In MASM, I want to send my variable num1 to a function and have it modify the original value num1 it is holding. I want to accomplish this by using addr operator. The output here need to be 6, instead of 2. But what I am getting is 2 despite trying to change the original value.

.386
.model flat, stdcall
.stack 4096
ExitProcess proto, dwExitCode:dword
include Irvine32.inc

.data
    num1 dword 2

.code
modify PROC var : DWORD
    mov eax, 6
    mov [var], eax
    ret
modify endp

main proc
    ; Call modify and pass the address of num1
    invoke modify, addr num1

    ; Print the updated value directly from num1
    mov eax, num1 ;Error, after the function call, num1 doesn't have the updated value of 6
    call WriteDec
    call Crlf

    invoke ExitProcess, 0
main endp

end main