Auto-declaration of externals in POASM

[Vortex]

Hi friends,

Like GoASM, POASM can detect undefined functions seen in call statements and declares them as externals. To avoid decorated symbols, the calling convention should be specified as syscall The imports libraries used in this project are extracted from DLLs by Polib
As you can see in the source code, there is no any single API function declaration.

Code Select Expand

; assembled with POASM 0.99.1

.386
.model flat,syscall
option casemap:none

includelib ..\kernel32.lib
includelib ..\user32.lib

WM_INITDIALOG EQU 110h
WM_SETCURSOR EQU 20h
WM_CLOSE EQU 10h
IDC_CROSS EQU 32515

.data
DlgName db "MyDialog",0

hInstance dd ?
CommandLine dd ?
hCursor dd ?

.code
start:
push 0
call GetModuleHandleA
mov hInstance,eax
push 0
push OFFSET DlgProc
push 0
push OFFSET DlgName
push hInstance
call DialogBoxParamA
push eax
call ExitProcess

DlgProc PROC hWnd:DWORD, uMsg:DWORD, wParam:DWORD, lParam:DWORD
cmp uMsg,WM_CLOSE

jne initdlg
push 0
push hWnd
call EndDialog
jmp true
initdlg:
cmp uMsg,WM_INITDIALOG

jne setcursor
push IDC_CROSS
push 0
call LoadCursorA
mov hCursor,eax
jmp true
setcursor:
cmp uMsg,WM_SETCURSOR

jne false
push hCursor
call SetCursor
jmp true
false:
xor eax,eax
ret
true:
mov eax,1
ret
DlgProc ENDP
END start


Check the Poasm example in the zip file :

http://vortex.masmcode.com/files/implib21.zip

[Vortex]

Here is another version with decorated functions , it uses the standart import library file set.

Code Select Expand

   .
   .
start:
   push   0
   call   GetModuleHandleA@4
   mov   hInstance,eax
   push   0
   push   OFFSET DlgProc
   push   0
   push   OFFSET DlgName
   push   hInstance
   call   DialogBoxParamA@20
   push   eax
   call   ExitProcess@4
   .
   .
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[Jimg]

what does that mean (auto declaration of externals)?  How about auto declaration of internals?

[PBrennick]

No, Vortex has it right and you have it wrong, read the documentation, please.

RFM, dude,
Paul

[Jimg]

I was not saying it meant auto declaration of internals, I was asking what auto declaration of externals meant.  How is it different than masm?  The second sentence meant and how about doing auto declaration of internals while you are at it! (assuming I have any idea what was meant by declaration of externals, which I really don't).  And what manual are you talking about anyway?

[PBrennick]

Darn it all, looks like I get egg on my face as there is NO help for this in the syntax.txt file.  My mistake. sorry.

About auto declaration of externals, it refers to libraries which refer to DLLs.  His simple32 includes two INCLUDELIB statements so don't trust me on that.  That is the answer I 'would ordinarily should' have given, but I connfess to being just as confused as you are so I wish, now, that I had just not said anything in this post.

Paul

[Vortex]

Hi Jimg,

Auto declaration of externals means that POASM keeps track of function names seen in the call statements and if those functions are not declared with EXTERN or PROTO , POASM assumes them as externals. MASM doesn't provide this capacity, simply , it will emit an error message if it detects a function wich is not declared by the user.

A simple example :

Code Select Expand

.386
.model flat, stdcall
option casemap:none

includelib \masm32\lib\kernel32.lib

.code
start:
push   0
call   ExitProcess@4
   
END start

Assembling with MASM :

Code Select Expand

error A2006: undefined symbol : ExitProcess@4

Poasm assembles the file without any error message. Disassembling the object file :

Code Select Expand

        public  _start
        extrn   _ExitProcess@4

includelib      /DEFAULTLIB:\masm32\lib\kernel32.lib /ENTRY:start
_TEXT   segment
        assume  CS:_TEXT
_start:
                push    0
                call    near ptr _ExitProcess@4
_TEXT   ends
        end

[PBrennick]

Vortex,
So this means it works similar to GOASM?  Or am I wrong about that?  Pelle's examples are pretty vague on this whole process.  Any I cannot find that in any of his documents...

Paul

[Jimg]

Hi Vortex-

Auto declaration of externals means that POASM keeps track of function names seen in the call statements and if those functions are not declared with EXTERN or PROTO , POASM assumes them as externals.

So if it was just a typo, it will be found as an error by the linker, right?  I like it as far as it goes, but it should add post declared PROC statements to EXTERN and PROTO as things it checks rather than complaining. For me, this would be MUCH more useful.

[Vortex]

Vortex,
So this means it works similar to GOASM?  Or am I wrong about that?  Pelle's examples are pretty vague on this whole process.  Any I cannot find that in any of his documents...

Paul

Hi Paul,

Yes, iit works like GoAsm. Probably, Pelle will prepare a documentation.

[Vortex]

Fixed bug with the NOfnDECL example. The stack is balanced manually with the RET 16 instruction according the SYSCALL convention.

http://vortex.masmcode.com/files/implib211.zip

[Vortex]

Here is another example of using the auto-declaration feature. I coded a macro simulating the invoke statement to call extrernal functions without function prototypes like in GoAsm. The usage of the _invoke is a little complicated, in most cases, it requires enclosing parameters between double < and > symbols.

Many thanks to Pelle who helped me to build the invoke simulator macro :U

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[Vortex]

Here is the second version of the invoke macro simulator. Now, there is no need anymore to enclose parameters between double  < and > , one pair of < and > is enough. I redesigned the _invoke macro to make easier the usage.

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[Vortex]

Here is another example using scan.exe to set the equates for ANSI functions.

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[Vortex]

Invoke simulator

There was some cases where the external function to be called was defined more than one time - bug fixed

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