private static void testEncodeDecodeRandom(GenericGF field, int dataSize, int ecSize)
{
Assert.IsTrue(dataSize > 0 && dataSize <= field.Size - 3, "Invalid data size for " + field);
Assert.IsTrue(ecSize > 0 && ecSize + dataSize <= field.Size, "Invalid ECC size for " + field);
ReedSolomonEncoder encoder = new ReedSolomonEncoder(field);
int[] message = new int[dataSize + ecSize];
int[] dataWords = new int[dataSize];
int[] ecWords = new int[ecSize];
Random random = getPseudoRandom();
int iterations = field.Size > 256 ? 1 : DECODER_RANDOM_TEST_ITERATIONS;
for (int i = 0; i < iterations; i++)
{
// generate random data
for (int k = 0; k < dataSize; k++)
{
dataWords[k] = random.Next(field.Size);
}
// generate ECC words
Array.Copy(dataWords, 0, message, 0, dataWords.Length);
encoder.encode(message, ecWords.Length);
Array.Copy(message, dataSize, ecWords, 0, ecSize);
// check to see if Decoder can fix up to ecWords/2 random errors
testDecoder(field, dataWords, ecWords);
}
}
public ReedSolomon(GenericGF galoisField, int correctionBytes)
{
_messageLength = galoisField.Size - 1;
_correctionLength = correctionBytes;
_informationLength = _messageLength - _correctionLength;
_reedSolomonEncoder = new ReedSolomonEncoder(galoisField);
_reedSolomonDecoder = new ReedSolomonDecoder(galoisField);
_simpleRsDecoder = new SimpleRSDecoder();
}
public ReedSolomon(int correctionBytes)
{
var galoisField = GenericGF.DATA_MATRIX_FIELD_256;
_messageLength = galoisField.Size - 1;
_correctionLength = correctionBytes;
_informationLength = _messageLength - _correctionLength;
_reedSolomonEncoder = new ReedSolomonEncoder(galoisField);
_reedSolomonDecoder = new ReedSolomonDecoder(galoisField);
_simpleRsDecoder = new SimpleRSDecoder();
}
private static void testEncoder(GenericGF field, int[] dataWords, int[] ecWords)
{
ReedSolomonEncoder encoder = new ReedSolomonEncoder(field);
int[] messageExpected = new int[dataWords.Length + ecWords.Length];
int[] message = new int[dataWords.Length + ecWords.Length];
Array.Copy(dataWords, 0, messageExpected, 0, dataWords.Length);
Array.Copy(ecWords, 0, messageExpected, dataWords.Length, ecWords.Length);
Array.Copy(dataWords, 0, message, 0, dataWords.Length);
encoder.encode(message, ecWords.Length);
assertDataEquals("Encode in " + field + " (" + dataWords.Length + ',' + ecWords.Length + ") failed",
messageExpected, message);
}
private static BitArray generateCheckWords(BitArray bitArray, int totalBits, int wordSize)
{
if (bitArray.Size % wordSize != 0)
throw new InvalidOperationException("size of bit array is not a multiple of the word size");
// bitArray is guaranteed to be a multiple of the wordSize, so no padding needed
int messageSizeInWords = bitArray.Size / wordSize;
var rs = new ReedSolomonEncoder(getGF(wordSize));
var totalWords = totalBits / wordSize;
var messageWords = bitsToWords(bitArray, wordSize, totalWords);
rs.encode(messageWords, totalWords - messageSizeInWords);
var startPad = totalBits % wordSize;
var messageBits = new BitArray();
messageBits.appendBits(0, startPad);
foreach (var messageWord in messageWords)
{
messageBits.appendBits(messageWord, wordSize);
}
return messageBits;
}
/// <summary>
/// Encodes the given binary content as an Aztec symbol
/// </summary>
/// <param name="data">input data string</param>
/// <param name="minECCPercent">minimal percentange of error check words (According to ISO/IEC 24778:2008,
/// a minimum of 23% + 3 words is recommended)</param>
/// <returns>Aztec symbol matrix with metadata</returns>
public static AztecCode encode(byte[] data, int minECCPercent)
{
// High-level encode
var bits = new HighLevelEncoder(data).encode();
// stuff bits and choose symbol size
int eccBits = bits.Size * minECCPercent / 100 + 11;
int totalSizeBits = bits.Size + eccBits;
int layers;
int wordSize = 0;
int totalSymbolBits = 0;
BitArray stuffedBits = null;
for (layers = 1; layers < NB_BITS_COMPACT.Length; layers++)
{
if (NB_BITS_COMPACT[layers] >= totalSizeBits)
{
if (wordSize != WORD_SIZE[layers])
{
wordSize = WORD_SIZE[layers];
stuffedBits = stuffBits(bits, wordSize);
}
totalSymbolBits = NB_BITS_COMPACT[layers];
if (stuffedBits.Size + eccBits <= NB_BITS_COMPACT[layers])
{
break;
}
}
}
bool compact = true;
