content: package com.alibaba.fastjson2.util;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.math.BigDecimal;
  import java.math.BigInteger;
  import java.nio.charset.StandardCharsets;
  import java.time.Instant;
  
  import static com.alibaba.fastjson2.util.JDKUtils.UNSAFE;
  import static java.lang.Long.rotateLeft;
  import static java.lang.Math.min;
  import static sun.misc.Unsafe.ARRAY_BYTE_BASE_OFFSET;
  
  public final class XxHash64 {
      private static final long PRIME64_1 = 0x9E3779B185EBCA87L;
      private static final long PRIME64_2 = 0xC2B2AE3D27D4EB4FL;
      private static final long PRIME64_3 = 0x165667B19E3779F9L;
      private static final long PRIME64_4 = 0x85EBCA77C2b2AE63L;
      private static final long PRIME64_5 = 0x27D4EB2F165667C5L;
  
      private static final long DEFAULT_SEED = 0;
  
      private final long seed;
  
      private static final long BUFFER_ADDRESS = ARRAY_BYTE_BASE_OFFSET;
      private final byte[] buffer = new byte[32];
      private int bufferSize;
  
      private long bodyLength;
  
      private long v1;
      private long v2;
      private long v3;
      private long v4;
  
      public XxHash64() {
          this(DEFAULT_SEED);
      }
  
      public XxHash64(long seed) {
          this.seed = seed;
          this.v1 = seed + PRIME64_1 + PRIME64_2;
          this.v2 = seed + PRIME64_2;
          this.v3 = seed;
          this.v4 = seed - PRIME64_1;
      }
  
      public XxHash64 update(byte[] data) {
          return update(data, 0, data.length);
      }
  
      public XxHash64 update(byte[] data, int offset, int length) {
          checkPositionIndexes(offset, offset + length, data.length);
          updateHash(data, ARRAY_BYTE_BASE_OFFSET + offset, length);
          return this;
      }
  
      public long hash() {
          long hash;
          if (bodyLength > 0) {
              hash = computeBody();
          } else {
              hash = seed + PRIME64_5;
          }
  
          hash += bodyLength + bufferSize;
  
          return updateTail(hash, buffer, BUFFER_ADDRESS, 0, bufferSize);
      }
  
      private long computeBody() {
          long hash = rotateLeft(v1, 1) + rotateLeft(v2, 7) + rotateLeft(v3, 12) + rotateLeft(v4, 18);
  
          hash = update(hash, v1);
          hash = update(hash, v2);
          hash = update(hash, v3);
          hash = update(hash, v4);
  
          return hash;
      }
  
      private void updateHash(Object base, long address, int length) {
          if (bufferSize > 0) {
              int available = min(32 - bufferSize, length);
  
              UNSAFE.copyMemory(base, address, buffer, BUFFER_ADDRESS + bufferSize, available);
  
              bufferSize += available;
              address += available;
              length -= available;
  
              if (bufferSize == 32) {
                  updateBody(buffer, BUFFER_ADDRESS, bufferSize);
                  bufferSize = 0;
              }
          }
  
          if (length >= 32) {
              int index = updateBody(base, address, length);
              address += index;
              length -= index;
          }
  
          if (length > 0) {
              UNSAFE.copyMemory(base, address, buffer, BUFFER_ADDRESS, length);
              bufferSize = length;
          }
      }
  
      private int updateBody(Object base, long address, int length) {
          int remaining = length;
          while (remaining >= 32) {
              v1 = mix(v1, UNSAFE.getLong(base, address));
              v2 = mix(v2, UNSAFE.getLong(base, address + 8));
              v3 = mix(v3, UNSAFE.getLong(base, address + 16));
              v4 = mix(v4, UNSAFE.getLong(base, address + 24));
  
              address += 32;
              remaining -= 32;
          }
  
          int index = length - remaining;
          bodyLength += index;
          return index;
      }
  
      public static long hash(long value) {
          long hash = DEFAULT_SEED + PRIME64_5 + SizeOf.SIZE_OF_LONG;
          hash = updateTail(hash, value);
          hash = finalShuffle(hash);
  
          return hash;
      }
  
      public static long hash(double value) {
          long longValue = (long) value;
          if (longValue != value) {
              longValue = Double.doubleToLongBits(value);
          }
  
          long hash = DEFAULT_SEED + PRIME64_5 + SizeOf.SIZE_OF_LONG;
          hash = updateTail(hash, longValue);
          hash = finalShuffle(hash);
  
          return hash;
      }
  
      public static long hash(Instant instant) {
          long seconds = instant.getEpochSecond();
          int nanos = instant.getNano();
          long millis;
          int nanos2;
          if (seconds < 0 && nanos > 0) {
              millis = Math.multiplyExact(seconds + 1, 1000);
              long adjustment = nanos / 1000_000 - 1000;
              millis = Math.addExact(millis, adjustment);
              nanos2 = nanos + (nanos / 1000) * 1000;
          } else {
              millis = Math.multiplyExact(seconds, 1000);
              millis = Math.addExact(millis, nanos / 1000_000);
              nanos2 = nanos - (nanos / 1000) * 1000;
          }
          return hash(millis, nanos2);
      }
  
