the stack

[ecube]

Cube,

You can pass the address of the first and calculate the rest in the called proc

can you give simple example please

[KeepingRealBusy]

Let me correct my first reply: "lea esp,[esp-12]".

Dave.

[ecube]

lea esp,[esp+4] before the call fixed it, I went with daves method, thanks guys.

[jj2007]

Messy, fail prone, but doable. MASM lets you get into as much trouble as you want.

Yes :green

Code Select Expand

include \masm32\include\masm32rt.inc

MyTest PROTO: DWORD, :DWORD
MyFake PROTO: DWORD, :DWORD

.code
AppName db "Masm32 is great!", 0
Hello db "A message:", 0
start: mov ebx, esp
invoke MyTest, offset AppName, addr Hello
invoke MyFake, offset AppName, addr Hello
.if ebx!=esp
MsgBox 0, "The stack is not correct", "Hi", MB_OK
.endif
exit

MyFake proc arg1:DWORD, arg2:DWORD
  MsgBox 0, arg1, "Now we are curious, aren't we?", MB_OK
  jmp TheTrick
MyFake endp

MyTest proc arg1:DWORD, arg2:DWORD
LOCAL lv1, lv2, locbuf[260]:BYTE
TheTrick::
  MsgBox 0, arg1, arg2, MB_OK
  ret
MyTest endp

end start


[dedndave]

well - it may help to simply think in terms of "what should the stack look like when we get to func2"
on the stack, you want:
1) p3
2) p2
3) p1
4) return address

if #4 is the return address inside func1, then the previous methods will work
but, if there is no code in func1 after the transfer to func2, there is an even simpler method

Code Select Expand

func1 proc p1,p2,p3
;presumably some code here
jmp func2
func1 endp

func2 proc p1,p2,p3
invoke dwtoa,p1,addr mybuff
invoke MessageBox,0,addr mybuff,NULL,MB_OK
ret
func2 endp

or even simpler...

Code Select Expand

func1 proc p1,p2,p3
;presumably some code here
func1 endp

func2 proc p1,p2,p3
invoke dwtoa,p1,addr mybuff
invoke MessageBox,0,addr mybuff,NULL,MB_OK
ret
func2 endp
which let's execution "fall through" to func2

with older assemblers, we could nest procedures
that seems to be a little trickier with newer masm versions - haven't played with it much

at any rate, it may help to turn off the default prologue and epilogue when playing with these kind of tricks
the mysterious p2 to p1 shift probably occured because the prologue pushes EBP

Code Select Expand

        OPTION  PROLOGUE:NONE
        OPTION  EPILOGUE:NONE

;E^Cube stuff here

        OPTION  PROLOGUE:PrologueDef
        OPTION  EPILOGUE:EpilogueDef

[sinsi]

Code Select Expand

func1 proc p1,p2,p3
;presumably some code here
jmp func2
func1 endp


I didn't have the nice comment but at least my code was indented  :bg

Code Select Expand


func1 proc p1,p2,p3
  jmp func2
func1 endp


[dedndave]

lol - yah - it can even be easier than that   :lol

Code Select Expand

func1:
func2 proc p1,p2,p3
invoke dwtoa,p1,addr mybuff
invoke MessageBox,0,addr mybuff,NULL,MB_OK
ret
func2 endp
or ...

Code Select Expand

func1   TEXTEQU  <func2>

[jj2007]

but, if there is no code in func1 after the transfer to func2, there is an even simpler method

Code Select Expand

func1 proc p1,p2,p3
;presumably some code here
jmp func2
func1 endp

func2 proc p1,p2,p3
invoke dwtoa,p1,addr mybuff
invoke MessageBox,0,addr mybuff,NULL,MB_OK
ret
func2 endp

or even simpler...

Code Select Expand

func1 proc p1,p2,p3
;presumably some code here
func1 endp

func2 proc p1,p2,p3
invoke dwtoa,p1,addr mybuff
invoke MessageBox,0,addr mybuff,NULL,MB_OK
ret
func2 endp
which let's execution "fall through" to func2

Dave, you are up for surprises :green
(take my example to find out - Olly is your friend)

[dedndave]

no surprises here Jochen - lol

Code Select Expand

        OPTION  PROLOGUE:NONE
        OPTION  EPILOGUE:NONE

;E^Cube stuff here

        OPTION  PROLOGUE:PrologueDef
        OPTION  EPILOGUE:EpilogueDef

in fact, i considered just using this at the beginning of my programs

Code Select Expand

        OPTION  PROLOGUE:NONE
        OPTION  EPILOGUE:NONE
because i always prefer to write that way
but, that would break compatibility with everyone in the forum   :P

back, before the advent of the internet, i used to use some abbreviations, too
i couldn't use my old abbreviations for the same reason - noone else would get it - lol

Code Select Expand

BPT     EQU     Byte Ptr
WPT     EQU     Word Ptr
DPT     EQU     Dword Ptr
OFS     EQU     Offset
SHO     EQU     Short

        mov BPT WordLabel,10h
        mov     ax,OFS ByteLabel
        jmp SHO BranchLabel

[jj2007]

no surprises here Jochen - lol

Dave,

fallthrough works fine if there are no local variables. Otherwise there is trouble, because part II of the framing, the sub esp, nnn is being done twice. Here is an example that works with local variables.

Code Select Expand

include \masm32\include\masm32rt.inc

MyTest PROTO: DWORD, :DWORD
MyFake PROTO: DWORD, :DWORD

.code
AppName db "Masm32 is great!", 0

start: mov ebx, esp
; int 3
invoke MyTest, offset AppName, chr$("The real thing:")
invoke MyFake, offset AppName, chr$("The fake:")
.if ebx!=esp
MsgBox 0, "The stack is not correct", "Hi", MB_OK
.endif
exit

MyFake proc arg1:DWORD, arg2:DWORD
LOCAL lv1, LocRetVal, locbuf[260]:BYTE
  MsgBox 0, arg1, "Now we are curious, aren't we?", MB_YESNOCANCEL
  mov LocRetVal, eax
  jmp TheTrick
MyFake endp

MyTest proc arg1:DWORD, arg2:DWORD
LOCAL lv1, WhatEver, locbuf[260]:BYTE
  mov WhatEver, IDNO
TheTrick::
  MsgBox 0, str$(WhatEver), arg2, MB_OK
  ret
MyTest endp

end start

[dedndave]

if i turn off prologues (and epilogues), the locals are literal and visible in the code   :bg