Mercurial > hg
annotate mercurial/pure/base85.py @ 36191:80301c90a2dc
py3: converts bytes to pycompat.bytestr to get bytechrs while enumerating
Differential Revision: https://phab.mercurial-scm.org/D2270
author | Pulkit Goyal <7895pulkit@gmail.com> |
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date | Wed, 14 Feb 2018 17:44:19 +0530 |
parents | 01b4d88ccb24 |
children | 2372284d9457 |
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7701 | 1 # base85.py: pure python base85 codec |
2 # | |
3 # Copyright (C) 2009 Brendan Cully <brendan@kublai.com> | |
4 # | |
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5 # This software may be used and distributed according to the terms of the |
10263 | 6 # GNU General Public License version 2 or any later version. |
7701 | 7 |
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8 from __future__ import absolute_import |
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9 |
7701 | 10 import struct |
11 | |
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12 from .. import pycompat |
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13 |
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14 _b85chars = pycompat.bytestr("0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdef" |
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15 "ghijklmnopqrstuvwxyz!#$%&()*+-;<=>?@^_`{|}~") |
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16 _b85chars2 = [(a + b) for a in _b85chars for b in _b85chars] |
7701 | 17 _b85dec = {} |
18 | |
19 def _mkb85dec(): | |
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20 for i, c in enumerate(_b85chars): |
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21 _b85dec[c] = i |
7701 | 22 |
23 def b85encode(text, pad=False): | |
24 """encode text in base85 format""" | |
25 l = len(text) | |
26 r = l % 4 | |
27 if r: | |
28 text += '\0' * (4 - r) | |
29 longs = len(text) >> 2 | |
30 words = struct.unpack('>%dL' % (longs), text) | |
31 | |
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32 out = ''.join(_b85chars[(word // 52200625) % 85] + |
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33 _b85chars2[(word // 7225) % 7225] + |
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34 _b85chars2[word % 7225] |
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35 for word in words) |
7701 | 36 |
37 if pad: | |
38 return out | |
39 | |
40 # Trim padding | |
41 olen = l % 4 | |
42 if olen: | |
43 olen += 1 | |
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44 olen += l // 4 * 5 |
7701 | 45 return out[:olen] |
46 | |
47 def b85decode(text): | |
48 """decode base85-encoded text""" | |
49 if not _b85dec: | |
50 _mkb85dec() | |
51 | |
52 l = len(text) | |
53 out = [] | |
54 for i in range(0, len(text), 5): | |
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55 chunk = text[i:i + 5] |
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56 chunk = pycompat.bytestr(chunk) |
7701 | 57 acc = 0 |
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58 for j, c in enumerate(chunk): |
7701 | 59 try: |
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60 acc = acc * 85 + _b85dec[c] |
7701 | 61 except KeyError: |
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62 raise ValueError('bad base85 character at position %d' |
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63 % (i + j)) |
7701 | 64 if acc > 4294967295: |
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65 raise ValueError('Base85 overflow in hunk starting at byte %d' % i) |
7701 | 66 out.append(acc) |
67 | |
68 # Pad final chunk if necessary | |
69 cl = l % 5 | |
70 if cl: | |
71 acc *= 85 ** (5 - cl) | |
72 if cl > 1: | |
73 acc += 0xffffff >> (cl - 2) * 8 | |
74 out[-1] = acc | |
75 | |
76 out = struct.pack('>%dL' % (len(out)), *out) | |
77 if cl: | |
78 out = out[:-(5 - cl)] | |
79 | |
80 return out |