if (layers == NB_BITS_COMPACT.Length)
{
compact = false;
for (layers = 1; layers < NB_BITS.Length; layers++)
{
if (NB_BITS[layers] >= totalSizeBits)
{
if (wordSize != WORD_SIZE[layers])
{
wordSize = WORD_SIZE[layers];
stuffedBits = stuffBits(bits, wordSize);
}
totalSymbolBits = NB_BITS[layers];
if (stuffedBits.Size + eccBits <= NB_BITS[layers])
{
break;
}
}
}
}
if (layers == NB_BITS.Length)
{
throw new ArgumentException("Data too large for an Aztec code");
}
// pad the end
int messageSizeInWords = (stuffedBits.Size + wordSize - 1) / wordSize;
for (int i = messageSizeInWords * wordSize - stuffedBits.Size; i > 0; i--)
{
stuffedBits.appendBit(true);
}
// generate check words
var rs = new ReedSolomonEncoder(getGF(wordSize));
var totalSizeInFullWords = totalSymbolBits / wordSize;
var messageWords = bitsToWords(stuffedBits, wordSize, totalSizeInFullWords);
rs.encode(messageWords, totalSizeInFullWords - messageSizeInWords);
// convert to bit array and pad in the beginning
var startPad = totalSymbolBits % wordSize;
var messageBits = new BitArray();
messageBits.appendBits(0, startPad);
foreach (var messageWord in messageWords)
{
messageBits.appendBits(messageWord, wordSize);
}
// generate mode message
var modeMessage = generateModeMessage(compact, layers, messageSizeInWords);
// allocate symbol
var baseMatrixSize = compact ? 11 + layers * 4 : 14 + layers * 4; // not including alignment lines
var alignmentMap = new int[baseMatrixSize];
int matrixSize;
if (compact)
{
// no alignment marks in compact mode, alignmentMap is a no-op
matrixSize = baseMatrixSize;
for (int i = 0; i < alignmentMap.Length; i++)
{
alignmentMap[i] = i;
}
}
else
{
matrixSize = baseMatrixSize + 1 + 2 * ((baseMatrixSize / 2 - 1) / 15);
int origCenter = baseMatrixSize / 2;
int center = matrixSize / 2;
for (int i = 0; i < origCenter; i++)
{
int newOffset = i + i / 15;
alignmentMap[origCenter - i - 1] = center - newOffset - 1;
alignmentMap[origCenter + i] = center + newOffset + 1;
}
}
var matrix = new BitMatrix(matrixSize);
// draw mode and data bits
for (int i = 0, rowOffset = 0; i < layers; i++)
{
int rowSize = compact ? (layers - i) * 4 + 9 : (layers - i) * 4 + 12;
for (int j = 0; j < rowSize; j++)
{
int columnOffset = j * 2;
for (int k = 0; k < 2; k++)
{
if (messageBits[rowOffset + columnOffset + k])
{
matrix[alignmentMap[i * 2 + k], alignmentMap[i * 2 + j]] = true;
}
if (messageBits[rowOffset + rowSize * 2 + columnOffset + k])
{
matrix[alignmentMap[i * 2 + j], alignmentMap[baseMatrixSize - 1 - i * 2 - k]] = true;
}
if (messageBits[rowOffset + rowSize * 4 + columnOffset + k])
{
matrix[alignmentMap[baseMatrixSize - 1 - i * 2 - k], alignmentMap[baseMatrixSize - 1 - i * 2 - j]] = true;
}
if (messageBits[rowOffset + rowSize * 6 + columnOffset + k])
{
matrix[alignmentMap[baseMatrixSize - 1 - i * 2 - j], alignmentMap[i * 2 + k]] = true;
}
}
}
rowOffset += rowSize * 8;
}
drawModeMessage(matrix, compact, matrixSize, modeMessage);
// draw alignment marks
if (compact)
{
drawBullsEye(matrix, matrixSize / 2, 5);
}
else
{
drawBullsEye(matrix, matrixSize / 2, 7);
for (int i = 0, j = 0; i < baseMatrixSize / 2 - 1; i += 15, j += 16)
{
for (int k = (matrixSize / 2) & 1; k < matrixSize; k += 2)
{
matrix[matrixSize / 2 - j, k] = true;
matrix[matrixSize / 2 + j, k] = true;
matrix[k, matrixSize / 2 - j] = true;
matrix[k, matrixSize / 2 + j] = true;
}
}
}
return new AztecCode
{
isCompact = compact,
Size = matrixSize,
Layers = layers,
CodeWords = messageSizeInWords,
Matrix = matrix
};
}
private static BitArray generateCheckWords(BitArray stuffedBits, int totalSymbolBits, int wordSize)
{
var messageSizeInWords = (stuffedBits.Size + wordSize - 1) / wordSize;
for (var i = messageSizeInWords * wordSize - stuffedBits.Size; i > 0; i--)
{
stuffedBits.appendBit(true);
}
var rs = new ReedSolomonEncoder(getGF(wordSize));
var totalSizeInFullWords = totalSymbolBits / wordSize;
var messageWords = bitsToWords(stuffedBits, wordSize, totalSizeInFullWords);
rs.encode(messageWords, totalSizeInFullWords - messageSizeInWords);
var startPad = totalSymbolBits % wordSize;
var messageBits = new BitArray();
messageBits.appendBits(0, startPad);
foreach (var messageWord in messageWords)
{
messageBits.appendBits(messageWord, wordSize);
}
return messageBits;
}