// k = 00 01 02 ...
  private static final long K0 = 0x0706050403020100L;
  private static final long K1 = 0x0f0e0d0c0b0a0908L;
  private static final HashFunction SIP_WITH_KEY = sipHash24(K0, K1);
  private static final HashFunction SIP_WITHOUT_KEY = sipHash24();

  // These constants were originally ported from https://www.131002.net/siphash/siphash24.c. See:

  // k = 00 01 02 ...
  private static final long K0 = 0x0706050403020100L;
  private static final long K1 = 0x0f0e0d0c0b0a0908L;
  private static final HashFunction SIP_WITH_KEY = sipHash24(K0, K1);
  private static final HashFunction SIP_WITHOUT_KEY = sipHash24();

  // These constants were originally ported from https://www.131002.net/siphash/siphash24.c. See:

import java.nio.ByteBuffer;
import org.jspecify.annotations.Nullable;

/**
 * {@link HashFunction} implementation of SipHash-c-d.
 *
 * @author Kurt Alfred Kluever
 * @author Jean-Philippe Aumasson
 * @author Daniel J. Bernstein
 */
@Immutable
final class SipHashFunction extends AbstractHashFunction implements Serializable {
  static final HashFunction SIP_HASH_24 =
      new SipHashFunction(2, 4, 0x0706050403020100L, 0x0f0e0d0c0b0a0908L);

import java.nio.ByteBuffer;
import java.nio.charset.Charset;
import org.jspecify.annotations.Nullable;

/**
 * Skeleton implementation of {@link HashFunction} in terms of {@link #newHasher()}.
 *
 * <p>TODO(lowasser): make public
 */
@Immutable
abstract class AbstractHashFunction implements HashFunction {
  @Override
  public <T extends @Nullable Object> HashCode hashObject(
      @ParametricNullness T instance, Funnel<? super T> funnel) {

@SuppressWarnings("IdentifierName") // the best we could do for adjacent digit blocks
final class Murmur3_128HashFunction extends AbstractHashFunction implements Serializable {
  static final HashFunction MURMUR3_128 = new Murmur3_128HashFunction(0);

  static final HashFunction GOOD_FAST_HASH_128 = new Murmur3_128HashFunction(GOOD_FAST_HASH_SEED);

  // TODO(user): when the shortcuts are implemented, update BloomFilterStrategies
  private final int seed;

    byte[] bytes = HashTestUtils.ascii(input);

    Checksum checksum = supplier.get();
    checksum.update(bytes, 0, bytes.length);
    long value = checksum.getValue();

    String toString = "name";
    HashFunction func = new ChecksumHashFunction(supplier, 32, toString);
    assertThat(func.toString()).isEqualTo(toString);
    assertEquals(value, func.hashBytes(bytes).padToLong());
  }

  private static void assertHash32(

final class Murmur3_32HashFunction extends AbstractHashFunction implements Serializable {
  static final HashFunction MURMUR3_32 =
      new Murmur3_32HashFunction(0, /* supplementaryPlaneFix= */ false);
  static final HashFunction MURMUR3_32_FIXED =
      new Murmur3_32HashFunction(0, /* supplementaryPlaneFix= */ true);

import static com.google.common.base.Preconditions.checkNotNull;

import com.google.errorprone.annotations.Immutable;
import java.io.Serializable;
import java.util.zip.Checksum;

/**
 * {@link HashFunction} adapter for {@link Checksum} instances.
 *
 * @author Colin Decker
 */
@Immutable
final class ChecksumHashFunction extends AbstractHashFunction implements Serializable {

import java.nio.ByteBuffer;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import javax.crypto.Mac;

/**
 * {@link HashFunction} adapter for {@link Mac} instances.
 *
 * @author Kurt Alfred Kluever
 */
@Immutable
final class MacHashFunction extends AbstractHashFunction {

  @SuppressWarnings("Immutable") // cloned before each use

      imports = "com.google.common.io.Files")
  public
  static HashCode hash(File file, HashFunction hashFunction) throws IOException {
    return asByteSource(file).hash(hashFunction);
  }

  /**
   * Fully maps a file read-only in to memory as per {@link
   * FileChannel#map(java.nio.channels.FileChannel.MapMode, long, long)}.
   *
   * <p>Files are mapped from offset 0 to its length.