struct.codon

from typing import Union

def unpack(fmt: str, s) -> Union[list[float],list[int]]:
    n = 1
    i = 0
    while i < len(fmt) and fmt[i].isdigit():
        i += 1
    if i > 1: n = int(fmt[0:i])

    fmt = fmt[i:]

    i = 0
    if fmt == 'I':
        return [ int(Ptr[u32](s[i:i+4].ptr)[0]) for i in range(0, len(s) // 4 * 4, 4) ]
    if fmt == 'i':
        return [ int(Ptr[i32](s[i:i+4].ptr)[0]) for i in range(0, len(s) // 4 * 4, 4) ]
    elif fmt == 'f':
        return [ float(Ptr[f32](s[i:i+4].ptr)[0]) for i in range(0, len(s) // 4 * 4, 4) ]

def calcsize(fmt: str):
    n = 1
    i = 0
    while i < len(fmt) and fmt[i].isdigit():
        i += 1
    if i > 0: n = int(fmt[0:i])

    fmt = fmt[i:]

    return n * 4 if fmt == 'I' or fmt == 'i' or fmt == 'f' else -1


if __name__ == "__main__":
    s='\x01\x00\x00\x00\xb0\xb1\xb2\xb3abcda000'
    print(unpack('I', s))
    print(unpack('i', s))
    print(unpack('f', s))