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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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namespace POSV.Utils
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{
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public class HashUtils
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{
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// BKDR Hash Function
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public static int Hash1(string str)
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{
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int seed = 131; // 31 131 1313 13131 131313 etc..
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int hash = 0;
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int count;
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char[] bitarray = str.ToCharArray();
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count = bitarray.Length;
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while (count > 0)
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{
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hash = hash * seed + (bitarray[bitarray.Length - count]);
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count--;
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}
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return (hash & 0x7FFFFFFF);
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}
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//AP hash function
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public static int Hash2(string str)
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{
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int hash = 0;
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int i;
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int count;
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char[] bitarray = str.ToCharArray();
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count = bitarray.Length;
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for (i = 0; i < count; i++)
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{
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if ((i & 1) == 0)
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{
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hash ^= ((hash << 7) ^ (bitarray[i]) ^ (hash >> 3));
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}
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else
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{
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hash ^= (~((hash << 11) ^ (bitarray[i]) ^ (hash >> 5)));
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}
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count--;
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}
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return (hash & 0x7FFFFFFF);
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}
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//SDBM Hash function
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public static int Hash3(string str)
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{
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int hash = 0;
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int i;
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int count;
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char[] bitarray = str.ToCharArray();
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count = bitarray.Length;
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while (count > 0)
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{
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// equivalent to: hash = 65599*hash + (*str++);
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hash = (bitarray[bitarray.Length - count]) + (hash << 6) + (hash << 16) - hash;
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count--;
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}
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return (hash & 0x7FFFFFFF);
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}
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// RS Hash Function
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public static int Hash4(string str)
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{
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int b = 378551;
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int a = 63689;
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int hash = 0;
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int i;
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int count;
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char[] bitarray = str.ToCharArray();
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count = bitarray.Length;
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while (count > 0)
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{
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hash = hash * a + (bitarray[bitarray.Length - count]);
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a *= b;
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count--;
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}
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return (hash & 0x7FFFFFFF);
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}
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// JS Hash Function
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public static int Hash5(string str)
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{
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int hash = 1315423911;
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int count;
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char[] bitarray = str.ToCharArray();
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count = bitarray.Length;
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while (count > 0)
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{
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hash ^= ((hash << 5) + (bitarray[bitarray.Length - count]) + (hash >> 2));
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count--;
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}
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return (hash & 0x7FFFFFFF);
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}
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// P. J. Weinberger Hash Function
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public static int Hash6(string str)
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{
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int BitsInUnignedInt = (int)(sizeof(int) * 8);
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int ThreeQuarters = (int)((BitsInUnignedInt * 3) / 4);
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int OneEighth = (int)(BitsInUnignedInt / 8);
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int hash = 0;
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unchecked
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{
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int HighBits = (int)(0xFFFFFFFF) << (BitsInUnignedInt - OneEighth);
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int test = 0;
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int count;
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char[] bitarray = str.ToCharArray();
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count = bitarray.Length;
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while (count > 0)
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{
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hash = (hash << OneEighth) + (bitarray[bitarray.Length - count]);
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if ((test = hash & HighBits) != 0)
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{
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hash = ((hash ^ (test >> ThreeQuarters)) & (~HighBits));
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}
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count--;
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}
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}
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return (hash & 0x7FFFFFFF);
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}
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// ELF Hash Function
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public static int Hash7(string str)
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{
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int hash = 0;
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int x = 0;
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int i;
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int count;
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char[] bitarray = str.ToCharArray();
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count = bitarray.Length;
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unchecked
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{
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while (count > 0)
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{
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hash = (hash << 4) + (bitarray[bitarray.Length - count]);
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if ((x = hash & (int)0xF0000000) != 0)
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{
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hash ^= (x >> 24);
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hash &= ~x;
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}
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count--;
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}
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}
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return (hash & 0x7FFFFFFF);
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}
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// DJB Hash Function
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public static int Hash8(string str)
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{
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int hash = 5381;
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int i;
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int count;
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char[] bitarray = str.ToCharArray();
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count = bitarray.Length;
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while (count > 0)
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{
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hash += (hash << 5) + (bitarray[bitarray.Length - count]);
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count--;
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}
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return (hash & 0x7FFFFFFF);
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}
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}
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}
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