macro! modulus %reg_1 %reg_2 %reg_3 {
    DIV %reg_1, %reg_2, %reg_3
    MUL %reg_3, %reg_2, %reg_3
    SUB %reg_1, %reg_3, %reg_3
}

LOAD r0, 12

LOAD r1, 5

modulus% r0, r1, r2

; Macros are basically glorified second files in a way, so you can put anything in them.
; (Second files as in the parser parses them using the file (root level) parsing rules.)
macro! my_really_strange_macro {
    custom! INS 0x0770 ; Custom instruction that only gets created when the macro gets called.
    INS ; Calling it.
}