Separated legacy tag format from actual one. Not tested

numass-core/src/main/java/inr/numass/NumassEnvelopeType.java

@@ -0,0 +1,103 @@
+package inr.numass;
+
+import hep.dataforge.io.envelopes.*;
+import hep.dataforge.values.Value;
+import org.slf4j.LoggerFactory;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.util.HashMap;
+import java.util.Map;
+
+import static hep.dataforge.io.envelopes.DefaultEnvelopeType.DEFAULT_ENVELOPE_TYPE;
+
+/**
+ * An envelope type for legacy numass tags. Reads legacy tag and writes DF02 tags
+ */
+public class NumassEnvelopeType implements EnvelopeType {
+
+    @Override
+    public int getCode() {
+        return DEFAULT_ENVELOPE_TYPE;
+    }
+
+    @Override
+    public String getName() {
+        return "numass";
+    }
+
+    @Override
+    public String description() {
+        return "Numass legacy envelope";
+    }
+
+    @Override
+    public EnvelopeReader getReader(Map<String, String> properties) {
+        return new NumassEnvelopeReader();
+    }
+
+    @Override
+    public EnvelopeWriter getWriter(Map<String, String> properties) {
+        return new DefaultEnvelopeWriter(this, MetaType.resolve(properties));
+    }
+
+    private static class LegacyTag extends EnvelopeTag {
+        private final byte[] START_SEQUENCE = {'#', '!'};
+        private final byte[] END_SEQUENCE = {'!', '#', '\r', '\n'};
+
+        @Override
+        protected byte[] getStartSequence() {
+            return START_SEQUENCE;
+        }
+
+        @Override
+        protected byte[] getEndSequence() {
+            return END_SEQUENCE;
+        }
+
+        /**
+         * Get the length of tag in bytes. -1 means undefined size in case tag was modified
+         *
+         * @return
+         */
+        public int getLength() {
+            return 30;
+        }
+
+        /**
+         * Read leagscy version 1 tag without leading tag head
+         *
+         * @param buffer
+         * @return
+         * @throws IOException
+         */
+        protected Map<String, Value> readHeader(ByteBuffer buffer) throws IOException {
+            Map<String, Value> res = new HashMap<>();
+
+            int type = buffer.getInt(2);
+            res.put(Envelope.TYPE_KEY, Value.of(type));
+
+            short metaTypeCode = buffer.getShort(10);
+            MetaType metaType = MetaType.resolve(metaTypeCode);
+
+            if (metaType != null) {
+                res.put(Envelope.META_TYPE_KEY, Value.of(metaType.getName()));
+            } else {
+                LoggerFactory.getLogger(EnvelopeTag.class).warn("Could not resolve meta type. Using default");
+            }
+
+            long metaLength = Integer.toUnsignedLong(buffer.getInt(14));
+            res.put(Envelope.META_LENGTH_KEY, Value.of(metaLength));
+            long dataLength = Integer.toUnsignedLong(buffer.getInt(22));
+            res.put(Envelope.DATA_LENGTH_KEY, Value.of(dataLength));
+            return res;
+        }
+    }
+
+    private static class NumassEnvelopeReader extends DefaultEnvelopeReader {
+        @Override
+        protected EnvelopeTag newTag() {
+            return new LegacyTag();
+        }
+    }
+}

numass-core/src/main/resources/META-INF/services/hep.dataforge.io.envelopes.EnvelopeType

@@ -0,0 +1 @@
+inr.numass.NumassEnvelopeType