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.spark.unsafe.types;
  
  import org.apache.spark.unsafe.Platform;
  
  import java.util.Arrays;
  
  public final class ByteArray {
  
    public static final byte[] EMPTY_BYTE = new byte[0];
  
    /**
     * Writes the content of a byte array into a memory address, identified by an object and an
     * offset. The target memory address must already been allocated, and have enough space to
     * hold all the bytes in this string.
     */
    public static void writeToMemory(byte[] src, Object target, long targetOffset) {
      Platform.copyMemory(src, Platform.BYTE_ARRAY_OFFSET, target, targetOffset, src.length);
    }
  
    /**
     * Returns a 64-bit integer that can be used as the prefix used in sorting.
     */
    public static long getPrefix(byte[] bytes) {
      if (bytes == null) {
        return 0L;
      } else {
        final int minLen = Math.min(bytes.length, 8);
        long p = 0;
        for (int i = 0; i < minLen; ++i) {
          p |= (128L + Platform.getByte(bytes, Platform.BYTE_ARRAY_OFFSET + i))
              << (56 - 8 * i);
        }
        return p;
      }
    }
  
    public static byte[] subStringSQL(byte[] bytes, int pos, int len) {
      // This pos calculation is according to UTF8String#subStringSQL
      if (pos > bytes.length) {
        return EMPTY_BYTE;
      }
      int start = 0;
      int end;
      if (pos > 0) {
        start = pos - 1;
      } else if (pos < 0) {
        start = bytes.length + pos;
      }
      if ((bytes.length - start) < len) {
        end = bytes.length;
      } else {
        end = start + len;
      }
      start = Math.max(start, 0); // underflow
      if (start >= end) {
        return EMPTY_BYTE;
      }
      return Arrays.copyOfRange(bytes, start, end);
    }
  }
  