micropython-lib/python-stdlib/binascii/binascii.py

from ubinascii import *

if not "unhexlify" in globals():

    def unhexlify(data):
        if len(data) % 2 != 0:
            raise ValueError("Odd-length string")

        return bytes([int(data[i : i + 2], 16) for i in range(0, len(data), 2)])


b2a_hex = hexlify
a2b_hex = unhexlify

# ____________________________________________________________

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

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

    leftchar = 0
    leftbits = 0
    for c in bin:
        # 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)
    if newline:
        res.append("\n")
    return "".join(res).encode("ascii")