68 lines
1.9 KiB
JavaScript
68 lines
1.9 KiB
JavaScript
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/*
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* base64-arraybuffer
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* https://github.com/niklasvh/base64-arraybuffer
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*
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* Copyright (c) 2012 Niklas von Hertzen
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* Licensed under the MIT license.
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*/
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(function(){
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"use strict";
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var chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
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// Use a lookup table to find the index.
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var lookup = new Uint8Array(256);
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for (var i = 0; i < chars.length; i++) {
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lookup[chars.charCodeAt(i)] = i;
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}
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exports.encode = function(arraybuffer) {
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var bytes = new Uint8Array(arraybuffer),
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i, len = bytes.length, base64 = "";
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for (i = 0; i < len; i+=3) {
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base64 += chars[bytes[i] >> 2];
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base64 += chars[((bytes[i] & 3) << 4) | (bytes[i + 1] >> 4)];
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base64 += chars[((bytes[i + 1] & 15) << 2) | (bytes[i + 2] >> 6)];
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base64 += chars[bytes[i + 2] & 63];
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}
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if ((len % 3) === 2) {
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base64 = base64.substring(0, base64.length - 1) + "=";
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} else if (len % 3 === 1) {
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base64 = base64.substring(0, base64.length - 2) + "==";
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}
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return base64;
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};
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exports.decode = function(base64) {
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var bufferLength = base64.length * 0.75,
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len = base64.length, i, p = 0,
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encoded1, encoded2, encoded3, encoded4;
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if (base64[base64.length - 1] === "=") {
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bufferLength--;
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if (base64[base64.length - 2] === "=") {
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bufferLength--;
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}
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}
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var arraybuffer = new ArrayBuffer(bufferLength),
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bytes = new Uint8Array(arraybuffer);
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for (i = 0; i < len; i+=4) {
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encoded1 = lookup[base64.charCodeAt(i)];
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encoded2 = lookup[base64.charCodeAt(i+1)];
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encoded3 = lookup[base64.charCodeAt(i+2)];
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encoded4 = lookup[base64.charCodeAt(i+3)];
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bytes[p++] = (encoded1 << 2) | (encoded2 >> 4);
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bytes[p++] = ((encoded2 & 15) << 4) | (encoded3 >> 2);
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bytes[p++] = ((encoded3 & 3) << 6) | (encoded4 & 63);
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}
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return arraybuffer;
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};
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})();
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