// Embed "dataBits" using "getMaskPattern". On success, modify the matrix and return true. // For debugging purposes, it skips masking process if "getMaskPattern" is -1. // See 8.7 of JISX0510:2004 (p.38) for how to embed data bits. public static void embedDataBits(BitVector dataBits, int maskPattern, ByteMatrix matrix) { int bitIndex = 0; int direction = -1; // Start from the right bottom cell. int x = matrix.Width - 1; int y = matrix.Height - 1; while (x > 0) { while (y >= 0 && y < matrix.Height) { for (int i = 0; i < 2; ++i) { int xx = x - i; // Skip the cell if it's not empty. if (!isEmpty(matrix.get_Renamed(xx, y))) { continue; } int bit; if (bitIndex < dataBits.size()) { bit = dataBits.at(bitIndex); ++bitIndex; } else { // Padding bit. If there is no bit left, we'll fill the left cells with 0, as described // in 8.4.9 of JISX0510:2004 (p. 24). bit = 0; } // Skip masking if mask_pattern is -1. if (maskPattern != -1) { if (MaskUtil.getDataMaskBit(maskPattern, xx, y)) { bit ^= 0x1; } } matrix.set_Renamed(xx, y, bit); } y += direction; } direction = -direction; // Reverse the direction. y += direction; x -= 2; // Move to the left. } // All bits should be consumed. if (bitIndex != dataBits.size()) { throw new WriterException("Not all bits consumed: " + bitIndex + '/' + dataBits.size()); } }
// Embed type information. On success, modify the matrix. public static void embedTypeInfo(ErrorCorrectionLevel ecLevel, int version, int maskPattern, ByteMatrix matrix) { BitVector typeInfoBits = new BitVector(); makeTypeInfoBits(ecLevel, version, maskPattern, typeInfoBits); for (int i = 0; i < typeInfoBits.size(); ++i) { // Place bits in LSB to MSB order. LSB (least significant bit) is the last value in // "typeInfoBits". int bit = typeInfoBits.at(typeInfoBits.size() - 1 - i); // Type info bits at the left top corner. See 8.9 of JISX0510:2004 (p.46). int x1 = TYPE_INFO_COORDINATES[i][0]; int y1 = TYPE_INFO_COORDINATES[i][1]; matrix.set_Renamed(x1, y1, bit); } }
/// <summary> /// Make bit vector of type information. On success, store the result in "bits" and return true. /// Encode error correction level and mask pattern. See 8.9 of /// JISX0510:2004 (p.45) for details. /// </summary> /// <param name="ecLevel"></param> /// <param name="maskPattern"></param> /// <param name="bits"></param> /// <remarks> /// ISO/IEC 18004:2006(E) 6.9 Format information /// </remarks> public static void makeTypeInfoBits(ErrorCorrectionLevel ecLevel, int version, int maskPattern, BitVector bits) { if (!MicroQRCode.isValidMaskPattern(maskPattern)) { throw new WriterException("Invalid mask pattern"); } //ISO/IEC 18004:2006(E) 6.9 Format information //Symbol number 0: 000 //Data mask pattern reference: 11 //Data bits (symbol number, data mask pattern reference): 00011 //BCH bits: 1101011001 //Unmasked bit sequence: 000111101011001 //Mask pattern for XOR operation: 100010001000101 //Format information module pattern: 100101100011100 int typeInfo = SYMBOL_NUMBERS_INFO[version - 1][ecLevel.ordinal()]; if (typeInfo == -1) { throw new WriterException("Invalid Version&Level info"); } typeInfo = (typeInfo << 2) | maskPattern; bits.appendBits(typeInfo, 5); int bchCode = calculateBCHCode(typeInfo, TYPE_INFO_POLY); bits.appendBits(bchCode, 10); BitVector maskBits = new BitVector(); maskBits.appendBits(TYPE_INFO_MASK_PATTERN, 15); bits.xor(maskBits); if (bits.size() != 15) { // Just in case. throw new WriterException("should not happen but we got: " + bits.size()); } }
