Added calibre fb2 modules

ebook_converter/ebooks/fb2/__init__.py

@@ -0,0 +1,50 @@
+#!/usr/bin/env python2
+# vim:fileencoding=UTF-8:ts=4:sw=4:sta:et:sts=4:ai
+from __future__ import absolute_import, division, print_function, unicode_literals
+
+__license__   = 'GPL v3'
+__copyright__ = '2012, Kovid Goyal <kovid@kovidgoyal.net>'
+__docformat__ = 'restructuredtext en'
+
+
+def base64_decode(raw):
+    from io import BytesIO
+    from polyglot.binary import from_base64_bytes
+
+    # First try the python implementation as it is faster
+    try:
+        return from_base64_bytes(raw)
+    except Exception:
+        pass
+
+    # Try a more robust version (adapted from FBReader sources)
+    A, Z, a, z, zero, nine, plus, slash, equal = bytearray(b'AZaz09+/=')
+    raw = bytearray(raw)
+    out = BytesIO()
+    pos = 0
+    while pos < len(raw):
+        tot = 0
+        i = 0
+        while i < 4 and pos < len(raw):
+            byt = raw[pos]
+            pos += 1
+            num = 0
+            if A <= byt <= Z:
+                num = byt - A
+            elif a <= byt <= z:
+                num = byt - a + 26
+            elif zero <= byt <= nine:
+                num = byt - zero + 52
+            else:
+                num = {plus:62, slash:63, equal:64}.get(byt, None)
+                if num is None:
+                    # Ignore this byte
+                    continue
+            tot += num << (6 * (3 - i))
+            i += 1
+        triple = bytearray(3)
+        for j in (2, 1, 0):
+            triple[j] = tot & 0xff
+            tot >>= 8
+        out.write(bytes(triple))
+    return out.getvalue()