mirror of https://github.com/NekoX-Dev/NekoX.git
75 lines
2.6 KiB
Java
Executable File
75 lines
2.6 KiB
Java
Executable File
/*
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* Copyright 2008 ZXing authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.zxing.common.reedsolomon;
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import java.util.ArrayList;
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import java.util.List;
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/**
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* <p>Implements Reed-Solomon encoding, as the name implies.</p>
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*
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* @author Sean Owen
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* @author William Rucklidge
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*/
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public final class ReedSolomonEncoder {
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private final GenericGF field;
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private final List<GenericGFPoly> cachedGenerators;
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public ReedSolomonEncoder(GenericGF field) {
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this.field = field;
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this.cachedGenerators = new ArrayList<>();
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cachedGenerators.add(new GenericGFPoly(field, new int[]{1}));
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}
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private GenericGFPoly buildGenerator(int degree) {
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if (degree >= cachedGenerators.size()) {
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GenericGFPoly lastGenerator = cachedGenerators.get(cachedGenerators.size() - 1);
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for (int d = cachedGenerators.size(); d <= degree; d++) {
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GenericGFPoly nextGenerator = lastGenerator.multiply(
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new GenericGFPoly(field, new int[] { 1, field.exp(d - 1 + field.getGeneratorBase()) }));
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cachedGenerators.add(nextGenerator);
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lastGenerator = nextGenerator;
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}
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}
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return cachedGenerators.get(degree);
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}
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public void encode(int[] toEncode, int ecBytes) {
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if (ecBytes == 0) {
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throw new IllegalArgumentException("No error correction bytes");
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}
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int dataBytes = toEncode.length - ecBytes;
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if (dataBytes <= 0) {
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throw new IllegalArgumentException("No data bytes provided");
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}
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GenericGFPoly generator = buildGenerator(ecBytes);
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int[] infoCoefficients = new int[dataBytes];
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System.arraycopy(toEncode, 0, infoCoefficients, 0, dataBytes);
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GenericGFPoly info = new GenericGFPoly(field, infoCoefficients);
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info = info.multiplyByMonomial(ecBytes, 1);
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GenericGFPoly remainder = info.divide(generator)[1];
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int[] coefficients = remainder.getCoefficients();
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int numZeroCoefficients = ecBytes - coefficients.length;
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for (int i = 0; i < numZeroCoefficients; i++) {
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toEncode[dataBytes + i] = 0;
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}
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System.arraycopy(coefficients, 0, toEncode, dataBytes + numZeroCoefficients, coefficients.length);
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}
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}
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