content: package sandbox.hashing;
  
  /**
   *  The MurmurHash3 algorithm was created by Austin Appleby and placed in the public domain.
   *  This java port was authored by Yonik Seeley and also placed into the public domain.
   *  The author hereby disclaims copyright to this source code.
   *  <p>
   *  This produces exactly the same hash values as the final C++
   *  version of MurmurHash3 and is thus suitable for producing the same hash values across
   *  platforms.
   *  <p>
   *  The 32 bit x86 version of this hash should be the fastest variant for relatively short keys like ids.
   *  murmurhash3_x64_128 is a good choice for longer strings or if you need more than 32 bits of hash.
   *  <p>
   *  Note - The x86 and x64 versions do _not_ produce the same results, as the
   *  algorithms are optimized for their respective platforms.
   *  <p>
   *  See http://github.com/yonik/java_util for future updates to this file.
   */
  public final class YonikMurmurHash3 {
  
      /** 128 bits of state */
      public static final class LongPair {
          public long val1;
          public long val2;
      }
  
      public static final int fmix32(int h) {
          h ^= h >>> 16;
          h *= 0x85ebca6b;
          h ^= h >>> 13;
          h *= 0xc2b2ae35;
          h ^= h >>> 16;
          return h;
      }
  
      public static final long fmix64(long k) {
          k ^= k >>> 33;
          k *= 0xff51afd7ed558ccdL;
          k ^= k >>> 33;
          k *= 0xc4ceb9fe1a85ec53L;
          k ^= k >>> 33;
          return k;
      }
  
      /** Gets a long from a byte buffer in little endian byte order. */
      public static final long getLongLittleEndian(byte[] buf, int offset) {
          return     ((long)buf[offset+7]    << 56)   // no mask needed
                     | ((buf[offset+6] & 0xffL) << 48)
                     | ((buf[offset+5] & 0xffL) << 40)
                     | ((buf[offset+4] & 0xffL) << 32)
                     | ((buf[offset+3] & 0xffL) << 24)
                     | ((buf[offset+2] & 0xffL) << 16)
                     | ((buf[offset+1] & 0xffL) << 8)
                     | ((buf[offset  ] & 0xffL));        // no shift needed
      }
  
  
      /** Returns the MurmurHash3_x86_32 hash. */
      public static int murmurhash3_x86_32(byte[] data, int offset, int len, int seed) {
  
          final int c1 = 0xcc9e2d51;
          final int c2 = 0x1b873593;
  
          int h1 = seed;
          int roundedEnd = offset + (len & 0xfffffffc);  // round down to 4 byte block
  
          for (int i=offset; i<roundedEnd; i+=4) {
              // little endian load order
              int k1 = (data[i] & 0xff) | ((data[i+1] & 0xff) << 8) | ((data[i+2] & 0xff) << 16) | (data[i+3] << 24);
              k1 *= c1;
              k1 = (k1 << 15) | (k1 >>> 17);  // ROTL32(k1,15);
              k1 *= c2;
  
              h1 ^= k1;
              h1 = (h1 << 13) | (h1 >>> 19);  // ROTL32(h1,13);
              h1 = h1*5+0xe6546b64;
          }
  
          // tail
          int k1 = 0;
  
          switch(len & 0x03) {
          case 3:
              k1 = (data[roundedEnd + 2] & 0xff) << 16;
              // fallthrough
          case 2:
              k1 |= (data[roundedEnd + 1] & 0xff) << 8;
              // fallthrough
          case 1:
              k1 |= (data[roundedEnd] & 0xff);
              k1 *= c1;
              k1 = (k1 << 15) | (k1 >>> 17);  // ROTL32(k1,15);
              k1 *= c2;
              h1 ^= k1;
          }
  
          // finalization
          h1 ^= len;
  
          // fmix(h1);
          h1 ^= h1 >>> 16;
          h1 *= 0x85ebca6b;
          h1 ^= h1 >>> 13;
          h1 *= 0xc2b2ae35;
          h1 ^= h1 >>> 16;
  
          return h1;
      }
  
  
      /** Returns the MurmurHash3_x86_32 hash of the UTF-8 bytes of the String without actually encoding
       * the string to a temporary buffer.  This is more than 2x faster than hashing the result
       * of String.getBytes().
       */
      public static int murmurhash3_x86_32(CharSequence data, int offset, int len, int seed) {
  
          final int c1 = 0xcc9e2d51;
          final int c2 = 0x1b873593;
  
          int h1 = seed;
  
          int pos = offset;
          int end = offset + len;
          int k1 = 0;
          int k2 = 0;
          int shift = 0;
          int bits = 0;
          int nBytes = 0;   // length in UTF8 bytes
  
  
          while (pos < end) {
              int code = data.charAt(pos++);
              if (code < 0x80) {
                  k2 = code;
                  bits = 8;
  
                  /***
                   // optimized ascii implementation (currently slower!!! code size?)
                   if (shift == 24) {
                   k1 = k1 | (code << 24);
  
                   k1 *= c1;
                   k1 = (k1 << 15) | (k1 >>> 17);  // ROTL32(k1,15);
                   k1 *= c2;
  
                   h1 ^= k1;
                   h1 = (h1 << 13) | (h1 >>> 19);  // ROTL32(h1,13);
                   h1 = h1*5+0xe6546b64;
  
                   shift = 0;
                   nBytes += 4;
                   k1 = 0;
                   } else {
                   k1 |= code << shift;
                   shift += 8;
                   }
                   continue;
                   ***/
  
