content: /*
   * 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.bookkeeper.common.util;
  
  import java.io.EOFException;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  
  /**
   * Variable-length encoding for integers.
   *
   * <p>Handles, in a common encoding format, signed bytes, shorts, ints, and longs.
   * Takes between 1 and 10 bytes.
   * Less efficient than BigEndian{Int,Long} coder for negative or large numbers.
   * All negative ints are encoded using 5 bytes, longs take 10 bytes.
   */
  public class VarInt {
  
      private static long convertIntToLongNoSignExtend(int v) {
          return v & 0xFFFFFFFFL;
      }
  
      /**
       * Encodes the given value onto the buffer.
       *
       * @param v   the value
       * @param buf the buffer
       * @throws IOException the io exception
       */
      public static void encode(int v, OutputStream buf) throws IOException {
          encode(convertIntToLongNoSignExtend(v), buf);
      }
  
      /**
       * Encodes the given value onto the buffer.
       *
       * @param v   the value
       * @param buf the buffer
       * @throws IOException the io exception
       */
      public static void encode(long v, OutputStream buf) throws IOException {
          do {
              // Encode next 7 bits + terminator bit
              long bits = v & 0x7F;
              v >>>= 7;
              int b = (int) (bits | ((v != 0) ? 0x80 : 0));
              buf.write(b);
          } while (v != 0);
      }
  
      /**
       * Decodes an integer value from the given buffer.
       *
       * @param buf the buffer
       * @return the int value that decoded
       * @throws IOException the io exception
       */
      public static int decodeInt(InputStream buf) throws IOException {
          long r = decodeLong(buf);
          if (r < 0 || r >= 1L << 32) {
              throw new IOException("var int overflow " + r);
          }
          return (int) r;
      }
  
      /**
       * Decodes a long value from the given buffer.
       *
       * @param buf the buf
       * @return the long value that decoded
       * @throws IOException the io exception
       */
      public static long decodeLong(InputStream buf) throws IOException {
          long result = 0;
          int shift = 0;
          int b;
          do {
              // Get 7 bits from next byte
              b = buf.read();
              if (b < 0) {
                  if (shift == 0) {
                      throw new EOFException();
                  } else {
                      throw new IOException("varint not terminated");
                  }
              }
              long bits = b & 0x7F;
              if (shift >= 64 || (shift == 63 && bits > 1)) {
                  // Out of range
                  throw new IOException("varint too long");
              }
              result |= bits << shift;
              shift += 7;
          } while ((b & 0x80) != 0);
          return result;
      }
  
      /**
       * Returns the length of the encoding of the given value (in bytes).
       *
       * @param v the value
       * @return the length
       */
      public static int getLength(int v) {
          return getLength(convertIntToLongNoSignExtend(v));
      }
  
      /**
       * Returns the length of the encoding of the given value (in bytes).
       *
       * @param v the value
       * @return the length
       */
      public static int getLength(long v) {
          int result = 0;
          do {
              result++;
              v >>>= 7;
          } while (v != 0);
          return result;
      }
  }
  