Problem in allocating values to the fields of a structure

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mns

Joined: 20 Dec 2007
Posts: 150
Location: Piliyandala,Sri lanka

mns 24 Dec 2020, 16:56

When I allocate values to the members of D3DXCOLOR structure as below assembled program don't work correctly(desired colour won't show) ,
(all files are attached).

Code:

;------------------------------------RenderFrame--------------------------------------------
 proc       RenderFrame

  push            ebx esi edi

   colorStrct2         D3DXCOLOR     1.0,0.3,0.2,0.8
   cominvk         devCntxt, ClearRenderTargetView,[BkBuffRndrTrgtVw],colorStrct2

   cominvk         swapchain,Present,0, 0

   pop     edi esi ebx
    ret
 endp
;----------------------------------------------------------------------------------------------

but if the values were allocated as below assembled program worked correctly.

Code:

 proc       RenderFrame

         push            ebx esi edi

         mov             [colorStrct1.r],1.0
         mov             [colorStrct1.g],0.3
         mov             [colorStrct1.b],0.2
         mov             [colorStrct1.a],0.8
         cominvk         devCntxt, ClearRenderTargetView,[BkBuffRndrTrgtVw],colorStrct1
         

         cominvk         swapchain,Present,0, 0

         pop     edi esi ebx
         ret
 endp

Please someone can help Confused

(I'm trying to learn directx 11 with FASM from a tutorial written in C++ and if the previous one is working, I can apply that to other structures and it will reduce great deal of code typing)

Description:		Download
Filename:	direct3d_4.zip
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24 Dec 2020, 16:56

Roman

Joined: 21 Apr 2012
Posts: 1795

Roman 24 Dec 2020, 17:46

Do this.

Code:

proc       RenderFrame

  push            ebx esi edi

   
   cominvk         devCntxt, ClearRenderTargetView,[BkBuffRndrTrgtVw],colorStrct2

   cominvk         swapchain,Present,0, 0

   pop     edi esi ebx
    ret
colorStrct2         D3DXCOLOR     1.0,0.3,0.2,0.8
 endp

Or this for one time to init somthing like texture or buffer:

Code:

proc       RenderFrame

  push            ebx esi edi

   jmp @f              ;this method not good for render or loops.
   colorStrct2         D3DXCOLOR     1.0,0.3,0.2,0.8
@@:
   cominvk         devCntxt, ClearRenderTargetView,[BkBuffRndrTrgtVw],colorStrct2

   cominvk         swapchain,Present,0, 0

   pop     edi esi ebx
    ret
 endp

When CPU in code step to colorStrct2, CPU flies away to the galaxies Smile

24 Dec 2020, 17:46

mns

Joined: 20 Dec 2007
Posts: 150
Location: Piliyandala,Sri lanka

mns 24 Dec 2020, 18:40

Thank you very much Roman for the help, the second solution worked well and first solution brings the desired colour but the program crashes after few seconds.
Still I don't understand the original problem. Is it a problem of struct macro?

24 Dec 2020, 18:40

bitshifter

Joined: 04 Dec 2007
Posts: 796
Location: Massachusetts, USA

bitshifter 24 Dec 2020, 18:49

the problem is executing data not code

_________________
Coding a 3D game engine with fasm is like trying to eat an elephant,
you just have to keep focused and take it one 'byte' at a time.

24 Dec 2020, 18:49

Roman

Joined: 21 Apr 2012
Posts: 1795

Roman 24 Dec 2020, 20:40

I think need
section '.code' code readable writeable executable

And check esp.
Maybe esp flowed.

using this for see on window border info:

Code:

cinvoke sprintf,pText,'ESP %d',esp
invoke SetWindowText,[hwnd],pText


in data:
pText db 128 dup (0)

24 Dec 2020, 20:40

mns

Joined: 20 Dec 2007
Posts: 150
Location: Piliyandala,Sri lanka

mns 25 Dec 2020, 03:22

Thank you very much Roman and bitshifter for your kind replies.
Roman I tried to display esp register using your code (by importing -msvcrt, 'msvcrt.dll' )but the program crashesd. Sad

When allocated the values to the structure, in the section '.data' , program worked fine.
It seems declaring the structure locally made the program to crash. Confused

25 Dec 2020, 03:22

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20343
Location: In your JS exploiting you and your system

revolution 25 Dec 2020, 03:31

It isn't that you declared them locally that causes the problem. It is that you declared them inline with executable code. The CPU tries to execute that data because that is what it sees as the next instruction.

