| /* |
| * 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.common.conf.TSFileConfig; |
| import org.apache.iotdb.tsfile.utils.ReadWriteIOUtils; |
| |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| import java.io.IOException; |
| import java.nio.ByteBuffer; |
| |
| /** Decoder for value value using gorilla. */ |
| public class SinglePrecisionDecoderV1 extends GorillaDecoderV1 { |
| |
| private static final Logger logger = LoggerFactory.getLogger(SinglePrecisionDecoderV1.class); |
| private int preValue; |
| |
| public SinglePrecisionDecoderV1() { |
| // do nothing |
| } |
| |
| @Override |
| public float readFloat(ByteBuffer buffer) { |
| if (!flag) { |
| flag = true; |
| try { |
| int ch1 = ReadWriteIOUtils.read(buffer); |
| int ch2 = ReadWriteIOUtils.read(buffer); |
| int ch3 = ReadWriteIOUtils.read(buffer); |
| int ch4 = ReadWriteIOUtils.read(buffer); |
| preValue = ch1 + (ch2 << 8) + (ch3 << 16) + (ch4 << 24); |
| leadingZeroNum = Integer.numberOfLeadingZeros(preValue); |
| tailingZeroNum = Integer.numberOfTrailingZeros(preValue); |
| float tmp = Float.intBitsToFloat(preValue); |
| fillBuffer(buffer); |
| getNextValue(buffer); |
| return tmp; |
| } catch (IOException e) { |
| logger.error("SinglePrecisionDecoderV1 cannot read first float number", e); |
| } |
| } else { |
| try { |
| float tmp = Float.intBitsToFloat(preValue); |
| getNextValue(buffer); |
| return tmp; |
| } catch (IOException e) { |
| logger.error("SinglePrecisionDecoderV1 cannot read following float number", e); |
| } |
| } |
| return Float.NaN; |
| } |
| |
| /** |
| * check whether there is any value to encode left. |
| * |
| * @param buffer stream to read |
| * @throws IOException cannot read from stream |
| */ |
| private void getNextValue(ByteBuffer buffer) throws IOException { |
| nextFlag1 = readBit(buffer); |
| // case: '0' |
| if (!nextFlag1) { |
| return; |
| } |
| nextFlag2 = readBit(buffer); |
| |
| if (!nextFlag2) { |
| // case: '10' |
| int tmp = 0; |
| for (int i = 0; |
| i < TSFileConfig.VALUE_BITS_LENGTH_32BIT - leadingZeroNum - tailingZeroNum; |
| i++) { |
| int bit = readBit(buffer) ? 1 : 0; |
| tmp |= bit << (TSFileConfig.VALUE_BITS_LENGTH_32BIT - 1 - leadingZeroNum - i); |
| } |
| tmp ^= preValue; |
| preValue = tmp; |
| } else { |
| // case: '11' |
| int leadingZeroNumTmp = |
| readIntFromStream(buffer, TSFileConfig.LEADING_ZERO_BITS_LENGTH_32BIT); |
| int lenTmp = readIntFromStream(buffer, TSFileConfig.FLOAT_VALUE_LENGTH); |
| int tmp = readIntFromStream(buffer, lenTmp); |
| tmp <<= (TSFileConfig.VALUE_BITS_LENGTH_32BIT - leadingZeroNumTmp - lenTmp); |
| tmp ^= preValue; |
| preValue = tmp; |
| } |
| leadingZeroNum = Integer.numberOfLeadingZeros(preValue); |
| tailingZeroNum = Integer.numberOfTrailingZeros(preValue); |
| if (Float.isNaN(Float.intBitsToFloat(preValue))) { |
| isEnd = true; |
| } |
| } |
| } |