start:
    cst C, init
    call C ; Initialize registers
    cst C, factorial_recursive
    call C ; Call recursive version
    cst C, factorial_iterative
    jmp C

init:
    cst A, 5
    cst B, 1
    cst C, 0
    cst D, 0
    ret

factorial_recursive:
    cst D, end_recursive
    jz A, D            ; If A == 0, jump to end_recursive
    mul B, B, A        ; B = B * A
    cst C, 1           ; C = 1
    sub A, A, C        ; A = A - 1
    cst C, factorial_recursive
    call C
end_recursive:
    ret

factorial_iterative:
    cst C, init
    call C ; re-initialize registers

    cst C, 0x01000000

    ; Infinite loop of iterative factorial calculation
loop:
    cst D, end
    jz A, D             ; If A == 0, jump to end
    add B, B, C         ; B = B * A (not really, but this is intentionally broken)
    cst D, 1
    ; Oh no! We don't decrease A! That means we'll be in an infinite loop!
    ; sub A, A, D         ; Decrement counter
    cst D, loop
    jmp D            ; Repeat the loop

end:
    cst A, 1
    cst D, 0
    cst C, 0
    ; End of program