must specify exactly one drive";
         drive = *drives.begin();
 
-        const auto& tracks = modifiers["t"].data;
-        const auto& sides = modifiers["s"].data;
+        const auto& tracks = spec.at("t").data;
+        const auto& sides = spec.at("s").data;
         for (auto track : tracks)
         {
             for (auto side : sides)
                 locations.push_back({ drive, track, side });
         }
+
+        for (const auto& e : spec.modifiers)
+        {
+            const auto name = e.second.name;
+            if ((name != "t") && (name != "s") && (name != "d"))
+                Error() << fmt::format("unknown fluxspec modifier '{}'", name);
+        }
+    }
+    catch (const MissingModifierException& e)
+    {
+        Error() << e.what() << " in fluxspec '" << spec << "'";
     }
 }
 
+ImageSpec::ImageSpec(const DataSpec& spec)
+{
+    try
+    {
+        filename = spec.filename;
+
+        if (!spec.has("c") && !spec.has("h") && !spec.has("s") && !spec.has("b"))
+        {
+            cylinders = heads = sectors = bytes = 0;
+            initialised = false;
+        }
+        else
+        {
+            cylinders = spec.at("c").only();
+            heads = spec.at("h").only();
+            sectors = spec.at("s").only();
+            bytes = spec.at("b").only();
+            initialised = true;
+        }
+    }
+    catch (const MissingModifierException& e)
+    {
+        Error() << e.what() << " in imagespec '" << spec << "'";
+    }
+
+    for (const auto& e : spec.modifiers)
+    {
+        const auto name = e.second.name;
+        if ((name != "c") && (name != "h") && (name != "s") && (name != "b"))
+            Error() << fmt::format("unknown fluxspec modifier '{}'", name);
+    }
+}
+
+ImageSpec::ImageSpec(const std::string filename,
+        unsigned cylinders, unsigned heads, unsigned sectors, unsigned bytes):
+    filename(filename),
+    cylinders(cylinders),
+    heads(heads),
+    sectors(sectors),
+    bytes(bytes),
+    initialised(true)
+{}
+
 DataSpec::operator std::string(void) const
 {
     std::stringstream ss;

lib/dataspec.h

@@ -1,8 +1,57 @@
 #ifndef DATASPEC_H
 #define DATASPEC_H
 
+class MissingModifierException : public std::runtime_error
+{
+public:
+    MissingModifierException(const std::string& mod);
+    const std::string mod;
+};
+
 class DataSpec
 {
+public:
+    struct Modifier
+    {
+        std::string name;
+        std::set<unsigned> data;
+        std::string source;
+
+        bool operator == (const Modifier& other) const
+        { return (name == other.name) && (data == other.data); }
+
+        bool operator != (const Modifier& other) const
+        { return (name != other.name) || (data != other.data); }
+
+        unsigned only() const
+        {
+            if (data.size() != 1)
+                Error() << "modifier " << name << " can only have one value";
+            return *(data.begin());
+        }
+    };
+
+public:
+    static std::vector<std::string> split(
+        const std::string& s, const std::string& delimiter);
+    static Modifier parseMod(const std::string& spec);
+
+public:
+    DataSpec(const std::string& spec)
+    { set(spec); }
+
+    void set(const std::string& spec);
+    operator std::string () const;
+
+    const Modifier& at(const std::string& mod) const;
+    bool has(const std::string& mod) const;
+
+    std::string filename;
+    std::map<std::string, Modifier> modifiers;
+};
+
+class FluxSpec
+{
 public:
     struct Location
     {
@@ -17,36 +66,29 @@ public:
         { return (drive != other.drive) || (track != other.track) || (side != other.side); }
     };
 
-    struct Modifier
-    {
-        std::string name;
-        std::set<unsigned> data;
-        std::string source;
-
-        bool operator == (const Modifier& other) const
-        { return (name == other.name) && (data == other.data); }
-
-        bool operator != (const Modifier& other) const
-        { return (name != other.name) || (data != other.data); }
-    };
+public:
+    FluxSpec(const DataSpec& dataspec);
 
 public:
-    static std::vector<std::string> split(
-        const std::string& s, const std::string& delimiter);
-    static Modifier parseMod(const std::string& spec);
-
-public:
-    DataSpec(const std::string& spec)
-    { set(spec); }
-
-    void set(const std::string& spec);
-    operator std::string () const;
-
     std::string filename;
-    std::map<std::string, Modifier> modifiers;
     std::vector<Location> locations;
     unsigned drive;
-    unsigned revolutions;
+};
+
+class ImageSpec
+{
+public:
+    ImageSpec(const DataSpec& dataspec);
+    ImageSpec(const std::string filename,
+        unsigned cylinders, unsigned heads, unsigned sectors, unsigned bytes);
+
+public:
+    std::string filename;
+    unsigned cylinders;
+    unsigned heads;
+    unsigned sectors;
+    unsigned bytes;
+    bool initialised : 1;
 };
 
 static inline std::ostream& operator << (std::ostream& os, const DataSpec& dataSpec)

lib/encoders/encoders.h

@@ -0,0 +1,18 @@
+#ifndef ENCODERS_H
+#define ENCODERS_H
+
+class Fluxmap;
+class SectorSet;
+
+class AbstractEncoder
+{
+public:
+    virtual ~AbstractEncoder() {}
+
+public:
+    virtual std::unique_ptr<Fluxmap> encode(
+        int physicalTrack, int physicalSide, const SectorSet& allSectors) = 0;
+};
+
+#endif
+

lib/fluxsink/fluxsink.cc

@@ -10,7 +10,7 @@ static bool ends_with(const std::string& value, const std::string& ending)
     return std::equal(ending.rbegin(), ending.rend(), value.rbegin());
 }
 
-std::unique_ptr<FluxSink> FluxSink::create(const DataSpec& spec)
+std::unique_ptr<FluxSink> FluxSink::create(const FluxSpec& spec)
 {
     const auto& filename = spec.filename;
 

lib/fluxsink/fluxsink.h

@@ -2,7 +2,7 @@
 #define FLUXSINK_H
 
 class Fluxmap;
-class DataSpec;
+class FluxSpec;
 
 class FluxSink
 {
@@ -14,7 +14,7 @@ private:
     static std::unique_ptr<FluxSink> createHardwareFluxSink(unsigned drive);
 
 public:
-    static std::unique_ptr<FluxSink> create(const DataSpec& spec);
+    static std::unique_ptr<FluxSink> create(const FluxSpec& spec);
 
 public:
     virtual void writeFlux(int track, int side, Fluxmap& fluxmap) = 0;

lib/fluxsource/fluxsource.cc

@@ -10,7 +10,7 @@ static bool ends_with(const std::string& value, const std::string& ending)
     return std::equal(ending.rbegin(), ending.rend(), value.rbegin());
 }
 
-std::unique_ptr<FluxSource> FluxSource::create(const DataSpec& spec)
+std::unique_ptr<FluxSource> FluxSource::create(const FluxSpec& spec)
 {
     const auto& filename = spec.filename;
 

lib/fluxsource/fluxsource.h

@@ -6,7 +6,7 @@
 extern FlagGroup hardwareFluxSourceFlags;
 
 class Fluxmap;
-class DataSpec;
+class FluxSpec;
 
 class FluxSource
 {
@@ -19,7 +19,7 @@ private:
     static std::unique_ptr<FluxSource> createStreamFluxSource(const std::string& path);
 
 public:
-    static std::unique_ptr<FluxSource> create(const DataSpec& spec);
+    static std::unique_ptr<FluxSource> create(const FluxSpec& spec);
 
 public:
     virtual std::unique_ptr<Fluxmap> readFlux(int track, int side) = 0;

lib/image.cc

@@ -1,150 +1,25 @@
 #include "globals.h"
 #include "image.h"
+#include "flags.h"
+#include "dataspec.h"
 #include "sector.h"
 #include "sectorset.h"
+#include "imagereader/imagereader.h"
+#include "imagewriter/imagewriter.h"
 #include "fmt/format.h"
 #include <algorithm>
 #include <iostream>
 #include <fstream>
 
-Geometry guessGeometry(const SectorSet& sectors)
+SectorSet readSectorsFromFile(const ImageSpec& spec)
 {
-	Geometry g;
-	sectors.calculateSize(g.tracks, g.heads, g.sectors, g.sectorSize);
-	return g;
+	return ImageReader::create(spec)->readImage();
 }
 
