qzxing/source/zxing/qrcode/decoder/DataBlock.cpp

/*
 *  DataBlock.cpp
 *  zxing
 *
 *  Created by Christian Brunschen on 19/05/2008.
 *  Copyright 2008 ZXing authors All rights reserved.
 *
 * 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.
 */

#include <zxing/qrcode/decoder/DataBlock.h>
#include <zxing/common/IllegalArgumentException.h>

namespace zxing {
namespace qrcode {

using namespace std;

DataBlock::DataBlock(int numDataCodewords, ArrayRef<unsigned char> codewords) :
    numDataCodewords_(numDataCodewords), codewords_(codewords) {
}

int DataBlock::getNumDataCodewords() {
  return numDataCodewords_;
}

ArrayRef<unsigned char> DataBlock::getCodewords() {
  return codewords_;
}


std::vector<Ref<DataBlock> > DataBlock::getDataBlocks(ArrayRef<unsigned char> rawCodewords, Version *version,
    ErrorCorrectionLevel &ecLevel) {


  // Figure out the number and size of data blocks used by this version and
  // error correction level
  ECBlocks &ecBlocks = version->getECBlocksForLevel(ecLevel);


  // First count the total number of data blocks
  int totalBlocks = 0;
  vector<ECB*> ecBlockArray = ecBlocks.getECBlocks();
  for (size_t i = 0; i < ecBlockArray.size(); i++) {
    totalBlocks += ecBlockArray[i]->getCount();
  }

  // Now establish DataBlocks of the appropriate size and number of data codewords
  std::vector<Ref<DataBlock> > result(totalBlocks);
  int numResultBlocks = 0;
  for (size_t j = 0; j < ecBlockArray.size(); j++) {
    ECB *ecBlock = ecBlockArray[j];
    for (int i = 0; i < ecBlock->getCount(); i++) {
      int numDataCodewords = ecBlock->getDataCodewords();
      int numBlockCodewords = ecBlocks.getECCodewords() + numDataCodewords;
      ArrayRef<unsigned char> buffer(numBlockCodewords);
      Ref<DataBlock> blockRef(new DataBlock(numDataCodewords, buffer));
      result[numResultBlocks++] = blockRef;
    }
  }

  // All blocks have the same amount of data, except that the last n
  // (where n may be 0) have 1 more byte. Figure out where these start.
  int shorterBlocksTotalCodewords = result[0]->codewords_.size();
  int longerBlocksStartAt = result.size() - 1;
  while (longerBlocksStartAt >= 0) {
    int numCodewords = result[longerBlocksStartAt]->codewords_.size();
    if (numCodewords == shorterBlocksTotalCodewords) {
      break;
    }
    if (numCodewords != shorterBlocksTotalCodewords + 1) {
      throw IllegalArgumentException("Data block sizes differ by more than 1");
    }
    longerBlocksStartAt--;
  }
  longerBlocksStartAt++;

  int shorterBlocksNumDataCodewords = shorterBlocksTotalCodewords - ecBlocks.getECCodewords();
  // The last elements of result may be 1 element longer;
  // first fill out as many elements as all of them have
  int rawCodewordsOffset = 0;
  for (int i = 0; i < shorterBlocksNumDataCodewords; i++) {
    for (int j = 0; j < numResultBlocks; j++) {
      result[j]->codewords_[i] = rawCodewords[rawCodewordsOffset++];
    }
  }
  // Fill out the last data block in the longer ones
  for (int j = longerBlocksStartAt; j < numResultBlocks; j++) {
    result[j]->codewords_[shorterBlocksNumDataCodewords] = rawCodewords[rawCodewordsOffset++];
  }
  // Now add in error correction blocks
  int max = result[0]->codewords_.size();
  for (int i = shorterBlocksNumDataCodewords; i < max; i++) {
    for (int j = 0; j < numResultBlocks; j++) {
      int iOffset = j < longerBlocksStartAt ? i : i + 1;
      result[j]->codewords_[iOffset] = rawCodewords[rawCodewordsOffset++];
    }
  }

  if ((size_t)rawCodewordsOffset != rawCodewords.size()) {
    throw IllegalArgumentException("rawCodewordsOffset != rawCodewords.length");
  }

  return result;
}

}
}