Question

Complete the following Intel assembly language program
which determines whether the byte sized operand stored
in memory location 'number' is prime or not. The program
will write the value of 0 into the memory location 'answer'
if the number is not prime, otherwise the initial value of '1' will
be left unmodified (indicating that the number is prime). The program
makes use of the DIV instruction to determine the value of quotient
and remainder when dividing the number by 2,3,4,... (number -1) .

section .data

; put your data in this section using
; db , dw, dd directions

number db 5
answer db 1 ; 1 means number is prime, 0 means number is not prime
section .bss

; put UNINITIALIZED data here using

section .text
global _start

_start:
mov esi, number ; get the offset of number into esi
keith: mov eax, 0 ; clear the entire eax register
mov al, [esi] ; get the number from memory into al
mov dl, al ; put it inside dl as well
mov bl, 2 ; bl holds each divisor starting from 2
loopy: div bl ; ax / bl with quot in al and rem in ah
and ax, 1111111100000000b ; isolate the rem in ah with a AND mask
; to determine whether the remainder is 0

; YOU COMPLETE THE REST OF THE CODE

HINT: The program is to implement the following high-level
pseudocode:

prime = true ;
divisor = 2 ;
while ( divisor < number )
{
if ( the remainder of number / divisor is 0 )
{
prime = false ; // we found a divisor which evenly divides number
} // so therefore number cannot be prime

divisor = divisor + 1 ; // check the next divisor and keep looping
}

Answer 1