-void readSectorsFromFile(SectorSet& sectors, const Geometry& geometry,
-		const std::string& filename)
+void writeSectorsToFile(const SectorSet& sectors, const ImageSpec& spec)
 {
-    std::ifstream inputFile(filename, std::ios::in | std::ios::binary);
-    if (!inputFile.is_open())
-		Error() << "cannot open input file";
-
-    size_t headSize = geometry.sectors * geometry.sectorSize;
-    size_t trackSize = headSize * geometry.heads;
-
-    std::cout << fmt::format("{} tracks, {} heads, {} sectors, {} bytes per sector, {} kB total",
-					geometry.tracks, geometry.heads,
-					geometry.sectors, geometry.sectorSize,
-					geometry.tracks * trackSize / 1024)
-			  << std::endl;
-
-	for (int track = 0; track < geometry.tracks; track++)
-	{
-		for (int head = 0; head < geometry.heads; head++)
-		{
-			for (int sectorId = 0; sectorId < geometry.sectors; sectorId++)
-			{
-				inputFile.seekg(track*trackSize + head*headSize + sectorId*geometry.sectorSize, std::ios::beg);
-
-				Bytes data(geometry.sectorSize);
-				inputFile.read((char*) data.begin(), geometry.sectorSize);
-
-				std::unique_ptr<Sector>& sector = sectors.get(track, head, sectorId);
-				sector.reset(new Sector);
-				sector->status = Sector::OK;
-				sector->logicalTrack = sector->physicalTrack = track;
-				sector->logicalSide = sector->physicalSide = head;
-				sector->logicalSector = sectorId;
-				sector->data = data;
-			}
-		}
-	}
-}
-
-void writeSectorsToFile(const SectorSet& sectors, const Geometry& geometry,
-		const std::string& filename)
-{
-	/* Emit the map. */
-
-	int badSectors = 0;
-	int missingSectors = 0;
-	int totalSectors = 0;
-	std::cout << "H.SS Tracks --->" << std::endl;
-	for (int head = 0; head < geometry.heads; head++)
-	{
-		for (int sectorId = 0; sectorId < geometry.sectors; sectorId++)
-		{
-			std::cout << fmt::format("{}.{:2} ", head, sectorId);
-			for (int track = 0; track < geometry.tracks; track++)
-			{
-				Sector* sector = sectors.get(track, head, sectorId);
-				if (!sector)
-				{
-					std::cout << 'X';
-					missingSectors++;
-				}
-				else
-				{
-					switch (sector->status)
-					{
-						case Sector::OK:
-                            std::cout << '.';
-                            break;
-
-                        case Sector::BAD_CHECKSUM:
-                            std::cout << 'B';
-                            badSectors++;
-                            break;
-
-                        case Sector::CONFLICT:
-                            std::cout << 'C';
-                            badSectors++;
-                            break;
-
-                        default:
-                            std::cout << '?';
-                            break;
-                    }
-				}
-				totalSectors++;
-			}
-			std::cout << std::endl;
-		}
-	}
-	int goodSectors = totalSectors - missingSectors - badSectors;
-	if (totalSectors == 0)
-		std::cout << "No sectors in output; skipping analysis" << std::endl;
-	else
-	{
-		std::cout << "Good sectors: " << goodSectors << "/" << totalSectors
-				  << " (" << (100*goodSectors/totalSectors) << "%)"
-				  << std::endl;
-		std::cout << "Missing sectors: " << missingSectors << "/" << totalSectors
-				  << " (" << (100*missingSectors/totalSectors) << "%)"
-				  << std::endl;
-		std::cout << "Bad sectors: " << badSectors << "/" << totalSectors
-				  << " (" << (100*badSectors/totalSectors) << "%)"
-				  << std::endl;
-    }
-
-    size_t headSize = geometry.sectors * geometry.sectorSize;
-    size_t trackSize = headSize * geometry.heads;
-
-    std::cout << fmt::format("{} tracks, {} heads, {} sectors, {} bytes per sector, {} kB total",
-					geometry.tracks, geometry.heads,
-					geometry.sectors, geometry.sectorSize,
-					geometry.tracks * trackSize / 1024)
-			  << std::endl;
-
-    std::ofstream outputFile(filename, std::ios::out | std::ios::binary);
-    if (!outputFile.is_open())
-		Error() << "cannot open output file";
-
-	for (int track = 0; track < geometry.tracks; track++)
-	{
-		for (int head = 0; head < geometry.heads; head++)
-		{
-			for (int sectorId = 0; sectorId < geometry.sectors; sectorId++)
-			{
-				auto sector = sectors.get(track, head, sectorId);
-				if (sector)
-				{
-					outputFile.seekp(sector->logicalTrack*trackSize + sector->logicalSide*headSize + sector->logicalSector*geometry.sectorSize, std::ios::beg);
-					outputFile.write((const char*) sector->data.cbegin(), sector->data.size());
-				}
-			}
-		}
-	}
+	std::unique_ptr<ImageWriter> writer(ImageWriter::create(sectors, spec));
+	writer->adjustGeometry();
+	writer->printMap();
+	writer->writeImage();
 }

lib/image.h

@@ -2,26 +2,13 @@
 #define IMAGE_H
 
 class SectorSet;
+class ImageSpec;
 
-class Geometry
-{
-public:
-	int tracks;
-	int heads;
-	int sectors;
-	int sectorSize;
-};
-
-extern Geometry guessGeometry(const SectorSet& sectors);
-
-extern void readSectorsFromFile(
-	SectorSet& sectors,
-	const Geometry& geometry,
-	const std::string& filename);
+extern SectorSet readSectorsFromFile(
+	const ImageSpec& filename);
 
 extern void writeSectorsToFile(
 	const SectorSet& sectors,
-	const Geometry& geometry,
-	const std::string& filename);
+	const ImageSpec& filename);
 
 #endif

lib/imagereader/imagereader.cc

@@ -0,0 +1,31 @@
+#include "globals.h"
+#include "image.h"
+#include "flags.h"
+#include "dataspec.h"
+#include "sector.h"
+#include "sectorset.h"
+#include "imagereader/imagereader.h"
+#include "fmt/format.h"
+
+static bool ends_with(const std::string& value, const std::string& ending)
+{
+    if (ending.size() > value.size())
+        return false;
+    return std::equal(ending.rbegin(), ending.rend(), value.rbegin());
+}
+
+std::unique_ptr<ImageReader> ImageReader::create(const ImageSpec& spec)
+{
+    const auto& filename = spec.filename;
+
+    if (ends_with(filename, ".img") || ends_with(filename, ".adf"))
+        return createImgImageReader(spec);
+
+    Error() << "unrecognised image filename extension";
+    return std::unique_ptr<ImageReader>();
+}
+
+ImageReader::ImageReader(const ImageSpec& spec):
+    spec(spec)
+{}
+

lib/imagereader/imagereader.h

@@ -0,0 +1,27 @@
+#ifndef IMAGEREADER_H
+#define IMAGEREADER_H
+
+class SectorSet;
+class ImageSpec;
+
+class ImageReader
+{
+public:
+	ImageReader(const ImageSpec& spec);
+	virtual ~ImageReader() {};
+
+public:
+    static std::unique_ptr<ImageReader> create(const ImageSpec& spec);
+
+private:
+    static std::unique_ptr<ImageReader> createImgImageReader(const ImageSpec& spec);
+
+public:
+	virtual SectorSet readImage() = 0;
+
+protected:
+	ImageSpec spec;
+};
+
+#endif
+

lib/imagereader/imgimagereader.cc

@@ -0,0 +1,66 @@
+#include "globals.h"
+#include "image.h"
+#include "flags.h"
+#include "dataspec.h"
+#include "sector.h"
+#include "sectorset.h"
+#include "imagereader/imagereader.h"
+#include "fmt/format.h"
+#include <algorithm>
+#include <iostream>
+#include <fstream>
+
+class ImgImageReader : public ImageReader
+{
+public:
+	ImgImageReader(const ImageSpec& spec):
+		ImageReader(spec)
+	{}
+
+	SectorSet readImage()
+	{
+        std::ifstream inputFile(spec.filename, std::ios::in | std::ios::binary);
+        if (!inputFile.is_open())
+            Error() << "cannot open input file";
+
+        size_t headSize = spec.sectors * spec.bytes;
+        size_t trackSize = headSize * spec.heads;
+
+        std::cout << fmt::format("reading {} tracks, {} heads, {} sectors, {} bytes per sector, {} kB total",
+                        spec.cylinders, spec.heads,
+                        spec.sectors, spec.bytes,
+                        spec.cylinders * trackSize / 1024)
+                << std::endl;
+
+        SectorSet sectors;
+        for (int track = 0; track < spec.cylinders; track++)
+        {
+            for (int head = 0; head < spec.heads; head++)
+            {
+                for (int sectorId = 0; sectorId < spec.sectors; sectorId++)
+                {
+                    inputFile.seekg(track*trackSize + head*headSize + sectorId*spec.bytes, std::ios::beg);
+
+                    Bytes data(spec.bytes);
+                    inputFile.read((char*) data.begin(), spec.bytes);
+
+                    std::unique_ptr<Sector>& sector = sectors.get(track, head, sectorId);
+                    sector.reset(new Sector);
+                    sector->status = Sector::OK;
+                    sector->logicalTrack = sector->physicalTrack = track;
+                    sector->logicalSide = sector->physicalSide = head;
+                    sector->logicalSector = sectorId;
+                    sector->data = data;
+                }
+            }
+        }
+        return sectors;
+	}
+};
+
+std::unique_ptr<ImageReader> ImageReader::createImgImageReader(
+	const ImageSpec& spec)
+{
+    return std::unique_ptr<ImageReader>(new ImgImageReader(spec));
+}
+

