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Index > Windows > Correct way to convert binary to decimal in windows?

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windwakr



Joined: 30 Jun 2004
Posts: 827
Location: Michigan, USA
windwakr
Is wsprintf with %u the right way to convert to decimal? Here is some code I wrote with it:

Code:
include "win32ax.inc"

.data
  test1 db "Length: ",0
  out1 rb 100
  windir rb 100

.code
  start:
        invoke GetWindowsDirectory,windir,100
        invoke wsprintf,out1,"%u",eax
        invoke lstrcat,test1,out1
        invoke MessageBox,NULL,windir,test1,MB_OK
        invoke ExitProcess,0
.end start           
    


I'm new to windows programming, I've only done dos programming.

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Post 03 Oct 2008, 23:45
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LocoDelAssembly
Your code has a bug


Joined: 06 May 2005
Posts: 4633
Location: Argentina
LocoDelAssembly
It is not wrong but you could save yourself from doing the string concatenation by just doing it this way
Code:
include "win32ax.inc"
PATH_SIZE = 256

.data
  fmt db "Length: %u", 0
  buff rb $ - fmt + 10
  windir rb PATH_SIZE

.code
  start:
        invoke GetWindowsDirectory, windir, PATH_SIZE ; The documentation says that it should be MAX_PATH
        cinvoke wsprintf, buff, fmt, eax
        invoke MessageBox, NULL, windir, buff, MB_OK
        invoke ExitProcess, 0
.end start    


[edit]It was something wrong, wsprintf must be called with cinvoke or "ccall [wsprintf], ..."
Post 04 Oct 2008, 00:04
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windwakr



Joined: 30 Jun 2004
Posts: 827
Location: Michigan, USA
windwakr
What is cinvoke and why does it need to be used instead of invoke?
Does this work on all windows versions 95 and up?
Thanks

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Post 06 Oct 2008, 00:35
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LocoDelAssembly
Your code has a bug


Joined: 06 May 2005
Posts: 4633
Location: Argentina
LocoDelAssembly
Well, you have to read http://flatassembler.net/docs.php?article=win32 , however it is not explained with an example what cinvoke/ccall does so here the same call without macros
Code:
push eax
push fmt
push buff
call [wsprintf]
add  esp, 4*3 ; Here the important part that invoke/stdcall don't have    


Because wsprintf uses cdecl calling convention instead of stdcall, you need cinvoke.

According to MSDN the minimum operating systems are Windows 95 and Windows NT 3.1.

BTW, this is not "the way" to convert to decimal, it is just one way but nothing stops you from doing your own routine (like you did it in DOS?). But it is very handy and many times the preferable way. I think it is better to use a function already loaded in memory than wasting more RAM writing your own for few to nothing speed improvement (which if it is used to show something on the display then it is very stupid to optimize for speed rather than for size).

PS: I know that importing wsprintf takes more space than a simple IntToStr, but when you need to produce a string with many values in it, the whole code dedicated to that will be bigger than just importing the function.
Post 06 Oct 2008, 00:49
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 17276
Location: In your JS exploiting you and your system
revolution
wsprintf (wsprintfA & wsprintfW) is the only Win32 API that uses CDECL calling convention so the caller must restore the stack. All other Win32 APIs use STDCALL convention so the stack is restored the the function called.


Last edited by revolution on 06 Oct 2008, 01:22; edited 1 time in total
Post 06 Oct 2008, 00:50
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windwakr



Joined: 30 Jun 2004
Posts: 827
Location: Michigan, USA
windwakr
Ok, thanks for explaining that to me.
Post 06 Oct 2008, 01:17
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