Add boilerplate for Roland D20 decoder.

arch/build.mk

@@ -24,6 +24,7 @@ LIBARCH_SRCS = \
 	arch/mx/decoder.cc \
 	arch/northstar/decoder.cc \
 	arch/northstar/encoder.cc \
+	arch/rolandd20/decoder.cc \
 	arch/smaky6/decoder.cc \
 	arch/tids990/decoder.cc \
 	arch/tids990/encoder.cc \

arch/rolandd20/decoder.cc

@@ -0,0 +1,49 @@
+#include "lib/globals.h"
+#include "lib/decoders/decoders.h"
+#include "lib/crc.h"
+#include "lib/fluxmap.h"
+#include "lib/decoders/fluxmapreader.h"
+#include "lib/sector.h"
+#include "lib/bytes.h"
+#include "rolandd20.h"
+#include <string.h>
+
+/* Sector header record:
+ *
+ * BF FF FF FF FF FF FE AB
+ *
+ *       f       f       f       f       f       e       a       b
+ * 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 0 1 0 1 0 1 1
+ * 1111111111111111111111111111111111111111111111011101110111011111
+ *    f   f   f   f   f   f   f   f   f   f   f   d   d   d   d   f
+ */
+
+static const FluxPattern SECTOR_PATTERN(64, 0xfffffffffffddddfLL);
+
+class RolandD20Decoder : public Decoder
+{
+public:
+	RolandD20Decoder(const DecoderProto& config):
+		Decoder(config)
+	{}
+
+    nanoseconds_t advanceToNextRecord() override
+	{
+		return seekToPattern(SECTOR_PATTERN);
+	}
+
+    void decodeSectorRecord() override
+	{
+		auto rawbits = readRawBits(128);
+		const auto& bytes = decodeFmMfm(rawbits);
+		hexdump(std::cout, bytes);
+	}
+};
+
+std::unique_ptr<Decoder> createRolandD20Decoder(const DecoderProto& config)
+{
+	return std::unique_ptr<Decoder>(new RolandD20Decoder(config));
+}
+
+
+

arch/rolandd20/rolandd20.h

@@ -0,0 +1,4 @@
+#pragma once
+
+extern std::unique_ptr<Decoder> createRolandD20Decoder(const DecoderProto& config);
+

arch/rolandd20/rolandd20.proto

@@ -0,0 +1,5 @@
+syntax = "proto2";
+
+message RolandD20DecoderProto {}
+
+