/*
    * 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.hadoop.hbase.util.vint;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.nio.ByteBuffer;
  
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.nio.ByteBuff;
  import org.apache.hadoop.hbase.nio.SingleByteBuff;
  
  /**
   * Simple Variable Length Integer encoding.  Left bit of 0 means we are on the last byte.  If left
   * bit of the current byte is 1, then there is at least one more byte.
   */
  @InterfaceAudience.Private
  public class UVLongTool{
  
    public static final byte
      BYTE_7_RIGHT_BITS_SET = 127,
      BYTE_LEFT_BIT_SET = -128;
  
    public static final long
      LONG_7_RIGHT_BITS_SET = 127,
      LONG_8TH_BIT_SET = 128;
  
    public static final byte[]
      MAX_VALUE_BYTES = new byte[] { -1, -1, -1, -1, -1, -1, -1, -1, 127 };
  
  
    /********************* long -> bytes **************************/
  
    public static int numBytes(long in) {// do a check for illegal arguments if not protected
      if (in == 0) {
        return 1;
      }// doesn't work with the formula below
      return (70 - Long.numberOfLeadingZeros(in)) / 7;// 70 comes from 64+(7-1)
    }
  
    public static byte[] getBytes(long value) {
      int numBytes = numBytes(value);
      byte[] bytes = new byte[numBytes];
      long remainder = value;
      for (int i = 0; i < numBytes - 1; ++i) {
        bytes[i] = (byte) ((remainder & LONG_7_RIGHT_BITS_SET) | LONG_8TH_BIT_SET);// set the left bit
        remainder >>= 7;
      }
      bytes[numBytes - 1] = (byte) (remainder & LONG_7_RIGHT_BITS_SET);// do not set the left bit
      return bytes;
    }
  
    public static int writeBytes(long value, OutputStream os) throws IOException {
      int numBytes = numBytes(value);
      long remainder = value;
      for (int i = 0; i < numBytes - 1; ++i) {
        // set the left bit
        os.write((byte) ((remainder & LONG_7_RIGHT_BITS_SET) | LONG_8TH_BIT_SET));
        remainder >>= 7;
      }
      // do not set the left bit
      os.write((byte) (remainder & LONG_7_RIGHT_BITS_SET));
      return numBytes;
    }
  
    /******************** bytes -&gt; long **************************/
  
    public static long getLong(byte[] bytes) {
      return getLong(new SingleByteBuff(ByteBuffer.wrap(bytes)), 0);
    }
  
    public static long getLong(ByteBuff buf, int offset) {
      long value = 0;
      for (int i = 0;; ++i) {
        byte b = buf.get(offset + i);
        long shifted = BYTE_7_RIGHT_BITS_SET & b;// kill leftmost bit
        shifted <<= 7 * i;
        value |= shifted;
        if (b >= 0) {
          break;
        }// first bit was 0, so that's the last byte in the VarLong
      }
     return value;
   }
 
   public static long getLong(InputStream is) throws IOException {
     long value = 0;
     int i = 0;
     int b;
     do {
       b = is.read();
       long shifted = BYTE_7_RIGHT_BITS_SET & b;// kill leftmost bit
       shifted <<= 7 * i;
       value |= shifted;
       ++i;
     } while (b > Byte.MAX_VALUE);
     return value;
   }
 }