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PearsonHashing.java
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50 lines (46 loc) · 2.23 KB
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/**
* Hash function designed for fast execution on processors with 8-bit registers.
*
* @author Atom
* @see <a href="https://en.wikipedia.org/wiki/Pearson_hashing">Pearson hashing</a>
* @see <a href="https://tools.ietf.org/html/rfc3074">RFC3074</a>
*/
public class PearsonHashing {
// A "mixing table" of 256 distinct values, in pseudo-random order.
// RFC3074 https://tools.ietf.org/html/rfc3074
private static final char[] mixingTable = {
251, 175, 119, 215, 81, 14, 79, 191, 103, 49, 181, 143, 186, 157, 0,
232, 31, 32, 55, 60, 152, 58, 17, 237, 174, 70, 160, 144, 220, 90, 57,
223, 59, 3, 18, 140, 111, 166, 203, 196, 134, 243, 124, 95, 222, 179,
197, 65, 180, 48, 36, 15, 107, 46, 233, 130, 165, 30, 123, 161, 209, 23,
97, 16, 40, 91, 219, 61, 100, 10, 210, 109, 250, 127, 22, 138, 29, 108,
244, 67, 207, 9, 178, 204, 74, 98, 126, 249, 167, 116, 34, 77, 193,
200, 121, 5, 20, 113, 71, 35, 128, 13, 182, 94, 25, 226, 227, 199, 75,
27, 41, 245, 230, 224, 43, 225, 177, 26, 155, 150, 212, 142, 218, 115,
241, 73, 88, 105, 39, 114, 62, 255, 192, 201, 145, 214, 168, 158, 221,
148, 154, 122, 12, 84, 82, 163, 44, 139, 228, 236, 205, 242, 217, 11,
187, 146, 159, 64, 86, 239, 195, 42, 106, 198, 118, 112, 184, 172, 87,
2, 173, 117, 176, 229, 247, 253, 137, 185, 99, 164, 102, 147, 45, 66,
231, 52, 141, 211, 194, 206, 246, 238, 56, 110, 78, 248, 63, 240, 189,
93, 92, 51, 53, 183, 19, 171, 72, 50, 33, 104, 101, 69, 8, 252, 83, 120,
76, 135, 85, 54, 202, 125, 188, 213, 96, 235, 136, 208, 162, 129, 190,
132, 156, 38, 47, 1, 7, 254, 24, 4, 216, 131, 89, 21, 28, 133, 37, 153,
149, 80, 170, 68, 6, 169, 234, 151
};
public static byte hash(String message) {
char hash = 0;
for (int i = 0; i < message.length(); i++) {
char c = message.charAt(i);
int index = (hash ^ c) & 0x0FF;
hash = mixingTable[index];
}
return (byte) hash;
}
public static void main(String[] args) {
System.out.println(String.format("0x%02X", hash("hello")));
System.out.println(String.format("0x%02X", hash("world")));
System.out.println(String.format("0x%02X", hash("hello, world!")));
System.out.println(String.format("0x%02X", hash("Hello, World!")));
System.out.println(String.format("0x%02X", hash("H€llo, World!")));
}
}