Copy of couchbase decodeBase64 for debugging

base64.js

var decodeBase64 = (function(b64) {
    var i, j, l, tmp, scratch, arr = [];
    var lookup = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
    if (typeof b64 !== 'string') {
        throw 'Input is not a string';
    }
    if (b64.length % 4 > 0) {
        throw 'Invalid base64 source.';
    }
    scratch = b64.indexOf('=');
    scratch = scratch > 0 ? b64.length - scratch : 0;
    l = scratch > 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);
        tmp |= (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 (scratch === 2) {
        tmp = (lookup.indexOf(b64[i]) << 2) | (lookup.indexOf(b64[i + 1]) >> 4);
        arr.push(tmp & 0xFF);
    } else if (scratch === 1) {
        tmp = (lookup.indexOf(b64[i]) << 10) | (lookup.indexOf(b64[i + 1]) << 4);
        tmp |= (lookup.indexOf(b64[i + 2]) >> 2);
        arr.push((tmp >> 8) & 0xFF);
        arr.push(tmp & 0xFF);
    }
    return arr;
})