[Patches] [ python-Patches-868496 ] base64.py support for RFC 3548

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Patches item #868496, was opened at 2003-12-31 11:34
Message generated for change (Comment added) made by bwarsaw
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Category: Library (Lib)
Group: Python 2.4
Status: Open
Resolution: None
Priority: 5
Submitted By: Barry A. Warsaw (bwarsaw)
Assigned to: Tim Peters (tim_one)
Summary: base64.py support for RFC 3548

Initial Comment:
I needed more complete RFC 3548 support, so I hacked up
the base64.py module.  Here's the patch and an updated
test suite.


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>Comment By: Barry A. Warsaw (bwarsaw)
Date: 2004-01-03 14:55

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Freenet alphabet is mentioned in the thread referenced by
footnote [8] in the RFC. 

Thanks for the other suggestions.  I'll work with those and
unless there are any other objections, I'll commit these
changes soon.


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Comment By: Martin v. Löwis (loewis)
Date: 2004-01-03 06:21

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Where does the Freenet encoding come from? Do we need that?

Performance of the algorithms can probably be improved. For
example, for base32
- _b32table should be a list (or tuple), not a dictionary:
  _b32table = tuple([_b32table[i] for i in range(32)])

- first hexlifying the string on encoding seems wasteful;
use struct instead

def f2(chunk):
    c1, c2, c3 = struct.unpack("!HHB", chunk)
    c2 += (c1 & 1) << 16 # total 17 bits
    c3 += (c2 & 3) << 8  # total 10 bits
    parts = [_b32table[c1 >> 11],
             _b32table[(c1 >> 6) & 31],
             _b32table[(c1>>1) & 31],
             _b32table[c2 >> 12],
             _b32table[(c2 >> 7) & 31],
             _b32table[(c2 >> 2) & 31],
             _b32table[c3 >> 5],
             _b32table[c3 & 31]]
    return ''.join(parts)

Apart from that, the change looks good.



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