/// <summary> Interleave "bits" with corresponding error correction bytes. On success, store the result in /// "result". The interleave rule is complicated. See 8.6 of JISX0510:2004 (p.37) for details. /// </summary> internal static void interleaveWithECBytes(BitVector bits, int versionNum, int numTotalBytes, int numDataBytes, int numRSBlocks, BitVector result) { // "bits" must have "getNumDataBytes" bytes of data. if (bits.sizeInBytes() != numDataBytes) { throw new WriterException("Number of bits and data bytes does not match"); } // Step 1. Divide data bytes into blocks and generate error correction bytes for them. We'll // store the divided data bytes blocks and error correction bytes blocks into "blocks". int dataBytesOffset = 0; int maxNumDataBytes = 0; int maxNumEcBytes = 0; // Since, we know the number of reedsolmon blocks, we can initialize the vector with the number. System.Collections.ArrayList blocks = System.Collections.ArrayList.Synchronized(new System.Collections.ArrayList(numRSBlocks)); for (int i = 0; i < numRSBlocks; ++i) { int[] numDataBytesInBlock = new int[1]; int[] numEcBytesInBlock = new int[1]; getNumDataBytesAndNumECBytesForBlockID(numTotalBytes, numDataBytes, numRSBlocks, i, numDataBytesInBlock, numEcBytesInBlock); ByteArray dataBytes = new ByteArray(); dataBytes.set_Renamed(bits.Array, dataBytesOffset, numDataBytesInBlock[0]); ByteArray ecBytes = generateECBytes(dataBytes, numEcBytesInBlock[0]); blocks.Add(new BlockPair(dataBytes, ecBytes)); maxNumDataBytes = System.Math.Max(maxNumDataBytes, dataBytes.size()); maxNumEcBytes = System.Math.Max(maxNumEcBytes, ecBytes.size()); dataBytesOffset += numDataBytesInBlock[0]; } if (numDataBytes != dataBytesOffset) { throw new WriterException("Data bytes does not match offset"); } // First, place data blocks. var bitLen = bits.size(); for (int i = 0; i < maxNumDataBytes; ++i) { for (int j = 0; j < blocks.Count; ++j) { ByteArray dataBytes = ((BlockPair)blocks[j]).DataBytes; if (i < dataBytes.size()) { if (bitLen == 4) { result.appendBits(dataBytes.at(i) >> 4, 4); } else { result.appendBits(dataBytes.at(i), 8); } } } bitLen -= 8; } // Then, place error correction blocks. for (int i = 0; i < maxNumEcBytes; ++i) { for (int j = 0; j < blocks.Count; ++j) { ByteArray ecBytes = ((BlockPair)blocks[j]).ErrorCorrectionBytes; if (i < ecBytes.size()) { result.appendBits(ecBytes.at(i), 8); } } } if (numTotalBytes != result.sizeInBytes()) { // Should be same. throw new WriterException("Interleaving error: " + numTotalBytes + " and " + result.sizeInBytes() + " differ."); } }
/// <summary> Terminate bits as described in 8.4.8 and 8.4.9 of JISX0510:2004 (p.24).</summary> internal static void terminateBits(int numDataBytes, BitVector bits, int versionNum) { int capacity = numDataBytes << 3; //ISO/IEC 18004:2006(E) 6.4.10 Bit stream to codeword conversion //All codewords are 8 bits in length, except for the final data symbol character in Micro //QR Code versions M1 and M3 symbols, which is 4 bits in length int bitLen = (versionNum == 1 || versionNum == 3) ? 4 : 8; if (bitLen == 4) { capacity -= 4; } if (bits.size() > capacity) { throw new WriterException("data bits cannot fit in the QR Code" + bits.size() + " > " + capacity); } // Append termination bits. See 8.4.8 of JISX0510:2004 (p.24) for details. // TODO: srowen says we can remove this for loop, since the 4 terminator bits are optional if // the last byte has less than 4 bits left. So it amounts to padding the last byte with zeroes // either way. var terminatorMode = Mode.TERMINATOR; var ctLen = terminatorMode.getBitsLength(versionNum); for (int i = 0; i < ctLen && bits.size() < capacity; ++i) { bits.appendBit(0); } int numBitsInLastByte = bits.size() % bitLen; // If the last byte isn't 8-bit aligned, we'll add padding bits. if (numBitsInLastByte > 0) { int numPaddingBits = bitLen - numBitsInLastByte; for (int i = 0; i < numPaddingBits; ++i) { bits.appendBit(0); } } // Should be 8-bit aligned here. if (bits.size() % bitLen != 0) { throw new WriterException("Number of bits is not a multiple of 8"); } //ISO/IEC 18004:2006(E) 6.4.10 Bit stream to codeword conversion //The message bit stream shall then