| /* |
| * 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.ReadWriteIOUtils; |
| |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| import java.io.IOException; |
| import java.nio.ByteBuffer; |
| |
| public abstract class GorillaDecoderV1 extends Decoder { |
| |
| protected static final int EOF = -1; |
| private static final Logger logger = LoggerFactory.getLogger(GorillaDecoderV1.class); |
| // flag to indicate whether the first value is read from stream |
| protected boolean flag; |
| protected int leadingZeroNum; |
| protected int tailingZeroNum; |
| protected boolean isEnd; |
| // 8-bit buffer of bits to write out |
| protected int buffer; |
| // number of bits remaining in buffer |
| protected int numberLeftInBuffer; |
| |
| protected boolean nextFlag1; |
| protected boolean nextFlag2; |
| |
| protected GorillaDecoderV1() { |
| super(TSEncoding.GORILLA_V1); |
| reset(); |
| } |
| |
| @Override |
| public void reset() { |
| this.flag = false; |
| this.isEnd = false; |
| this.numberLeftInBuffer = 0; |
| } |
| |
| @Override |
| public boolean hasNext(ByteBuffer buffer) throws IOException { |
| return buffer.remaining() > 0 || !isEnd; |
| } |
| |
| protected boolean isEmpty() { |
| return buffer == EOF; |
| } |
| |
| protected boolean readBit(ByteBuffer buffer) throws IOException { |
| if (numberLeftInBuffer == 0 && !isEnd) { |
| fillBuffer(buffer); |
| } |
| if (isEmpty()) { |
| throw new IOException("Reading from empty buffer"); |
| } |
| numberLeftInBuffer--; |
| return ((this.buffer >> numberLeftInBuffer) & 1) == 1; |
| } |
| |
| /** |
| * read one byte and save it in the buffer. |
| * |
| * @param buffer ByteBuffer to read |
| */ |
| protected void fillBuffer(ByteBuffer buffer) { |
| if (buffer.remaining() >= 1) { |
| this.buffer = ReadWriteIOUtils.read(buffer); |
| numberLeftInBuffer = 8; |
| } else { |
| logger.error("Failed to fill a new buffer, because there is no byte to read"); |
| this.buffer = EOF; |
| numberLeftInBuffer = -1; |
| } |
| } |
| |
| /** |
| * read some bits and convert them to an int value. |
| * |
| * @param buffer stream to read |
| * @param len number of bit to read |
| * @return converted int value |
| * @throws IOException cannot read from stream |
| */ |
| protected int readIntFromStream(ByteBuffer buffer, int len) throws IOException { |
| int num = 0; |
| for (int i = 0; i < len; i++) { |
| int bit = readBit(buffer) ? 1 : 0; |
| num |= bit << (len - 1 - i); |
| } |
| return num; |
| } |
| |
| /** |
| * read some bits and convert them to a long value. |
| * |
| * @param buffer stream to read |
| * @param len number of bit to read |
| * @return converted long value |
| * @throws IOException cannot read from stream |
| */ |
| protected long readLongFromStream(ByteBuffer buffer, int len) throws IOException { |
| long num = 0; |
| for (int i = 0; i < len; i++) { |
| long bit = readBit(buffer) ? 1 : 0; |
| num |= bit << (len - 1 - i); |
| } |
| return num; |
| } |
| } |