Add a DiskCopy 4.2 image reader. We can now write files to floppy, and they

almost work.

doc/disk-macintosh.md

@@ -55,11 +55,25 @@ You should end up with a `mac.diskcopy` file which is compatible with DiskCopy
 different sizes and the odd sector size. If you use a normal `.img` file, then
 FluxEngine will store them in a simple 524 x 12 x 2 x 80 layout, with holes
 where missing sectors should be; this was easiest, but is unlikely to work with
-most Mac emulators and other software. In these files, the The 12 bytes of
+most Mac emulators and other software. In these files, 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`.
 
+Writing discs
+-------------
+
+Just do:
+
+```
+fluxengine write mac -i mac.diskcopy
+```
+
+It'll read the DiskCopy 4.2 file and write it out.
+
+The same warning as above applies --- you can use normal `.img` files but it's
+problematic. Use DiskCopy 4.2 files instead.
+
 Useful references
 -----------------
 

lib/imagereader/diskcopyimagereader.cc

@@ -0,0 +1,128 @@
+#include "globals.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 DiskCopyImageReader : public ImageReader
+{
+public:
+	DiskCopyImageReader(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";
+
+		Bytes data;
+		data.writer() += inputFile;
+		ByteReader br(data);
+
+		br.seek(1);
+		std::string label = br.read(data[0]);
+
+		br.seek(0x40);
+		uint32_t dataSize = br.read_be32();
+
+		br.seek(0x50);
+		uint8_t encoding = br.read_8();
+		uint8_t formatByte = br.read_8();
+
+		unsigned numCylinders = 80;
+		unsigned numHeads = 2;
+		unsigned numSectors = 0;
+		bool mfm = false;
+
+		switch (encoding)
+		{
+			case 0: /* GCR CLV 400kB */
+				numHeads = 1;
+				break;
+
+			case 1: /* GCR CLV 800kB */
+				break;
+
+			case 2: /* MFM CAV 720kB */
+				numSectors = 9;
+				mfm = true;
+				break;
+
+			case 3: /* MFM CAV 1440kB */
+				numSectors = 18;
+				mfm = true;
+				break;
+
+			default:
+				Error() << fmt::format("don't understant DiskCopy disks of type {}", encoding);
+		}
+
+		std::cout << "reading DiskCopy 4.2 image\n"
+		          << fmt::format("{} cylinders, {} heads; {}; {}\n",
+				  		numCylinders, numHeads,
+						mfm ? "MFM" : "GCR",
+						label);
+
+		auto sectorsPerTrack = [&](int track) -> int
+		{
+			if (mfm)
+				return numSectors;
+
+			if (track < 16)
+				return 12;
+			if (track < 32)
+				return 11;
+			if (track < 48)
+				return 10;
+			if (track < 64)
+				return 9;
+			return 8;
+		};
+
+		uint32_t dataPtr = 0x54;
+		uint32_t tagPtr = dataPtr + dataSize;
+
+        SectorSet sectors;
+        for (int track = 0; track < numCylinders; track++)
+        {
+			int numSectors = sectorsPerTrack(track);
+            for (int head = 0; head < numHeads; head++)
+            {
+                for (int sectorId = 0; sectorId < numSectors; sectorId++)
+                {
+					br.seek(dataPtr);
+					Bytes payload = br.read(512);
+					dataPtr += 512;
+
+					br.seek(tagPtr);
+					Bytes tag = br.read(12);
+					tagPtr += 12;
+
+                    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.writer().append(payload).append(tag);
+                }
+            }
+        }
+        return sectors;
+	}
+};
+
+std::unique_ptr<ImageReader> ImageReader::createDiskCopyImageReader(
+	const ImageSpec& spec)
+{
+    return std::unique_ptr<ImageReader>(new DiskCopyImageReader(spec));
+}
+
+

lib/imagereader/imagereader.cc

@@ -12,6 +12,7 @@ std::map<std::string, ImageReader::Constructor> ImageReader::formats =
 {
 	{".adf", ImageReader::createImgImageReader},
 	{".d81", ImageReader::createImgImageReader},
+	{".diskcopy", ImageReader::createDiskCopyImageReader},
 	{".img", ImageReader::createImgImageReader},
 	{".ima", ImageReader::createImgImageReader},
 };

lib/imagereader/imagereader.h

@@ -23,6 +23,7 @@ private:
 
 	static std::map<std::string, Constructor> formats;
 
+    static std::unique_ptr<ImageReader> createDiskCopyImageReader(const ImageSpec& spec);
     static std::unique_ptr<ImageReader> createImgImageReader(const ImageSpec& spec);
 
 	static Constructor findConstructor(const ImageSpec& spec);

lib/imagewriter/diskcopyimagewriter.cc

@@ -47,7 +47,6 @@ public:
 		else
 			Error() << "this image is not compatible with the DiskCopy 4.2 format";
 
-
 		std::cout << "writing DiskCopy 4.2 image\n"
 		          << fmt::format("{} tracks, {} heads, {} sectors, {} bytes per sector; {}\n",
 				  		spec.cylinders, spec.heads, spec.sectors, spec.bytes,

mkninja.sh

@@ -151,6 +151,7 @@ buildlibrary libfmt.a \
     dep/fmt/posix.cc \
 
 buildlibrary libbackend.a \
+	lib/imagereader/diskcopyimagereader.cc \
 	lib/imagereader/imagereader.cc \
 	lib/imagereader/imgimagereader.cc \
 	lib/imagewriter/d64imagewriter.cc \