content: /*
   * Licensed 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 io.airlift.compress.v3.zstd;
  
  import io.airlift.compress.v3.IncompatibleJvmException;
  import sun.misc.Unsafe;
  
  import java.lang.foreign.MemorySegment;
  import java.lang.reflect.Field;
  import java.nio.ByteOrder;
  
  import static java.lang.String.format;
  import static sun.misc.Unsafe.ARRAY_BYTE_BASE_OFFSET;
  
  final class UnsafeUtil
  {
      public static final Unsafe UNSAFE;
  
      private UnsafeUtil() {}
  
      static {
          ByteOrder order = ByteOrder.nativeOrder();
          if (!order.equals(ByteOrder.LITTLE_ENDIAN)) {
              throw new IncompatibleJvmException(format("Zstandard requires a little endian platform (found %s)", order));
          }
  
          try {
              Field theUnsafe = Unsafe.class.getDeclaredField("theUnsafe");
              theUnsafe.setAccessible(true);
              UNSAFE = (Unsafe) theUnsafe.get(null);
          }
          catch (Exception e) {
              throw new IncompatibleJvmException("Zstandard requires access to sun.misc.Unsafe");
          }
      }
  
      public static byte[] getBase(MemorySegment segment)
      {
          if (segment.isNative()) {
              return null;
          }
          if (segment.isReadOnly()) {
              throw new IllegalArgumentException("MemorySegment is read-only");
          }
          Object inputBase = segment.heapBase().orElse(null);
          if (!(inputBase instanceof byte[] byteArray)) {
              throw new IllegalArgumentException("MemorySegment is not backed by a byte array");
          }
          return byteArray;
      }
  
      public static long getAddress(MemorySegment segment)
      {
          if (segment.isNative()) {
              return segment.address();
          }
          return segment.address() + ARRAY_BYTE_BASE_OFFSET;
      }
  }
  