import { Buffer } from 'buffer';
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import createBuffer from './create_buffer';
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import defineCrc from './define_crc';
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const crc16xmodem = defineCrc('xmodem', function(buf, previous) {
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if (!Buffer.isBuffer(buf)) buf = createBuffer(buf);
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let crc = typeof previous !== 'undefined' ? ~~previous : 0x0;
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for (let index = 0; index < buf.length; index++) {
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const byte = buf[index];
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let code = (crc >>> 8) & 0xff;
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code ^= byte & 0xff;
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code ^= code >>> 4;
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crc = (crc << 8) & 0xffff;
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crc ^= code;
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code = (code << 5) & 0xffff;
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crc ^= code;
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code = (code << 7) & 0xffff;
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crc ^= code;
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}
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return crc;
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});
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export default crc16xmodem;
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