@tjieco/library
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TypeScript port of ZXing multi-format 1D/2D barcode image processing library, with Code128 and ITF support.
82 lines (72 loc) • 3.23 kB
text/typescript
/*
* Copyright 2008 ZXing authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*namespace com.google.zxing.common.reedsolomon {*/
/*import java.util.ArrayList;*/
/*import java.util.List;*/
import GenericGF from './GenericGF';
import GenericGFPoly from './GenericGFPoly';
import Exception from './../../Exception';
import System from './../../util/System';
/**
* <p>Implements Reed-Solomon encoding, as the name implies.</p>
*
* @author Sean Owen
* @author William Rucklidge
*/
export default class ReedSolomonEncoder {
private field: GenericGF;
private cachedGenerators: GenericGFPoly[];
public constructor(field: GenericGF) {
this.field = field;
this.cachedGenerators = [];
this.cachedGenerators.push(new GenericGFPoly(field, Int32Array.from([1])));
}
private buildGenerator(degree: number /*int*/): GenericGFPoly {
const cachedGenerators = this.cachedGenerators;
if (degree >= cachedGenerators.length) {
let lastGenerator = cachedGenerators[cachedGenerators.length - 1];
const field = this.field;
for (let d = cachedGenerators.length; d <= degree; d++) {
const nextGenerator = lastGenerator.multiply(
new GenericGFPoly(field, Int32Array.from([1, field.exp(d - 1 + field.getGeneratorBase())])));
cachedGenerators.push(nextGenerator);
lastGenerator = nextGenerator;
}
}
return cachedGenerators[degree];
}
public encode(toEncode: Int32Array, ecBytes: number /*int*/): void {
if (ecBytes === 0) {
throw new Exception(Exception.IllegalArgumentException, 'No error correction bytes');
}
const dataBytes = toEncode.length - ecBytes;
if (dataBytes <= 0) {
throw new Exception(Exception.IllegalArgumentException, 'No data bytes provided');
}
const generator = this.buildGenerator(ecBytes);
const infoCoefficients: Int32Array = new Int32Array(dataBytes);
System.arraycopy(toEncode, 0, infoCoefficients, 0, dataBytes);
let info = new GenericGFPoly(this.field, infoCoefficients);
info = info.multiplyByMonomial(ecBytes, 1);
const remainder = info.divide(generator)[1];
const coefficients = remainder.getCoefficients();
const numZeroCoefficients = ecBytes - coefficients.length;
for (let i = 0; i < numZeroCoefficients; i++) {
toEncode[dataBytes + i] = 0;
}
System.arraycopy(coefficients, 0, toEncode, dataBytes + numZeroCoefficients, coefficients.length);
}
}