package org.frameworkset.util;

public class HashUtil {
	/**//**
	 * 加法hash
	 * 
	 * @param key
	 *            字符串
	 * @param prime
	 *            一个质数
	 * @return hash结果
	 */
	public static int additiveHash(String key, int prime) {
		int hash, i;
		for (hash = key.length(), i = 0; i < key.length(); i++)
			hash += key.charAt(i);
		return (hash % prime);
	}

	/**//**
	 * 旋转hash
	 * 
	 * @param key
	 *            输入字符串
	 * @param prime
	 *            质数
	 * @return hash值
	 */
	public static int rotatingHash(String key, int prime) {
		int hash, i;
		for (hash = key.length(), i = 0; i < key.length(); ++i)
			hash = (hash << 4) ^ (hash >> 28) ^ key.charAt(i);
		return (hash % prime);
		// return (hash ^ (hash>>10) ^ (hash>>20));
	}

	// 替代：
	// 使用：hash = (hash ^ (hash>>10) ^ (hash>>20)) & mask;
	// 替代：hash %= prime;

	/**//**
	 * MASK值，随便找一个值，最好是质数
	 */
	static int M_MASK = 0x8765fed1;

	/**//**
	 * 一次一个hash
	 * 
	 * @param key
	 *            输入字符串
	 * @return 输出hash值
	 */
	public static int oneByOneHash(String key) {
		int hash, i;
		for (hash = 0, i = 0; i < key.length(); ++i) {
			hash += key.charAt(i);
			hash += (hash << 10);
			hash ^= (hash >> 6);
		}
		hash += (hash << 3);
		hash ^= (hash >> 11);
		hash += (hash << 15);
		// return (hash & M_MASK);
		return hash;
	}

	/**//**
	 * Bernstein's hash
	 * 
	 * @param key
	 *            输入字节数组
	 * @param level
	 *            初始hash常量
	 * @return 结果hash
	 */
	public static int bernstein(String key) {
		int hash = 0;
		int i;
		for (i = 0; i < key.length(); ++i)
			hash = 33 * hash + key.charAt(i);
		return hash;
	}

	//
	/**/// // Pearson's Hash
	// char pearson(char[]key, ub4 len, char tab[256])
	// {
	// char hash;
	// ub4 i;
	// for (hash=len, i=0; i<len; ++i)
	// hash=tab[hash^key[i]];
	// return (hash);
	// }

	/**/// // CRC Hashing，计算crc,具体代码见其他
	// ub4 crc(char *key, ub4 len, ub4 mask, ub4 tab[256])
	// {
	// ub4 hash, i;
	// for (hash=len, i=0; i<len; ++i)
	// hash = (hash >> 8) ^ tab[(hash & 0xff) ^ key[i]];
	// return (hash & mask);
	// }

	/**//**
	 * Universal Hashing
	 */
	public static int universal(char[] key, int mask, int[] tab) {
		int hash = key.length, i, len = key.length;
		for (i = 0; i < (len << 3); i += 8) {
			char k = key[i >> 3];
			if ((k & 0x01) == 0)
				hash ^= tab[i + 0];
			if ((k & 0x02) == 0)
				hash ^= tab[i + 1];
			if ((k & 0x04) == 0)
				hash ^= tab[i + 2];
			if ((k & 0x08) == 0)
				hash ^= tab[i + 3];
			if ((k & 0x10) == 0)
				hash ^= tab[i + 4];
			if ((k & 0x20) == 0)
				hash ^= tab[i + 5];
			if ((k & 0x40) == 0)
				hash ^= tab[i + 6];
			if ((k & 0x80) == 0)
				hash ^= tab[i + 7];
		}
		return (hash & mask);
	}

	/**//**
	 * Zobrist Hashing
	 */
	public static int zobrist(char[] key, int mask, int[][] tab) {
		int hash, i;
		for (hash = key.length, i = 0; i < key.length; ++i)
			hash ^= tab[i][key[i]];
		return (hash & mask);
	}

	// LOOKUP3
	// 见Bob Jenkins(3).c文件

	// 32位FNV算法
	static int M_SHIFT = 0;

	/**//**
	 * 32位的FNV算法
	 * 
	 * @param data
	 *            数组
	 * @return int值
	 */
	public static int FNVHash(byte[] data) {
		int hash = (int) 2166136261L;
		for (byte b : data)
			hash = (hash * 16777619) ^ b;
		if (M_SHIFT == 0)
			return hash;
		return (hash ^ (hash >> M_SHIFT)) & M_MASK;
	}

	/**//**
	 * 改进的32位FNV算法1
	 * 
	 * @param data
	 *            数组
	 * @return int值
	 */
	public static int FNVHash1(byte[] data) {
		final int p = 16777619;
		int hash = (int) 2166136261L;
		for (byte b : data)
			hash = (hash ^ b) * p;
		hash += hash << 13;
		hash ^= hash >> 7;
		hash += hash << 3;
		hash ^= hash >> 17;
		hash += hash << 5;
		return hash;
	}

