Question

Write a short program in assembly that reads the numbers stored in an array named once, doubles the value, and writes them to another array named twice. Initialize both arrays in the ram using assembler directives. The array once should contain the numbers {0x3, 0xe, 0xf8, 0xfe0}. You can initialize the array twice to all zeros

Answer 1

Assuming it's talking about x86-64 architecture, here's the program:

section .data

once: dd 0x3, 0xe, 0xf8, 0xfe0

twice: times 4 dd 0

section .text

global _start

_start:

mov esi, once ; set esi to the start of the once array

mov edi, twice ; set edi to the start of the twice array

mov ecx, 4 ; set the loop counter to 4 (the number of elements in the arrays)

loop:

mov eax, [esi] ; load a value from once into eax

add eax, eax ; double the value

mov [edi], eax ; store the result in twice

add esi, 4 ; advance to the next element in once

add edi, 4 ; advance to the next element in twice

loop loop ; repeat until ecx is zero

; exit the program

mov eax, 60 ; system call for exit

xor ebx, ebx ; return code of zero

syscall

Step-by-step explanation:

The 'dd' directive defines the once array with the specified values, and the 'times' directive defines the twice array with four zero values.

It uses the 'mov' instruction to set the registers 'esi' and 'edi' to the start of the once and twice arrays respectively. Then it sets the loop counter 'ecx' to 4.

The program then enters a loop that loads a value from once into 'eax', doubles the value by adding it to itself, stores the result in twice, and then advances to the next element in both arrays. This loop will repeat until 'ecx' is zero.

Hope this helps! (By the way, the comments (;) aren't necessary, they're just there to help - remember, they're not instructions).