Question

I’m searching for a simple algorithm that ‘combines’ two 2bytes integers into one unique 4bytes integer.

The two 2bytes integers are both whole positive numbers in the range 0..65535.

I want to create one 4bytes integer that is the exact combination of both, in a way that will make it easy to:

(1) given the two 2bytes integers –> calculate the value of that 4bytes integer.

(2) given the 4bytes integer –> parse the contents of the two 2bytes integers.

Any idea how to achieve this in python?

Answer 1

How about:

def combine(n, m):
    return (n << 16) | m

def extract(c):
    return (c >> 16), c & 0xffff

This solution places one of the 2-byte integers in the upper half of a 32-bit word, and the other into the lower half. In order to extract the values, simply take the upper half of the word (c >> 16), and the lower half (c & 0xffff).