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.cassandra.io.util;
  
  import java.io.IOException;
  import java.nio.ByteBuffer;
  
  /**
   * Utility class for sizing, writing and reading ints with length stored separately.
   * Used for trie payloads.
   */
  public class SizedInts
  {
      /**
       * Returns the number of bytes we need to store the given position.
       * This method understands 0 to need 1 byte.
       * <p>
       * If your use case permits 0 to be encoded in 0 length, use {@link #sizeAllowingZero} below.
       */
      public static int nonZeroSize(long value)
      {
          if (value < 0)
              value = ~value;
          int lz = Long.numberOfLeadingZeros(value);       // 1 <= lz <= 64
          return (64 - lz + 1 + 7) / 8;   // significant bits, +1 for sign, rounded up. At least 1, at most 8.
      }
  
      /**
       * Returns the number of bytes we need to store the given position. Returns 0 for 0 argument.
       */
      public static int sizeAllowingZero(long value)
      {
          if (value == 0)
              return 0;
          return nonZeroSize(value);
      }
  
      public static long read(ByteBuffer src, int startPos, int bytes)
      {
          switch (bytes)
          {
              case 0:
                  return 0;
              case 1:
                  return src.get(startPos);
              case 2:
                  return src.getShort(startPos);
              case 3:
              {
                  long high = src.get(startPos);
                  return (high << 16L) | (src.getShort(startPos + 1) & 0xFFFFL);
              }
              case 4:
                  return src.getInt(startPos);
              case 5:
              {
                  long high = src.get(startPos);
                  return (high << 32L) | (src.getInt(startPos + 1) & 0xFFFFFFFFL);
              }
              case 6:
              {
                  long high = src.getShort(startPos);
                  return (high << 32L) | (src.getInt(startPos + 2) & 0xFFFFFFFFL);
              }
              case 7:
              {
                  long high = src.get(startPos);
                  high = (high << 16L) | (src.getShort(startPos + 1) & 0xFFFFL);
                  return (high << 32L) | (src.getInt(startPos + 3) & 0xFFFFFFFFL);
              }
              case 8:
                  return src.getLong(startPos);
              default:
                  throw new AssertionError();
          }
      }
  
      public static long readUnsigned(ByteBuffer src, int startPos, int bytes)
      {
          if (bytes == 8)
              return src.getLong(startPos);
          else
              return read(src, startPos, bytes) & ((1L << (bytes * 8)) - 1);
      }
  
      public static void write(DataOutputPlus dest, long value, int size) throws IOException
      {
          dest.writeMostSignificantBytes(value << ((8 - size) * 8), size);
      }
  }