src/common/base64.js

/*
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 *
*/

var base64 = exports;

base64.fromArrayBuffer = function(arrayBuffer) {
    var array = new Uint8Array(arrayBuffer);
    return uint8ToBase64(array);
};

base64.toArrayBuffer = function(str) {
    var decodedStr = typeof atob != 'undefined' ? atob(str) : new Buffer(str,'base64').toString('binary');
    var arrayBuffer = new ArrayBuffer(decodedStr.length);
    var array = new Uint8Array(arrayBuffer);
    for (var i=0, len=decodedStr.length; i < len; i++) {
        array[i] = decodedStr.charCodeAt(i);
    }
    return arrayBuffer;
};

//------------------------------------------------------------------------------

/* This code is based on the performance tests at http://jsperf.com/b64tests
 * This 12-bit-at-a-time algorithm was the best performing version on all
 * platforms tested.
 */

var b64_6bit = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
var b64_12bit;

var b64_12bitTable = function() {
    b64_12bit = [];
    for (var i=0; i<64; i++) {
        for (var j=0; j<64; j++) {
            b64_12bit[i*64+j] = b64_6bit[i] + b64_6bit[j];
        }
    }
    b64_12bitTable = function() { return b64_12bit; };
    return b64_12bit;
};

function uint8ToBase64(rawData) {
    var numBytes = rawData.byteLength;
    var output="";
    var segment;
    var table = b64_12bitTable();
    for (var i=0;i<numBytes-2;i+=3) {
        segment = (rawData[i] << 16) + (rawData[i+1] << 8) + rawData[i+2];
        output += table[segment >> 12];
        output += table[segment & 0xfff];
    }
    if (numBytes - i == 2) {
        segment = (rawData[i] << 16) + (rawData[i+1] << 8);
        output += table[segment >> 12];
        output += b64_6bit[(segment & 0xfff) >> 6];
        output += '=';
    } else if (numBytes - i == 1) {
        segment = (rawData[i] << 16);
        output += table[segment >> 12];
        output += '==';
    }
    return output;
}