lib/imagewriter/imagewriter.cc

@@ -0,0 +1,107 @@
+#include "globals.h"
+#include "image.h"
+#include "flags.h"
+#include "dataspec.h"
+#include "sector.h"
+#include "sectorset.h"
+#include "imagewriter/imagewriter.h"
+#include "fmt/format.h"
+
+static bool ends_with(const std::string& value, const std::string& ending)
+{
+    if (ending.size() > value.size())
+        return false;
+    return std::equal(ending.rbegin(), ending.rend(), value.rbegin());
+}
+
+std::unique_ptr<ImageWriter> ImageWriter::create(const SectorSet& sectors, const ImageSpec& spec)
+{
+    const auto& filename = spec.filename;
+
+    if (ends_with(filename, ".img") || ends_with(filename, ".adf"))
+        return createImgImageWriter(sectors, spec);
+	else if (ends_with(filename, ".ldbs"))
+		return createLDBSImageWriter(sectors, spec);
+
+    Error() << "unrecognised image filename extension";
+    return std::unique_ptr<ImageWriter>();
+}
+
+ImageWriter::ImageWriter(const SectorSet& sectors, const ImageSpec& spec):
+    sectors(sectors),
+    spec(spec)
+{}
+
+void ImageWriter::adjustGeometry()
+{
+	if (!spec.initialised)
+	{
+		sectors.calculateSize(spec.cylinders, spec.heads, spec.sectors, spec.bytes);
+        spec.initialised = true;
+		std::cout << "Autodetecting output geometry\n";
+	}
+}
+
+void ImageWriter::printMap()
+{
+	int badSectors = 0;
+	int missingSectors = 0;
+	int totalSectors = 0;
+	std::cout << "H.SS Tracks --->" << std::endl;
+	for (int head = 0; head < spec.heads; head++)
+	{
+		for (int sectorId = 0; sectorId < spec.sectors; sectorId++)
+		{
+			std::cout << fmt::format("{}.{:2} ", head, sectorId);
+			for (int track = 0; track < spec.cylinders; track++)
+			{
+				const auto& sector = sectors.get(track, head, sectorId);
+				if (!sector)
+				{
+					std::cout << 'X';
+					missingSectors++;
+				}
+				else
+				{
+					switch (sector->status)
+					{
+						case Sector::OK:
+                            std::cout << '.';
+                            break;
+
+                        case Sector::BAD_CHECKSUM:
+                            std::cout << 'B';
+                            badSectors++;
+                            break;
+
+                        case Sector::CONFLICT:
+                            std::cout << 'C';
+                            badSectors++;
+                            break;
+
+                        default:
+                            std::cout << '?';
+                            break;
+                    }
+				}
+				totalSectors++;
+			}
+			std::cout << std::endl;
+		}
+	}
+	int goodSectors = totalSectors - missingSectors - badSectors;
+	if (totalSectors == 0)
+		std::cout << "No sectors in output; skipping analysis" << std::endl;
+	else
+	{
+		std::cout << "Good sectors: " << goodSectors << "/" << totalSectors
+				  << " (" << (100*goodSectors/totalSectors) << "%)"
+				  << std::endl;
+		std::cout << "Missing sectors: " << missingSectors << "/" << totalSectors
+				  << " (" << (100*missingSectors/totalSectors) << "%)"
+				  << std::endl;
+		std::cout << "Bad sectors: " << badSectors << "/" << totalSectors
+				  << " (" << (100*badSectors/totalSectors) << "%)"
+				  << std::endl;
+    }
+}

lib/imagewriter/imagewriter.h

@@ -0,0 +1,32 @@
+#ifndef IMAGEWRITER_H
+#define IMAGEWRITER_H
+
+class SectorSet;
+class ImageSpec;
+
+class ImageWriter
+{
+public:
+	ImageWriter(const SectorSet& sectors, const ImageSpec& spec);
+	virtual ~ImageWriter() {};
+
+public:
+    static std::unique_ptr<ImageWriter> create(const SectorSet& sectors, const ImageSpec& spec);
+
+private:
+    static std::unique_ptr<ImageWriter> createImgImageWriter(
+		const SectorSet& sectors, const ImageSpec& spec);
+    static std::unique_ptr<ImageWriter> createLDBSImageWriter(
+		const SectorSet& sectors, const ImageSpec& spec);
+
+public:
+	virtual void adjustGeometry();
+	void printMap();
+	virtual void writeImage() = 0;
+
+protected:
+	const SectorSet& sectors;
+	ImageSpec spec;
+};
+
+#endif

lib/imagewriter/imgimagewriter.cc

@@ -0,0 +1,62 @@
+#include "globals.h"
+#include "image.h"
+#include "flags.h"
+#include "dataspec.h"
+#include "sector.h"
+#include "sectorset.h"
+#include "imagewriter/imagewriter.h"
+#include "fmt/format.h"
+#include <algorithm>
+#include <iostream>
+#include <fstream>
+
+class ImgImageWriter : public ImageWriter
+{
+public:
+	ImgImageWriter(const SectorSet& sectors, const ImageSpec& spec):
+		ImageWriter(sectors, spec)
+	{}
+
+	void writeImage()
+	{
+		unsigned numCylinders = spec.cylinders;
+		unsigned numHeads = spec.heads;
+		unsigned numSectors = spec.sectors;
+		unsigned numBytes = spec.bytes;
+
+		size_t headSize = numSectors * numBytes;
+		size_t trackSize = headSize * numHeads;
+
+		std::cout << fmt::format("writing {} tracks, {} heads, {} sectors, {} bytes per sector, {} kB total",
+						numCylinders, numHeads,
+						numSectors, numBytes,
+						numCylinders * trackSize / 1024)
+				<< std::endl;
+
+		std::ofstream outputFile(spec.filename, std::ios::out | std::ios::binary);
+		if (!outputFile.is_open())
+			Error() << "cannot open output file";
+
+		for (int track = 0; track < numCylinders; track++)
+		{
+			for (int head = 0; head < numHeads; head++)
+			{
+				for (int sectorId = 0; sectorId < numSectors; sectorId++)
+				{
+					const auto& sector = sectors.get(track, head, sectorId);
+					if (sector)
+					{
+						outputFile.seekp(sector->logicalTrack*trackSize + sector->logicalSide*headSize + sector->logicalSector*numBytes, std::ios::beg);
+						outputFile.write((const char*) sector->data.cbegin(), sector->data.size());
+					}
+				}
+			}
+		}
+	}
+};
+
+std::unique_ptr<ImageWriter> ImageWriter::createImgImageWriter(
+	const SectorSet& sectors, const ImageSpec& spec)
+{
+    return std::unique_ptr<ImageWriter>(new ImgImageWriter(sectors, spec));
+}

