How to calculate Two's (2's) Complement in Python [duplicate]

Question

I am writing my own Servo Driver Program in Python and I struggle quite a bit with Two's (2's) Complement calculation.

Example: I want to have "-100" as an input and get "FF9C" or just "9C" which would also work for the output.

The following picture might help to clarify:

2's calculation I want in python

hex(-100 & 0xffff) == '0xff9c' and hex(-100 & 0xff) == '0x9c'. This of course works with other negative numbers, too. — Michael Butscher
– Michael Butscher, Commented Jun 24, 2022 at 12:37
n = -100 ; print(f'hex "{n:x}" ; two complement: "{n&(2**16-1):x}"') -> hex "-64" ; two complement: "ff9c" — mozway
– mozway, Commented Jun 24, 2022 at 12:40

Iver · Accepted Answer · 2022-06-28 09:19:22Z

1

Thanks so much for the help. I ended up using this for my code for other people having the same difficulty.

n = -100
x = f'{n&(2**16-1):x}'
print(x) # -> ff9c

answered Jun 27, 2022 at 9:12

Iver

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