reedsolomon.ts

TypeScript port of cho45/reedsolomon.js, which is itself a port of ZXing's Reed-Solomon codec.

Reed-Solomon error correction encoding and decoding over GF(2^8). Zero dependencies.

Install

npm install reedsolomon.ts

Usage

import {
    RS_Encoder,
    RS_Decoder,
    GF_DATA_MATRIX_256,
} from 'reedsolomon.ts';

const field = GF_DATA_MATRIX_256();
const encoder = new RS_Encoder(field);
const decoder = new RS_Decoder(field);

// message = 24 data bytes + 8 parity bytes = 32 total
const message = new Int32Array(32);
for (let i = 0; i < 24; i++) message[i] = i;

// Encode: parity bytes are written to positions [24, 32)
encoder.encode(message, 8);

// Corrupt up to 4 bytes (8 parity bytes / 2 = 4 correctable errors)
message[5] = 0xff;
message[10] = 0xff;
message[20] = 0xff;
message[30] = 0xff;

// Decode: corrects errors in-place
decoder.decode(message, 8);
// message[0..24] is restored to original data

API

GF_DATA_MATRIX_256()

Returns a Generic_GF field for GF(2^8) with primitive polynomial x^8 + x^5 + x^3 + x^2 + 1 (0x012D), generator base 1. Used by Data Matrix and Aztec codes.

GF_QR_CODE_256()

Returns a Generic_GF field for GF(2^8) with primitive polynomial x^8 + x^4 + x^3 + x^2 + 1 (0x011D), generator base 0. Used by QR codes.

new RS_Encoder(field)

Creates an encoder for the given Galois field.

encoder.encode(data: Int32Array, ec_bytes: number): void

Encodes in-place. data must have length = data bytes + ec_bytes. Data occupies positions [0, data_bytes) and parity is written to [data_bytes, length).

new RS_Decoder(field)

Creates a decoder for the given Galois field.

decoder.decode(received: Int32Array, ec_bytes: number): void

Decodes (corrects errors) in-place. Can correct up to ec_bytes / 2 byte errors. Throws if errors exceed correction capacity.

Generic_GF

Galois field implementation. Use the factory functions above unless you need a custom field.

new Generic_GF(primitive: number, size: number, generator_base: number)

Creates a custom Galois field with the given primitive polynomial, size, and generator base.

License

Apache-2.0. See LICENSE.

Original Java implementation: Copyright 2007 ZXing authors. JavaScript port: cho45. TypeScript port: ecartz.