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binascii: Reduce module RAM overhead and compiled footprint. #1157

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315 changes: 31 additions & 284 deletions python-stdlib/binascii/binascii.py
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Original file line number Diff line number Diff line change
Expand Up @@ -14,277 +14,27 @@ def unhexlify(data):

# ____________________________________________________________

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
_PAD = const("=")

# a2b = bytearray('\xff' * 256); for i, j in enumerate(b2a): a2b[ord(j)] = i
_TABLE_A2B_BASE64 = const(
b"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff"
b"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff"
b"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\x3e\xff\xff\xff\x3f"
b"\x34\x35\x36\x37\x38\x39\x3a\x3b\x3c\x3d\xff\xff\xff\xff\xff\xff"
b"\xff\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e"
b"\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\xff\xff\xff\xff\xff"
b"\xff\x1a\x1b\x1c\x1d\x1e\x1f\x20\x21\x22\x23\x24\x25\x26\x27\x28"
b"\x29\x2a\x2b\x2c\x2d\x2e\x2f\x30\x31\x32\x33\xff\xff\xff\xff\xff"
b"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff"
b"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff"
b"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff"
b"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff"
b"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff"
b"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff"
b"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff"
b"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff"
)


def a2b_base64(ascii):
Expand All @@ -297,13 +47,12 @@ def a2b_base64(ascii):
last_char_was_a_pad = False

for c in ascii:
c = chr(c)
if c == PAD:
if c == 61: # ord('=')
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)])
n = _TABLE_A2B_BASE64[c]
if n == 0xFF:
continue # ignore strange characters
#
Expand All @@ -328,14 +77,12 @@ def a2b_base64(ascii):

# ____________________________________________________________

table_b2a_base64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
_TABLE_B2A_BASE64 = const("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/")


def b2a_base64(bin, newline=True):
"Base64-code line of data."

newlength = (len(bin) + 2) // 3
newlength = newlength * 4 + 1
res = []

leftchar = 0
Expand All @@ -344,19 +91,19 @@ def b2a_base64(bin, newline=True):
# Shift into our buffer, and output any 6bits ready
leftchar = (leftchar << 8) | c
leftbits += 8
res.append(table_b2a_base64[(leftchar >> (leftbits - 6)) & 0x3F])
res.append(_TABLE_B2A_BASE64[(leftchar >> (leftbits - 6)) & 0x3F])
leftbits -= 6
if leftbits >= 6:
res.append(table_b2a_base64[(leftchar >> (leftbits - 6)) & 0x3F])
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)
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(_TABLE_B2A_BASE64[(leftchar & 0xF) << 2])
res.append(_PAD)
if newline:
res.append("\n")
return "".join(res).encode("ascii")
2 changes: 1 addition & 1 deletion python-stdlib/binascii/manifest.py
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Original file line number Diff line number Diff line change
@@ -1,3 +1,3 @@
metadata(version="2.4.1")
metadata(version="2.5.0")

module("binascii.py")
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