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Core barcode encoding/decoding library
/*
* Copyright 2008 ZXing authors
*
* 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.
*/
package com.google.zxing.datamatrix.decoder;
import com.google.zxing.FormatException;
import com.google.zxing.common.BitSource;
import com.google.zxing.common.DecoderResult;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
/**
* Data Matrix Codes can encode text as bits in one of several modes, and can use multiple modes
* in one Data Matrix Code. This class decodes the bits back into text.
*
* See ISO 16022:2006, 5.2.1 - 5.2.9.2
*
* @author [email protected] (Brian Brown)
* @author Sean Owen
*/
final class DecodedBitStreamParser {
private enum Mode {
PAD_ENCODE, // Not really a mode
ASCII_ENCODE,
C40_ENCODE,
TEXT_ENCODE,
ANSIX12_ENCODE,
EDIFACT_ENCODE,
BASE256_ENCODE
}
/**
* See ISO 16022:2006, Annex C Table C.1
* The C40 Basic Character Set (*'s used for placeholders for the shift values)
*/
private static final char[] 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'
};
private static final char[] C40_SHIFT2_SET_CHARS = {
'!', '"', '#', '$', '%', '&', '\'', '(', ')', '*', '+', ',', '-', '.',
'/', ':', ';', '<', '=', '>', '?', '@', '[', '\\', ']', '^', '_'
};
/**
* See ISO 16022:2006, Annex C Table C.2
* The Text Basic Character Set (*'s used for placeholders for the shift values)
*/
private static final char[] 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'
};
private static final char[] 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', '{', '|', '}', '~', (char) 127
};
private DecodedBitStreamParser() {
}
static DecoderResult decode(byte[] bytes) throws FormatException {
BitSource bits = new BitSource(bytes);
StringBuilder result = new StringBuilder(100);
StringBuilder resultTrailer = new StringBuilder(0);
List byteSegments = new ArrayList(1);
Mode mode = Mode.ASCII_ENCODE;
do {
if (mode == 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.getFormatInstance();
}
mode = Mode.ASCII_ENCODE;
}
} while (mode != Mode.PAD_ENCODE && bits.available() > 0);
if (resultTrailer.length() > 0) {
result.append(resultTrailer.toString());
}
return new DecoderResult(bytes, result.toString(), byteSegments.isEmpty() ? null : byteSegments, null);
}
/**
* See ISO 16022:2006, 5.2.3 and Annex C, Table C.2
*/
private static Mode decodeAsciiSegment(BitSource bits,
StringBuilder result,
StringBuilder resultTrailer) throws FormatException {
boolean upperShift = false;
do {
int oneByte = bits.readBits(8);
if (oneByte == 0) {
throw FormatException.getFormatInstance();
} else if (oneByte <= 128) { // ASCII data (ASCII value + 1)
if (upperShift) {
oneByte += 128;
//upperShift = false;
}
result.append((char) (oneByte - 1));
return Mode.ASCII_ENCODE;
} else if (oneByte == 129) { // Pad
return Mode.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.append('0');
}
result.append(value);
} else if (oneByte == 230) { // Latch to C40 encodation
return Mode.C40_ENCODE;
} else if (oneByte == 231) { // Latch to Base 256 encodation
return Mode.BASE256_ENCODE;
} else if (oneByte == 232) {
// FNC1
result.append((char) 29); // translate as ASCII 29
} else if (oneByte == 233 || oneByte == 234) {
// Structured Append, Reader Programming
// Ignore these symbols for now
//throw ReaderException.getInstance();
} else if (oneByte == 235) { // Upper Shift (shift to Extended ASCII)
upperShift = true;
} else if (oneByte == 236) { // 05 Macro
result.append("[)>\u001E05\u001D");
resultTrailer.insert(0, "\u001E\u0004");
} else if (oneByte == 237) { // 06 Macro
result.append("[)>\u001E06\u001D");
resultTrailer.insert(0, "\u001E\u0004");
} else if (oneByte == 238) { // Latch to ANSI X12 encodation
return Mode.ANSIX12_ENCODE;
} else if (oneByte == 239) { // Latch to Text encodation
return Mode.TEXT_ENCODE;
} else if (oneByte == 240) { // Latch to EDIFACT encodation
return Mode.EDIFACT_ENCODE;
} else if (oneByte == 241) { // ECI Character
// TODO(bbrown): I think we need to support ECI
//throw ReaderException.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) {
// Ignore
} else {
throw FormatException.getFormatInstance();
}
}
} while (bits.available() > 0);
return Mode.ASCII_ENCODE;
}
/**
* See ISO 16022:2006, 5.2.5 and Annex C, Table C.1
*/
private static void decodeC40Segment(BitSource bits, StringBuilder result) throws FormatException {
// 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
boolean upperShift = false;
int[] cValues = new int[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 (cValue < C40_BASIC_SET_CHARS.length) {
char c40char = C40_BASIC_SET_CHARS[cValue];
if (upperShift) {
result.append((char) (c40char + 128));
upperShift = false;
} else {
result.append(c40char);
}
} else {
throw FormatException.getFormatInstance();
}
break;
case 1:
if (upperShift) {
