Some Blob refactoring

convex-core/src/main/java/convex/core/data/ABlob.java

@@ -148,7 +148,12 @@ public final Hash computeHash(MessageDigest digest) {
 		return Hash.wrap(digest.digest());
 	}
 
-	protected abstract void updateDigest(MessageDigest digest);
+	/**
+	 * Updates a MessageDigest with the contents of this Blob
+	 * 
+	 * @param digest MessageDigest instance
+	 */
+	public abstract void updateDigest(MessageDigest digest);
 
 	/**
 	 * Gets the byte at the specified position 

convex-core/src/main/java/convex/core/data/BlobTree.java

@@ -241,7 +241,7 @@ public Blob toFlatBlob() {
 	}
 
 	@Override
-	protected void updateDigest(MessageDigest digest) {
+	public void updateDigest(MessageDigest digest) {
 		int n = children.length;
 		for (int i = 0; i < n; i++) {
 			getChild(i).updateDigest(digest);

convex-core/src/main/java/convex/core/data/LongBlob.java

@@ -41,9 +41,10 @@ public ABlob slice(long start, long end) {
 
 
 	@Override
-	protected void updateDigest(MessageDigest digest) {
-		byte[] bs = getEncoding().getInternalArray();
-		digest.update(bs, 2, (int) LENGTH);
+	public void updateDigest(MessageDigest digest) {
+		Blob b=getEncoding();
+		byte[] bs = b.getInternalArray();
+		digest.update(bs, b.getInternalOffset()+2, (int) LENGTH);
 	}
 
 	@Override

convex-core/src/main/java/convex/core/data/ADerivedBlob.java → convex-core/src/main/java/convex/core/data/impl/ADerivedBlob.java

@@ -1,8 +1,11 @@
-package convex.core.data;
+package convex.core.data.impl;
 
 import java.nio.ByteBuffer;
 import java.security.MessageDigest;
 
+import convex.core.data.ABlob;
+import convex.core.data.ABlobLike;
+import convex.core.data.Blob;
 import convex.core.util.Utils;
 
 /**
@@ -51,7 +54,7 @@ public Blob toFlatBlob() {
 	}
 
 	@Override
-	protected void updateDigest(MessageDigest digest) {
+	public void updateDigest(MessageDigest digest) {
 		ABlob can=getCanonical();
 		can.updateDigest(digest);
 	}

convex-core/src/main/java/convex/core/data/impl/RepeatByteBlob.java

@@ -0,0 +1,30 @@
+package convex.core.data.impl;
+
+import org.bouncycastle.util.Arrays;
+
+public class RepeatByteBlob extends ADerivedBlob {
+	private final byte b;
+
+	protected RepeatByteBlob(long count, byte b) {
+		super(count);
+		this.b=b;
+	}
+
+	@Override
+	public RepeatByteBlob sliceImpl(long start, long end) {
+		return new RepeatByteBlob(end-start,b);
+	}
+
+	@Override
+	public int getBytes(byte[] dest, int destOffset) {
+		int end=destOffset+size();
+		Arrays.fill(dest, destOffset,end,(byte)0);
+		return end;
+	}
+
+	@Override
+	public byte byteAtUnchecked(long i) {
+		return b;
+	}
+
+}

convex-core/src/main/java/convex/core/data/impl/ZeroBlob.java

@@ -3,7 +3,6 @@
 import org.bouncycastle.util.Arrays;
 
 import convex.core.data.ABlob;
-import convex.core.data.ADerivedBlob;
 import convex.core.data.Cells;
 
 /**

convex-core/src/test/java/convex/core/data/BlobsTest.java

@@ -578,6 +578,19 @@ public void testLongBlobBroken() throws BadFormatException, IOException {
 	   assertEquals(b, Format.encodedBlob(o));
 	   assertEquals(pref.getValue(), o);
 	}
+
+	@Test
+	public void testLongBlobDecoded() throws BadFormatException {
+		long V=0xFF1234567899L;
+		// LongBlob has custom hash implementation, we want to make sure it reads from encoding correctly
+		LongBlob l0=LongBlob.create(V);
+		Blob enc=(Blob.fromHex("F000").append(l0.getEncoding()).toFlatBlob().slice(2));
+
+		LongBlob l1=LongBlob.create(V);
+		l1.attachEncoding(enc);
+
+		assertEquals(l0.getHash(),l1.getHash());
+	}
 
 	/**
 	 * Generic tests for an arbitrary ABlob instance