PE5) Array Exchange

Write a program with a loop with indexed addressing that exchanges every pair of values in an array with an even number of elements.  Therefore, item i will exchange with item i + 1, and item i + 2 will exchange with item i + 3, and so on.  Example:  [1,2,3,4,5,6,7,8]  →   [2,1,4,3,6,5,8,7]

.model flat,stdcall
.stack 4096
ExitProcess proto,dwExitCode:dword
array DWORD 1,2,3,4,5,6,7,8
main proc
  ; must offset the array so that esi regester 
  ; holds the address of the first item in the array
	mov esi, OFFSET array			
  ; ecx register is now 4
	mov ecx, LENGTHOF array / 2				

myLoop: ; will loop 4 times because ecx has 4
  ; get the pair numbers from array
	mov eax, [esi]
	mov ebx, [esi + 4]

  ; swap the pairs in array
	mov [esi], ebx
	mov [esi + 4], eax

  ; A DWORD is 4 bytes so we must increment the 
  ; esi register by 8 to get the next pair.
	add esi, TYPE array * 2

loop myLoop

	invoke ExitProcess,0
main endp
end main

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