TITLE Demonstrate the AddTwo Procedure     (AddTwo.asm)

; Last update: 8/30/01

INCLUDE Irvine32.inc

.data
sum DWORD ?

.code
main PROC

    call MySub

; Restore the stack after the call.
; This is what C/C++ programs do:
    call DumpRegs
    push 5
    push 6
    call AddTwo2
    add  esp,8
    call DumpRegs

    INVOKE ExitProcess,0
main ENDP

MySub PROC
    call DumpRegs    ; check ESP

; Let the procedure clean up the stack.
; This is what Pascal/stdcall procedures do:
    push 5
    push 6
    call AddTwo
    mov  sum,eax

    call DumpRegs    ; check ESP again
    ret
MySub ENDP

AddTwo PROC
; Adds two integers, returns sum in EAX.
; The RET instruction cleans up the stack.
    push ebp
    mov  ebp,esp
    mov  eax,[ebp + 12]           ; first parameter
    add  eax,[ebp + 8]        ; second parameter
    pop  ebp
    ret  8        ; clean up the stack
AddTwo ENDP

AddTwo2 PROC
; Adds two integers, return sum in EAX.
; RET does not clean up the stack.
    push ebp
    mov  ebp,esp
    mov  eax,[ebp + 12]           ; first parameter
    add  eax,[ebp + 8]        ; second parameter
    pop  ebp
    ret
AddTwo2 ENDP

END main