Split a non-power-of-two based int

Question

I know that you can split a power-of-two number in half like so:

halfintR = some32bitint & 0xFFFF
halfintL = some32bitint >> 16

can you do the same thing for an integer which is bounded by a non-power of two space?

(say that you want your range to be limited to the set of integers that will fit into 4 digit base 52 space unsigned)

Answer 1

Well, of course. & 0xffff is the same as % 0x10000 and >> 16 is the same as / 0x10000. It is just that division by a power-of-two is more efficient when done with bit operations like shifting and masking. Division works with any number (within range of representation).

Answer 2

You could use the following

rightDigits = number % 2704 // 52 squared
leftDigits = number / 2704

Answer 3

Once you realize that the & and >> are used for doing modulo und division calculation respectively, you can write what you want as:

lower = some4DigitsNumberBase52 % (52 * 52)
upper = some4DigitaNumberBase52 / (52 * 52)

This is the basis for doing base calculation. You can also derive the solution from the algorithm that displays a number in a specific base: how do you come up with the rightmost two digits and the 2 leftmost digits.