result.append((char) (cValue + 128));
upperShift = false;
} else {
result.append((char) cValue);
}
shift = 0;
break;
case 2:
if (cValue < C40_SHIFT2_SET_CHARS.length) {
char c40char = C40_SHIFT2_SET_CHARS[cValue];
if (upperShift) {
result.append((char) (c40char + 128));
upperShift = false;
} else {
result.append(c40char);
}
} else if (cValue == 27) { // FNC1
result.append((char) 29); // translate as ASCII 29
} else if (cValue == 30) { // Upper Shift
upperShift = true;
} else {
throw FormatException.getFormatInstance();
}
shift = 0;
break;
case 3:
if (upperShift) {
result.append((char) (cValue + 224));
upperShift = false;
} else {
result.append((char) (cValue + 96));
}
shift = 0;
break;
default:
throw FormatException.getFormatInstance();
}
}
} while (bits.available() > 0);
}
/**
* See ISO 16022:2006, 5.2.6 and Annex C, Table C.2
*/
private static void decodeTextSegment(BitSource bits, StringBuilder result) throws FormatException {
// 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
boolean upperShift = false;
int[] cValues = new int[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 (cValue < TEXT_BASIC_SET_CHARS.length) {
char textChar = TEXT_BASIC_SET_CHARS[cValue];
if (upperShift) {
result.append((char) (textChar + 128));
upperShift = false;
} else {
result.append(textChar);
}
} else {
throw FormatException.getFormatInstance();
}
break;
case 1:
if (upperShift) {
result.append((char) (cValue + 128));
upperShift = false;
} else {
result.append((char) cValue);
}
shift = 0;
break;
case 2:
// Shift 2 for Text is the same encoding as C40
if (cValue < C40_SHIFT2_SET_CHARS.length) {
char c40char = C40_SHIFT2_SET_CHARS[cValue];
if (upperShift) {
result.append((char) (c40char + 128));
upperShift = false;
} else {
result.append(c40char);
}
} else if (cValue == 27) { // FNC1
result.append((char) 29); // translate as ASCII 29
} else if (cValue == 30) { // Upper Shift
upperShift = true;
} else {
throw FormatException.getFormatInstance();
}
shift = 0;
break;
case 3:
if (cValue < TEXT_SHIFT3_SET_CHARS.length) {
char textChar = TEXT_SHIFT3_SET_CHARS[cValue];
if (upperShift) {
result.append((char) (textChar + 128));
upperShift = false;
} else {
result.append(textChar);
}
shift = 0;
} else {
throw FormatException.getFormatInstance();
}
break;
default:
throw FormatException.getFormatInstance();
}
}
} while (bits.available() > 0);
}
/**
* See ISO 16022:2006, 5.2.7
*/
private static void decodeAnsiX12Segment(BitSource bits,
StringBuilder result) throws FormatException {
// Three ANSI X12 values are encoded in a 16-bit value as
// (1600 * C1) + (40 * C2) + C3 + 1
int[] cValues = new int[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
result.append('\r');
} else if (cValue == 1) { // X12 segment separator *
result.append('*');
} else if (cValue == 2) { // X12 sub-element separator >
result.append('>');
} else if (cValue == 3) { // space
result.append(' ');
} else if (cValue < 14) { // 0 - 9
result.append((char) (cValue + 44));
} else if (cValue < 40) { // A - Z
result.append((char) (cValue + 51));
} else {
throw FormatException.getFormatInstance();
}
}
} while (bits.available() > 0);
}
private static void 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;
}
/**
* See ISO 16022:2006, 5.2.8 and Annex C Table C.3
*/
private static void decodeEdifactSegment(BitSource bits, StringBuilder result) {
boolean unlatch = false;
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
unlatch = true;
// If we encounter the unlatch code then continue reading because the Codeword triple
// is padded with 0's
}
if (!unlatch) {
if ((edifactValue & 0x20) == 0) { // no 1 in the leading (6th) bit
edifactValue |= 0x40; // Add a leading 01 to the 6 bit binary value
}
result.append((char) edifactValue);
}
}
} while (!unlatch && bits.available() > 0);
}
/**
* See ISO 16022:2006, 5.2.9 and Annex B, B.2
*/
private static void decodeBase256Segment(BitSource bits,
StringBuilder result,
Collection byteSegments)
throws FormatException {
// 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.getFormatInstance();
}
byte[] bytes = new byte[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.getFormatInstance();
}
bytes[i] = (byte) unrandomize255State(bits.readBits(8), codewordPosition++);
}
byteSegments.add(bytes);
try {
result.append(new String(bytes, "ISO8859_1"));
} catch (UnsupportedEncodingException uee) {
throw new IllegalStateException("Platform does not support required encoding: " + uee);
}
}
/**
* See ISO 16022:2006, Annex B, B.2
*/
private static int unrandomize255State(int randomizedBase256Codeword,
int base256CodewordPosition) {
int pseudoRandomNumber = ((149 * base256CodewordPosition) % 255) + 1;
int tempVariable = randomizedBase256Codeword - pseudoRandomNumber;
return tempVariable >= 0 ? tempVariable : tempVariable + 256;
}
}
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