lib/imagewriter/ldbsimagewriter.cc

@@ -0,0 +1,107 @@
+#include "globals.h"
+#include "image.h"
+#include "flags.h"
+#include "dataspec.h"
+#include "sector.h"
+#include "sectorset.h"
+#include "imagewriter/imagewriter.h"
+#include "fmt/format.h"
+#include "ldbs.h"
+#include <algorithm>
+#include <iostream>
+#include <fstream>
+
+class LDBSImageWriter : public ImageWriter
+{
+public:
+	LDBSImageWriter(const SectorSet& sectors, const ImageSpec& spec):
+		ImageWriter(sectors, spec)
+	{}
+
+	void writeImage()
+	{
+        LDBS ldbs;
+
+		unsigned numCylinders = spec.cylinders;
+		unsigned numHeads = spec.heads;
+		unsigned numSectors = spec.sectors;
+		unsigned numBytes = spec.bytes;
+		std::cout << fmt::format("writing {} tracks, {} heads, {} sectors, {} bytes per sector",
+						numCylinders, numHeads,
+						numSectors, numBytes)
+				<< std::endl;
+
+        Bytes trackDirectory;
+        ByteWriter trackDirectoryWriter(trackDirectory);
+        int trackDirectorySize = 0;
+        trackDirectoryWriter.write_le16(0);
+
+		for (int track = 0; track < numCylinders; track++)
+		{
+			for (int head = 0; head < numHeads; head++)
+			{
+                Bytes trackHeader;
+                ByteWriter trackHeaderWriter(trackHeader);
+
+                int actualSectors = 0;
+				for (int sectorId = 0; sectorId < numSectors; sectorId++)
+				{
+					const auto& sector = sectors.get(track, head, sectorId);
+					if (sector)
+                        actualSectors++;
+                }
+
+                trackHeaderWriter.write_le16(0x000C); /* offset of sector headers */
+                trackHeaderWriter.write_le16(0x0012); /* length of each sector descriptor */
+                trackHeaderWriter.write_le16(actualSectors);
+                trackHeaderWriter.write_8(0); /* data rate unknown */
+                trackHeaderWriter.write_8(0); /* recording mode unknown */
+                trackHeaderWriter.write_8(0); /* format gap length */
+                trackHeaderWriter.write_8(0); /* filler byte */
+                trackHeaderWriter.write_le16(0); /* approximate track length */
+
+				for (int sectorId = 0; sectorId < numSectors; sectorId++)
+				{
+					const auto& sector = sectors.get(track, head, sectorId);
+					if (sector)
+					{
+                        uint32_t sectorLabel = (('S') << 24) | ((track & 0xff) << 16) | (head << 8) | sectorId;
+                        uint32_t sectorAddress = ldbs.put(sector->data, sectorLabel);
+
+                        trackHeaderWriter.write_8(track);
+                        trackHeaderWriter.write_8(head);
+                        trackHeaderWriter.write_8(sectorId);
+                        trackHeaderWriter.write_8(0); /* power-of-two size */
+                        trackHeaderWriter.write_8((sector->status == Sector::OK) ? 0x00 : 0x20); /* 8272 status 1 */
+                        trackHeaderWriter.write_8(0); /* 8272 status 2 */
+                        trackHeaderWriter.write_8(1); /* number of copies */
+                        trackHeaderWriter.write_8(0); /* filler byte */
+                        trackHeaderWriter.write_le32(sectorAddress);
+                        trackHeaderWriter.write_le16(0); /* trailing bytes */
+                        trackHeaderWriter.write_le16(0); /* approximate offset */
+                        trackHeaderWriter.write_le16(sector->data.size());
+					}
+				}
+
+                uint32_t trackLabel = (('T') << 24) | ((track & 0xff) << 16) | ((track >> 8) << 8) | head;
+                uint32_t trackHeaderAddress = ldbs.put(trackHeader, trackLabel);
+                trackDirectoryWriter.write_be32(trackLabel);
+                trackDirectoryWriter.write_le32(trackHeaderAddress);
+                trackDirectorySize++;
+			}
+		}
+
+        trackDirectoryWriter.seek(0);
+        trackDirectoryWriter.write_le16(trackDirectorySize);
+
+        uint32_t trackDirectoryAddress = ldbs.put(trackDirectory, LDBS_TRACK_BLOCK);
+        Bytes data = ldbs.write(trackDirectoryAddress);
+        data.writeToFile(spec.filename);
+    }
+};
+
+std::unique_ptr<ImageWriter> ImageWriter::createLDBSImageWriter(
+	const SectorSet& sectors, const ImageSpec& spec)
+{
+    return std::unique_ptr<ImageWriter>(new LDBSImageWriter(sectors, spec));
+}

lib/ldbs.cc

@@ -0,0 +1,81 @@
+#include "globals.h"
+#include <string.h>
+#include "bytes.h"
+#include "ldbs.h"
+#include "fmt/format.h"
+
+LDBS::LDBS()
+{}
+
+uint32_t LDBS::put(const Bytes& data, uint32_t type)
+{
+    uint32_t address = top;
+    Block& block = blocks[address];
+    block.type = type;
+    block.data = data;
+
+    top += data.size() + 20;
+    return address;
+}
+
+uint32_t LDBS::read(const Bytes& data)
+{
+    ByteReader br(data);
+
+    br.seek(0);
+    if ((br.read_be32() != LDBS_FILE_MAGIC)
+        || (br.read_be32() != LDBS_FILE_TYPE))
+        Error() << "not a valid LDBS file";
+
+    uint32_t address = br.read_le32();
+    br.skip(4);
+    uint32_t trackDirectory = br.read_le32();
+
+    while (address)
+    {
+        br.seek(address);
+        if (br.read_be32() != LDBS_BLOCK_MAGIC)
+            Error() << fmt::format("invalid block at address 0x{:x}", address);
+
+        Block& block = blocks[address];
+        block.type = br.read_be32();
+
+        uint32_t size = br.read_le32();
+        br.skip(4);
+        address = br.read_le32();
+
+        block.data.writer().append(br.read(size));
+    }
+        
+    top = data.size();
+    return trackDirectory;
+}
+
+const Bytes LDBS::write(uint32_t trackDirectory)
+{
+    Bytes data(top);
+    ByteWriter bw(data);
+
+    uint32_t previous = 0;
+    for (const auto& e : blocks)
+    {
+        bw.seek(e.first);
+        bw.write_be32(LDBS_BLOCK_MAGIC);
+        bw.write_be32(e.second.type);
+        bw.write_le32(e.second.data.size());
+        bw.write_le32(e.second.data.size());
+        bw.write_le32(previous);
+        bw.append(e.second.data);
+
+        previous = e.first;
+    }
+
+    bw.seek(0);
+    bw.write_be32(LDBS_FILE_MAGIC);
+    bw.write_be32(LDBS_FILE_TYPE);
+    bw.write_le32(previous);
+    bw.write_le32(0);
+    bw.write_le32(trackDirectory);
+    
+    return data;
+}

lib/ldbs.h

@@ -0,0 +1,41 @@
+#ifndef LDBS_H
+#define LDBS_H
+
+class Bytes;
+
+/* A very simple interface to John Elliott's LDBS image format:
+ * http://www.seasip.info/Unix/LibDsk/ldbs.html
+ */
+
+#define LDBS_FILE_MAGIC 0x4C425301 /* "LBS\01" */
+#define LDBS_FILE_TYPE 0x44534B02 /* "DSK\02" */
+#define LDBS_BLOCK_MAGIC 0x4C444201 /* "LDB\01" */
+#define LDBS_TRACK_BLOCK 0x44495201 /* "DIR\01" */
+
+class LDBS
+{
+public:
+    LDBS();
+
+public:
+    const Bytes& get(uint32_t address) const
+    { return blocks.at(address).data; }
+
+    uint32_t put(const Bytes& data, uint32_t type);
+
+public:
+    const Bytes write(uint32_t trackDirectory);
+    uint32_t read(const Bytes& bytes);
+
+private:
+    struct Block
+    {
+        uint32_t type;
+        Bytes data;
+    };
+
+    std::map<uint32_t, Block> blocks;
+    unsigned top = 20;
+};
+
+#endif

lib/reader.cc

@@ -23,6 +23,11 @@ static DataSpecFlag source(
     "source for data",
     ":t=0-79:s=0-1:d=0");
 
+static DataSpecFlag output(
+	{ "--output", "-o" },
+	"output image file to write to",
+	"");
+
 static StringFlag destination(
     { "--write-flux", "-f" },
     "write the raw magnetic flux to this file",
@@ -52,6 +57,11 @@ void setReaderDefaultSource(const std::string& source)
     ::source.set(source);
 }
 
+void setReaderDefaultOutput(const std::string& output)
+{
+    ::output.set(output);
+}
+
 void setReaderRevolutions(int revolutions)
 {
 	setHardwareFluxSourceRevolutions(revolutions);
@@ -71,9 +81,9 @@ void Track::readFluxmap()
 
 std::vector<std::unique_ptr<Track>> readTracks()
 {
-    const DataSpec& dataSpec = source;
+    const FluxSpec spec(source);
 
-    std::cout << "Reading from: " << dataSpec << std::endl;
+    std::cout << "Reading from: " << source << std::endl;
 
 	setHardwareFluxSourceDensity(highDensityFlag);
 
@@ -92,10 +102,10 @@ std::vector<std::unique_ptr<Track>> readTracks()
 		);
 	}
 
-	std::shared_ptr<FluxSource> fluxSource = FluxSource::create(dataSpec);
+	std::shared_ptr<FluxSource> fluxSource = FluxSource::create(spec);
 
 	std::vector<std::unique_ptr<Track>> tracks;
-    for (const auto& location : dataSpec.locations)
+    for (const auto& location : spec.locations)
 	{
 		auto track = std::make_unique<Track>(location.track, location.side);
 		track->fluxsource = fluxSource;
@@ -140,8 +150,10 @@ static void replace_sector(std::unique_ptr<Sector>& replacing, Sector& replaceme
 	}
 }
 
