macro: howto get function parameters as offset from ebp

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wisepenguin

Joined: 30 Mar 2005
Posts: 129

wisepenguin

ive been trying to make a simple macro to help in making a function.
all it does is set up a label, and parameters.

first i tried setting up the parameters as equates to ebp+OFFSET but that wasnt working, and kept on being ebp+8 for every argument.

so now i tried this, and gives the same.
im trying to use %, from the manual to get the current time through repeating, and use (% * 4) + 4, to give the offset.

here is the simplest form of what i have and i cant make it work.
any help would be appreciated.

Code:

; ----- ----- ----- -----
; .function
; declares a function, and parameters is has
; ----- ----- ----- -----
macro .function funcname, [args]
{       
        forward
                virtual at ebp+%*4+4
                        args dd ?
                end virtual
; args equ ebp+%*4+4  ; tried this aswell
        common
                funcname:

                push ebp
                mov ebp, esp

                push ebx
                push edi
                push esi
                
}

23 Jan 2006, 07:44

wisepenguin

Joined: 30 Mar 2005
Posts: 129

wisepenguin

my mistake, i cant use % because there is no repeat.

does anyone know how to achieve what im trying to do without % ?

23 Jan 2006, 07:53

chris

Joined: 05 Jan 2006
Posts: 62
Location: China->US->China->?

chris

I think all you need is a variable inside this macro which increases with the number of arguments. You can define this variable in the 'common'
block, and inc it in the forward block. Like this one:

Code:

macro test [arg]
{
        common
                argn = 0
        forward
                display `arg
                display argn + '0',' '
                argn = argn + 1
}

test arg,arg,arg

24 Jan 2006, 03:22

wisepenguin

Joined: 30 Mar 2005
Posts: 129

wisepenguin

thanks chris.
i tried your way and it worked. the several ways i tried were obviously wrong Smile

here is the code that works, and sample usage

Code:

; ----- ----- ----- -----
; .function
; declares a function, and parameters is has
; ----- ----- ----- -----
macro .function funcname, [args]
{               
        common
                count = 8
                funcname:

                push ebp
                mov ebp, esp

                push ebx
                push edi
                push esi
                
        forward
                virtual at ebp+count
                        args dd ?
                end virtual
                count = count + 4
}

; sample usage
.function my_func, param1, second_param

cmp [param1], 12
je .SOME_LABEL

; rest of function etc. ..
; restore stack etc....

thanks again

24 Jan 2006, 03:44

chris

Joined: 05 Jan 2006
Posts: 62
Location: China->US->China->?

chris

well, I think Tomasz has defined a macro 'proc' with this purpose and as well as a set of fully featured procedure macros(in PROC32.INC). You can look it up in the fasm manual if you don't want to do everything from scratch. And actually the count/argn is better preceeded with 'local', sorry for that. I just switched to fasm a couple of weeks ago, so mistakes are expected Wink

24 Jan 2006, 04:43

wisepenguin

Joined: 30 Mar 2005
Posts: 129

wisepenguin

oh i know about the macros provided, they are good!
i was just doing this as an exercise to try and improve my macro skills.

i like fasm Smile

one reason is i like that varname is always address, and [varname] is value because i started with masm and sometimes got a bit confused by putting OFFSET and ADDR before names.

24 Jan 2006, 07:27

Borsuc

Joined: 29 Dec 2005
Posts: 2466
Location: Bucharest, Romania

Borsuc

wisepenguin wrote:

i like fasm one reason is i like that varname is always address, and [varname] is value because i started with masm and sometimes got a bit confused by putting OFFSET and ADDR before names.

I like Fasm because of it's powerful macro preprocessor and assembler, and also because of it's clear syntax (like you said). Wink

25 Jan 2006, 19:01

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