content: /*
   * 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.
   */
  
  package com.ailiwean.core.zxing.core.common.reedsolomon;
  
  
  import java.util.ArrayList;
  import java.util.List;
  
  /**
   * <p>Implements Reed-Solomon encoding, as the name implies.</p>
   *
   * @author Sean Owen
   * @author William Rucklidge
   */
  public final class ReedSolomonEncoder {
  
    private final GenericGF field;
    private final List<GenericGFPoly> cachedGenerators;
  
    public ReedSolomonEncoder(GenericGF field) {
      this.field = field;
      this.cachedGenerators = new ArrayList<>();
      cachedGenerators.add(new GenericGFPoly(field, new int[]{1}));
    }
  
    private GenericGFPoly buildGenerator(int degree) {
      if (degree >= cachedGenerators.size()) {
        GenericGFPoly lastGenerator = cachedGenerators.get(cachedGenerators.size() - 1);
        for (int d = cachedGenerators.size(); d <= degree; d++) {
          GenericGFPoly nextGenerator = lastGenerator.multiply(
              new GenericGFPoly(field, new int[] { 1, field.exp(d - 1 + field.getGeneratorBase()) }));
          cachedGenerators.add(nextGenerator);
          lastGenerator = nextGenerator;
        }
      }
      return cachedGenerators.get(degree);
    }
  
    public void encode(int[] toEncode, int ecBytes) {
      if (ecBytes == 0) {
        throw new IllegalArgumentException("No error correction bytes");
      }
      int dataBytes = toEncode.length - ecBytes;
      if (dataBytes <= 0) {
        throw new IllegalArgumentException("No data bytes provided");
      }
      GenericGFPoly generator = buildGenerator(ecBytes);
      int[] infoCoefficients = new int[dataBytes];
      System.arraycopy(toEncode, 0, infoCoefficients, 0, dataBytes);
      GenericGFPoly info = new GenericGFPoly(field, infoCoefficients);
      info = info.multiplyByMonomial(ecBytes, 1);
      GenericGFPoly remainder = info.divide(generator)[1];
      int[] coefficients = remainder.getCoefficients();
      int numZeroCoefficients = ecBytes - coefficients.length;
      for (int i = 0; i < numZeroCoefficients; i++) {
        toEncode[dataBytes + i] = 0;
      }
      System.arraycopy(coefficients, 0, toEncode, dataBytes + numZeroCoefficients, coefficients.length);
    }
  
  }
  