content: /*
   * Copyright 2007 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.qrcode.decoder;
  
  
  /**
   * <p>Encapsulates a QR Code's format information, including the data mask used and
   * error correction level.</p>
   *
   * @author Sean Owen
   * @see DataMask
   * @see ErrorCorrectionLevel
   */
  final class FormatInformation {
  
    private static final int FORMAT_INFO_MASK_QR = 0x5412;
  
    /**
     * See ISO 18004:2006, Annex C, Table C.1
     */
    private static final int[][] FORMAT_INFO_DECODE_LOOKUP = {
        {0x5412, 0x00},
        {0x5125, 0x01},
        {0x5E7C, 0x02},
        {0x5B4B, 0x03},
        {0x45F9, 0x04},
        {0x40CE, 0x05},
        {0x4F97, 0x06},
        {0x4AA0, 0x07},
        {0x77C4, 0x08},
        {0x72F3, 0x09},
        {0x7DAA, 0x0A},
        {0x789D, 0x0B},
        {0x662F, 0x0C},
        {0x6318, 0x0D},
        {0x6C41, 0x0E},
        {0x6976, 0x0F},
        {0x1689, 0x10},
        {0x13BE, 0x11},
        {0x1CE7, 0x12},
        {0x19D0, 0x13},
        {0x0762, 0x14},
        {0x0255, 0x15},
        {0x0D0C, 0x16},
        {0x083B, 0x17},
        {0x355F, 0x18},
        {0x3068, 0x19},
        {0x3F31, 0x1A},
        {0x3A06, 0x1B},
        {0x24B4, 0x1C},
        {0x2183, 0x1D},
        {0x2EDA, 0x1E},
        {0x2BED, 0x1F},
    };
  
    private final ErrorCorrectionLevel errorCorrectionLevel;
    private final byte dataMask;
  
    private FormatInformation(int formatInfo) {
      // Bits 3,4
      errorCorrectionLevel = ErrorCorrectionLevel.forBits((formatInfo >> 3) & 0x03);
      // Bottom 3 bits
      dataMask = (byte) (formatInfo & 0x07);
    }
  
    static int numBitsDiffering(int a, int b) {
      return Integer.bitCount(a ^ b);
    }
  
    /**
     * @param maskedFormatInfo1 format info indicator, with mask still applied
     * @param maskedFormatInfo2 second copy of same info; both are checked at the same time
     *  to establish best match
     * @return information about the format it specifies, or {@code null}
     *  if doesn't seem to match any known pattern
     */
    static FormatInformation decodeFormatInformation(int maskedFormatInfo1, int maskedFormatInfo2) {
      FormatInformation formatInfo = doDecodeFormatInformation(maskedFormatInfo1, maskedFormatInfo2);
      if (formatInfo != null) {
        return formatInfo;
      }
      // Should return null, but, some QR codes apparently
      // do not mask this info. Try again by actually masking the pattern
      // first
      return doDecodeFormatInformation(maskedFormatInfo1 ^ FORMAT_INFO_MASK_QR,
                                       maskedFormatInfo2 ^ FORMAT_INFO_MASK_QR);
    }
  
    private static FormatInformation doDecodeFormatInformation(int maskedFormatInfo1, int maskedFormatInfo2) {
      // Find the int in FORMAT_INFO_DECODE_LOOKUP with fewest bits differing
      int bestDifference = Integer.MAX_VALUE;
      int bestFormatInfo = 0;
      for (int[] decodeInfo : FORMAT_INFO_DECODE_LOOKUP) {
        int targetInfo = decodeInfo[0];
        if (targetInfo == maskedFormatInfo1 || targetInfo == maskedFormatInfo2) {
          // Found an exact match
          return new FormatInformation(decodeInfo[1]);
        }
        int bitsDifference = numBitsDiffering(maskedFormatInfo1, targetInfo);
        if (bitsDifference < bestDifference) {
          bestFormatInfo = decodeInfo[1];
          bestDifference = bitsDifference;
        }
        if (maskedFormatInfo1 != maskedFormatInfo2) {
          // also try the other option
          bitsDifference = numBitsDiffering(maskedFormatInfo2, targetInfo);
          if (bitsDifference < bestDifference) {
            bestFormatInfo = decodeInfo[1];
            bestDifference = bitsDifference;
          }
        }
      }
      // Hamming distance of the 32 masked codes is 7, by construction, so <= 3 bits
      // differing means we found a match
      if (bestDifference <= 3) {
        return new FormatInformation(bestFormatInfo);
      }
      return null;
    }
  
    ErrorCorrectionLevel getErrorCorrectionLevel() {
      return errorCorrectionLevel;
    }
  
    byte getDataMask() {
      return dataMask;
    }
  
    @Override
    public int hashCode() {
      return (errorCorrectionLevel.ordinal() << 3) | dataMask;
    }
  
    @Override
    public boolean equals(Object o) {
      if (!(o instanceof FormatInformation)) {
        return false;
      }
      FormatInformation other = (FormatInformation) o;
      return this.errorCorrectionLevel == other.errorCorrectionLevel &&
          this.dataMask == other.dataMask;
    }
  
  }
  