/**
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*create by 2012-08-25 pm 17:48
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*@author hexinglun@gmail.com
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*BASE64 Encode and Decode By UTF-8 unicode
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*可以和java的BASE64编码和解码互相转化
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*/
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(function () {
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var BASE64_MAPPING = [
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'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
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'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
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'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
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'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
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'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
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'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
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'w', 'x', 'y', 'z', '0', '1', '2', '3',
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'4', '5', '6', '7', '8', '9', '+', '/'
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];
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/**
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*ascii convert to binary
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*/
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var _toBinary = function (ascii) {
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var binary = new Array();
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while (ascii > 0) {
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var b = ascii % 2;
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ascii = Math.floor(ascii / 2);
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binary.push(b);
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}
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/*
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var len = binary.length;
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if(6-len > 0){
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for(var i = 6-len ; i > 0 ; --i){
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binary.push(0);
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}
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}*/
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binary.reverse();
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return binary;
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};
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/**
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*binary convert to decimal
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*/
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var _toDecimal = function (binary) {
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var dec = 0;
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var p = 0;
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for (var i = binary.length - 1; i >= 0; --i) {
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var b = binary[i];
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if (b == 1) {
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dec += Math.pow(2, p);
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}
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++p;
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}
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return dec;
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};
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/**
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*unicode convert to utf-8
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*/
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var _toUTF8Binary = function (c, binaryArray) {
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var mustLen = (8 - (c + 1)) + ((c - 1) * 6);
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var fatLen = binaryArray.length;
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var diff = mustLen - fatLen;
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while (--diff >= 0) {
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binaryArray.unshift(0);
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}
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var binary = [];
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var _c = c;
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while (--_c >= 0) {
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binary.push(1);
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}
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binary.push(0);
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var i = 0, len = 8 - (c + 1);
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for (; i < len; ++i) {
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binary.push(binaryArray[i]);
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}
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for (var j = 0; j < c - 1; ++j) {
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binary.push(1);
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binary.push(0);
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var sum = 6;
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while (--sum >= 0) {
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binary.push(binaryArray[i++]);
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}
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}
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return binary;
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};
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var __BASE64 = {
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/**
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*BASE64 Encode
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*/
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encoder: function (str) {
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var base64_Index = [];
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var binaryArray = [];
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for (var i = 0, len = str.length; i < len; ++i) {
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var unicode = str.charCodeAt(i);
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var _tmpBinary = _toBinary(unicode);
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if (unicode < 0x80) {
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var _tmpdiff = 8 - _tmpBinary.length;
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while (--_tmpdiff >= 0) {
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_tmpBinary.unshift(0);
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}
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binaryArray = binaryArray.concat(_tmpBinary);
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} else if (unicode >= 0x80 && unicode <= 0x7FF) {
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binaryArray = binaryArray.concat(_toUTF8Binary(2, _tmpBinary));
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} else if (unicode >= 0x800 && unicode <= 0xFFFF) {//UTF-8 3byte
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binaryArray = binaryArray.concat(_toUTF8Binary(3, _tmpBinary));
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} else if (unicode >= 0x10000 && unicode <= 0x1FFFFF) {//UTF-8 4byte
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binaryArray = binaryArray.concat(_toUTF8Binary(4, _tmpBinary));
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} else if (unicode >= 0x200000 && unicode <= 0x3FFFFFF) {//UTF-8 5byte
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binaryArray = binaryArray.concat(_toUTF8Binary(5, _tmpBinary));
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} else if (unicode >= 4000000 && unicode <= 0x7FFFFFFF) {//UTF-8 6byte
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binaryArray = binaryArray.concat(_toUTF8Binary(6, _tmpBinary));
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}
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}
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var extra_Zero_Count = 0;
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for (var i = 0, len = binaryArray.length; i < len; i += 6) {
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var diff = (i + 6) - len;
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if (diff == 2) {
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extra_Zero_Count = 2;
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} else if (diff == 4) {
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extra_Zero_Count = 4;
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}
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//if(extra_Zero_Count > 0){
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// len += extra_Zero_Count+1;
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//}
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var _tmpExtra_Zero_Count = extra_Zero_Count;
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while (--_tmpExtra_Zero_Count >= 0) {
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binaryArray.push(0);
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}
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base64_Index.push(_toDecimal(binaryArray.slice(i, i + 6)));
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}
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var base64 = '';
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for (var i = 0, len = base64_Index.length; i < len; ++i) {
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base64 += BASE64_MAPPING[base64_Index[i]];
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}
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for (var i = 0, len = extra_Zero_Count / 2; i < len; ++i) {
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base64 += '=';
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}
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return base64;
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},
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/**
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*BASE64 Decode for UTF-8
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*/
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decoder: function (_base64Str) {
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var _len = _base64Str.length;
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var extra_Zero_Count = 0;
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/**
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*计算在进行BASE64编码的时候，补了几个0
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*/
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if (_base64Str.charAt(_len - 1) == '=') {
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//alert(_base64Str.charAt(_len-1));
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//alert(_base64Str.charAt(_len-2));
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if (_base64Str.charAt(_len - 2) == '=') {//两个等号说明补了4个0
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extra_Zero_Count = 4;
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_base64Str = _base64Str.substring(0, _len - 2);
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} else {//一个等号说明补了2个0
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extra_Zero_Count = 2;
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_base64Str = _base64Str.substring(0, _len - 1);
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}
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}
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var binaryArray = [];
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for (var i = 0, len = _base64Str.length; i < len; ++i) {
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var c = _base64Str.charAt(i);
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for (var j = 0, size = BASE64_MAPPING.length; j < size; ++j) {
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if (c == BASE64_MAPPING[j]) {
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var _tmp = _toBinary(j);
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/*不足6位的补0*/
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var _tmpLen = _tmp.length;
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if (6 - _tmpLen > 0) {
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for (var k = 6 - _tmpLen; k > 0; --k) {
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_tmp.unshift(0);
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}
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}
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binaryArray = binaryArray.concat(_tmp);
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break;
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}
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}
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}
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if (extra_Zero_Count > 0) {
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binaryArray = binaryArray.slice(0, binaryArray.length - extra_Zero_Count);
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}
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var unicode = [];
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var unicodeBinary = [];
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for (var i = 0, len = binaryArray.length; i < len;) {
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if (binaryArray[i] == 0) {
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unicode = unicode.concat(_toDecimal(binaryArray.slice(i, i + 8)));
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i += 8;
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} else {
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var sum = 0;
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while (i < len) {
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if (binaryArray[i] == 1) {
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++sum;
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} else {
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break;
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}
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++i;
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}
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unicodeBinary = unicodeBinary.concat(binaryArray.slice(i + 1, i + 8 - sum));
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i += 8 - sum;
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while (sum > 1) {
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unicodeBinary = unicodeBinary.concat(binaryArray.slice(i + 2, i + 8));
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i += 8;
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--sum;
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}
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unicode = unicode.concat(_toDecimal(unicodeBinary));
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unicodeBinary = [];
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}
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}
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return unicode;
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}
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};
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window.BASE64 = __BASE64;
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})();
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