def decode(self, byts, version):
bits = BitSource(byts)
result = ''
###CharacterSetECI currentCharacterSetECI = None
fc1InEffect = False
###Vector byteSegments = new Vector(1)
###Mode mode
while True:
# While still another segment to read...
if (bits.available() < 4):
# OK, assume we're done. Really, a TERMINATOR mode should have been recorded here
mode = Mode.TERMINATOR
else:
try:
mode = Mode.forBits(bits.readBits(4)); # mode is encoded by 4 bits
except IllegalArgumentException as iae:
raise ReaderException.getInstance()
if (not mode.equals(Mode.TERMINATOR)):
if (mode.equals(Mode.FNC1_FIRST_POSITION) or mode.equals(Mode.FNC1_SECOND_POSITION)):
# We do little with FNC1 except alter the parsed result a bit according to the spec
fc1InEffect = True
elif (mode.equals(Mode.STRUCTURED_APPEND)):
# not really supported; all we do is ignore it
# Read next 8 bits (symbol sequence #) and 8 bits (parity data), then continue
bits.readBits(16)
elif (mode.equals(Mode.ECI)):
# Count doesn't apply to ECI
value = parseECIValue(bits)
currentCharacterSetECI = CharacterSetECI.getCharacterSetECIByValue(value)
if (currentCharacterSetECI == None):
raise ReaderException.getInstance()
else:
# How many characters will follow, encoded in this mode?
count = bits.readBits(mode.getCharacterCountBits(version))
if (mode.equals(Mode.NUMERIC)):
decodeNumericSegment(bits, result, count)
elif (mode.equals(Mode.ALPHANUMERIC)):
decodeAlphanumericSegment(bits, result, count, fc1InEffect)
elif (mode.equals(Mode.BYTE)):
decodeByteSegment(bits, result, count, currentCharacterSetECI, byteSegments)
elif (mode.equals(Mode.KANJI)):
decodeKanjiSegment(bits, result, count)
else:
raise ReaderException.getInstance()
if (mode.equals(Mode.TERMINATOR)):
break
return DecoderResult(byts, str(result), None if byteSegments.isEmpty() else byteSegments)
def decodeByteSegment(bits, result, count, currentCharacterSetECI,
byteSegments):
readBytes = bytearray[count]
if (count << 3 > bits.available()):
raise ReaderException.getInstance()
for i in range(count):
readBytes[i] = bits.readBits(8)
if (currentCharacterSetECI == None):
# The spec isn't clear on this mode; see
# section 6.4.5: t does not say which encoding to assuming
# upon decoding. I have seen ISO-8859-1 used as well as
# Shift_JIS -- without anything like an ECI designator to
# give a hint.
encoding = guessEncoding(readBytes)
else:
encoding = currentCharacterSetECI.getEncodingName()
try:
result.append(readBytes.decode(encoding))
except UnsupportedEncodingException as uce:
raise ReaderException.getInstance()
byteSegments.addElement(readBytes)
def decodeNumericSegment(bits, result, count):
# Read three digits at a time
while (count >= 3):
# Each 10 bits encodes three digits
threeDigitsBits = bits.readBits(10)
if (threeDigitsBits >= 1000):
raise ReaderException.getInstance()
result.append(ALPHANUMERIC_CHARS[int(threeDigitsBits / 100)])
result.append(ALPHANUMERIC_CHARS[int(threeDigitsBits / 10) % 10])
result.append(ALPHANUMERIC_CHARS[threeDigitsBits % 10])
count -= 3
if (count == 2):
# Two digits left over to read, encoded in 7 bits
twoDigitsBits = bits.readBits(7)
if (twoDigitsBits >= 100):
raise ReaderException.getInstance()
result.append(ALPHANUMERIC_CHARS[int(twoDigitsBits / 10)])
result.append(ALPHANUMERIC_CHARS[twoDigitsBits % 10])
elif (count == 1):
# One digit left over to read
digitBits = bits.readBits(4)
if (digitBits >= 10):
raise ReaderException.getInstance()
result.append(ALPHANUMERIC_CHARS[digitBits])
def decodeKanjiSegment(bits, result, count):
# Each character will require 2 bytes. Read the characters as 2-byte pairs
# and decode as Shift_JIS afterwards
buffer = bytearray(2 * count)
offset = 0
while (count > 0):
# Each 13 bits encodes a 2-byte character
twoBytes = bits.readBits(13)
assembledTwoBytes = ((twoBytes / 0x0C0) << 8) | (twoBytes % 0x0C0)
if (assembledTwoBytes < 0x01F00):
# In the 0x8140 to 0x9FFC range
assembledTwoBytes += 0x08140
else:
# In the 0xE040 to 0xEBBF range
assembledTwoBytes += 0x0C140
buffer[offset] = (assembledTwoBytes >> 8)
buffer[offset + 1] = assembledTwoBytes
offset += 2
count-=1
# Shift_JIS may not be supported in some environments:
try:
result.append(buffer.decode(SHIFT_JIS))
except UnsupportedEncodingException as uee:
raise ReaderException.getInstance()
