base64-string-v1.0.0.js

// Copyright (c) 2013 Pieroxy <pieroxy@pieroxy.net>
// This work is free. You can redistribute it and/or modify it
// under the terms of the WTFPL, Version 2
// For more information see LICENSE.txt or http://www.wtfpl.net/
//
// This lib is part of the lz-string project.
// For more information, the home page:
// http://pieroxy.net/blog/pages/lz-string/index.html
//
// Base64 compression / decompression for already compressed content (gif, png, jpg, mp3, ...) 
// version 1.0.0
var Base64String = {
  
  // private property
  _keyStr : "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",
  
  decompress : function (input) {
    var output = "";
    var chr1, chr2, chr3, enc1, enc2, enc3, enc4;
    var i = 1;
    var odd = input.charCodeAt(0) >> 8;
    
    while (i < input.length*2 && (i < input.length*2-1 || odd==0)) {
      
      if (i%2==0) {
        chr1 = input.charCodeAt(i/2) >> 8;
        chr2 = input.charCodeAt(i/2) & 255;
        if (i/2+1 < input.length) 
          chr3 = input.charCodeAt(i/2+1) >> 8;
        else 
          chr3 = NaN;
      } else {
        chr1 = input.charCodeAt((i-1)/2) & 255;
        if ((i+1)/2 < input.length) {
          chr2 = input.charCodeAt((i+1)/2) >> 8;
          chr3 = input.charCodeAt((i+1)/2) & 255;
        } else 
          chr2=chr3=NaN;
      }
      i+=3;
      
      enc1 = chr1 >> 2;
      enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
      enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
      enc4 = chr3 & 63;
      
      if (isNaN(chr2) || (i==input.length*2+1 && odd)) {
        enc3 = enc4 = 64;
      } else if (isNaN(chr3) || (i==input.length*2 && odd)) {
        enc4 = 64;
      }
      
      output = output +
        this._keyStr.charAt(enc1) + this._keyStr.charAt(enc2) +
          this._keyStr.charAt(enc3) + this._keyStr.charAt(enc4);
      
    }
    
    return output;
  },
  
  compress : function (input) {
    var output = "",
        ol = 1, 
        output_,
        chr1, chr2, chr3,
        enc1, enc2, enc3, enc4,
        i = 0, flush=false;
    
    input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");
    
    while (i < input.length) {
      
      enc1 = this._keyStr.indexOf(input.charAt(i++));
      enc2 = this._keyStr.indexOf(input.charAt(i++));
      enc3 = this._keyStr.indexOf(input.charAt(i++));
      enc4 = this._keyStr.indexOf(input.charAt(i++));
      
      chr1 = (enc1 << 2) | (enc2 >> 4);
      chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
      chr3 = ((enc3 & 3) << 6) | enc4;
      
      if (ol%2==0) {
        output_ = chr1 << 8;
        flush = true;
        
        if (enc3 != 64) {
          output += String.fromCharCode(output_ | chr2);
          flush = false;
        }
        if (enc4 != 64) {
          output_ = chr3 << 8;
          flush = true;
        }
      } else {
        output = output + String.fromCharCode(output_ | chr1);
        flush = false;
        
        if (enc3 != 64) {
          output_ = chr2 << 8;
          flush = true;
        }
        if (enc4 != 64) {
          output += String.fromCharCode(output_ | chr3);
          flush = false;
        }
      }
      ol+=3;
    }
    
    if (flush) {
      output += String.fromCharCode(output_);
      output = String.fromCharCode(output.charCodeAt(0)|256) + output.substring(1);
    }
    
    return output;
    
  }
}