add hg and python

sys/lib/python/mercurial/pure/base85.py

@@ -0,0 +1,74 @@
+# base85.py: pure python base85 codec
+#
+# Copyright (C) 2009 Brendan Cully <brendan@kublai.com>
+#
+# This software may be used and distributed according to the terms of the
+# GNU General Public License version 2, incorporated herein by reference.
+
+import struct
+
+_b85chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ" \
+            "abcdefghijklmnopqrstuvwxyz!#$%&()*+-;<=>?@^_`{|}~"
+_b85chars2 = [(a + b) for a in _b85chars for b in _b85chars]
+_b85dec = {}
+
+def _mkb85dec():
+    for i, c in enumerate(_b85chars):
+        _b85dec[c] = i
+
+def b85encode(text, pad=False):
+    """encode text in base85 format"""
+    l = len(text)
+    r = l % 4
+    if r:
+        text += '\0' * (4 - r)
+    longs = len(text) >> 2
+    words = struct.unpack('>%dL' % (longs), text)
+
+    out = ''.join(_b85chars[(word // 52200625) % 85] +
+                  _b85chars2[(word // 7225) % 7225] +
+                  _b85chars2[word % 7225]
+                  for word in words)
+
+    if pad:
+        return out
+
+    # Trim padding
+    olen = l % 4
+    if olen:
+        olen += 1
+    olen += l // 4 * 5
+    return out[:olen]
+
+def b85decode(text):
+    """decode base85-encoded text"""
+    if not _b85dec:
+        _mkb85dec()
+
+    l = len(text)
+    out = []
+    for i in range(0, len(text), 5):
+        chunk = text[i:i+5]
+        acc = 0
+        for j, c in enumerate(chunk):
+            try:
+                acc = acc * 85 + _b85dec[c]
+            except KeyError:
+                raise TypeError('Bad base85 character at byte %d' % (i + j))
+        if acc > 4294967295:
+            raise OverflowError('Base85 overflow in hunk starting at byte %d' % i)
+        out.append(acc)
+
+    # Pad final chunk if necessary
+    cl = l % 5
+    if cl:
+        acc *= 85 ** (5 - cl)
+        if cl > 1:
+            acc += 0xffffff >> (cl - 2) * 8
+        out[-1] = acc
+
+    out = struct.pack('>%dL' % (len(out)), *out)
+    if cl:
+        out = out[:-(5 - cl)]
+
+    return out