-void readDiskCommand(AbstractDecoder& decoder, const std::string& outputFilename)
+void readDiskCommand(AbstractDecoder& decoder)
 {
+	const ImageSpec outputSpec(output);
+
 	bool failures = false;
 	SectorSet allSectors;
 	auto tracks = readTracks();
@@ -160,8 +172,9 @@ void readDiskCommand(AbstractDecoder& decoder, const std::string& outputFilename
 					track->rawrecords.size(),
 					track->sectors.size());
 				if (track->sectors.size() > 0)
-					std::cout << fmt::format("{:.2f}us clock; ",
-						track->sectors.begin()->clock / 1000.0);
+					std::cout << fmt::format("{:.2f}us clock ({:.0f}kHz); ",
+						track->sectors.begin()->clock / 1000.0,
+                        1000000.0 / track->sectors.begin()->clock);
 
 				for (auto& sector : track->sectors)
 				{
@@ -238,8 +251,7 @@ void readDiskCommand(AbstractDecoder& decoder, const std::string& outputFilename
         std::cout << size << " bytes decoded." << std::endl;
     }
 
-	Geometry geometry = guessGeometry(allSectors);
-    writeSectorsToFile(allSectors, geometry, outputFilename);
+    writeSectorsToFile(allSectors, outputSpec);
 	if (failures)
 		std::cerr << "Warning: some sectors could not be decoded." << std::endl;
 }

lib/reader.h

@@ -11,10 +11,11 @@ class Track;
 extern FlagGroup readerFlags;
 
 extern void setReaderDefaultSource(const std::string& source);
+extern void setReaderDefaultOutput(const std::string& output);
 extern void setReaderRevolutions(int revolutions);
 
 extern std::vector<std::unique_ptr<Track>> readTracks();
 
-extern void readDiskCommand(AbstractDecoder& decoder, const std::string& outputFilename);
+extern void readDiskCommand(AbstractDecoder& decoder);
 
 #endif

lib/sectorset.cc

@@ -18,8 +18,9 @@ Sector* SectorSet::get(int track, int head, int sector) const
 	return i->second.get();
 }
 
-void SectorSet::calculateSize(int& numTracks, int& numHeads, int& numSectors,
-	int& sectorSize) const
+void SectorSet::calculateSize(
+	unsigned& numTracks, unsigned& numHeads,
+	unsigned& numSectors, unsigned& sectorSize) const
 {
 	numTracks = numHeads = numSectors = sectorSize = 0;
 
@@ -28,10 +29,10 @@ void SectorSet::calculateSize(int& numTracks, int& numHeads, int& numSectors,
 		auto& sector = i.second;
 		if (sector)
 		{
-			numTracks = std::max(numTracks, sector->logicalTrack+1);
-			numHeads = std::max(numHeads, sector->logicalSide+1);
-			numSectors = std::max(numSectors, sector->logicalSector+1);
-			sectorSize = std::max(sectorSize, (int)sector->data.size());
+			numTracks = std::max(numTracks, (unsigned)sector->logicalTrack+1);
+			numHeads = std::max(numHeads, (unsigned)sector->logicalSide+1);
+			numSectors = std::max(numSectors, (unsigned)sector->logicalSector+1);
+			sectorSize = std::max(sectorSize, (unsigned)sector->data.size());
 		}
 	}
 }

lib/sectorset.h

@@ -17,8 +17,9 @@ public:
 	std::unique_ptr<Sector>& get(int track, int head, int sector);
 	Sector* get(int track, int head, int sector) const;
 
-	void calculateSize(int& numTracks, int& numHeads, int& numSectors,
-		int& sectorSize) const;
+	void calculateSize(
+		unsigned& numTracks, unsigned& numHeads, unsigned& numSectors,
+		unsigned& sectorSize) const;
 
 private:
 	std::map<const key_t, std::unique_ptr<Sector>> _data;

lib/writer.cc

@@ -6,9 +6,14 @@
 #include "protocol.h"
 #include "usb.h"
 #include "dataspec.h"
+#include "encoders/encoders.h"
 #include "fluxsource/fluxsource.h"
 #include "fluxsink/fluxsink.h"
 #include "fmt/format.h"
+#include "record.h"
+#include "image.h"
+#include "sector.h"
+#include "sectorset.h"
 
 FlagGroup writerFlags { &hardwareFluxSourceFlags };
 
@@ -17,6 +22,11 @@ static DataSpecFlag dest(
     "destination for data",
     ":d=0:t=0-79:s=0-1");
 
+static DataSpecFlag input(
+    { "--input", "-i" },
+    "input image file to read from",
+    "");
+
 static SettableFlag highDensityFlag(
 	{ "--high-density", "-H" },
 	"set the drive to high density mode");
@@ -28,12 +38,17 @@ void setWriterDefaultDest(const std::string& dest)
     ::dest.set(dest);
 }
 
+void setWriterDefaultInput(const std::string& input)
+{
+    ::input.set(input);
+}
+
 void writeTracks(
 	const std::function<std::unique_ptr<Fluxmap>(int track, int side)> producer)
 {
-    const DataSpec& spec = dest;
+    const FluxSpec spec(dest);
 
-    std::cout << "Writing to: " << spec << std::endl;
+    std::cout << "Writing to: " << dest << std::endl;
 
 	setHardwareFluxSourceDensity(highDensityFlag);
 	setHardwareFluxSinkDensity(highDensityFlag);
@@ -60,10 +75,12 @@ void writeTracks(
         {
             if (!outdb)
             {
-                std::cout << "erasing" << std::endl;
+                std::cout << "erasing\n";
                 usbSeek(location.track);
                 usbErase(location.side);
             }
+            else
+                std::cout << "skipping\n";
         }
         else
         {
@@ -96,3 +113,14 @@ void fillBitmapTo(std::vector<bool>& bitmap,
 	}
 }
 
+void writeDiskCommand(AbstractEncoder& encoder)
+{
+    const ImageSpec spec(input);
+	SectorSet allSectors = readSectorsFromFile(spec);
+	writeTracks(
+		[&](int track, int side) -> std::unique_ptr<Fluxmap>
+		{
+			return encoder.encode(track, side, allSectors);
+		}
+	);
+}

lib/writer.h

@@ -6,8 +6,11 @@
 extern FlagGroup writerFlags;
 
 class Fluxmap;
+class AbstractEncoder;
+class Geometry;
 
 extern void setWriterDefaultDest(const std::string& dest);
+extern void setWriterDefaultInput(const std::string& input);
 
 extern void writeTracks(const std::function<std::unique_ptr<Fluxmap>(int track, int side)> producer);
 
@@ -15,5 +18,6 @@ extern void fillBitmapTo(std::vector<bool>& bitmap,
 		unsigned& cursor, unsigned terminateAt,
 		const std::vector<bool>& pattern);
 	
+extern void writeDiskCommand(AbstractEncoder& encoder);
 
 #endif

mkninja.sh

@@ -137,22 +137,32 @@ buildlibrary libfmt.a \
     dep/fmt/posix.cc \
 
 buildlibrary libbackend.a \
-    lib/aeslanier/decoder.cc \
-    lib/amiga/decoder.cc \
-    lib/apple2/decoder.cc \
-    lib/brother/decoder.cc \
-    lib/brother/encoder.cc \
+	lib/imagereader/imagereader.cc \
+	lib/imagereader/imgimagereader.cc \
+	lib/imagewriter/imagewriter.cc \
+	lib/imagewriter/imgimagewriter.cc \
+	lib/imagewriter/ldbsimagewriter.cc \
+    arch/aeslanier/decoder.cc \
+    arch/amiga/decoder.cc \
+    arch/apple2/decoder.cc \
+    arch/brother/decoder.cc \
+    arch/brother/encoder.cc \
+    arch/c64/decoder.cc \
+    arch/f85/decoder.cc \
+    arch/fb100/decoder.cc \
+    arch/ibm/decoder.cc \
+    arch/macintosh/decoder.cc \
+    arch/mx/decoder.cc \
+    arch/victor9k/decoder.cc \
+    arch/zilogmcz/decoder.cc \
     lib/bytes.cc \
-    lib/c64/decoder.cc \
     lib/common/crunch.c \
     lib/crc.cc \
     lib/dataspec.cc \
     lib/decoders/decoders.cc \
     lib/decoders/fluxmapreader.cc \
     lib/decoders/fmmfm.cc \
-    lib/encoder.cc \
-    lib/f85/decoder.cc \
-    lib/fb100/decoder.cc \
+    lib/encoders/encoders.cc \
     lib/flags.cc \
     lib/fluxmap.cc \
     lib/fluxsink/fluxsink.cc \
@@ -165,18 +175,14 @@ buildlibrary libbackend.a \
     lib/fluxsource/streamfluxsource.cc \
     lib/globals.cc \
     lib/hexdump.cc \
-    lib/ibm/decoder.cc \
     lib/image.cc \
-    lib/macintosh/decoder.cc \
-    lib/mx/decoder.cc \
+    lib/ldbs.cc \
     lib/reader.cc \
     lib/sector.cc \
     lib/sectorset.cc \
     lib/sql.cc \
     lib/usb.cc \
-    lib/victor9k/decoder.cc \
     lib/writer.cc \
-    lib/zilogmcz/decoder.cc \
 
 buildlibrary libfrontend.a \
     src/fe-cwftoflux.cc \
@@ -223,12 +229,13 @@ buildsimpleprogram brother120tool \
     libemu.a \
     libfmt.a \
 
