@Override
    public void readBytes(final ByteBuffer bb) throws IOException
    {
        final int length = readRawVarint32();
        if (length < 0)
            throw ProtobufException.negativeSize();

        if (buffer.remaining() < length)
            // if(offset + length > limit)
            throw ProtobufException.misreportedSize();

        bb.put(buffer);
    }
Read an {@code sint64} field value from the internal buffer.
protostuff-core/src/main/java/io/protostuff/ByteBufferInput.java