63 lines
2.1 KiB
TypeScript
63 lines
2.1 KiB
TypeScript
import * as plugins from './smartbuffer.plugins.js';
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export function arrayBufferToBase64(arrayBuffer: ArrayBufferLike | Buffer): string {
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var base64 = ''
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var encodings = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
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var bytes = new Uint8Array(arrayBuffer)
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var byteLength = bytes.byteLength
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var byteRemainder = byteLength % 3
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var mainLength = byteLength - byteRemainder
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var a, b, c, d
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var chunk
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// Main loop deals with bytes in chunks of 3
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for (var i = 0; i < mainLength; i = i + 3) {
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// Combine the three bytes into a single integer
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chunk = (bytes[i] << 16) | (bytes[i + 1] << 8) | bytes[i + 2]
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// Use bitmasks to extract 6-bit segments from the triplet
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a = (chunk & 16515072) >> 18 // 16515072 = (2^6 - 1) << 18
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b = (chunk & 258048) >> 12 // 258048 = (2^6 - 1) << 12
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c = (chunk & 4032) >> 6 // 4032 = (2^6 - 1) << 6
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d = chunk & 63 // 63 = 2^6 - 1
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// Convert the raw binary segments to the appropriate ASCII encoding
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base64 += encodings[a] + encodings[b] + encodings[c] + encodings[d]
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}
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// Deal with the remaining bytes and padding
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if (byteRemainder == 1) {
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chunk = bytes[mainLength]
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a = (chunk & 252) >> 2 // 252 = (2^6 - 1) << 2
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// Set the 4 least significant bits to zero
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b = (chunk & 3) << 4 // 3 = 2^2 - 1
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base64 += encodings[a] + encodings[b] + '=='
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} else if (byteRemainder == 2) {
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chunk = (bytes[mainLength] << 8) | bytes[mainLength + 1]
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a = (chunk & 64512) >> 10 // 64512 = (2^6 - 1) << 10
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b = (chunk & 1008) >> 4 // 1008 = (2^6 - 1) << 4
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// Set the 2 least significant bits to zero
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c = (chunk & 15) << 2 // 15 = 2^4 - 1
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base64 += encodings[a] + encodings[b] + encodings[c] + '='
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}
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return base64
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}
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export function base64ToArrayBuffer(base64: string): Uint8Array {
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const binaryString = window.atob(base64);
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const arrayLength = binaryString.length;
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const arrayBuffer = new Uint8Array( arrayLength );
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for (var i = 0; i < arrayLength; i++) {
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arrayBuffer[i] = binaryString.charCodeAt(i);
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}
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return arrayBuffer;
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} |