mediocre-blog/assets/trading-in-the-rain/MIDI.js/inc/shim/Base64.js
2020-04-26 18:15:15 -06:00

61 lines
2.2 KiB
JavaScript

//https://github.com/davidchambers/Base64.js
;(function () {
var object = typeof exports != 'undefined' ? exports : this; // #8: web workers
var chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';
function InvalidCharacterError(message) {
this.message = message;
}
InvalidCharacterError.prototype = new Error;
InvalidCharacterError.prototype.name = 'InvalidCharacterError';
// encoder
// [https://gist.github.com/999166] by [https://github.com/nignag]
object.btoa || (
object.btoa = function (input) {
for (
// initialize result and counter
var block, charCode, idx = 0, map = chars, output = '';
// if the next input index does not exist:
// change the mapping table to "="
// check if d has no fractional digits
input.charAt(idx | 0) || (map = '=', idx % 1);
// "8 - idx % 1 * 8" generates the sequence 2, 4, 6, 8
output += map.charAt(63 & block >> 8 - idx % 1 * 8)
) {
charCode = input.charCodeAt(idx += 3/4);
if (charCode > 0xFF) {
throw new InvalidCharacterError("'btoa' failed: The string to be encoded contains characters outside of the Latin1 range.");
}
block = block << 8 | charCode;
}
return output;
});
// decoder
// [https://gist.github.com/1020396] by [https://github.com/atk]
object.atob || (
object.atob = function (input) {
input = input.replace(/=+$/, '')
if (input.length % 4 == 1) {
throw new InvalidCharacterError("'atob' failed: The string to be decoded is not correctly encoded.");
}
for (
// initialize result and counters
var bc = 0, bs, buffer, idx = 0, output = '';
// get next character
buffer = input.charAt(idx++);
// character found in table? initialize bit storage and add its ascii value;
~buffer && (bs = bc % 4 ? bs * 64 + buffer : buffer,
// and if not first of each 4 characters,
// convert the first 8 bits to one ascii character
bc++ % 4) ? output += String.fromCharCode(255 & bs >> (-2 * bc & 6)) : 0
) {
// try to find character in table (0-63, not found => -1)
buffer = chars.indexOf(buffer);
}
return output;
});
}());