Refactor the write code to make it easier to add new encoders.

lib/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;
 
@@ -26,11 +29,11 @@ class BrotherEncoder : public AbstractEncoder
 {
 public:
 	virtual ~BrotherEncoder() {}
+
+public:
+    std::unique_ptr<Fluxmap> encode(int physicalTrack, int physicalSide, const SectorSet& allSectors);
 };
 
-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);
+extern FlagGroup brotherEncoderFlags;
 
 #endif

lib/brother/encoder.cc

@@ -4,6 +4,35 @@
 #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)
 {
@@ -41,7 +70,7 @@ static void write_bits(std::vector<bool>& bits, unsigned& cursor, uint32_t data,
 	}
 }
 
-void writeBrotherSectorHeader(std::vector<bool>& bits, unsigned& cursor,
+static void write_sector_header(std::vector<bool>& bits, unsigned& cursor,
 		int track, int sector)
 {
 	write_bits(bits, cursor, 0xffffffff, 31);
@@ -51,7 +80,7 @@ void writeBrotherSectorHeader(std::vector<bool>& bits, unsigned& cursor,
 	write_bits(bits, cursor, encode_header_gcr(0x2f), 16);
 }
 
-void writeBrotherSectorData(std::vector<bool>& bits, unsigned& cursor, const Bytes& data)
+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);
@@ -90,4 +119,49 @@ void writeBrotherSectorData(std::vector<bool>& bits, unsigned& cursor, const Byt
         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;
+}

lib/encoders/encoders.h

@@ -1,7 +1,18 @@
 #ifndef ENCODERS_H
 #define ENCODERS_H
 
-class AbstractEncoder {};
+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/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 };
 
@@ -60,10 +65,12 @@ 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 +103,16 @@ void fillBitmapTo(std::vector<bool>& bitmap,
 	}
 }
 
+void writeDiskCommand(
+    AbstractEncoder& encoder, const Geometry& geometry, const std::string& inputFilename)
+{
+    SectorSet allSectors;
+
+	readSectorsFromFile(allSectors, geometry, inputFilename);
+	writeTracks(
+		[&](int track, int side) -> std::unique_ptr<Fluxmap>
+		{
+			return encoder.encode(track, side, allSectors);
+		}
+	);
+}

lib/writer.h

@@ -6,6 +6,8 @@
 extern FlagGroup writerFlags;
 
 class Fluxmap;
+class AbstractEncoder;
+class Geometry;
 
 extern void setWriterDefaultDest(const std::string& dest);
 
@@ -15,5 +17,7 @@ extern void fillBitmapTo(std::vector<bool>& bitmap,
 		unsigned& cursor, unsigned terminateAt,
 		const std::vector<bool>& pattern);
 
+extern void writeDiskCommand(
+    AbstractEncoder& encoder, const Geometry& geometry, const std::string& inputFilename);
 
 #endif

src/fe-writebrother.cc

@@ -1,109 +1,28 @@
 #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 FlagGroup flags { &writerFlags, &brotherEncoderFlags };
 
 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';
-}
-
 int mainWriteBrother(int argc, const char* argv[])
 {
 	setWriterDefaultDest(":d=0:t=0-77:s=0");
     flags.parseFlags(argc, argv);
 
-	SectorSet allSectors;
+	BrotherEncoder encoder;
 	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;
-		}
-	);
+	writeDiskCommand(encoder, geometry, inputFilename);
 
     return 0;
 }