If you declared them either before or after the executable code then it would be fine, but you have to make sure the values are properly initialised each time, since the stack only lasts as long as the function is active.

25 Dec 2020, 03:31

mns

Joined: 20 Dec 2007
Posts: 150
Location: Piliyandala,Sri lanka

mns 25 Dec 2020, 04:34

Thank you revolution.
(bear with me if this question is foolish) if the structure defined as local variable as below,

Code:

 
locals
colorStrct2         D3DXCOLOR     1.0,0.3,0.2,0.8 
endl

will it still be declaring inline with executable code? Confused

25 Dec 2020, 04:34

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20343
Location: In your JS exploiting you and your system

revolution 25 Dec 2020, 04:36

locals/endl is a good place for the structure. It exists on the stack, not in the code stream.

25 Dec 2020, 04:36

mns

Joined: 20 Dec 2007
Posts: 150
Location: Piliyandala,Sri lanka

mns 25 Dec 2020, 04:46

Thank you revolution. But then the assembler complain as, it is invalid value, when it use in

cominvk devCntxt, ClearRenderTargetView,[BkBuffRndrTrgtVw],colorStrct2

and if used as below

cominvk devCntxt, ClearRenderTargetView,[BkBuffRndrTrgtVw],[colorStrct2]

it assembled but the program crashes.

25 Dec 2020, 04:46

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20343
Location: In your JS exploiting you and your system

revolution 25 Dec 2020, 04:52

You need the address of the structure:

Code:

cominvk devCntxt, ClearRenderTargetView,[BkBuffRndrTrgtVw],addr colorStrct2

25 Dec 2020, 04:52

mns

Joined: 20 Dec 2007
Posts: 150
Location: Piliyandala,Sri lanka

mns 25 Dec 2020, 08:22

thanks revolution. so then it should be

Code:

cominvk devCntxt, ClearRenderTargetView,[BkBuffRndrTrgtVw],colorStrct2

which make compiler to complain as "invalid value". (when colorStrct2 declared as local variable.)

any help is appreciated. Sad

25 Dec 2020, 08:22

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20343
Location: In your JS exploiting you and your system

revolution 25 Dec 2020, 08:23

I posted the syntax above. Use addr

25 Dec 2020, 08:23

mns

Joined: 20 Dec 2007
Posts: 150
Location: Piliyandala,Sri lanka

mns 26 Dec 2020, 10:31

(sorry to take long time to respond)
Thank you very much revolution, your solution worked. Very Happy

(I had to change include file from WIN32A.inc to WIN32AX.inc for addr ).

I thought a variable without Square Brackets mean address of the variable in FASM. Confused

anyway thanks again.

26 Dec 2020, 10:31

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20343
Location: In your JS exploiting you and your system

revolution 26 Dec 2020, 10:38

mns wrote:

I thought a variable without Square Brackets mean address of the variable in FASM.

It does. But it is a fixed address.

When the address is a stack location there is no fixed value. It is computed at runtime. So when you put addr it generates something like:

Code:

lea edx,[ebp+offset]
push edx

Compare to just a plain address:

Code:

push address

That is why the plain address can't work with stack values, it tries to push a composite value:

Code:

push <ebp+offset> ; no such instruction exists

26 Dec 2020, 10:38

mns

Joined: 20 Dec 2007
Posts: 150
Location: Piliyandala,Sri lanka

mns 26 Dec 2020, 10:48

revolution, now I understand thank you very much. Very Happy

26 Dec 2020, 10:48

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