b64.js
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(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;
}());