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44 lines
1.8 KiB
JavaScript
44 lines
1.8 KiB
JavaScript
8 months ago
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// imported from https://github.com/socketio/base64-arraybuffer
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const chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
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// Use a lookup table to find the index.
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const lookup = typeof Uint8Array === 'undefined' ? [] : new Uint8Array(256);
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for (let i = 0; i < chars.length; i++) {
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lookup[chars.charCodeAt(i)] = i;
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}
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export const encode = (arraybuffer) => {
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let bytes = new Uint8Array(arraybuffer), 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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}
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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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export const decode = (base64) => {
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let bufferLength = base64.length * 0.75, len = base64.length, i, p = 0, 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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const arraybuffer = new ArrayBuffer(bufferLength), 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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