DataMatrixDecodedBitStreamParser.cpp Example File

 // -*- mode:c++; tab-width:2; indent-tabs-mode:nil; c-basic-offset:2 -*-
 /*
  *  DecodedBitStreamParser.cpp
  *  zxing
  *
  *  Created by Luiz Silva on 09/02/2010.
  *  Copyright 2010 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/FormatException.h>
 #include <zxing/datamatrix/decoder/DecodedBitStreamParser.h>
 #include <iostream>
 #include <zxing/common/DecoderResult.h>

 namespace zxing {
 namespace datamatrix {

 using namespace std;

 const char DecodedBitStreamParser::C40_BASIC_SET_CHARS[] = {
     '*', '*', '*', ' ', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
     'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N',
     'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'
 };

 const char DecodedBitStreamParser::C40_SHIFT2_SET_CHARS[] = {
     '!', '"', '#', '$', '%', '&', '\'', '(', ')', '*', '+', ',', '-', '.',
     '/', ':', ';', '<', '=', '>', '?', '@', '[', '\\', ']', '^', '_'
 };

 const char DecodedBitStreamParser::TEXT_BASIC_SET_CHARS[] = {
     '*', '*', '*', ' ', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
     'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
     'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'
 };

 const char DecodedBitStreamParser::TEXT_SHIFT3_SET_CHARS[] = {
     '\'', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N',
     'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', '{', '|', '}', '~', (byte) 127
 };

 Ref<DecoderResult> DecodedBitStreamParser::decode(ArrayRef<byte> bytes) {
   Ref<BitSource> bits(new BitSource(bytes));
   ostringstream result;
   ostringstream resultTrailer;
   vector<byte> byteSegments;
   int mode = ASCII_ENCODE;
   do {
     if (mode == ASCII_ENCODE) {
       mode = decodeAsciiSegment(bits, result, resultTrailer);
     } else {
       switch (mode) {
         case C40_ENCODE:
           decodeC40Segment(bits, result);
           break;
         case TEXT_ENCODE:
           decodeTextSegment(bits, result);
           break;
         case ANSIX12_ENCODE:
           decodeAnsiX12Segment(bits, result);
           break;
         case EDIFACT_ENCODE:
           decodeEdifactSegment(bits, result);
           break;
         case BASE256_ENCODE:
           decodeBase256Segment(bits, result, byteSegments);
           break;
         default:
           throw FormatException("Unsupported mode indicator");
       }
       mode = ASCII_ENCODE;
     }
   } while (mode != PAD_ENCODE && bits->available() > 0);

   if (resultTrailer.str().size() > 0) {
     result << resultTrailer.str();
   }
   ArrayRef<byte> rawBytes(bytes);
   Ref<String> text(new String(result.str()));
   return Ref<DecoderResult>(new DecoderResult(rawBytes, text));
 }

 int DecodedBitStreamParser::decodeAsciiSegment(Ref<BitSource> bits, ostringstream & result,
   ostringstream & resultTrailer) {
   bool upperShift = false;
   do {
     int oneByte = bits->readBits(8);
     if (oneByte == 0) {
       throw FormatException("Not enough bits to decode");
     } else if (oneByte <= 128) {  // ASCII data (ASCII value + 1)
       oneByte = upperShift ? (oneByte + 128) : oneByte;
       // upperShift = false;
       result << (byte) (oneByte - 1);
       return ASCII_ENCODE;
     } else if (oneByte == 129) {  // Pad
       return PAD_ENCODE;
     } else if (oneByte <= 229) {  // 2-digit data 00-99 (Numeric Value + 130)
       int value = oneByte - 130;
       if (value < 10) { // padd with '0' for single digit values
         result << '0';
       }
       result << value;
     } else if (oneByte == 230) {  // Latch to C40 encodation
       return C40_ENCODE;
     } else if (oneByte == 231) {  // Latch to Base 256 encodation
       return BASE256_ENCODE;
     } else if (oneByte == 232) {  // FNC1
       result << ((byte) 29); // translate as ASCII 29
     } else if (oneByte == 233 || oneByte == 234) {
       // Structured Append, Reader Programming
       // Ignore these symbols for now
       // throw FormatException.getInstance();
     } else if (oneByte == 235) {  // Upper Shift (shift to Extended ASCII)
       upperShift = true;
     } else if (oneByte == 236) {  // 05 Macro
         result << ("[)>RS05GS");
         resultTrailer << ("RSEOT");
     } else if (oneByte == 237) {  // 06 Macro
       result << ("[)>RS06GS");
       resultTrailer <<  ("RSEOT");
     } else if (oneByte == 238) {  // Latch to ANSI X12 encodation
       return ANSIX12_ENCODE;
     } else if (oneByte == 239) {  // Latch to Text encodation
       return TEXT_ENCODE;
     } else if (oneByte == 240) {  // Latch to EDIFACT encodation
       return EDIFACT_ENCODE;
     } else if (oneByte == 241) {  // ECI Character
       // TODO(bbrown): I think we need to support ECI
       // throw FormatException.getInstance();
       // Ignore this symbol for now
     } else if (oneByte >= 242) { // Not to be used in ASCII encodation
       // ... but work around encoders that end with 254, latch back to ASCII
       if (oneByte != 254 || bits->available() != 0) {
         throw FormatException("Not to be used in ASCII encodation");
       }
     }
   } while (bits->available() > 0);
   return ASCII_ENCODE;
 }

