lsb to msb (two's complement)

lsb_msb.py

#
# https://en.wikipedia.org/wiki/Two%27s_complement#Working_from_LSB_towards_MSB
#
# (c) 2022 Paulus Gandung Prakosa <[email protected]>
#

import sys
import math

num = int(sys.argv[1])
res = 0
exp = 32

if num == 0 or num == 1:
	print(~(num & (pow(2, num) - 1)) + 1)
	sys.exit(0)

for i in range(0, math.floor(math.log2(num)) + 1):
	if num & (pow(2, i)) > 0:
		res += ~((1 << i) & (pow(2, exp) - 1)) + 1

print(res)