Cast a 10 bit unsigned integer to a signed integer in python

Question

I have a list of numbers in the range 0-1023. I would like to convert them to integers such that 1023 maps to -1, 1022 maps to -2 etc.. while 0, 1, 2, ....511 remain unchanged.

I came up with a simple:

def convert(x):
    return (x - 2**9) % 2**10 - 2**9

is there a better way?

Answer 1

Naivest possible solution:

def convert(x):
    if x >= 512:
        x -= 1024
    return x

Answer 2

def convert(x):
    return x - (x >> 9) * 1024

Using ctypes:

from ctypes import c_short

def convert(x):
    return c_short(x << 6).value >> 6

Answer 3

 max_uint_value = 512

 def unassigned_to_int(uint):
      return uint - max_uint_value if uint >= max_uint_value else uint