 void DecodedBitStreamParser::decodeC40Segment(Ref<BitSource> bits, ostringstream & result) {
   // Three C40 values are encoded in a 16-bit value as
   // (1600 * C1) + (40 * C2) + C3 + 1
   // TODO(bbrown): The Upper Shift with C40 doesn't work in the 4 value scenario all the time
   bool upperShift = false;

   int cValues[3];
   int shift = 0;
   do {
     // If there is only one byte left then it will be encoded as ASCII
     if (bits->available() == 8) {
       return;
     }
     int firstByte = bits->readBits(8);
     if (firstByte == 254) {  // Unlatch codeword
       return;
     }

     parseTwoBytes(firstByte, bits->readBits(8), cValues);

     for (int i = 0; i < 3; i++) {
       int cValue = cValues[i];
       switch (shift) {
         case 0:
           if (cValue < 3) {
             shift = cValue + 1;
           } else {
             if (upperShift) {
               result << (byte) (C40_BASIC_SET_CHARS[cValue] + 128);
               upperShift = false;
             } else {
               result << C40_BASIC_SET_CHARS[cValue];
             }
           }
           break;
         case 1:
           if (upperShift) {
             result << (byte) (cValue + 128);
             upperShift = false;
           } else {
             result << (byte) cValue;
           }
           shift = 0;
           break;
         case 2:
           if (cValue < 27) {
             if (upperShift) {
               result << (byte) (C40_SHIFT2_SET_CHARS[cValue] + 128);
               upperShift = false;
             } else {
               result << C40_SHIFT2_SET_CHARS[cValue];
             }
           } else if (cValue == 27) {  // FNC1
             result << ((byte) 29); // translate as ASCII 29
           } else if (cValue == 30) {  // Upper Shift
             upperShift = true;
           } else {
             throw FormatException("decodeC40Segment: Upper Shift");
           }
           shift = 0;
           break;
         case 3:
           if (upperShift) {
             result << (byte) (cValue + 224);
             upperShift = false;
           } else {
             result << (byte) (cValue + 96);
           }
           shift = 0;
           break;
         default:
           throw FormatException("decodeC40Segment: no case");
       }
     }
   } while (bits->available() > 0);
 }

 void DecodedBitStreamParser::decodeTextSegment(Ref<BitSource> bits, ostringstream & result) {
   // Three Text values are encoded in a 16-bit value as
   // (1600 * C1) + (40 * C2) + C3 + 1
   // TODO(bbrown): The Upper Shift with Text doesn't work in the 4 value scenario all the time
   bool upperShift = false;

   int cValues[3];
   int shift = 0;
   do {
     // If there is only one byte left then it will be encoded as ASCII
     if (bits->available() == 8) {
       return;
     }
     int firstByte = bits->readBits(8);
     if (firstByte == 254) {  // Unlatch codeword
       return;
     }

     parseTwoBytes(firstByte, bits->readBits(8), cValues);

     for (int i = 0; i < 3; i++) {
       int cValue = cValues[i];
       switch (shift) {
         case 0:
           if (cValue < 3) {
             shift = cValue + 1;
           } else {
             if (upperShift) {
               result << (byte) (TEXT_BASIC_SET_CHARS[cValue] + 128);
               upperShift = false;
             } else {
               result << (TEXT_BASIC_SET_CHARS[cValue]);
             }
           }
           break;
         case 1:
           if (upperShift) {
             result << (byte) (cValue + 128);
             upperShift = false;
           } else {
             result << (byte) (cValue);
           }
           shift = 0;
           break;
         case 2:
           // Shift 2 for Text is the same encoding as C40
           if (cValue < 27) {
             if (upperShift) {
               result << (byte) (C40_SHIFT2_SET_CHARS[cValue] + 128);
               upperShift = false;
             } else {
               result << (C40_SHIFT2_SET_CHARS[cValue]);
             }
           } else if (cValue == 27) {  // FNC1
             result << ((byte) 29); // translate as ASCII 29
           } else if (cValue == 30) {  // Upper Shift
             upperShift = true;
           } else {
             throw FormatException("decodeTextSegment: Upper Shift");
           }
           shift = 0;
           break;
         case 3:
           if (upperShift) {
             result << (byte) (TEXT_SHIFT3_SET_CHARS[cValue] + 128);
             upperShift = false;
           } else {
             result << (TEXT_SHIFT3_SET_CHARS[cValue]);
           }
           shift = 0;
           break;
         default:
           throw FormatException("decodeTextSegment: no case");
       }
     }
   } while (bits->available() > 0);
 }

