2-ADD and SUB

add and sub instructions simply add the source and destination operands and the result will store in destination. The destination could be a register or location in memory.

add destination, source

                    

section .text

global _start

_start:
    xor eax, eax
    mov eax, 5
    mov ebx, -1
    add eax, ebx
    
    ; eax = 4
    
    mov ebx, -10
    sub ebx, eax
    
    ;ebx = -14
    ret

3- MUL and IMUL

mul it is for multiply unsigned numbers, imul used for signed numbers. There is one thing you should consider when you try to use them, mul/imul take is one operand, and assume that the other operand already store in first general purpose register AX.

                    

section .text

global _start

_start:
    xor eax, eax
    mov eax, 5
    mov ebx, 5
    mul ebx
    
    ;eax = 25

    mov ebx, -3
    mul ebx         
    
    ;eax = -75
    
    ret

4-DIV and IDIV

As you guess, that div for division of unsigned numbers and idiv for signed numbers.

Note: rdx should be zero.

Note: the reminder of the divison will store in:

• if the divisor is 8-bit, remainder store in ah and the result in al.


• f the divisor is 16-bit, the remainder will store in dx and the result in ax.


• If the divisor is 32-bit, the remainder will store in edx and the result ineax.


• If the divisor is 64-bit, the remainder will store in rdx and the result inrax.

section .text

global _start

_start:
    xor eax, eax
    xor edx, edx
    mov eax, 25
    mov ebx, 5
    div ebx
                    
    ;eax = 5
                        
    mov ebx, -5
    idiv ebx
                
    ;eax = -1
                    
    ret