(function (exports) {
  	'use strict';
  
  	var lookup = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
  
  	function b64ToByteArray(b64) {
  		var i, j, l, tmp, placeHolders, arr;
  	
  		if (b64.length % 4 > 0) {
  			throw 'Invalid string. Length must be a multiple of 4';
  		}
  
  		// the number of equal signs (place holders)
  		// if there are two placeholders, than the two characters before it
  		// represent one byte
  		// if there is only one, then the three characters before it represent 2 bytes
  		// this is just a cheap hack to not do indexOf twice
  		placeHolders = b64.indexOf('=');
  		placeHolders = placeHolders > 0 ? b64.length - placeHolders : 0;
  
  		// base64 is 4/3 + up to two characters of the original data
  		arr = [];//new Uint8Array(b64.length * 3 / 4 - placeHolders);
  
  		// if there are placeholders, only get up to the last complete 4 chars
  		l = placeHolders > 0 ? b64.length - 4 : b64.length;
  
  		for (i = 0, j = 0; i < l; i += 4, j += 3) {
  			tmp = (lookup.indexOf(b64[i]) << 18) | (lookup.indexOf(b64[i + 1]) << 12) | (lookup.indexOf(b64[i + 2]) << 6) | lookup.indexOf(b64[i + 3]);
  			arr.push((tmp & 0xFF0000) >> 16);
  			arr.push((tmp & 0xFF00) >> 8);
  			arr.push(tmp & 0xFF);
  		}
  
  		if (placeHolders === 2) {
  			tmp = (lookup.indexOf(b64[i]) << 2) | (lookup.indexOf(b64[i + 1]) >> 4);
  			arr.push(tmp & 0xFF);
  		} else if (placeHolders === 1) {
  			tmp = (lookup.indexOf(b64[i]) << 10) | (lookup.indexOf(b64[i + 1]) << 4) | (lookup.indexOf(b64[i + 2]) >> 2);
  			arr.push((tmp >> 8) & 0xFF);
  			arr.push(tmp & 0xFF);
  		}
  
  		return arr;
  	}
  
  	function uint8ToBase64(uint8) {
  		var i,
  			extraBytes = uint8.length % 3, // if we have 1 byte left, pad 2 bytes
  			output = "",
  			temp, length;
  
  		function tripletToBase64 (num) {
  			return lookup[num >> 18 & 0x3F] + lookup[num >> 12 & 0x3F] + lookup[num >> 6 & 0x3F] + lookup[num & 0x3F];
  		};
  
  		// go through the array every three bytes, we'll deal with trailing stuff later
  		for (i = 0, length = uint8.length - extraBytes; i < length; i += 3) {
  			temp = (uint8[i] << 16) + (uint8[i + 1] << 8) + (uint8[i + 2]);
  			output += tripletToBase64(temp);
  		}
  
  		// pad the end with zeros, but make sure to not forget the extra bytes
  		switch (extraBytes) {
  			case 1:
  				temp = uint8[uint8.length - 1];
  				output += lookup[temp >> 2];
  				output += lookup[(temp << 4) & 0x3F];
  				output += '==';
  				break;
  			case 2:
  				temp = (uint8[uint8.length - 2] << 8) + (uint8[uint8.length - 1]);
  				output += lookup[temp >> 10];
  				output += lookup[(temp >> 4) & 0x3F];
  				output += lookup[(temp << 2) & 0x3F];
  				output += '=';
  				break;
  		}
  
  		return output;
  	}
  
  	module.exports.toByteArray = b64ToByteArray;
  	module.exports.fromByteArray = uint8ToBase64;
  }());