+runtest bitaccumulator-test tests/bitaccumulator.cc
+runtest bytes-test          tests/bytes.cc
+runtest compression-test    tests/compression.cc
+runtest crunch-test         tests/crunch.cc
 runtest dataspec-test       tests/dataspec.cc
 runtest flags-test          tests/flags.cc
-runtest fmmfm-test          tests/fmmfm.cc
-runtest bitaccumulator-test tests/bitaccumulator.cc
-runtest kryoflux-test       tests/kryoflux.cc
-runtest compression-test    tests/compression.cc
-runtest bytes-test          tests/bytes.cc
-runtest crunch-test         tests/crunch.cc
 runtest fluxpattern-test    tests/fluxpattern.cc
+runtest fmmfm-test          tests/fmmfm.cc
+runtest kryoflux-test       tests/kryoflux.cc
+runtest ldbs-test           tests/ldbs.cc

src/fe-fluxtoau.cc

@@ -34,14 +34,15 @@ int mainConvertFluxToAu(int argc, const char* argv[])
 {
     flags.parseFlags(argc, argv);
 
-    const auto& locations = source.get().locations;
+    FluxSpec spec(source);
+    const auto& locations = spec.locations;
     if (locations.size() != 1)
         Error() << "the source dataspec must contain exactly one track (two sides count as two tracks)";
     const auto& location = *(locations.begin());
 
     std::cerr << "Reading source flux...\n";
     setHardwareFluxSourceDensity(highDensityFlag);
-    std::shared_ptr<FluxSource> fluxsource = FluxSource::create(source);
+    std::shared_ptr<FluxSource> fluxsource = FluxSource::create(spec);
     const auto& fluxmap = fluxsource->readFlux(location.track, location.side);
     unsigned totalTicks = fluxmap->ticks() + 2;
     unsigned channels = withIndex ? 2 : 1;

src/fe-fluxtovcd.cc

@@ -30,14 +30,15 @@ int mainConvertFluxToVcd(int argc, const char* argv[])
 {
     flags.parseFlags(argc, argv);
 
-    const auto& locations = source.get().locations;
+    const FluxSpec spec(source);
+    const auto& locations = spec.locations;
     if (locations.size() != 1)
         Error() << "the source dataspec must contain exactly one track (two sides count as two tracks)";
     const auto& location = *(locations.begin());
 
     std::cerr << "Reading source flux...\n";
     setHardwareFluxSourceDensity(highDensityFlag);
-    std::shared_ptr<FluxSource> fluxsource = FluxSource::create(source);
+    std::shared_ptr<FluxSource> fluxsource = FluxSource::create(spec);
     const auto& fluxmap = fluxsource->readFlux(location.track, location.side);
 
     std::cerr << "Writing destination VCD...\n";

src/fe-readadfs.cc

@@ -12,11 +12,6 @@
 
 static FlagGroup flags { &readerFlags };
 
-static StringFlag outputFilename(
-    { "--output", "-o" },
-    "The output image file to write to.",
-    "adfs.img");
-
 static IntFlag sectorIdBase(
 	{ "--sector-id-base" },
 	"Sector ID of the first sector.",
@@ -25,10 +20,11 @@ static IntFlag sectorIdBase(
 int mainReadADFS(int argc, const char* argv[])
 {
 	setReaderDefaultSource(":t=0-79:s=0-1");
+	setReaderDefaultOutput("adfs.img");
     flags.parseFlags(argc, argv);
 
 	IbmDecoder decoder(sectorIdBase);
-	readDiskCommand(decoder, outputFilename);
+	readDiskCommand(decoder);
     return 0;
 }
 

src/fe-readaeslanier.cc

@@ -20,11 +20,12 @@ static StringFlag outputFilename(
 int mainReadAESLanier(int argc, const char* argv[])
 {
 	setReaderDefaultSource(":t=0-79:s=0");
+	setReaderDefaultOutput("aeslanier.img");
     setReaderRevolutions(2);
     flags.parseFlags(argc, argv);
 
 	AesLanierDecoder decoder;
-	readDiskCommand(decoder, outputFilename);
+	readDiskCommand(decoder);
     return 0;
 }
 

src/fe-readamiga.cc

@@ -13,19 +13,15 @@
 
 static FlagGroup flags { &readerFlags };
 
-static StringFlag outputFilename(
-    { "--output", "-o" },
-    "The output image file to write to.",
-    "amiga.adf");
-
 int mainReadAmiga(int argc, const char* argv[])
 {
 	setReaderDefaultSource(":t=0-79:s=0-1");
+	setReaderDefaultOutput("amiga.adf:c=80:h=2:s=11:b=512");
     setReaderRevolutions(2);
     flags.parseFlags(argc, argv);
 
 	AmigaDecoder decoder;
-	readDiskCommand(decoder, outputFilename);
+	readDiskCommand(decoder);
 
     return 0;
 }

src/fe-readampro.cc

@@ -12,11 +12,6 @@
 
 static FlagGroup flags { &readerFlags };
 
-static StringFlag outputFilename(
-    { "--output", "-o" },
-    "The output image file to write to.",
-    "ampro.img");
-
 static IntFlag sectorIdBase(
 	{ "--sector-id-base" },
 	"Sector ID of the first sector.",
@@ -25,11 +20,12 @@ static IntFlag sectorIdBase(
 int mainReadAmpro(int argc, const char* argv[])
 {
 	setReaderDefaultSource(":t=0-79:s=0");
+	setReaderDefaultOutput("ampro.adf");
     setReaderRevolutions(2);
     flags.parseFlags(argc, argv);
 
 	IbmDecoder decoder(sectorIdBase);
-	readDiskCommand(decoder, outputFilename);
+	readDiskCommand(decoder);
     return 0;
 }
 

src/fe-readapple2.cc

@@ -13,19 +13,15 @@
 
 static FlagGroup flags { &readerFlags };
 
-static StringFlag outputFilename(
-    { "--output", "-o" },
-    "The output image file to write to.",
-    "apple2.img");
-
 int mainReadApple2(int argc, const char* argv[])
 {
 	setReaderDefaultSource(":t=0-79:s=0");
+	setReaderDefaultOutput("apple2.adf");
     setReaderRevolutions(2);
     flags.parseFlags(argc, argv);
 
 	Apple2Decoder decoder;
-	readDiskCommand(decoder, outputFilename);
+	readDiskCommand(decoder);
 
     return 0;
 }

src/fe-readbrother.cc

@@ -3,6 +3,7 @@
 #include "reader.h"
 #include "fluxmap.h"
 #include "decoders/decoders.h"
+#include "encoders/encoders.h"
 #include "brother/brother.h"
 #include "sector.h"
 #include "sectorset.h"
@@ -13,19 +14,15 @@
 
 static FlagGroup flags { &readerFlags };
 
-static StringFlag outputFilename(
-    { "--output", "-o" },
-    "The output image file to write to.",
-    "brother.img");
-
 int mainReadBrother(int argc, const char* argv[])
 {
 	setReaderDefaultSource(":t=0-81:s=0");
+	setReaderDefaultOutput("brother.img");
     setReaderRevolutions(2);
     flags.parseFlags(argc, argv);
 
 	BrotherDecoder decoder;
-	readDiskCommand(decoder, outputFilename);
+	readDiskCommand(decoder);
 
     return 0;
 }

src/fe-readc64.cc

@@ -13,19 +13,15 @@
 
 static FlagGroup flags { &readerFlags };
 
-static StringFlag outputFilename(
-    { "--output", "-o" },
-    "The output image file to write to.",
-    "c64.img");
-
 int mainReadC64(int argc, const char* argv[])
 {
 	setReaderDefaultSource(":t=0-79x2:s=0");
+	setReaderDefaultOutput("c64.img");
     setReaderRevolutions(2);
     flags.parseFlags(argc, argv);
 
