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 com.scurrilous.circe.checksum;
  
  import com.scurrilous.circe.crc.Sse42Crc32C;
  import io.netty.buffer.ByteBuf;
  
  public class Crc32cIntChecksum {
  
      private final static IntHash CRC32C_HASH;
  
      static {
          if (Sse42Crc32C.isSupported()) {
              CRC32C_HASH = new JniIntHash();
          } else if (Java9IntHash.HAS_JAVA9_CRC32C) {
              CRC32C_HASH = new Java9IntHash();
          } else {
              CRC32C_HASH = new Java8IntHash();
          }
      }
  
      /**
       * Computes crc32c checksum: if it is able to load crc32c native library then it computes using that native library
       * which is faster as it computes using hardware machine instruction else it computes using crc32c algo.
       *
       * @param payload
       * @return
       */
      public static int computeChecksum(ByteBuf payload) {
          return CRC32C_HASH.calculate(payload);
      }
  
      /**
       * Computes crc32c checksum: if it is able to load crc32c native library then it computes using that native library
       * which is faster as it computes using hardware machine instruction else it computes using crc32c algo.
       *
       * @param payload
       * @return
       */
      public static int computeChecksum(ByteBuf payload, int offset, int len) {
          return CRC32C_HASH.calculate(payload, offset, len);
      }
  
      /**
       * Computes incremental checksum with input previousChecksum and input payload
       *
       * @param previousChecksum : previously computed checksum
       * @param payload
       * @return
       */
      public static int resumeChecksum(int previousChecksum, ByteBuf payload) {
          return CRC32C_HASH.resume(previousChecksum, payload);
      }
  
      /**
       * Computes incremental checksum with input previousChecksum and input payload
       *
       * @param previousChecksum the previously computed checksum
       * @param payload the data for which the checksum is to be computed
       * @param offset the starting position in the payload
       * @param len the number of bytes to include in the checksum computation
       * @return the updated checksum
       */
      public static int resumeChecksum(int previousChecksum, ByteBuf payload, int offset, int len) {
          return CRC32C_HASH.resume(previousChecksum, payload, offset, len);
      }
  
      /**
       * Computes incremental checksum with input previousChecksum and input payload
       *
       * @param previousChecksum the previously computed checksum
       * @param payload the data for which the checksum is to be computed
       * @param offset the starting position in the payload
       * @param len the number of bytes to include in the checksum computation
       * @return the updated checksum
       */
      public static int resumeChecksum(int previousChecksum, byte[] payload, int offset, int len) {
          return CRC32C_HASH.resume(previousChecksum, payload, offset, len);
      }
  
      public static boolean acceptsMemoryAddressBuffer() {
          return CRC32C_HASH.acceptsMemoryAddressBuffer();
      }
  }
  