CRC32

Cycle Redundancy Check 32 (CRC32).

Calculates unsigned 32 bit checksum for 0xEDB88320 polynomial.

Speed optimization is done through using pre-calculated values from lookup tables.

Performance

Performance totally depends on the hardware. Results below are made on a very basic hardware with NodeJS v18.16.0, IntelCore i5 1.6 GHz CPU and DDR3 RAM.

Processor	Rate	CRC32OPS	Input	Time
CRC32	1.2047 Gbit/s	147059	10K random 1024-Bytes items	68 msec
CRC32Streams	850.1594 Mbit/s	-	100MB random data file	941 msec

Compatibility

class CRC32
// Browser and NodeJS compatible.

class CRC32Streams
// Depends on NodeJS "stream" module.

TypeScript Support

"@tsxper/crc32" package is originally written in TypeScript. TypeScript type definitions are included.

UTF-8 Support

UTF8 characters are fully supported.

crc32.calculate('español sí');

Transitive Dependencies

None.

Example

For String

const crc32 = new CRC32();
crc32.calculate('crc32 test');
// or
crc32.forString('crc32 test');

For Uint8Array

const crc32 = new CRC32();
crc32.forBytes(new TextEncoder().encode('crc32 test'));

For Buffer

Buffer extends Uint8Array.

const crc32 = new CRC32();
crc32.forBuffer(new TextEncoder().encode('crc32 test'));

For File

const crc32 = new CRC32Streams();
const checksum = await crc32.forFile(filePath);

Calculate CRC32 For String or File In Browser

See "Compatibility".

HTML Copy/Paste Example

This example also shows how to calculate CRC32 for ArrayBuffer.

<!DOCTYPE html>
<html>
<body>
  <p>Calculating crc32 for text "hello crc32": <span id="placeholder"></span></p>
  <div>
    <input type="file" id="input" />
    <p>CRC32 of the file: <span id="filecrc32"></span></p>
  </div>
  <script type="importmap">
    {
      "imports": {
        "@tsxper/crc32": "https://www.unpkg.com/@tsxper/crc32@2.1.0/esm/CRC32.js"
      }
    }
  </script>
  <script type="module">
    import { CRC32 } from "@tsxper/crc32";
    const crc32 = new CRC32();

    function handleString() {
      const crc = crc32.calculate("hello crc32");
      document.getElementById('placeholder').innerText = crc;
    }
    handleString();

    const fileInput = document.getElementById("input");
    fileInput.addEventListener("change", handleFiles, false);

    function handleFiles(e) {
      if (!this.files.length) return;
      const file = this.files[0];
      const reader = new FileReader();
      reader.onload = (e) => {
        const buffer = e.target.result; // ArrayBuffer
        const view = new Uint8Array(buffer);
        document.getElementById('filecrc32').innerText = crc32.forBytes(view);
      };
      reader.readAsArrayBuffer(file);
    }
  </script>
</body>
</html>

Customization. Calculate for chunks, chunk by chunk.

For example, for sequence of events, converted into Uint8Array[] chunks.

const chunks = [new TextEncoder().encode('text1 text2')];
const crc32 = new CRC32();
let crc = 0;
for (const chunk of chunks) {
  crc = crc32.forBytes(chunk, crc);
}

Convert CRC32 decimal to hexadecimal

const crc32 = new CRC32();
const checksum10 = crc32.calculate("hi"); // 3633523372
const checksum16 = `0x${checksum10.toString(16)}`; // 0xd8932aac

Supporting CommonJS and ECMAScript modules

Both, CommonJS and ESM modules are supported.

import { CRC32 } from '@tsxper/crc32';
// or
const { CRC32 } = require('@tsxper/crc32');

Supporting of the both module systems is done through "import", "require" and "default" conditions.

License

MIT License.

Links

Implementing CRC32 in TypeScript.
Conditional exports, NodeJS.
Package exports, Webpack.

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