 	Commodore64Decoder decoder;
-	readDiskCommand(decoder, outputFilename);
+	readDiskCommand(decoder);
 
     return 0;
 }

src/fe-readdfs.cc

@@ -12,11 +12,6 @@
 
 static FlagGroup flags { &readerFlags };
 
-static StringFlag outputFilename(
-    { "--output", "-o" },
-    "The output image file to write to.",
-    "dfs.img");
-
 static IntFlag sectorIdBase(
 	{ "--sector-id-base" },
 	"Sector ID of the first sector.",
@@ -25,11 +20,12 @@ static IntFlag sectorIdBase(
 int mainReadDFS(int argc, const char* argv[])
 {
 	setReaderDefaultSource(":t=0-79:s=0");
+	setReaderDefaultOutput("dfs.img");
     setReaderRevolutions(2);
     flags.parseFlags(argc, argv);
 
 	IbmDecoder decoder(sectorIdBase);
-	readDiskCommand(decoder, outputFilename);
+	readDiskCommand(decoder);
     return 0;
 }
 

src/fe-readf85.cc

@@ -13,19 +13,15 @@
 
 static FlagGroup flags { &readerFlags };
 
-static StringFlag outputFilename(
-    { "--output", "-o" },
-    "The output image file to write to.",
-    "f85.img");
-
 int mainReadF85(int argc, const char* argv[])
 {
 	setReaderDefaultSource(":t=0-79:s=0");
+	setReaderDefaultOutput("f85.img");
     setReaderRevolutions(2);
     flags.parseFlags(argc, argv);
 
 	DurangoF85Decoder decoder;
-	readDiskCommand(decoder, outputFilename);
+	readDiskCommand(decoder);
 
     return 0;
 }

src/fe-readfb100.cc

@@ -12,19 +12,15 @@
 
 static FlagGroup flags { &readerFlags };
 
-static StringFlag outputFilename(
-    { "--output", "-o" },
-    "The output image file to write to.",
-    "fb100.img");
-
 int mainReadFB100(int argc, const char* argv[])
 {
 	setReaderDefaultSource(":t=0-79x2:s=0");
+	setReaderDefaultOutput("fb100.img");
     setReaderRevolutions(2);
     flags.parseFlags(argc, argv);
 
 	Fb100Decoder decoder;
-	readDiskCommand(decoder, outputFilename);
+	readDiskCommand(decoder);
     return 0;
 }
 

src/fe-readibm.cc

@@ -12,11 +12,6 @@
 
 static FlagGroup flags { &readerFlags };
 
-static StringFlag outputFilename(
-    { "--output", "-o" },
-    "The output image file to write to.",
-    "ibm.img");
-
 static IntFlag sectorIdBase(
 	{ "--sector-id-base" },
 	"Sector ID of the first sector.",
@@ -25,10 +20,11 @@ static IntFlag sectorIdBase(
 int mainReadIBM(int argc, const char* argv[])
 {
 	setReaderDefaultSource(":t=0-79:s=0-1");
+	setReaderDefaultOutput("ibm.img");
     flags.parseFlags(argc, argv);
 
 	IbmDecoder decoder(sectorIdBase);
-	readDiskCommand(decoder, outputFilename);
+	readDiskCommand(decoder);
     return 0;
 }
 

src/fe-readmac.cc

@@ -13,19 +13,15 @@
 
 static FlagGroup flags { &readerFlags };
 
-static StringFlag outputFilename(
-    { "--output", "-o" },
-    "The output image file to write to.",
-    "mac.img");
-
 int mainReadMac(int argc, const char* argv[])
 {
 	setReaderDefaultSource(":t=0-79:s=0-1");
+	setReaderDefaultOutput("mac.img");
     setReaderRevolutions(2);
     flags.parseFlags(argc, argv);
 
 	MacintoshDecoder decoder;
-	readDiskCommand(decoder, outputFilename);
+	readDiskCommand(decoder);
 
     return 0;
 }

src/fe-readmx.cc

@@ -12,18 +12,14 @@
 
 static FlagGroup flags { &readerFlags };
 
-static StringFlag outputFilename(
-    { "--output", "-o" },
-    "The output image file to write to.",
-    "mx.img");
-
 int mainReadMx(int argc, const char* argv[])
 {
 	setReaderDefaultSource(":t=0-79:s=0-1");
+	setReaderDefaultOutput("mx.img");
     flags.parseFlags(argc, argv);
 
 	MxDecoder decoder;
-	readDiskCommand(decoder, outputFilename);
+	readDiskCommand(decoder);
     return 0;
 }
 

src/fe-readvictor9k.cc

@@ -13,19 +13,15 @@
 
 static FlagGroup flags { &readerFlags };
 
-static StringFlag outputFilename(
-    { "--output", "-o" },
-    "The output image file to write to.",
-    "victor9k.img");
-
 int mainReadVictor9K(int argc, const char* argv[])
 {
 	setReaderDefaultSource(":t=0-79:s=0");
+	setReaderDefaultOutput("victor9k.img");
     setReaderRevolutions(2);
     flags.parseFlags(argc, argv);
 
 	Victor9kDecoder decoder;
-	readDiskCommand(decoder, outputFilename);
+	readDiskCommand(decoder);
 
     return 0;
 }

src/fe-readzilogmcz.cc

@@ -12,19 +12,15 @@
 
 static FlagGroup flags { &readerFlags };
 
-static StringFlag outputFilename(
-    { "--output", "-o" },
-    "The output image file to write to.",
-    "zilogmcz.img");
-
 int mainReadZilogMCZ(int argc, const char* argv[])
 {
 	setReaderDefaultSource(":t=0-76:s=0");
+	setReaderDefaultOutput("zilogmcz.img");
     setReaderRevolutions(2);
     flags.parseFlags(argc, argv);
 
 	ZilogMczDecoder decoder;
-	readDiskCommand(decoder, outputFilename);
+	readDiskCommand(decoder);
     return 0;
 }
 

src/fe-rpm.cc

@@ -14,7 +14,8 @@ int mainRpm(int argc, const char* argv[])
 {
     flags.parseFlags(argc, argv);
 
-    usbSetDrive(source.get().drive, false);
+    FluxSpec spec(source);
+    usbSetDrive(spec.drive, false);
     nanoseconds_t period = usbGetRotationalPeriod();
     std::cout << "Rotational period is " << period/1000 << " ms (" << 60e6/period << " rpm)" << std::endl;
 

src/fe-writebrother.cc

@@ -1,108 +1,23 @@
 #include "globals.h"
 #include "flags.h"
-#include "fluxmap.h"
-#include "sector.h"
-#include "sectorset.h"
 #include "decoders/decoders.h"
+#include "encoders/encoders.h"
 #include "brother/brother.h"
-#include "image.h"
 #include "writer.h"
 #include "fmt/format.h"
+#include "image.h"
 #include <fstream>
-#include <ctype.h>
 
-static FlagGroup flags { &writerFlags };
-
-static StringFlag inputFilename(
-    { "--input", "-i" },
-    "The input image file to read from.",
-    "brother.img");
-
-static DoubleFlag clockRateUs(
-	{ "--clock-rate" },
-	"Encoded data clock rate (microseconds).",
-	3.83);
-
-static DoubleFlag postIndexGapMs(
-	{ "--post-index-gap" },
-	"Post-index gap before first sector header (milliseconds).",
-	1.0);
-
-static DoubleFlag sectorSpacingMs(
-	{ "--sector-spacing" },
-	"Time between successive sector headers (milliseconds).",
-	16.2);
-
-static DoubleFlag postHeaderSpacingMs(
-	{ "--post-header-spacing" },
-	"Time between a sector's header and data records (milliseconds).",
-	0.69);
-
-
-static StringFlag sectorSkew(
-	{ "--sector-skew" },
-	"Order in which to write sectors.",
-	"05a3816b4927");
-
-static int charToInt(char c)
-{
-	if (isdigit(c))
-		return c - '0';
-	return 10 + tolower(c) - 'a';
-}
+static FlagGroup flags { &writerFlags, &brotherEncoderFlags };
 
 int mainWriteBrother(int argc, const char* argv[])
 {
+    setWriterDefaultInput(":c=78:h=1:s=12:b=256");
 	setWriterDefaultDest(":d=0:t=0-77:s=0");
     flags.parseFlags(argc, argv);
 
