Avoid allocation in BigDecimal serializer with alternative way to write bytes.

src/com/esotericsoftware/kryo/io/ByteBufferInput.java

@@ -352,6 +352,30 @@ public void readBytes (byte[] bytes, int offset, int count) throws KryoException
 		}
 	}
 
+	public int readInt (int count) {
+		if (count < 0 || count > 4) throw new IllegalArgumentException("count must be >= 0 and <= 4: " + count);
+		require(count);
+		position += count;
+		ByteBuffer byteBuffer = this.byteBuffer;
+		switch (count) {
+			case 1:
+				return byteBuffer.get();
+			case 2:
+				return byteBuffer.get() << 8
+					| byteBuffer.get() & 0xFF;
+			case 3:
+				return byteBuffer.get() << 16
+					| (byteBuffer.get() & 0xFF) << 8
+					| byteBuffer.get() & 0xFF;
+			case 4:
+				return byteBuffer.get() << 24
+					| (byteBuffer.get() & 0xFF) << 16
+					| (byteBuffer.get() & 0xFF) << 8
+					| byteBuffer.get() & 0xFF;
+		}
+		throw new IllegalStateException(); // impossible
+	}
+
 	// int:
 
 	public int readInt () throws KryoException {

src/com/esotericsoftware/kryo/io/ByteBufferOutput.java

@@ -276,6 +276,33 @@ public void writeBytes (byte[] bytes, int offset, int count) throws KryoExceptio
 		}
 	}
 
+	public void writeInt (int bytes, int count) {
+		if (count < 0 || count > 4) throw new IllegalArgumentException("count must be >= 0 and <= 4: " + count);
+		require(count);
+		position += count;
+		ByteBuffer byteBuffer = this.byteBuffer;
+		switch (count) {
+			case 1:
+				byteBuffer.put((byte)bytes);
+				break;
+			case 2:
+				byteBuffer.put((byte)(bytes >> 8));
+				byteBuffer.put((byte)bytes);
+				break;
+			case 3:
+				byteBuffer.put((byte)(bytes >> 16));
+				byteBuffer.put((byte)(bytes >> 8));
+				byteBuffer.put((byte)bytes);
+				break;
+			case 4:
+				byteBuffer.put((byte)(bytes >> 24));
+				byteBuffer.put((byte)(bytes >> 16));
+				byteBuffer.put((byte)(bytes >> 8));
+				byteBuffer.put((byte)bytes);
+				break;
+		}
+	}
+
 	// int:
 
 	public void writeInt (int value) throws KryoException {

src/com/esotericsoftware/kryo/io/Input.java

@@ -373,6 +373,44 @@ public void readBytes (byte[] bytes, int offset, int count) throws KryoException
 		}
 	}
 
+	/** Reads count bytes and returns them as int, the last byte read will be the lowest byte in the int. */
+	public int readInt (int count) {
+		if (count < 0 || count > 4) throw new IllegalArgumentException("count must be >= 0 and <= 4: " + count);
+		require(count);
+		int p = position;
+		position = p + count;
+		switch (count) {
+			case 1:
+				return buffer[p];
+			case 2:
+				return buffer[p] << 8
+					| buffer[p+1] & 0xFF;
+			case 3:
+				return buffer[p] << 16
+					| (buffer[p+1] & 0xFF) << 8
+					| buffer[p+2] & 0xFF;
+			case 4:
+				return buffer[p] << 24
+					| (buffer[p+1] & 0xFF) << 16
+					| (buffer[p+2] & 0xFF) << 8
+					| buffer[p+3] & 0xFF;
+		}
+		throw new IllegalStateException(); // impossible
+	}
+
+	/** Reads count bytes and returns them as long, the last byte read will be the lowest byte in the long. */
+	public long readLong (int count) {
+		if (count < 0 || count > 8) throw new IllegalArgumentException("count must be >= 0 and <= 8: " + count);
+		if (count <= 4) {
+			return readInt(count);
+		} else {
+			require(count);
+			long highBytes = ((long) readInt(count - 4)) << 32;
+			long lowBytes = ((long) readInt(4)) & (1L << 32) - 1;
+			return highBytes | lowBytes;
+		}
+	}
+
 	// int:
 
 	/** Reads a 4 byte int. */

src/com/esotericsoftware/kryo/io/Output.java

@@ -20,7 +20,6 @@
 package com.esotericsoftware.kryo.io;
 
 import com.esotericsoftware.kryo.KryoException;
-import com.esotericsoftware.kryo.io.KryoBufferOverflowException;
 import com.esotericsoftware.kryo.util.Pool.Poolable;
 import com.esotericsoftware.kryo.util.Util;
 
@@ -274,6 +273,48 @@ public void writeBytes (byte[] bytes, int offset, int count) throws KryoExceptio
 		}
 	}
 
+	/** Writes count bytes from long, the last byte written is the lowest byte from the long.
+	 *  Note the number of bytes is not written. */
+	public void writeInt (int bytes, int count) {
+		if (count < 0 || count > 4) throw new IllegalArgumentException("count must be >= 0 and <= 4: " + count);
+		require(count);
+		int p = position;
+		position = p + count;
+		switch (count) {
+			case 1:
+				buffer[p] = (byte)bytes;
+				break;
+			case 2:
+				buffer[p] = (byte)(bytes >> 8);
+				buffer[p+1] = (byte)bytes;
+				break;
+			case 3:
+				buffer[p] = (byte)(bytes >> 16);
+				buffer[p+1] = (byte)(bytes >> 8);
+				buffer[p+2] = (byte)bytes;
+				break;
+			case 4:
+				buffer[p] = (byte)(bytes >> 24);
+				buffer[p+1] = (byte)(bytes >> 16);
+				buffer[p+2] = (byte)(bytes >> 8);
+				buffer[p+3] = (byte)bytes;
+				break;
+		}
+	}
+
+	/** Writes count bytes from long, the last byte written is the lowest byte from the long.
+	 *  Note the number of bytes is not written. */
+	public void writeLong (long bytes, int count) {
+		if (count < 0 || count > 8) throw new IllegalArgumentException("count must be >= 0 and <= 8: " + count);
+		if (count <= 4) {
+			writeInt((int) bytes, count);
+		} else {
+			require(count);
+			writeInt((int) (bytes >> 32), count - 4);
+			writeInt((int) bytes, 4);
+		}
+	}
+
 	// int:
 
 	/** Writes a 4 byte int. */