@tsxper/crc32

v2.1.3

Published

a month ago

Calculates unsigned CRC32. Optimized Cycle Redundancy Check.

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crc32 string buffer uint8array file readable stream typescript commonjs esm cjs

CRC32

npm type definitions

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.

Release Notes.

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/[email protected]/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.