be //extended to fill the data capacity of the symbol corresponding to the Version and Error Correction Level, as //defined in Table 8, by adding the Pad Codewords 11101100 and 00010001 alternately. // If we have more space, we'll fill the space with padding patterns defined in 8.4.9 (p.24). int numPaddingBytes = numDataBytes - bits.sizeInBytes(); while (numPaddingBytes * 8 > (capacity - bits.size()) && numPaddingBytes > 0) { numPaddingBytes--; } for (int i = 0; i < numPaddingBytes; ++i) { if (i % 2 == 0) { bits.appendBits(0xec, 8); //11101100 } else { bits.appendBits(0x11, 8);//00010001 } } //For Micro QR Code versions M1 and M3 symbols, the final data codeword is 4 bits long. The Pad Codeword used in the final data //symbol character position in Micro QR Code versions M1 and M3 symbols shall be represented as 0000. if (bitLen == 4 && bits.size() < capacity) { bits.appendBits(0x0, 4);//0000 } if (bits.size() != capacity) { throw new WriterException("Bits size does not equal capacity"); } }
/// <summary> Terminate bits as described in 8.4.8 and 8.4.9 of JISX0510:2004 (p.24).</summary> internal static void terminateBits(int numDataBytes, BitVector bits, int versionNum) { int capacity = numDataBytes << 3; //ISO/IEC 18004:2006(E) 6.4.10 Bit stream to codeword conversion //All codewords are 8 bits in length, except for the final data symbol character in Micro //QR Code versions M1 and M3 symbols, which is 4 bits in length int bitLen = (versionNum == 1 || versionNum == 3) ? 4 : 8; if (bitLen == 4) capacity -= 4; if (bits.size() > capacity) { throw new WriterException("data bits cannot fit in the QR Code" + bits.size() + " > " + capacity); } // Append termination bits. See 8.4.8 of JISX0510:2004 (p.24) for details. // TODO: srowen says we can remove this for loop, since the 4 terminator bits are optional if // the last byte has less than 4 bits left. So it amounts to padding the last byte with zeroes // either way. var terminatorMode = Mode.TERMINATOR; var ctLen = terminatorMode.getBitsLength(versionNum); for (int i = 0; i < ctLen && bits.size() < capacity; ++i) { bits.appendBit(0); } int numBitsInLastByte = bits.size() % bitLen; // If the last byte isn't 8-bit aligned, we'll add padding bits. if (numBitsInLastByte > 0) { int numPaddingBits = bitLen - numBitsInLastByte; for (int i = 0; i < numPaddingBits; ++i) { bits.appendBit(0); } } // Should be 8-bit aligned here. if (bits.size() % bitLen != 0) { throw new WriterException("Number of bits is not a multiple of 8"); } //ISO/IEC 18004:2006(E) 6.4.10 Bit stream to codeword conversion //The message bit stream shall then be //extended to fill the data capacity of the symbol corresponding to the Version and Error Correction Level, as //defined in Table 8, by adding the Pad Codewords 11101100 and 00010001 alternately. // If we have more space, we'll fill the space with padding patterns defined in 8.4.9 (p.24). int numPaddingBytes = numDataBytes - bits.sizeInBytes(); while (numPaddingBytes * 8 > (capacity - bits.size()) && numPaddingBytes > 0) numPaddingBytes--; for (int i = 0; i < numPaddingBytes; ++i) { if (i % 2 == 0) { bits.appendBits(0xec, 8); //11101100 } else { bits.appendBits(0x11, 8);//00010001 } } //For Micro QR Code versions M1 and M3 symbols, the final data codeword is 4 bits long. The Pad Codeword used in the final data //symbol character position in Micro QR Code versions M1 and M3 symbols shall be represented as 0000. if (bitLen == 4 && bits.size() < capacity) bits.appendBits(0x0, 4);//0000 if (bits.size() != capacity) { throw new WriterException("Bits size does not equal capacity"); } }
