57 lines
1.5 KiB
JavaScript
57 lines
1.5 KiB
JavaScript
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function createCrcTable() {
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const table = [];
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for (let n = 0; n < 256; n++) {
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let c = n;
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for (let k = 0; k < 8; k++) {
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c = (c & 1) ? (0xEDB88320 ^ (c >>> 1)) : (c >>> 1);
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}
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table[n] = c;
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}
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return table;
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}
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async function crc32(buffer) {
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let crc = 0 ^ (-1);
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const bytes = new Uint8Array(buffer);
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for (let i = 0; i < bytes.byteLength; i++) {
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crc = (crc >>> 8) ^ crcTable[(crc ^ bytes[i]) & 0xFF];
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}
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return ((crc ^ (-1)) >>> 0).toString(16).padStart(8, '0');
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}
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async function sha1(buffer) {
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const hashBuffer = await crypto.subtle.digest('SHA-1', buffer);
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return Array.from(new Uint8Array(hashBuffer))
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.map(b => b.toString(16).padStart(2, '0'))
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.join('');
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}
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const crcTable = createCrcTable();
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export async function calculate( file ){
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return new Promise( ( resolve, reject ) => {
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const freader = new FileReader();
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freader.onload = async e => {
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try {
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const buffer = e.target.result;
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const crc32V = await crc32(buffer);
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const sha1V = await sha1(buffer);
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resolve({
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filename: file.name,
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crc32: crc32V,
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sha1: sha1V
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});
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} catch (error) {
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reject(error);
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}
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}
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freader.onerror = () => {
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reject( new Error(`Could not parse file: ${file.name}`) );
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}
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freader.readAsArrayBuffer(file);
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})
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}
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