/usr/share/pyshared/pdfminer/ascii85.py is in python-pdfminer 20110515+dfsg-1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 | #!/usr/bin/env python2
""" Python implementation of ASCII85/ASCIIHex decoder (Adobe version).
This code is in the public domain.
"""
import re
import struct
# ascii85decode(data)
def ascii85decode(data):
"""
In ASCII85 encoding, every four bytes are encoded with five ASCII
letters, using 85 different types of characters (as 256**4 < 85**5).
When the length of the original bytes is not a multiple of 4, a special
rule is used for round up.
The Adobe's ASCII85 implementation is slightly different from
its original in handling the last characters.
The sample string is taken from:
http://en.wikipedia.org/w/index.php?title=Ascii85
>>> ascii85decode('9jqo^BlbD-BleB1DJ+*+F(f,q')
'Man is distinguished'
>>> ascii85decode('E,9)oF*2M7/c~>')
'pleasure.'
"""
n = b = 0
out = ''
for c in data:
if '!' <= c and c <= 'u':
n += 1
b = b*85+(ord(c)-33)
if n == 5:
out += struct.pack('>L',b)
n = b = 0
elif c == 'z':
assert n == 0
out += '\0\0\0\0'
elif c == '~':
if n:
for _ in range(5-n):
b = b*85+84
out += struct.pack('>L',b)[:n-1]
break
return out
# asciihexdecode(data)
hex_re = re.compile(r'([a-f\d]{2})', re.IGNORECASE)
trail_re = re.compile(r'^(?:[a-f\d]{2}|\s)*([a-f\d])[\s>]*$', re.IGNORECASE)
def asciihexdecode(data):
"""
ASCIIHexDecode filter: PDFReference v1.4 section 3.3.1
For each pair of ASCII hexadecimal digits (0-9 and A-F or a-f), the
ASCIIHexDecode filter produces one byte of binary data. All white-space
characters are ignored. A right angle bracket character (>) indicates
EOD. Any other characters will cause an error. If the filter encounters
the EOD marker after reading an odd number of hexadecimal digits, it
will behave as if a 0 followed the last digit.
>>> asciihexdecode('61 62 2e6364 65')
'ab.cde'
>>> asciihexdecode('61 62 2e6364 657>')
'ab.cdep'
>>> asciihexdecode('7>')
'p'
"""
decode = (lambda hx: chr(int(hx, 16)))
out = map(decode, hex_re.findall(data))
m = trail_re.search(data)
if m:
out.append(decode("%c0" % m.group(1)))
return ''.join(out)
if __name__ == '__main__':
import doctest
doctest.testmod()
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