How can i pass parameters in assembler x86 function call

Question

Look at this assembler code. It is designed for 32 bits x86 and will be compiled by nasm

   ...
   my_function:
        pop %eax
        ...
        ret


           


        

Answer 1

See below for explanation:-

[BITS 32]

%include "nagoa+.inc"

%include "cfunctions.txt"

[SEGMENT .DATA USE32]

    ret_value   db  "I am the Return Value",0
    localvar    db  "My Local Variable Value",0

[SEGMENT .BSS USE32]
    arg_param   resb    160


[SEGMENT .TEXT USE32]

my_function:
    ;save arguments/parameters as this esp+ space will be destroyed by system function calls
        mov eax,[esp+4]

    ;enjoy local variables for processing
    ;enter 4,0 
        mov dword [esp-4],localvar

        call printf,`Argument/Parmeter=%s  and Local Variable=%s`,eax,[esp-4]
        add esp,12
    ;leave

    ;fill-up return values
        mov eax,ret_value

    ret 
    ;ret 4

..start:
    call puts,`Enter Argument/Parmeter`
    add esp,4
    call gets,arg_param
    add esp,4

    push arg_param
    CALL my_function

    call printf,`Return Value From Called Function=%s`,eax
    add esp,4

call exit, 0