              }
              else if (code < 0x800) {
                  k2 = (0xC0 | (code >> 6))
                       | ((0x80 | (code & 0x3F)) << 8);
                  bits = 16;
              }
              else if (code < 0xD800 || code > 0xDFFF || pos>=end) {
                  // we check for pos>=end to encode an unpaired surrogate as 3 bytes.
                  k2 = (0xE0 | (code >> 12))
                       | ((0x80 | ((code >> 6) & 0x3F)) << 8)
                       | ((0x80 | (code & 0x3F)) << 16);
                  bits = 24;
              } else {
                  // surrogate pair
                  // int utf32 = pos < end ? (int) data.charAt(pos++) : 0;
                  int utf32 = (int) data.charAt(pos++);
                  utf32 = ((code - 0xD7C0) << 10) + (utf32 & 0x3FF);
                  k2 = (0xff & (0xF0 | (utf32 >> 18)))
                       | ((0x80 | ((utf32 >> 12) & 0x3F))) << 8
                       | ((0x80 | ((utf32 >> 6) & 0x3F))) << 16
                       |  (0x80 | (utf32 & 0x3F)) << 24;
                  bits = 32;
              }
  
  
              k1 |= k2 << shift;
  
              // int used_bits = 32 - shift;  // how many bits of k2 were used in k1.
              // int unused_bits = bits - used_bits; //  (bits-(32-shift)) == bits+shift-32  == bits-newshift
  
              shift += bits;
              if (shift >= 32) {
                  // mix after we have a complete word
  
                  k1 *= c1;
                  k1 = (k1 << 15) | (k1 >>> 17);  // ROTL32(k1,15);
                  k1 *= c2;
  
                  h1 ^= k1;
                  h1 = (h1 << 13) | (h1 >>> 19);  // ROTL32(h1,13);
                  h1 = h1*5+0xe6546b64;
  
                  shift -= 32;
                  // unfortunately, java won't let you shift 32 bits off, so we need to check for 0
                  if (shift != 0) {
                      k1 = k2 >>> (bits-shift);   // bits used == bits - newshift
                  } else {
                      k1 = 0;
                  }
                  nBytes += 4;
              }
  
          } // inner
  
          // handle tail
          if (shift > 0) {
              nBytes += shift >> 3;
              k1 *= c1;
              k1 = (k1 << 15) | (k1 >>> 17);  // ROTL32(k1,15);
              k1 *= c2;
              h1 ^= k1;
          }
  
          // finalization
          h1 ^= nBytes;
  
          // fmix(h1);
          h1 ^= h1 >>> 16;
          h1 *= 0x85ebca6b;
          h1 ^= h1 >>> 13;
          h1 *= 0xc2b2ae35;
          h1 ^= h1 >>> 16;
  
          return h1;
      }
  
  
      /** Returns the MurmurHash3_x64_128 hash, placing the result in "out". */
      public static void murmurhash3_x64_128(byte[] key, int offset, int len, int seed, LongPair out) {
          // The original algorithm does have a 32 bit unsigned seed.
          // We have to mask to match the behavior of the unsigned types and prevent sign extension.
          long h1 = seed & 0x00000000FFFFFFFFL;
          long h2 = seed & 0x00000000FFFFFFFFL;
  
          final long c1 = 0x87c37b91114253d5L;
          final long c2 = 0x4cf5ad432745937fL;
  
          int roundedEnd = offset + (len & 0xFFFFFFF0);  // round down to 16 byte block
          for (int i=offset; i<roundedEnd; i+=16) {
              long k1 = getLongLittleEndian(key, i);
              long k2 = getLongLittleEndian(key, i+8);
              k1 *= c1; k1  = Long.rotateLeft(k1,31); k1 *= c2; h1 ^= k1;
              h1 = Long.rotateLeft(h1,27); h1 += h2; h1 = h1*5+0x52dce729;
              k2 *= c2; k2  = Long.rotateLeft(k2,33); k2 *= c1; h2 ^= k2;
              h2 = Long.rotateLeft(h2,31); h2 += h1; h2 = h2*5+0x38495ab5;
          }
  
          long k1 = 0;
          long k2 = 0;
  
          switch (len & 15) {
          case 15: k2  = (key[roundedEnd+14] & 0xffL) << 48;
          case 14: k2 |= (key[roundedEnd+13] & 0xffL) << 40;
          case 13: k2 |= (key[roundedEnd+12] & 0xffL) << 32;
          case 12: k2 |= (key[roundedEnd+11] & 0xffL) << 24;
          case 11: k2 |= (key[roundedEnd+10] & 0xffL) << 16;
          case 10: k2 |= (key[roundedEnd+ 9] & 0xffL) << 8;
          case  9: k2 |= (key[roundedEnd+ 8] & 0xffL);
              k2 *= c2; k2  = Long.rotateLeft(k2, 33); k2 *= c1; h2 ^= k2;
          case  8: k1  = ((long)key[roundedEnd+7]) << 56;
          case  7: k1 |= (key[roundedEnd+6] & 0xffL) << 48;
          case  6: k1 |= (key[roundedEnd+5] & 0xffL) << 40;
          case  5: k1 |= (key[roundedEnd+4] & 0xffL) << 32;
          case  4: k1 |= (key[roundedEnd+3] & 0xffL) << 24;
          case  3: k1 |= (key[roundedEnd+2] & 0xffL) << 16;
          case  2: k1 |= (key[roundedEnd+1] & 0xffL) << 8;
          case  1: k1 |= (key[roundedEnd  ] & 0xffL);
              k1 *= c1; k1  = Long.rotateLeft(k1,31); k1 *= c2; h1 ^= k1;
          }
  
          //----------
          // finalization
  
          h1 ^= len; h2 ^= len;
  
          h1 += h2;
          h2 += h1;
  
          h1 = fmix64(h1);
          h2 = fmix64(h2);
  
          h1 += h2;
          h2 += h1;
  
          out.val1 = h1;
          out.val2 = h2;
      }
  
  }