Re: Changing the menu color in the vc++ mfc applications - C / C++ / MFC Discussion Boards

Re: strange 4 assembly instructions for a function [modified]

Rajkumar R21-Jul-08 3:05

21-Jul-08 3:05

George_George wrote:
I think the 4 assembly instruction is doing stack initialization work for the stack space used for foo function, correct?

i think so (i admit), to facilitate ease debug VC++ compiler fills stack variables with 0cch and heap with 0cdh(if my knowledge is correct Smile | :)

George_George wrote:
But from the 4 assembly instruction, how do you know it ends from address ebp-0C0h and is 30 * 4 bytes length?

as naveen said, it is the stack frame size calculated by compiler, refer fixed-allocation-size
in [Prolog and Epilog^] and [Stack Allocation^] for paramters considered for that.

modified on Monday, July 21, 2008 9:28 AM

Re: strange 4 assembly instructions for a function

George_George21-Jul-08 19:50

George_George

21-Jul-08 19:50

Thanks Rajkumar,

1.

Rajkumar R wrote:
it is the stack frame size calculated by compiler, refer fixed-allocation-size

Do you mean stack will be initialized just according to how much data will be used actually? Or no matter how much data will be used, a fixed size will be initialized?

2.

My confusion is, from the assembly code I posted, more stack space than I acually used is initialized. Any comments?

regards,
George

Re: strange 4 assembly instructions for a function

Luc Pattyn21-Jul-08 2:53

Luc Pattyn

21-Jul-08 2:53

Hi George,

I believe the whole idea is twofold:

1. to initialize your function's local variables to a strange value,
increasing the probability that you will discover potential "variable value used before
being set" mistakes. Your function does not have local variabled, so this does not apply here.

2. allocate more stack space than needed, and fill it with something that springs out
in a hex dump, so you can easily recognize the stack frames of each of your functions.

Both of these reasons don't hold true for release code, since they cost both CPU cycles
and stack space.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

Voting for dummies? No thanks. Dead | X|

Re: strange 4 assembly instructions for a function

George_George21-Jul-08 19:45

George_George

21-Jul-08 19:45

Thanks Luc,

Luc Pattyn wrote:
allocate more stack space than needed

It is ok. But how to calculate the actual stack space used? For example, in my sample?

regards,
George

Re: strange 4 assembly instructions for a function

Luc Pattyn22-Jul-08 1:12

Luc Pattyn

22-Jul-08 1:12

The compiler is responsible for stack allocation. It knows what it wants
to store on stack, and it can round it up to whatever number it chooses,
as long as it emits correct code (e.g. it should not initialize more memory
than it has allocated for each and every function).

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

Voting for dummies? No thanks. Dead | X|

Re: strange 4 assembly instructions for a function

George_George10-Aug-08 21:54

George_George

10-Aug-08 21:54

Thanks Luc,

How does compiler calculate the size of the stack in my sample, I do not know why the size is 30h in my sample. It is much more than actually used?

regards,
George

Changing the menu color in the vc++ mfc applications

hariakuthota20-Jul-08 22:35

hariakuthota

20-Jul-08 22:35

Hi i am new to this forum can u please suggest me or refer me to apt links for changing the color for the menu other than the default one

Harish Akuthota

Re: Changing the menu color in the vc++ mfc applications

Nelek20-Jul-08 23:46

Nelek

20-Jul-08 23:46

Take a look on menu section[^] of the site. You may find lots of articles that have usefull info for you.

Regards.
--------
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Re: Changing the menu color in the vc++ mfc applications

ThatsAlok21-Jul-08 0:59

ThatsAlok

21-Jul-08 0:59

might be you have to find way to subclass the MENU class!.. you then paint the MENU with your choice of color

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow
Never mind - my own stupidity is the source of every "problem" - Mixture

cheers,
Alok Gupta
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How to extract header information from image files?

Nilesh Hamane20-Jul-08 22:11

Nilesh Hamane

20-Jul-08 22:11

Actually i want to read each pixel of image, it may be of any type. For exa take .ppm image file, which contains less information. But i don`t know the exact structure of header or pixel. I am interested in C/C++ only. Plz tell me something about how to open image headers or pixels in C/C++? or tell me any sitename where i can found all information.

http://nnhamane.googlepages.com/

Re: How to extract header information from image files?

Nelek20-Jul-08 23:44

Nelek

20-Jul-08 23:44

Quote: "or tell me any sitename where i can found all information. " //Damm I hate the restrictions on the work... I am missing all buttons :S

Try with the CodeProject searching about DDB (Device Dependant Bitmap), DIB (Device Independant Bitmaps), BITMAPINFOHEADER, DDB to DIB... and restricting the search with NOT MFC. You should find usefull information.

