bits 64

    SECTION .data
; empty

    SECTION .text
global _start
_start:
    %include "header.asm.inc"

    ; multiplication: 2 * 0xFFFFFFFF
    mov     eax, 2          ; 2
    mov     edx, 0xFFFFFFFF ; (2^32)-1
    mul     edx             ; edx:eax = eax * edx
                            ; edx becomes 0x1 (LSB is 1)
                            ; eax becomes 0xFFFFFFFE (LSB is 0)

    
    ; caveat: EDX is cleared even if even multiplaction
    ;         does not require it
    ; e.g., multiply 2 * 4
    mov     edx, 0x11223344 ; init with random value
    mov     eax, 2          ; 2 (first factor, implicit)
    mov     ebx, 4          ; 4 (second factor, explicit)
    mul     ebx             ; eax = 8, edx = 0
    
    
    ; multiplication with signed integers
    mov     bl, -3         ; -3 or 0xFD

    mov     al, -2         ; -2 or 0xFE
    mul     bl             ; dl:al = bl * al (unsigned)
    
    mov     al, -2         ; -2 or 0xFE
    imul    bl             ; dl:al = bl * al (signed)

    ; challenge: (2^32)-1 * 2^8
    mov     eax, 0xffffffff
    mov     edx, 0x100
    mul     edx

    %include "sysexit.asm.inc"