	/**//**
	 * 改进的32位FNV算法1
	 * 
	 * @param data
	 *            字符串
	 * @return int值
	 */
	public static int FNVHash1(String data) {
		final int p = 16777619;
		int hash = (int) 2166136261L;
		for (int i = 0; i < data.length(); i++)
			hash = (hash ^ data.charAt(i)) * p;
		hash += hash << 13;
		hash ^= hash >> 7;
		hash += hash << 3;
		hash ^= hash >> 17;
		hash += hash << 5;
		return hash;
	}

	/**//**
	 * Thomas Wang的算法，整数hash
	 */
	public static int intHash(int key) {
		key += ~(key << 15);
		key ^= (key >>> 10);
		key += (key << 3);
		key ^= (key >>> 6);
		key += ~(key << 11);
		key ^= (key >>> 16);
		return key;
	}

	/**//**
	 * RS算法hash
	 * 
	 * @param str
	 *            字符串
	 */
	public static int RSHash(String str) {
		int b = 378551;
		int a = 63689;
		int hash = 0;

		for (int i = 0; i < str.length(); i++) {
			hash = hash * a + str.charAt(i);
			a = a * b;
		}

		return (hash & 0x7FFFFFFF);
	}

	/**//* End Of RS Hash Function */

	/**//**
	 * JS算法
	 */
	public static int JSHash(String str) {
		int hash = 1315423911;

		for (int i = 0; i < str.length(); i++) {
			hash ^= ((hash << 5) + str.charAt(i) + (hash >> 2));
		}

		return (hash & 0x7FFFFFFF);
	}

	/**//* End Of JS Hash Function */

	/**//**
	 * PJW算法
	 */
	public static int PJWHash(String str) {
		int BitsInUnsignedInt = 32;
		int ThreeQuarters = (BitsInUnsignedInt * 3) / 4;
		int OneEighth = BitsInUnsignedInt / 8;
		int HighBits = 0xFFFFFFFF << (BitsInUnsignedInt - OneEighth);
		int hash = 0;
		int test = 0;

		for (int i = 0; i < str.length(); i++) {
			hash = (hash << OneEighth) + str.charAt(i);

			if ((test = hash & HighBits) != 0) {
				hash = ((hash ^ (test >> ThreeQuarters)) & (~HighBits));
			}
		}

		return (hash & 0x7FFFFFFF);
	}

	/**//* End Of P. J. Weinberger Hash Function */

	/**//**
	 * ELF算法
	 */
	public static int ELFHash(String str) {
		int hash = 0;
		int x = 0;

		for (int i = 0; i < str.length(); i++) {
			hash = (hash << 4) + str.charAt(i);
			if ((x = (int) (hash & 0xF0000000L)) != 0) {
				hash ^= (x >> 24);
				hash &= ~x;
			}
		}

		return (hash & 0x7FFFFFFF);
	}

	/**//* End Of ELF Hash Function */

	/**//**
	 * BKDR算法
	 */
	public static int BKDRHash(String str) {
		int seed = 131; // 31 131 1313 13131 131313 etc..
		int hash = 0;

		for (int i = 0; i < str.length(); i++) {
			hash = (hash * seed) + str.charAt(i);
		}

		return (hash & 0x7FFFFFFF);
	}

	/**//* End Of BKDR Hash Function */

	/**//**
	 * SDBM算法
	 */
	public static int SDBMHash(String str) {
		int hash = 0;

		for (int i = 0; i < str.length(); i++) {
			hash = str.charAt(i) + (hash << 6) + (hash << 16) - hash;
		}

		return (hash & 0x7FFFFFFF);
	}

	/**//* End Of SDBM Hash Function */

	/**//**
	 * DJB算法
	 */
	public static int DJBHash(String str) {
		int hash = 5381;

		for (int i = 0; i < str.length(); i++) {
			hash = ((hash << 5) + hash) + str.charAt(i);
		}

		return (hash & 0x7FFFFFFF);
	}

	/**//* End Of DJB Hash Function */

	/**//**
	 * DEK算法
	 */
	public static int DEKHash(String str) {
		int hash = str.length();

		for (int i = 0; i < str.length(); i++) {
			hash = ((hash << 5) ^ (hash >> 27)) ^ str.charAt(i);
		}

		return (hash & 0x7FFFFFFF);
	}

	/**//* End Of DEK Hash Function */

	/**//**
	 * AP算法
	 */
	public static int APHash(String str) {
		int hash = 0;

		for (int i = 0; i < str.length(); i++) {
			hash ^= ((i & 1) == 0) ? ((hash << 7) ^ str.charAt(i) ^ (hash >> 3))
					: (~((hash << 11) ^ str.charAt(i) ^ (hash >> 5)));
		}

		// return (hash & 0x7FFFFFFF);
		return hash;
	}

	/**//* End Of AP Hash Function */

	/**//**
	 * JAVA自己带的算法
	 */
	public static int java(String str) {
		int h = 0;
		int off = 0;
		int len = str.length();
		for (int i = 0; i < len; i++) {
			h = 31 * h + str.charAt(off++);
		}
		return h;
	}

	/**//**
	 * 混合hash算法，输出64位的值
	 */
	public static long mixHash(String str) {
		long hash = str.hashCode();
		hash <<= 32;
		hash |= FNVHash1(str);
		return hash;
	}
	

}