      public static long hash(long v1, long v2) {
          long hash = DEFAULT_SEED + PRIME64_5 + SizeOf.SIZE_OF_LONG;
          hash = updateTail(hash, v1);
          hash = updateTail(hash, v2);
          hash = finalShuffle(hash);
          return hash;
      }
  
      static final BigInteger INT64_MIN = BigInteger.valueOf(Long.MIN_VALUE);
      static final BigInteger INT64_MAX = BigInteger.valueOf(Long.MAX_VALUE);
      public static long hash(BigInteger value) {
          if (INT64_MIN.compareTo(value) <= 0 && INT64_MAX.compareTo(value) >= 0) {
              long longValue = value.longValue();
              long hash = DEFAULT_SEED + PRIME64_5 + SizeOf.SIZE_OF_LONG;
              hash = updateTail(hash, longValue);
              hash = finalShuffle(hash);
  
              return hash;
          }
  
          String str = value.toString();
          byte[] bytes = str.getBytes();
          return hash(0, bytes, 0, bytes.length);
      }
  
      public static long hash(BigDecimal value) {
          value = value.stripTrailingZeros();
          if (value.scale() == 0) {
              return hash(value.unscaledValue());
          }
  
          byte[] bytes = value.toPlainString().getBytes();
          return hash(0, bytes, 0, bytes.length);
      }
  
      public static long hash(String value) {
          byte[] bytes = value.getBytes(StandardCharsets.UTF_8);
          return hash(0, bytes, 0, bytes.length);
      }
  
      public static long hash(long seed, byte[] bytes, int off, int len) {
          XxHash64 hash = new XxHash64(seed);
          hash.update(bytes, 0, len);
          return hash.hash();
      }
  
      public static long hash(InputStream in)
              throws IOException {
          return hash(DEFAULT_SEED, in);
      }
  
      public static long hash(long seed, InputStream in)
              throws IOException {
          XxHash64 hash = new XxHash64(seed);
          byte[] buffer = new byte[8192];
          while (true) {
              int length = in.read(buffer);
              if (length == -1) {
                  break;
              }
              hash.update(buffer, 0, length);
          }
          return hash.hash();
      }
  
      private static long updateTail(long hash, Object base, long address, int index, int length) {
          while (index <= length - 8) {
              hash = updateTail(hash, UNSAFE.getLong(base, address + index));
              index += 8;
          }
  
          if (index <= length - 4) {
              hash = updateTail(hash, UNSAFE.getInt(base, address + index));
              index += 4;
          }
  
          while (index < length) {
              hash = updateTail(hash, UNSAFE.getByte(base, address + index));
              index++;
          }
  
          hash = finalShuffle(hash);
  
          return hash;
      }
  
      private static long mix(long current, long value) {
          return rotateLeft(current + value * PRIME64_2, 31) * PRIME64_1;
      }
  
      private static long update(long hash, long value) {
          long temp = hash ^ mix(0, value);
          return temp * PRIME64_1 + PRIME64_4;
      }
  
      private static long updateTail(long hash, long value) {
          long temp = hash ^ mix(0, value);
          return rotateLeft(temp, 27) * PRIME64_1 + PRIME64_4;
      }
  
      private static long updateTail(long hash, int value) {
          long unsigned = value & 0xFFFF_FFFFL;
          long temp = hash ^ (unsigned * PRIME64_1);
          return rotateLeft(temp, 23) * PRIME64_2 + PRIME64_3;
      }
  
      private static long updateTail(long hash, byte value) {
          int unsigned = value & 0xFF;
          long temp = hash ^ (unsigned * PRIME64_5);
          return rotateLeft(temp, 11) * PRIME64_1;
      }
  
      private static long finalShuffle(long hash) {
          hash ^= hash >>> 33;
          hash *= PRIME64_2;
          hash ^= hash >>> 29;
          hash *= PRIME64_3;
          hash ^= hash >>> 32;
          return hash;
      }
  
      public static void checkPositionIndexes(int start, int end, int size) {
          // Carefully optimized for execution by hotspot (explanatory comment above)
          if (start < 0 || end < start || end > size) {
              throw new IndexOutOfBoundsException();
          }
      }
  
      interface SizeOf {
          byte SIZE_OF_BYTE = 1;
          byte SIZE_OF_SHORT = 2;
          byte SIZE_OF_INT = 4;
          byte SIZE_OF_LONG = 8;
          byte SIZE_OF_FLOAT = 4;
          byte SIZE_OF_DOUBLE = 8;
      }
  }
  