几个常用字符串hash算法的node封装

为下一步开发做的一些技术储备

把一些常用的字符串hash算法做了一下封装

代码如下

// hash.js

exports.additive = function (key, prime) {

	key = key instanceof Buffer ? key : new Buffer(key);

	prime = prime == undefined ? 0xffffffff : prime;

	for (var hash = key.length, i = 0; i < key.length; i++) {

		hash += key[i];

	}

	return (hash % prime);

}



exports.rotating = function(key) {

	key = key instanceof Buffer ? key : new Buffer(key);

	for (var hash = key.length, i = 0; i		hash = (hash << 4) ^ (hash >> 28) ^ key[i];

	}

	return hash;

}



exports.bernstein = function(key, prime) {

	key = key instanceof Buffer ? key : new Buffer(key);

	prime = prime == undefined ? 0xffffffff : prime;

	var hash = 0;

	for (i=0; i		hash =  (hash << 5 + hash) + key[i];

	}

	return hash;

}



exports.fnv = function (key){

	key = key instanceof Buffer ? key : new Buffer(key);

	var p = 16777619, hash = 0x811C9DC5;

	for(var i=0; i< key.length; i++) {

		hash = (hash * p) ^ key[i];

	}

	hash += hash << 13;

	hash ^= hash >> 7;

	hash += hash << 3;

	hash ^= hash >> 17;

	hash += hash << 5;

	return hash;

}



exports.fnv1a = function (key){

	key = key instanceof Buffer ? key : new Buffer(key);

	var p = 16777619, hash = 0x811C9DC5;

	for(var i=0; i< key.length; i++) {

		hash = (hash ^ key[i]) * p;

	}

	hash += hash << 13;

	hash ^= hash >> 7;

	hash += hash << 3;

	hash ^= hash >> 17;

	hash += hash << 5;

	return hash;

}