The intent of this Lab assignment is to introduce you to more asm instructions/r

Question

The intent of this Lab assignment is to introduce you to more asm instructions/rules including working with different size data, variations of the move command, the XCHG instruction, and simple LOOP and ARRAY manipulations.

General Instructions: C++

1.Create a BYTE array containing the integers 2-4-6-8-10

2.Use a loop to move these integers into an array of  DWORD

3.Use another loop to display the contents of this DWORD array to the console.

4.Use the XCHG instruction to reorder the integers to 10-8-6-4-2

5.Display contents again.

Explanation / Answer

.data
byteArray BYTE 2, 4, 6, 8, 10
intArray DWORD lengthof byteArray dup (?)

.code
main PROC
xor     ecx, ecx                ; index into arrays, 0 on start
    mov     esi, offset byteArray   ; address of byteArray
    mov     edi, offset intArray    ; address of intArray

MoveEm:
    movzx   eax, byte ptr [esi + ecx]   ; move byte from (address) byteArray + ecx into eax, zero extending eax
    mov     dword ptr [edi + 4 * ecx], eax ; move byte in eax, into (address) intArray + 4 * ecx
    inc     ecx
    cmp     ecx, lengthof byteArray
    jne     MoveEm

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