text: /**
   * Copyright 2008 - 2019 The Loon Game Engine 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.
   * 
   * @project loon
   * @author cping
   * @email：javachenpeng@yahoo.com
   * @version 0.5
   */
  package loon.utils.qrcode;
  
  import loon.utils.StrBuilder;
  
  public class QRPolynomial {
  
  	private final int[] num;
  
  	public QRPolynomial(int[] num) {
  		this(num, 0);
  	}
  
  	public QRPolynomial(int[] num, int shift) {
  		int offset = 0;
  		while (offset < num.length && num[offset] == 0) {
  			offset++;
  		}
  		this.num = new int[num.length - offset + shift];
  		System.arraycopy(num, offset, this.num, 0, num.length - offset);
  	}
  
  	public int get(int index) {
  		return num[index];
  	}
  
  	public int getLength() {
  		return num.length;
  	}
  
  	public QRPolynomial multiply(QRPolynomial e) {
  
  		int[] num = new int[getLength() + e.getLength() - 1];
  		for (int i = 0; i < getLength(); i++) {
  			for (int j = 0; j < e.getLength(); j++) {
  				num[i + j] ^= QRMath.gexp(QRMath.glog(get(i)) + QRMath.glog(e.get(j)));
  			}
  		}
  
  		return new QRPolynomial(num);
  	}
  
  	public QRPolynomial mod(QRPolynomial e) {
  
  		if (getLength() - e.getLength() < 0) {
  			return this;
  		}
  		int ratio = QRMath.glog(get(0)) - QRMath.glog(e.get(0));
  		int[] num = new int[getLength()];
  		for (int i = 0; i < getLength(); i++) {
  			num[i] = get(i);
  		}
  
  		for (int i = 0; i < e.getLength(); i++) {
  			num[i] ^= QRMath.gexp(QRMath.glog(e.get(i)) + ratio);
  		}
  
  		return new QRPolynomial(num).mod(e);
  	}
  
  	public String toLogString() {
  		StrBuilder buffer = new StrBuilder();
  		for (int i = 0; i < getLength(); i++) {
  			if (i > 0) {
  				buffer.append(",");
  			}
  			buffer.append(QRMath.glog(get(i)));
  		}
  		return buffer.toString();
  	}
  
  	@Override
  	public String toString() {
  		StrBuilder buffer = new StrBuilder();
  		for (int i = 0; i < getLength(); i++) {
  			if (i > 0) {
  				buffer.append(",");
  			}
  			buffer.append(get(i));
  		}
  		return buffer.toString();
  	}
  }
  