share/nitdoc/scripts/base64.js

   1 /*
   2 * Base64
   3 */
   4 base64 = {};
   5 base64.PADCHAR = '=';
   6 base64.ALPHA = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
   7 base64.getbyte64 = function(s,i) {
   8     // This is oddly fast, except on Chrome/V8.
   9     //  Minimal or no improvement in performance by using a
  10     //   object with properties mapping chars to value (eg. 'A': 0)
  11     var idx = base64.ALPHA.indexOf(s.charAt(i));
  12     if (idx == -1) {
  13     throw "Cannot decode base64";
  14     }
  15     return idx;
  16 }
  17
  18 base64.decode = function(s) {
  19     // convert to string
  20     s = "" + s;
  21     var getbyte64 = base64.getbyte64;
  22     var pads, i, b10;
  23     var imax = s.length
  24     if (imax == 0) {
  25         return s;
  26     }
  27
  28     if (imax % 4 != 0) {
  29     throw "Cannot decode base64";
  30     }
  31
  32     pads = 0
  33     if (s.charAt(imax -1) == base64.PADCHAR) {
  34         pads = 1;
  35         if (s.charAt(imax -2) == base64.PADCHAR) {
  36             pads = 2;
  37         }
  38         // either way, we want to ignore this last block
  39         imax -= 4;
  40     }
  41
  42     var x = [];
  43     for (i = 0; i < imax; i += 4) {
  44         b10 = (getbyte64(s,i) << 18) | (getbyte64(s,i+1) << 12) |
  45             (getbyte64(s,i+2) << 6) | getbyte64(s,i+3);
  46         x.push(String.fromCharCode(b10 >> 16, (b10 >> 8) & 0xff, b10 & 0xff));
  47     }
  48
  49     switch (pads) {
  50     case 1:
  51         b10 = (getbyte64(s,i) << 18) | (getbyte64(s,i+1) << 12) | (getbyte64(s,i+2) << 6)
  52         x.push(String.fromCharCode(b10 >> 16, (b10 >> 8) & 0xff));
  53         break;
  54     case 2:
  55         b10 = (getbyte64(s,i) << 18) | (getbyte64(s,i+1) << 12);
  56         x.push(String.fromCharCode(b10 >> 16));
  57         break;
  58     }
  59     return x.join('');
  60 }
  61
  62 base64.getbyte = function(s,i) {
  63     var x = s.charCodeAt(i);
  64     if (x > 255) {
  65         throw "INVALID_CHARACTER_ERR: DOM Exception 5";
  66     }
  67     return x;
  68 }
  69
  70
  71 base64.encode = function(s) {
  72     if (arguments.length != 1) {
  73     throw "SyntaxError: Not enough arguments";
  74     }
  75     var padchar = base64.PADCHAR;
  76     var alpha   = base64.ALPHA;
  77     var getbyte = base64.getbyte;
  78
  79     var i, b10;
  80     var x = [];
  81
  82     // convert to string
  83     s = "" + s;
  84
  85     var imax = s.length - s.length % 3;
  86
  87     if (s.length == 0) {
  88         return s;
  89     }
  90     for (i = 0; i < imax; i += 3) {
  91         b10 = (getbyte(s,i) << 16) | (getbyte(s,i+1) << 8) | getbyte(s,i+2);
  92         x.push(alpha.charAt(b10 >> 18));
  93         x.push(alpha.charAt((b10 >> 12) & 0x3F));
  94         x.push(alpha.charAt((b10 >> 6) & 0x3f));
  95         x.push(alpha.charAt(b10 & 0x3f));
  96     }
  97     switch (s.length - imax) {
  98     case 1:
  99         b10 = getbyte(s,i) << 16;
 100         x.push(alpha.charAt(b10 >> 18) + alpha.charAt((b10 >> 12) & 0x3F) +
 101                padchar + padchar);
 102         break;
 103     case 2:
 104         b10 = (getbyte(s,i) << 16) | (getbyte(s,i+1) << 8);
 105         x.push(alpha.charAt(b10 >> 18) + alpha.charAt((b10 >> 12) & 0x3F) +
 106                alpha.charAt((b10 >> 6) & 0x3f) + padchar);
 107         break;
 108     }
 109     return x.join('');
 110 }