| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| */ |
| |
| package org.apache.iotdb.tsfile.encoding.decoder; |
| |
| import org.apache.iotdb.tsfile.file.metadata.enums.TSEncoding; |
| import org.apache.iotdb.tsfile.utils.ReadWriteForEncodingUtils; |
| |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| import java.nio.ByteBuffer; |
| |
| public class LongZigzagDecoder extends Decoder { |
| private static final Logger logger = LoggerFactory.getLogger(IntZigzagDecoder.class); |
| |
| /** how many bytes for all encoded data in input stream. */ |
| private int length; |
| |
| /** number of encoded data. */ |
| private int number; |
| |
| /** number of data left for reading in current buffer. */ |
| private int currentCount; |
| |
| /** |
| * each time decoder receives a inputstream, decoder creates a buffer to save all encoded data. |
| */ |
| private ByteBuffer byteCache; |
| |
| public LongZigzagDecoder() { |
| super(TSEncoding.ZIGZAG); |
| this.reset(); |
| logger.debug("tsfile-encoding LongZigzagDecoder: long zigzag decoder"); |
| } |
| |
| /** decoding */ |
| @Override |
| public long readLong(ByteBuffer buffer) { |
| if (currentCount == 0) { |
| reset(); |
| getLengthAndNumber(buffer); |
| currentCount = number; |
| } |
| long n = 0; |
| int i = 0; |
| long b = 0; |
| |
| while (byteCache.hasRemaining() && ((b = byteCache.get()) & 0x80) != 0) { |
| n |= (b & 0x7F) << i; |
| i += 7; |
| } |
| n = n | (b << i); |
| currentCount--; |
| return (n >>> 1) ^ -(n & 1); // back to two's-complement |
| } |
| |
| private void getLengthAndNumber(ByteBuffer buffer) { |
| this.length = ReadWriteForEncodingUtils.readUnsignedVarInt(buffer); |
| this.number = ReadWriteForEncodingUtils.readUnsignedVarInt(buffer); |
| byte[] tmp = new byte[length]; |
| buffer.get(tmp, 0, length); |
| this.byteCache = ByteBuffer.wrap(tmp); |
| } |
| |
| @Override |
| public boolean hasNext(ByteBuffer buffer) { |
| if (currentCount > 0 || buffer.remaining() > 0) { |
| return true; |
| } |
| return false; |
| } |
| |
| @Override |
| public void reset() { |
| this.length = 0; |
| this.number = 0; |
| this.currentCount = 0; |
| if (this.byteCache == null) { |
| this.byteCache = ByteBuffer.allocate(0); |
| } else { |
| this.byteCache.position(0); |
| } |
| } |
| } |