With ASM, how would you do modulo?

There are a couple of ways in fr. There is software interrupt 0x6, which is a bios function call that does division and modulo. There is routine 081E4018 developed by gamefreak, that does division and modulo as well.

R0 = dividend

R1 = divisor

returning

R0 = quotient

R1 = modulo answer

081E4684 is another routine made by gamefreak that does modulo only.

A few other math routines:

081E460C: another division routine

081E3B9C: square root, calls swi 0x8

I've stumbled across a few others that I dont remember..