Needed until next beta with binascii C module

Author: dastels

PyPortal_Halloween_Countdown/binascii.py

@@ -0,0 +1,99 @@
+PAD = '='
+
+table_a2b_base64 = [
+    -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
+    -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
+    -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,62, -1,-1,-1,63,
+    52,53,54,55, 56,57,58,59, 60,61,-1,-1, -1,-1,-1,-1, # Note PAD->-1 here
+    -1, 0, 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,-1, -1,-1,-1,-1,
+    -1,26,27,28, 29,30,31,32, 33,34,35,36, 37,38,39,40,
+    41,42,43,44, 45,46,47,48, 49,50,51,-1, -1,-1,-1,-1,
+    -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
+    -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
+    -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
+    -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
+    -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
+    -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
+    -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
+    -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
+]
+def _transform(n):
+    if n == -1:
+        return '\xff'
+    else:
+        return chr(n)
+table_a2b_base64 = ''.join(map(_transform, table_a2b_base64))
+assert len(table_a2b_base64) == 256
+
+def a2b_base64(ascii):
+    "Decode a line of base64 data."
+
+    res = []
+    quad_pos = 0
+    leftchar = 0
+    leftbits = 0
+    last_char_was_a_pad = False
+
+    for c in ascii:
+        c = chr(c)
+        if c == PAD:
+            if quad_pos > 2 or (quad_pos == 2 and last_char_was_a_pad):
+                break      # stop on 'xxx=' or on 'xx=='
+            last_char_was_a_pad = True
+        else:
+            n = ord(table_a2b_base64[ord(c)])
+            if n == 0xff:
+                continue    # ignore strange characters
+            #
+            # Shift it in on the low end, and see if there's
+            # a byte ready for output.
+            quad_pos = (quad_pos + 1) & 3
+            leftchar = (leftchar << 6) | n
+            leftbits += 6
+            #
+            if leftbits >= 8:
+                leftbits -= 8
+                res.append((leftchar >> leftbits).to_bytes(1, 'big'))
+                leftchar &= ((1 << leftbits) - 1)
+            #
+            last_char_was_a_pad = False
+    else:
+        if leftbits != 0:
+            raise Exception("Incorrect padding")
+
+    return b''.join(res)
+
+# ____________________________________________________________
+
+table_b2a_base64 = (
+    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/")
+
+def b2a_base64(bindata):
+    "Base64-code line of data."
+
+    newlength = (len(bindata) + 2) // 3
+    newlength = newlength * 4 + 1
+    res = []
+
+    leftchar = 0
+    leftbits = 0
+    for c in bindata:
+        # Shift into our buffer, and output any 6bits ready
+        leftchar = (leftchar << 8) | c
+        leftbits += 8
+        res.append(table_b2a_base64[(leftchar >> (leftbits-6)) & 0x3f])
+        leftbits -= 6
+        if leftbits >= 6:
+            res.append(table_b2a_base64[(leftchar >> (leftbits-6)) & 0x3f])
+            leftbits -= 6
+    #
+    if leftbits == 2:
+        res.append(table_b2a_base64[(leftchar & 3) << 4])
+        res.append(PAD)
+        res.append(PAD)
+    elif leftbits == 4:
+        res.append(table_b2a_base64[(leftchar & 0xf) << 2])
+        res.append(PAD)
+    res.append('\n')
+    return ''.join(res).encode('ascii')