/** See ISO 16022:2006, 5.2.9 and Annex B, B.2 */
private static void decodeBase256Segment(
BitSource bits, StringBuilder result, Collection<byte[]> 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);
}
}