 void DecodedBitStreamParser::decodeAnsiX12Segment(Ref<BitSource> bits, ostringstream & result) {
   // Three ANSI X12 values are encoded in a 16-bit value as
   // (1600 * C1) + (40 * C2) + C3 + 1

   int cValues[3];
   do {
     // If there is only one byte left then it will be encoded as ASCII
     if (bits->available() == 8) {
       return;
     }
     int firstByte = bits->readBits(8);
     if (firstByte == 254) {  // Unlatch codeword
       return;
     }

     parseTwoBytes(firstByte, bits->readBits(8), cValues);

     for (int i = 0; i < 3; i++) {
       int cValue = cValues[i];
       if (cValue == 0) {  // X12 segment terminator <CR>
         result << '\r';
       } else if (cValue == 1) {  // X12 segment separator *
         result << '*';
       } else if (cValue == 2) {  // X12 sub-element separator >
         result << '>';
       } else if (cValue == 3) {  // space
         result << ' ';
       } else if (cValue < 14) {  // 0 - 9
         result << (byte) (cValue + 44);
       } else if (cValue < 40) {  // A - Z
         result << (byte) (cValue + 51);
       } else {
         throw FormatException("decodeAnsiX12Segment: no case");
       }
     }
   } while (bits->available() > 0);
 }

 void DecodedBitStreamParser::parseTwoBytes(int firstByte, int secondByte, int* result) {
   int fullBitValue = (firstByte << 8) + secondByte - 1;
   int temp = fullBitValue / 1600;
   result[0] = temp;
   fullBitValue -= temp * 1600;
   temp = fullBitValue / 40;
   result[1] = temp;
   result[2] = fullBitValue - temp * 40;
 }

 void DecodedBitStreamParser::decodeEdifactSegment(Ref<BitSource> bits, ostringstream & result) {
   do {
     // If there is only two or less bytes left then it will be encoded as ASCII
     if (bits->available() <= 16) {
       return;
     }

     for (int i = 0; i < 4; i++) {
       int edifactValue = bits->readBits(6);

       // Check for the unlatch character
       if (edifactValue == 0x1f) {  // 011111
         // Read rest of byte, which should be 0, and stop
         int bitsLeft = 8 - bits->getBitOffset();
         if (bitsLeft != 8) {
           bits->readBits(bitsLeft);
         }
         return;
       }

       if ((edifactValue & 0x20) == 0) {  // no 1 in the leading (6th) bit
         edifactValue |= 0x40;  // Add a leading 01 to the 6 bit binary value
       }
       result << (byte)(edifactValue);
     }
   } while (bits->available() > 0);
 }

 void DecodedBitStreamParser::decodeBase256Segment(Ref<BitSource> bits, ostringstream& result, vector<byte> byteSegments) {
   // Figure out how long the Base 256 Segment is.
   int codewordPosition = 1 + bits->getByteOffset(); // position is 1-indexed
   int d1 = unrandomize255State(bits->readBits(8), codewordPosition++);
   int count;
   if (d1 == 0) {  // Read the remainder of the symbol
     count = bits->available() / 8;
   } else if (d1 < 250) {
     count = d1;
   } else {
     count = 250 * (d1 - 249) + unrandomize255State(bits->readBits(8), codewordPosition++);
   }

   // We're seeing NegativeArraySizeException errors from users.
   if (count < 0) {
     throw FormatException("NegativeArraySizeException");
   }

   char* bytes = new char[count];
   for (int i = 0; i < count; i++) {
     // Have seen this particular error in the wild, such as at
     // http://www.bcgen.com/demo/IDAutomationStreamingDataMatrix.aspx?MODE=3&D=Fred&PFMT=3&PT=F&X=0.3&O=0&LM=0.2
     if (bits->available() < 8) {
       throw FormatException("byteSegments");
     }
     bytes[i] = unrandomize255State(bits->readBits(8), codewordPosition++);
     byteSegments.push_back(bytes[i]);
     result << (byte)bytes[i];
   }
   delete bytes;
 }
 }
 }