Regards.
--------
M.D.V. Wink | ;)

Resizing and saving images

William Engberts20-Jul-08 21:28

William Engberts

20-Jul-08 21:28

Hi you all,

I am trying to build a bit of software to generate a web picture book. I know that there are a lot of programs around to do just that, but I want to write my own HTML that fits into existing websites. The HTML is no problem, but I need to be able to load images from different formats (.jpg, .bmp, .tiff, etc) and generate .jpg images from them for both a thumbnail and the actual image to be shown. Does anyone have any suggestions for the way to
a: load the images
b: resize them so that a relatively neat image will result
c: save them as .jpg images?

Thanks a lot in advance.
William

Re: Resizing and saving images

KarstenK20-Jul-08 21:53

KarstenK

20-Jul-08 21:53

I like this most: http://www.codeproject.com/KB/graphics/extendedbitmap2.aspx[^]

Greetings from Germany

Re: Resizing and saving images

William Engberts20-Jul-08 22:43

William Engberts

20-Jul-08 22:43

Thanks a lot. It does what I would like to do!
There is only one thing though: I do not see any function to save the altered image (preferably as a .jpg file) Do you have any information on how to do this?

Thanks a lot!
William

Re: Resizing and saving images

CPallini20-Jul-08 22:03

CPallini

20-Jul-08 22:03

Have a look at GDI+ [^].
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
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[My articles]

EIP register

George_George20-Jul-08 21:28

George_George

20-Jul-08 21:28

Hello everyone,

I have debugged into the assembly language for the following simple sample, but I never saw any instructions dealing with push eip/pop eip, which dealing with saving/restoring the return address when function foo completes. Any ideas?

int foo (int a, int b)
{
	return a+b;
}

int main()
{
	int a1 = 100;
	int b1 = a1 + 100;

	a1 = foo (a1, b1);

	return 0;
}

thanks in advance,
George

Re: EIP register

Stephen Hewitt20-Jul-08 21:33

Stephen Hewitt

20-Jul-08 21:33

The call family of instructions push the address of the next statement onto the stack and load the EIP register with its (the call instruction's) argument. The ret family of instructions pop the return address off the stack and load it into the EIP register. It can get a little more complicated than that but that's the general idea.

Steve

Re: EIP register

George_George20-Jul-08 21:38

George_George

20-Jul-08 21:38

Cool, Steve!

regards,
George

Re: EIP register

CPallini20-Jul-08 21:37

CPallini

20-Jul-08 21:37

Well, I'm far from being an expert, anyway IMHO this sentence [^] explains why you cannot find it into the disassembled code.
Smile | :)

Re: EIP register

George_George20-Jul-08 21:41

George_George

20-Jul-08 21:41

Thanks CPallini,

The document describes well how to read/write to EIP, but this is not my question. Smile | :)

My question is why there is no explicit push/pop EIP instruction in the code for my sample program?

regards,
George

Re: EIP register

CPallini20-Jul-08 21:59

CPallini

20-Jul-08 21:59

George_George wrote:
The document describes well how to read/write to EIP, but this is not my question.

George_George wrote:
My question is why there is no explicit push/pop EIP instruction in the code for my sample program?

from the document:
The EIP register cannot be accessed by the programmer directly
hence you never see direct push eip / pop eip instructions in code, simply because they don't exist. Register eip is accessed by the call/ret mechanism.

Re: EIP register

George_George20-Jul-08 22:04

George_George

20-Jul-08 22:04

Thanks CPallini,

Cool!

regards,
George

Re: EIP register

CPallini20-Jul-08 22:12

CPallini

20-Jul-08 22:12

George_George wrote:
Cool!

Well, not so cool... Standard, I think: using call/ret mechanism is a well established method to manipulate the PC (program counter) register on wide range of different architectures.

Anyway, you're always welcome, George.
Smile | :)

Re: EIP register

George_George20-Jul-08 22:17

George_George

20-Jul-08 22:17

Thanks CPallini,

Question answered.

regards,
George

Compilation error :Cannot convert from char to LPWSTR

V K 220-Jul-08 19:46

V K 2

20-Jul-08 19:46

Hi,
I am getting this compilation while passing lpszFileName which is a char[260] to GetPrivateProfileInt which accepts LPWSTR. Can I know how to typecast this inorder to avoid compilation error.

Thanks,
Venkat

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