Created by Austin Appleby,Authored by Yonik Seeley
package util.hash; /**
* 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 MurmurHash3 { /** 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;
} }