convert hex utf-8 bytes to hex Unicode number

utf8_to_unicode.py

import sys


def ch2int(ch):
    if '0' <= ch <= '9':
        return ord(ch) - ord('0')
    if 'a' <= ch <= 'f':
        return ord(ch) - ord('a') + 10
    if 'A' <= ch <= 'F':
        return ord(ch) - ord('A') + 10
    return 0


def utf8_to_unicode(utf8):
    w = utf8
    if not w or not w.lower().startswith('0x'):
        return None

    w = w[2:]
    if len(w) % 2 == 1:
        w = '0' + w

    if len(w) < 2:
        return None

    c = (ch2int(w[0]) << 4) + ch2int(w[1])
    w = w[2:]

    if (c & 0b10000000) == 0:
        c &= ~0b10000000
        nb = 0
    elif (c & 0b11100000) == 0b11000000:
        c &= ~0b11100000
        nb = 1
    elif (c & 0b11110000) == 0b11100000:
        c &= ~0b11110000
        nb = 2
    elif (c & 0b11111000) == 0b11110000:
        c &= ~0b11111000
        nb = 3
    else:
        return None

    while nb > 0:
        if len(w) < 2:
            return None

        cc = (ch2int(w[0]) << 4) + ch2int(w[1])
        w = w[2:]
        if (cc & 0b11000000) != 0b10000000:
            return None
        cc &= ~0b11000000
        c <<= 6
        c += cc
        nb -= 1

    if w:
        return None

    c = hex(c)[2:].upper()
    c = ('0000' + c)[-4:]
    c = 'U+' + c
    return c


# $ python ./utf8_to_unicode.py 0xe282ac 0x24 0xc2a2 0xe0a4b9 0xed959c 0xf0908d8888 0x0
# ('0xe282ac', '-->', 'U+20AC')
# ('0x24', '-->', 'U+0024')
# ('0xc2a2', '-->', 'U+00A2')
# ('0xe0a4b9', '-->', 'U+0939')
# ('0xed959c', '-->', 'U+D55C')
# ('0xf0908d8888', '-->', None)
# ('0x0', '-->', 'U+0000')
if __name__ == "__main__":
    for w in sys.argv[1:]:
        print(w, '-->', utf8_to_unicode(w))