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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.document.predicate;
import com.yahoo.text.Utf8;
/**
* This hash function must match the corresponding C++ hash function in 'ConvertClass',
* currently located at 'rise_platform/src/interface/cpp/api/ConvertClass.h'
*
* @author Magnar Nedland
*/
public class PredicateHash {
@SuppressWarnings("fallthrough")
public static long hash64(String s) {
byte[] bytes = Utf8.toBytes(s);
long a=0L, b=0L;
long c=0x9e3779b97f4a7c13L;
int len = bytes.length;
int offset = 0;
while (len >= 24) {
c += ((0xffL & (long)bytes[offset + 23]) << 56) +
((0xffL & (long)bytes[offset + 22]) << 48) +
((0xffL & (long)bytes[offset + 21]) << 40) +
((0xffL & (long)bytes[offset + 20]) << 32) +
((0xffL & (long)bytes[offset + 19]) << 24) +
((0xffL & (long)bytes[offset + 18]) << 16) +
((0xffL & (long)bytes[offset + 17]) << 8) +
((0xffL & (long)bytes[offset + 16]));
b += ((0xffL & (long)bytes[offset + 15]) << 56) +
((0xffL & (long)bytes[offset + 14]) << 48) +
((0xffL & (long)bytes[offset + 13]) << 40) +
((0xffL & (long)bytes[offset + 12]) << 32) +
((0xffL & (long)bytes[offset + 11]) << 24) +
((0xffL & (long)bytes[offset + 10]) << 16) +
((0xffL & (long)bytes[offset + 9]) << 8) +
((0xffL & (long)bytes[offset + 8]));
a += ((0xffL & (long)bytes[offset + 7]) << 56) +
((0xffL & (long)bytes[offset + 6]) << 48) +
((0xffL & (long)bytes[offset + 5]) << 40) +
((0xffL & (long)bytes[offset + 4]) << 32) +
((0xffL & (long)bytes[offset + 3]) << 24) +
((0xffL & (long)bytes[offset + 2]) << 16) +
((0xffL & (long)bytes[offset + 1]) << 8) +
((0xffL & (long)bytes[offset + 0]));
// Mix. This arithmetic must match the mix below.
a -= b; a -= c; a ^= (c>>>43);
b -= c; b -= a; b ^= (a<<9);
c -= a; c -= b; c ^= (b>>>8);
a -= b; a -= c; a ^= (c>>>38);
b -= c; b -= a; b ^= (a<<23);
c -= a; c -= b; c ^= (b>>>5);
a -= b; a -= c; a ^= (c>>>35);
b -= c; b -= a; b ^= (a<<49);
c -= a; c -= b; c ^= (b>>>11);
a -= b; a -= c; a ^= (c>>>12);
b -= c; b -= a; b ^= (a<<18);
c -= a; c -= b; c ^= (b>>>22);
// End mix.
offset += 24;
len -= 24;
}
c += bytes.length;
switch (len) {
case 23: c+= (0xffL & (long)bytes[offset + 22]) << 56;
case 22: c+= (0xffL & (long)bytes[offset + 21]) << 48;
case 21: c+= (0xffL & (long)bytes[offset + 20]) << 40;
case 20: c+= (0xffL & (long)bytes[offset + 19]) << 32;
case 19: c+= (0xffL & (long)bytes[offset + 18]) << 24;
case 18: c+= (0xffL & (long)bytes[offset + 17]) << 16;
case 17: c+= (0xffL & (long)bytes[offset + 16]) << 8;
// The first byte of c is reserved for the length
case 16: b+= (0xffL & (long)bytes[offset + 15]) << 56;
case 15: b+= (0xffL & (long)bytes[offset + 14]) << 48;
case 14: b+= (0xffL & (long)bytes[offset + 13]) << 40;
case 13: b+= (0xffL & (long)bytes[offset + 12]) << 32;
case 12: b+= (0xffL & (long)bytes[offset + 11]) << 24;
case 11: b+= (0xffL & (long)bytes[offset + 10]) << 16;
case 10: b+= (0xffL & (long)bytes[offset + 9]) << 8;
case 9: b+= (0xffL & (long)bytes[offset + 8]);
case 8: a+= (0xffL & (long)bytes[offset + 7]) << 56;
case 7: a+= (0xffL & (long)bytes[offset + 6]) << 48;
case 6: a+= (0xffL & (long)bytes[offset + 5]) << 40;
case 5: a+= (0xffL & (long)bytes[offset + 4]) << 32;
case 4: a+= (0xffL & (long)bytes[offset + 3]) << 24;
case 3: a+= (0xffL & (long)bytes[offset + 2]) << 16;
case 2: a+= (0xffL & (long)bytes[offset + 1]) << 8;
case 1: a+= (0xffL & (long)bytes[offset + 0]);
}
// Mix. This arithmetic must match the mix above.
a -= b; a -= c; a ^= (c>>>43);
b -= c; b -= a; b ^= (a<<9);
c -= a; c -= b; c ^= (b>>>8);
a -= b; a -= c; a ^= (c>>>38);
b -= c; b -= a; b ^= (a<<23);
c -= a; c -= b; c ^= (b>>>5);
a -= b; a -= c; a ^= (c>>>35);
b -= c; b -= a; b ^= (a<<49);
c -= a; c -= b; c ^= (b>>>11);
a -= b; a -= c; a ^= (c>>>12);
b -= c; b -= a; b ^= (a<<18);
c -= a; c -= b; c ^= (b>>>22);
// End mix.
return c;
}
}
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