Add a special reader program for Acorn disks as I keep getting the parameters

wrong.

doc/acorn-adfs.md

@@ -10,6 +10,7 @@ Tested ones are:
 
   - ADFS L: 80 track, 16 sector, 2 sides, 256 bytes per sector == 640kB.
   - ADFE D/E: 80 track, 5 sector, 2 sides, 1024 bytes per sector == 800kB.
+  - ADFS F: 80 track, 10 sector, 2 sides, 1024 bytes per sector == 1600kB.
 
 I expect the others to work, but haven't tried them; [get in
 touch](https://github.com/davidgiven/fluxengine/issues/new) if you have any
@@ -28,8 +29,8 @@ Reading discs
 Just do:
 
 ```
-.obj/fe-readibm --sector-id-base=0
+.obj/fe-readacorn
 ```
 
-You should end up with an `ibm.img` of the appropriate size for your disk
+You should end up with an `acorn.img` of the appropriate size for your disk
 format.

meson.build

@@ -84,6 +84,7 @@ brotherinc = include_directories('lib/brother')
 
 executable('fe-erase',             ['src/fe-erase.cc'],             include_directories: [feinc], link_with: [felib, writerlib])
 executable('fe-inspect',           ['src/fe-inspect.cc'],           include_directories: [feinc, fmtinc, decoderinc], link_with: [felib, readerlib, decoderlib, fmtlib])
+executable('fe-readacorn',         ['src/fe-readacorn.cc'],         include_directories: [feinc, fmtinc, decoderinc], link_with: [felib, readerlib, decoderlib, fmtlib])
 executable('fe-readbrother',       ['src/fe-readbrother.cc'],       include_directories: [feinc, fmtinc, decoderinc, brotherinc], link_with: [felib, readerlib, decoderlib, brotherdecoderlib, fmtlib])
 executable('fe-readibm',           ['src/fe-readibm.cc'],           include_directories: [feinc, fmtinc, decoderinc], link_with: [felib, readerlib, decoderlib, fmtlib])
 executable('fe-rpm',               ['src/fe-rpm.cc'],               include_directories: [feinc], link_with: [felib])

src/fe-readacorn.cc

@@ -0,0 +1,32 @@
+#include "globals.h"
+#include "flags.h"
+#include "reader.h"
+#include "fluxmap.h"
+#include "decoders.h"
+#include "image.h"
+#include "sector.h"
+#include "sectorset.h"
+#include "record.h"
+#include <fmt/format.h>
+
+static StringFlag outputFilename(
+    { "--output", "-o" },
+    "The output image file to write to.",
+    "acorn.img");
+
+static IntFlag sectorIdBase(
+	{ "--sector-id-base" },
+	"Sector ID of the first sector.",
+	0);
+
+int main(int argc, const char* argv[])
+{
+	setReaderDefaultSource(":t=0-79:s=0-1");
+    Flag::parseFlags(argc, argv);
+
+	MfmBitmapDecoder bitmapDecoder;
+	IbmRecordParser recordParser(sectorIdBase);
+	readDiskCommand(bitmapDecoder, recordParser, outputFilename);
+    return 0;
+}
+