8. Program to Shifting the Elements in an Array in Assembly Language using Visual Studio

Chapter 3

Assembly Language Fundamentals

Assembly Language Programming Exercise

Problem # 8:

Using a loop and indexed addressing, write code that rotates the members of a 32-bit integer array forward one position. The value at the end of the array must wrap around to the first position. For example, the array [10,20,30,40] would be transformed into [40,10,20,30].

Solution:

.386
.model flat,stdcall
.stack 4096
ExitProcess PROTO, dwExitCode:DWORD

.data
array DWORD 10,20,30,40
arrayType DWORD TYPE array
newArray DWORD LENGTHOF array DUP(?)
lastElement DWORD ?

.code
main PROC
  
    ;Get first element address in ESI
    MOV ESI, OFFSET array

    ;Get address of next element in EDI
    MOV EDI, OFFSET newArray
    ADD EDI, TYPE newArray

    ;set loop count into ecx
    mov ECX, LENGTHOF array

L2:
    MOV EAX, [ESI]
    MOV [EDI], EAX

    ADD ESI, TYPE array
    ADD EDI, TYPE array

    LOOP L2

    ;set last element from array in newArray first position
    MOV EDI,OFFSET newArray
    MOV EAX, [ESI]
    MOV [EDI], EAX

INVOKE ExitProcess,0
main ENDP
END main

Let me know in the comment section if you have any question.

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