/**
* Decodes a Data Matrix Code represented as a {@link BitMatrix}. A 1 or "true" is taken to mean a
* black module.
*
* @param bits booleans representing white/black Data Matrix Code modules
* @return text and bytes encoded within the Data Matrix Code
* @throws FormatException if the Data Matrix Code cannot be decoded
* @throws ChecksumException if error correction fails
*/
public DecoderResult decode(BitMatrix bits) throws FormatException, ChecksumException {
// Construct a parser and read version, error-correction level
BitMatrixParser parser = new BitMatrixParser(bits);
Version version = parser.getVersion();
// Read codewords
byte[] codewords = parser.readCodewords();
// Separate into data blocks
DataBlock[] dataBlocks = DataBlock.getDataBlocks(codewords, version);
int dataBlocksCount = dataBlocks.length;
// Count total number of data bytes
int totalBytes = 0;
for (int i = 0; i < dataBlocksCount; i++) {
totalBytes += dataBlocks[i].getNumDataCodewords();
}
byte[] resultBytes = new byte[totalBytes];
// Error-correct and copy data blocks together into a stream of bytes
for (int j = 0; j < dataBlocksCount; j++) {
DataBlock dataBlock = dataBlocks[j];
byte[] codewordBytes = dataBlock.getCodewords();
int numDataCodewords = dataBlock.getNumDataCodewords();
correctErrors(codewordBytes, numDataCodewords);
for (int i = 0; i < numDataCodewords; i++) {
// De-interlace data blocks.
resultBytes[i * dataBlocksCount + j] = codewordBytes[i];
}
}
// Decode the contents of that stream of bytes
return DecodedBitStreamParser.decode(resultBytes);
}
private DecoderResult decode(BitMatrixParser parser, Map<DecodeHintType, ?> hints)
throws FormatException, ChecksumException {
Version version = parser.readVersion();
ErrorCorrectionLevel ecLevel = parser.readFormatInformation().getErrorCorrectionLevel();
// Read codewords
byte[] codewords = parser.readCodewords();
// Separate into data blocks
DataBlock[] dataBlocks = DataBlock.getDataBlocks(codewords, version, ecLevel);
// Count total number of data bytes
int totalBytes = 0;
for (DataBlock dataBlock : dataBlocks) {
totalBytes += dataBlock.getNumDataCodewords();
}
byte[] resultBytes = new byte[totalBytes];
int resultOffset = 0;
// Error-correct and copy data blocks together into a stream of bytes
for (DataBlock dataBlock : dataBlocks) {
byte[] codewordBytes = dataBlock.getCodewords();
int numDataCodewords = dataBlock.getNumDataCodewords();
correctErrors(codewordBytes, numDataCodewords);
for (int i = 0; i < numDataCodewords; i++) {
resultBytes[resultOffset++] = codewordBytes[i];
}
}
// Decode the contents of that stream of bytes
return DecodedBitStreamParser.decode(resultBytes, version, ecLevel, hints);
}
/**
* 각 slot에 저장되어 있는 block들을 검색하여 key에 해당하는 값을 가져온다.
*
* @param key
* @return null if not found
*/
public /* synchronized */ D find(K key) {
int keyIndex = keys.indexOf(key);
if (keyIndex < 0) return null;
int blkIndex = keyIndex / blockSize;
DataBlock<K, D> blk = slots.getSlot(blkIndex);
// load data block into data space ; 해당 블럭이 없으면 DB에서 로드한다.
if (blk == null) {
if (keyIndex < 0) {
return null;
}
// 범위지정
int from = keyIndex - (keyIndex % blockSize);
int to = from + blockSize - 1;
if (to >= keys.size()) {
to = keys.size() - 1; // 최대 범위를 넘어가는 것을 제한
}
blk = reader.read(keys, from, to);
slots.feedNewSlot(blkIndex, blk);
}
return blk.find(key);
}
