ceph/src/rocksdb/java/src/main/java/org/rocksdb/util/ByteUtil.java

   1 //  Copyright (c) Meta Platforms, Inc. and affiliates.
   2 //
   3 //  This source code is licensed under both the GPLv2 (found in the
   4 //  COPYING file in the root directory) and Apache 2.0 License
   5 //  (found in the LICENSE.Apache file in the root directory).
   6
   7 package org.rocksdb.util;
   8
   9 import java.nio.ByteBuffer;
  10
  11 import static java.nio.charset.StandardCharsets.UTF_8;
  12
  13 public class ByteUtil {
  14
  15   /**
  16    * Convert a String to a UTF-8 byte array.
  17    *
  18    * @param str the string
  19    *
  20    * @return the byte array.
  21    */
  22   public static byte[] bytes(final String str) {
  23     return str.getBytes(UTF_8);
  24   }
  25
  26   /**
  27    * Compares the first {@code count} bytes of two areas of memory.  Returns
  28    * zero if they are the same, a value less than zero if {@code x} is
  29    * lexically less than {@code y}, or a value greater than zero if {@code x}
  30    * is lexically greater than {@code y}.  Note that lexical order is determined
  31    * as if comparing unsigned char arrays.
  32    *
  33    * Similar to <a href="https://github.com/gcc-mirror/gcc/blob/master/libiberty/memcmp.c">memcmp.c</a>.
  34    *
  35    * @param x the first value to compare with
  36    * @param y the second value to compare against
  37    * @param count the number of bytes to compare
  38    *
  39    * @return the result of the comparison
  40    */
  41   public static int memcmp(final ByteBuffer x, final ByteBuffer y,
  42                             final int count) {
  43     for (int idx = 0; idx < count; idx++) {
  44       final int aa = x.get(idx) & 0xff;
  45       final int bb = y.get(idx) & 0xff;
  46       if (aa != bb) {
  47         return aa - bb;
  48       }
  49     }
  50     return 0;
  51   }
  52 }