def c_schar(i):
    """
    Convert arbitrary integer to c signed char type range as if casted in c.

    >>> c_schar(0x12345678)
    120
    >>> (c_schar(-128), c_schar(-129), c_schar(127), c_schar(128))
    (-128, 127, 127, -128)
    """
    return (i + 128) % 256 - 128
