Python binary manipulation

swap_bytes.py

def swap_bytes(byte_string):
    """
    Swaps every second byte in an string. If string is uneven, the last byte is untouched.
    1 2 3 4 becomes 2 1 4 3
    1 2 3 4 5 becomes 2 1 4 3 5
    """
    return b"".join([(byte_string[i:i + 2])[::-1] for i in range(0, len(byte_string), 2)])

twos_comp.py

def twos_comp(val, bits=16):
    """compute the 2's complement of int value """
    if bits == 0:      # Use as many bits needed for the value.
        bits = val.bit_length()
    return ((val & (2 ** bits) - 1) - (2 ** bits)) * -1  # 2's compliment


value = 6752
print(f'{value:05d} = 0x{value:04x} = 0b{value:016b}')  # 06752 = 0x1a60 = 0b0001101001100000
value = twos_comp(value)
print(f'{value:05d} = 0x{value:04x} = 0b{value:016b}')  # 01440 = 0x05a0 = 0b0000010110100000
value = twos_comp(value)
print(f'{value:05d} = 0x{value:04x} = 0b{value:016b}')  # 06752 = 0x1a60 = 0b0001101001100000