Python Truncating to 32-bit

Question

How do I truncate my return value to 32-bits? I have the following code:

def rotate_left(value, shift):
    return hex((value << shift) | (value >> (32 - shift)))

I would like the return value to be

0x0000_000A instead of 0xA_0000_000A when calling rotate_right(0xA00_0000)

Answer 1

0xFFFFFFFF is 32 bits so you can just do a logical or:

result = number & 0xFFFFFFFF

Answer 2

If you'd prefer to do this generally and not just for 32 bits:

def truncate(value, bit_count):
    return value & (2**bit_count - 1)

This works because 2**bit_count -1 is all 1's in binary.