I'm trying to do my own proc that has one parameter with the size of a byte.
Depending on the value of that byte the procedure makes different things.



I can't use the invoke macro since that would use 'call [theproc]' which wouldn't work so i tried to push the parameter myself and then call the proc:



This does not work either because (my guess) the proc macro doesn't know that it should pop a byte for the "byteparam" parameter.

So I'm wondering if there is some way to do this when using the proc macro?
If not, how should I do?

Snifit, let me tell what i know about it. It is not a good idea to put 1 byte to stack because it becomes unaligned.
About your words "This does not work either because (my guess) the proc macro doesn't know that it should pop a byte...". Proc macro doesn't do any pop. You can try this:

myownproc:

byteparam equ ebp+8

push ebp
mov ebp,esp

mov al,[byteparam] ; read passed parameter
; ...
mov esp,ebp
pop ebp
retn 1

When you can call it in this way:

xor eax,eax
or al,[byteparam]
stdcall myownproc,eax

Stdcall is invoke analog, but it make 'call myownproc'.

Regards.

Sorry, small mistake: i used 'retn 1' to return from function and had to pass only one byte ('push byte byteparam' instead of using eax)! For my stdcall example at the end of the function must be 'retn 4'.

AFAIK, you never can push one byte using the instruction "push". You can push word or dword only. The only way to push only one byte is to store it in the stack with "mov" instruction and to decrement esp by 1.

Big thanks guys!
I didn't realize it was such a problem with a single byte at the stack, and if I knew I'd used word or dword instead
Anyways, I fixed it by using a dword value instead and by using the stdcall macro.

Thanks again.