/// <summary> Interleave "bits" with corresponding error correction bytes. On success, store the result in /// "result". The interleave rule is complicated. See 8.6 of JISX0510:2004 (p.37) for details. /// </summary> internal static void interleaveWithECBytes(BitVector bits, int versionNum, int numTotalBytes, int numDataBytes, int numRSBlocks, BitVector result) { // "bits" must have "getNumDataBytes" bytes of data. if (bits.sizeInBytes() != numDataBytes) { throw new WriterException("Number of bits and data bytes does not match"); } // Step 1. Divide data bytes into blocks and generate error correction bytes for them. We'll // store the divided data bytes blocks and error correction bytes blocks into "blocks". int dataBytesOffset = 0; int maxNumDataBytes = 0; int maxNumEcBytes = 0; // Since, we know the number of reedsolmon blocks, we can initialize the vector with the number. System.Collections.ArrayList blocks = System.Collections.ArrayList.Synchronized(new System.Collections.ArrayList(numRSBlocks)); for (int i = 0; i < numRSBlocks; ++i) { int[] numDataBytesInBlock = new int[1]; int[] numEcBytesInBlock = new int[1]; getNumDataBytesAndNumECBytesForBlockID(numTotalBytes, numDataBytes, numRSBlocks, i, numDataBytesInBlock, numEcBytesInBlock); ByteArray dataBytes = new ByteArray(); dataBytes.set_Renamed(bits.Array, dataBytesOffset, numDataBytesInBlock[0]); ByteArray ecBytes = generateECBytes(dataBytes, numEcBytesInBlock[0]); blocks.Add(new BlockPair(dataBytes, ecBytes)); maxNumDataBytes = System.Math.Max(maxNumDataBytes, dataBytes.size()); maxNumEcBytes = System.Math.Max(maxNumEcBytes, ecBytes.size()); dataBytesOffset += numDataBytesInBlock[0]; } if (numDataBytes != dataBytesOffset) { throw new WriterException("Data bytes does not match offset"); } // First, place data blocks. var bitLen = bits.size(); for (int i = 0; i < maxNumDataBytes; ++i) { for (int j = 0; j < blocks.Count; ++j) { ByteArray dataBytes = ((BlockPair)blocks[j]).DataBytes; if (i < dataBytes.size()) { if (bitLen == 4) result.appendBits(dataBytes.at(i) >> 4, 4); else result.appendBits(dataBytes.at(i), 8); } } bitLen -= 8; } // Then, place error correction blocks. for (int i = 0; i < maxNumEcBytes; ++i) { for (int j = 0; j < blocks.Count; ++j) { ByteArray ecBytes = ((BlockPair)blocks[j]).ErrorCorrectionBytes; if (i < ecBytes.size()) { result.appendBits(ecBytes.at(i), 8); } } } if (numTotalBytes != result.sizeInBytes()) { // Should be same. throw new WriterException("Interleaving error: " + numTotalBytes + " and " + result.sizeInBytes() + " differ."); } }
/// <summary> /// Make bit vector of type information. On success, store the result in "bits" and return true. /// Encode error correction level and mask pattern. See 8.9 of /// JISX0510:2004 (p.45) for details. /// </summary> /// <param name="ecLevel"></param> /// <param name="maskPattern"></param> /// <param name="bits"></param> /// <remarks> /// ISO/IEC 18004:2006(E) 6.9 Format information /// </remarks> public static void makeTypeInfoBits(ErrorCorrectionLevel ecLevel, int version, int maskPattern, BitVector bits) { if (!MicroQRCode.isValidMaskPattern(maskPattern)) { throw new WriterException("Invalid mask pattern"); } //ISO/IEC 18004:2006(E) 6.9 Format information //Symbol number 0: 000 //Data mask pattern reference: 11 //Data bits (symbol number, data mask pattern reference): 00011 //BCH bits: 1101011001 //Unmasked bit sequence: 000111101011001 //Mask pattern for XOR operation: 100010001000101 //Format information module pattern: 100101100011100 int typeInfo = SYMBOL_NUMBERS_INFO[version - 1][ecLevel.ordinal()]; if (typeInfo == -1) throw new WriterException("Invalid Version&Level info"); typeInfo = (typeInfo << 2) | maskPattern; bits.appendBits(typeInfo, 5); int bchCode = calculateBCHCode(typeInfo, TYPE_INFO_POLY); bits.appendBits(bchCode, 10); BitVector maskBits = new BitVector(); maskBits.appendBits(TYPE_INFO_MASK_PATTERN, 15); bits.xor(maskBits); if (bits.size() != 15) { // Just in case. throw new WriterException("should not happen but we got: " + bits.size()); } }