/* xxtea.js
 *
 * Author:       Ma Bingyao <andot@ujn.edu.cn>
 * Copyright:    CoolCode.CN
 * Version:      1.21
 * LastModified: 2006-06-17
 * This library is free.  You can redistribute it and/or modify it.
 * http://www.coolcode.cn/?p=128
 */

function long2str(v, w) {
    var vl = v.length;
    var sl = v[vl - 1] & 0xffffffff;
    for (var i = 0; i < vl; i++)
    {
        v[i] = String.fromCharCode(v[i] & 0xff,
                                   v[i] >>> 8 & 0xff,
                                   v[i] >>> 16 & 0xff, 
                                   v[i] >>> 24 & 0xff);
    }
    if (w) {
        return v.join('').substring(0, sl);
    }
    else {
        return v.join('');
    }
}

function str2long(s, w) {
    var len = s.length;
    var v = [];
    for (var i = 0; i < len; i += 4)
    {
        v[i >> 2] = s.charCodeAt(i)
                  | s.charCodeAt(i + 1) << 8
                  | s.charCodeAt(i + 2) << 16
                  | s.charCodeAt(i + 3) << 24;
    }
    if (w) {
        v[v.length] = len;
    }
    return v;
}



function xxtea_encrypt(str, key) {
    if (str == "") {
        return "";
    }
    var v = str2long(str, true);
    var k = str2long(key, false);
    var n = v.length - 1;

    var z = v[n], y = v[0], delta = 0x9E3779B9;
    var mx, e, q = Math.floor(6 + 52 / (n + 1)), sum = 0;
    while (0 < q--) {
        sum = sum + delta & 0xffffffff;
        e = sum >>> 2 & 3;
        for (var p = 0; p < n; p++) {
            y = v[p + 1];
            mx = (z >>> 5 ^ y << 2) + (y >>> 3 ^ z << 4) ^ (sum ^ y) + (k[p & 3 ^ e] ^ z);
            z = v[p] = v[p] + mx & 0xffffffff;
        }
        y = v[0];
        mx = (z >>> 5 ^ y << 2) + (y >>> 3 ^ z << 4) ^ (sum ^ y) + (k[p & 3 ^ e] ^ z);
        z = v[n] = v[n] + mx & 0xffffffff;
    }

    return long2str(v, false);
}

function xxtea_decrypt(str, key) {
    if (str == "") {
        return "";
    }
    var v = str2long(str, false);
    var k = str2long(key, false);
    var n = v.length - 1;

    var z = v[n - 1], y = v[0], delta = 0x9E3779B9;
    var mx, e, q = Math.floor(6 + 52 / (n + 1)), sum = q * delta & 0xffffffff;
    while (sum != 0) {
        e = sum >>> 2 & 3;
        for (var p = n; p > 0; p--) {
            z = v[p - 1];
            mx = (z >>> 5 ^ y << 2) + (y >>> 3 ^ z << 4) ^ (sum ^ y) + (k[p & 3 ^ e] ^ z);
            y = v[p] = v[p] - mx & 0xffffffff;
        }
        z = v[n];
        mx = (z >>> 5 ^ y << 2) + (y >>> 3 ^ z << 4) ^ (sum ^ y) + (k[p & 3 ^ e] ^ z);
        y = v[0] = v[0] - mx & 0xffffffff;
        sum = sum - delta & 0xffffffff;
    }

    return long2str(v, true);
}

/*
 * Interfaces:
 * utf8 = utf16to8(utf16);
 * utf16 = utf16to8(utf8);
 */

function utf16to8(str) {
    var out, i, len, c;

    out = [];
    len = str.length;
    for(i = 0; i < len; i++) {
	    c = str.charCodeAt(i);
	    if ((c >= 0x0001) && (c <= 0x007F)) {
	        out[i] = str.charAt(i);
	    } else if (c > 0x07FF) {
	        out[i] = String.fromCharCode(0xE0 | ((c >> 12) & 0x0F),
	                                     0x80 | ((c >>  6) & 0x3F),
	                                     0x80 | ((c >>  0) & 0x3F));
	    } else {
	        out[i] = String.fromCharCode(0xC0 | ((c >>  6) & 0x1F),
	                                     0x80 | ((c >>  0) & 0x3F));
	    }
    }
    return out.join('');
}

function utf8to16(str) {
    var out, i, len, c;
    var char2, char3;

    out = [];
    len = str.length;
    i = 0;
    while(i < len) {
	    c = str.charCodeAt(i++);
	    switch(c >> 4)
	    { 
	        case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7:
	        // 0xxxxxxx
	        out[out.length] = str.charAt(i-1);
	        break;
	        case 12: case 13:
    	    // 110x xxxx   10xx xxxx
	        char2 = str.charCodeAt(i++);
	        out[out.length] = String.fromCharCode(((c & 0x1F) << 6) | (char2 & 0x3F));
    	    break;
            case 14:
    	    // 1110 xxxx  10xx xxxx  10xx xxxx
	        char2 = str.charCodeAt(i++);
	        char3 = str.charCodeAt(i++);
    	    out[out.length] = String.fromCharCode(((c & 0x0F) << 12) |
	    	    ((char2 & 0x3F) << 6) | ((char3 & 0x3F) << 0));
	        break;
    	}
    }

    return out.join('');
}

/**
* xxtea 安全加密(中文)
*/
function xxtea_encrypt_safe(str,key){
	return xxtea_encrypt(utf16to8(str),key);
}
/**
* xxtea 安全解密(中文)
*/
function xxtea_decrypt_safe(str,key){
	return utf8to16(xxtea_decrypt(str, key));
}