-	SectorSet allSectors;
-	Geometry geometry = {78, 1, 12, 256};
-	readSectorsFromFile(allSectors, geometry, inputFilename);
-
-	int bitsPerRevolution = 200000.0 / clockRateUs;
-	std::cerr << bitsPerRevolution << " bits per 200ms revolution" << std::endl
-	          << fmt::format("post-index gap: {:.3f}ms\n", (double)postIndexGapMs);
-
-	const std::string& skew = sectorSkew;
-
-	writeTracks(
-		[&](int track, int side) -> std::unique_ptr<Fluxmap>
-		{
-			if ((track < 0) || (track > 77) || (side != 0))
-				return std::unique_ptr<Fluxmap>();
-
-			std::vector<bool> bits(bitsPerRevolution);
-			unsigned cursor = 0;
-
-			for (int sectorCount=0; sectorCount<geometry.sectors; sectorCount++)
-			{
-				int sectorId = charToInt(skew.at(sectorCount));
-				double headerMs = postIndexGapMs + sectorCount*sectorSpacingMs;
-				unsigned headerCursor = headerMs*1e3 / clockRateUs;
-				double dataMs = headerMs + postHeaderSpacingMs;
-				unsigned dataCursor = dataMs*1e3 / clockRateUs;
-
-				auto& sectorData = allSectors.get(track, 0, sectorId);
-
-				fillBitmapTo(bits, cursor, headerCursor, { true, false });
-				writeBrotherSectorHeader(bits, cursor, track, sectorId);
-				fillBitmapTo(bits, cursor, dataCursor, { true, false });
-				writeBrotherSectorData(bits, cursor, sectorData->data);
-			}
-
-			if (cursor > bits.size())
-				Error() << "track data overrun";
-            fillBitmapTo(bits, cursor, bits.size(), { true, false });
-
-			// The pre-index gap is not normally reported.
-			// std::cerr << "pre-index gap " << 200.0 - (double)cursor*clockRateUs/1e3 << std::endl;
-			
-			std::unique_ptr<Fluxmap> fluxmap(new Fluxmap);
-			fluxmap->appendBits(bits, clockRateUs*1e3);
-			return fluxmap;
-		}
-	);
+	BrotherEncoder encoder;
+	writeDiskCommand(encoder);
 
     return 0;
 }

tests/dataspec.cc

@@ -33,48 +33,79 @@ static void test_parsemod(void)
         == (DataSpec::Modifier{"x", {2, 4, 9}}));
 }
 
-static void test_dataspec(void)
+static void test_fluxspec(void)
 {
     DataSpec spec("foo:t=0-2:s=0-1:d=0");
-    assert(spec.filename == "foo");
-    assert((spec.locations
-        == std::vector<DataSpec::Location>
-        {{0, 0, 0}, {0, 0, 1}, {0, 1, 0}, {0, 1, 1}, {0, 2, 0}, {0, 2, 1}}));
-    assert((std::string)spec == "foo:d=0:s=0-1:t=0-2");
+
+    {
+        FluxSpec fspec(spec);
+        assert(fspec.filename == "foo");
+        assert((fspec.locations
+            == std::vector<FluxSpec::Location>
+            {{0, 0, 0}, {0, 0, 1}, {0, 1, 0}, {0, 1, 1}, {0, 2, 0}, {0, 2, 1}}));
+        assert((std::string)spec == "foo:d=0:s=0-1:t=0-2");
+    }
 
     spec.set("bar");
-    assert(spec.filename == "bar");
-    assert((spec.locations
-        == std::vector<DataSpec::Location>
-        {{0, 0, 0}, {0, 0, 1}, {0, 1, 0}, {0, 1, 1}, {0, 2, 0}, {0, 2, 1}}));
-    assert((std::string)spec == "bar:d=0:s=0-1:t=0-2");
+    {
+        FluxSpec fspec(spec);
+        assert(fspec.filename == "bar");
+        assert((fspec.locations
+            == std::vector<FluxSpec::Location>
+            {{0, 0, 0}, {0, 0, 1}, {0, 1, 0}, {0, 1, 1}, {0, 2, 0}, {0, 2, 1}}));
+        assert((std::string)spec == "bar:d=0:s=0-1:t=0-2");
+    }
 
     spec.set(":t=0");
-    assert(spec.filename.empty());
-    assert((spec.locations
-        == std::vector<DataSpec::Location>
-        {{0, 0, 0}, {0, 0, 1}}));
-    assert((std::string)spec == ":d=0:s=0-1:t=0");
+    {
+        FluxSpec fspec(spec);
+        assert(fspec.filename.empty());
+        assert((fspec.locations
+            == std::vector<FluxSpec::Location>
+            {{0, 0, 0}, {0, 0, 1}}));
+        assert((std::string)spec == ":d=0:s=0-1:t=0");
+    }
 
     spec.set(":s=1");
-    assert(spec.filename.empty());
-    assert((spec.locations
-        == std::vector<DataSpec::Location>
-        {{0, 0, 1}}));
-    assert((std::string)spec == ":d=0:s=1:t=0");
+    {
+        FluxSpec fspec(spec);
+        assert(fspec.filename.empty());
+        assert((fspec.locations
+            == std::vector<FluxSpec::Location>
+            {{0, 0, 1}}));
+        assert((std::string)spec == ":d=0:s=1:t=0");
+    }
 
     spec.set(":t=9:d=1");
-    assert(spec.filename.empty());
-    assert((spec.locations
-        == std::vector<DataSpec::Location>
-        {{1, 9, 1}}));
-    assert((std::string)spec == ":d=1:s=1:t=9");
+    {
+        FluxSpec fspec(spec);
+        assert(fspec.filename.empty());
+        assert((fspec.locations
+            == std::vector<FluxSpec::Location>
+            {{1, 9, 1}}));
+        assert((std::string)spec == ":d=1:s=1:t=9");
+    }
+}
+
+static void test_imagespec(void)
+{
+    DataSpec spec("foo:c=9:h=2:s=99:b=256");
+
+    {
+        ImageSpec ispec(spec);
+        assert(ispec.filename == "foo");
+        assert(ispec.cylinders == 9);
+        assert(ispec.heads == 2);
+        assert(ispec.sectors == 99);
+        assert(ispec.bytes = 256);
+    }
 }
 
 int main(int argc, const char* argv[])
 {
     test_split();
     test_parsemod();
-    test_dataspec();
+    test_fluxspec();
+    test_imagespec();
     return 0;
 }

tests/ldbs.cc

@@ -0,0 +1,70 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include "globals.h"
+#include "bytes.h"
+#include "ldbs.h"
+
+static Bytes testdata
+{
+    'L',  'B',  'S',  0x01,  'D',  'S',  'K',  0x02,
+    0x29, 0x00, 0x00, 0x00,  0x00, 0x00, 0x00, 0x00,
+    0x34, 0x12, 0x00, 0x00,  'L',  'D',  'B',  0x01,
+    0x00, 0x00, 0x00, 0x01,  0x01, 0x00, 0x00, 0x00,
+    0x01, 0x00, 0x00, 0x00,  0x00, 0x00, 0x00, 0x00,
+    0x01, 'L',  'D',  'B',   0x01, 0x00, 0x00, 0x00,
+    0x02, 0x01, 0x00, 0x00,  0x00, 0x01, 0x00, 0x00,
+    0x00, 0x14, 0x00, 0x00,  0x00, 0x02
+};
+
+static void assertBytes(const Bytes& want, const Bytes& got)
+{
+    if (want != got)
+    {
+        std::cout << "Wanted bytes:" << std::endl;
+        hexdump(std::cout, want);
+        std::cout << std::endl << "Produced bytes:" << std::endl;
+        hexdump(std::cout, got);
+        abort();
+    }
+}
+static void test_getset()
+{
+    LDBS ldbs;
+
+    uint32_t block1 = ldbs.put(Bytes { 1 }, 1);
+    uint32_t block2 = ldbs.put(Bytes { 2 }, 2);
+    assert(block1 != block2);
+
+    assert(ldbs.get(block1) == Bytes { 1 });
+    assert(ldbs.get(block2) == Bytes { 2 });
+}
+
+static void test_write()
+{
+    LDBS ldbs;
+
+    uint32_t block1 = ldbs.put(Bytes { 1 }, 1);
+    uint32_t block2 = ldbs.put(Bytes { 2 }, 2);
+    Bytes data = ldbs.write(0x1234);
+
+    assertBytes(testdata, data);
+}
+
+static void test_read()
+{
+    LDBS ldbs;
+    uint32_t trackDirectory = ldbs.read(testdata);
+
+    assert(trackDirectory == 0x1234);
+    assert(ldbs.get(0x14) == Bytes { 1 });
+    assert(ldbs.get(0x29) == Bytes { 2 });
+}
+
+int main(int argc, const char* argv[])
+{
+    test_getset();
+    test_write();
+    test_read();
+    return 0;
+}