Base32 decoder

base32decode.js

(function(){
    "use strict";

    //Generate dictionary 
    var arr = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ234567'.split(''),
        dict = {};
    for(var i=0, len=arr.length; i<arr.length; i++){
        dict[arr[i]] = i;
    }

    var decode = function(hash){

        var cache = 0,
            count = 0,
            bytes = [];

        //remove placeholder chars
        hash = hash.replace(/=/g,'');

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

            //add bits from val to cache
            cache = (cache << 5) + dict[hash[i]];

            count += 5;

            if( count >= 8 ){

                count -= 8;

                //store decoded chaacter
                bytes.push(cache >> count);

                //remove used bits by masking agains unused bits
                cache &= ((1 << count)-1);

            }

        }

        return bytes;
    }

    //define as a global. Cheap way to make this work in a browser or node environment
    var self = typeof window !== 'undefined'?
        window:
        GLOBAL;

    self.base32decode = function(hash, handler){
 
        var bytes = decode(hash);
 
        //if the bytes need additional work, the user can specify a handler function that should return an array of the modified bytes
        if( handler ){
            bytes = handler(bytes);
        }
 
        //convert to text
        for(var i=0; i<bytes.length; i++){
            bytes[i] = String.fromCharCode(bytes[i]);
        }
        return bytes.join('');
 
    };

})();