Inline assembly with Pelle's C

[Vortex]

Hi friends,

Here is an example of using inline assembly with Pelle's C. The original source code of szUpper comes with Hutch's masm32 package.

Code Select Expand


#define WIN32_LEAN_AND_MEAN
#include <windows.h>

char *szUpper(char *text)
{
__asm{
mov eax, text
dec eax
@repeat:
add eax, 1
cmp BYTE PTR [eax], 0
je @end
cmp BYTE PTR [eax], "a"
jb @repeat
cmp BYTE PTR [eax], "z"
ja @repeat
sub BYTE PTR [eax], 32
jmp @repeat
@end:
}
return text;
}


int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,LPSTR lpCmdLine, int nCmdShow)
{
char msg[]="inline assembly programming";
MessageBox(0,szUpper(msg),"Hello!",MB_OK);
return 0;
}


[petezl]

Hi Vortex,
Thanks for another interesting forum. ..
Having done some minimal in-line assembly with Digital Mars. I'm looking forward to having a bash with Pelle'sC.
I did a major re-organisation of my HD so will be a while before i get it all installed again. I also lost my password for Pelle's forum, will have to get back there soon to thank him for some links he gave me.
Peter.

[Vortex]

Hi Peter,

I hope you will recover successfully your system.

Glad to learn that you will rejoin Pelle's forum :U

[Vortex]

Here is another method, the C source code:

Code Select Expand


#define WIN32_LEAN_AND_MEAN
#include <windows.h>

extern char *szUpper(char *text);

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,LPSTR lpCmdLine, int nCmdShow)
{
char msg[]="inline assembly programming";
MessageBox(0,szUpper(msg),"Hello!",MB_OK);
return 0;
}


Pelle's C compiler, pocc.exe accepts asm source files based on a variant of NASM syntax:

Code Select Expand


[cpu 486]
[global _szUpper]
[section .text]
[function _szUpper]
_szUpper:
push ebp
mov ebp,esp
mov eax,[EBP+8]
dec eax
@restart:
add eax,1
cmp byte [eax],0
je near @end
cmp byte [eax],97
jb near @restart
cmp byte [eax],122
ja near @restart
sub byte [eax],32
jmp near @restart
@end:
mov eax,dword [ebp+8]
mov esp,ebp
pop ebp
ret

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[petezl]

Vortex,
That code you posted shows the way to completing my original aim of creating an asm project for the PPC. A nice addition to Pelles soft. All I have to do now is learn a bit about NASM.
Peter.

[Farabi]

How to debuging it if I want to see the code generated?

[GregL]

Farabi,

If you don't already have Pelle's C, you need to get it. Open the project. Do a debug build. Start the debugger. Right click on the source code and select Show assembly.

Or, you could use OllyDbg (with no debug information).

[PellesC]

...or possibly add an "int 3" instruction somewhere, which will give the debugger a reason to break...

(int 3 = interrupt 3 -- trap to debugger = opcode 0xCC)

Pelle

[Farabi]

Farabi,

If you don't already have Pelle's C, you need to get it. Open the project. Do a debug build. Start the debugger. Right click on the source code and select Show assembly.

Or, you could use OllyDbg (with no debug information).

I have it. But dont know how to start. But now I know how to use it after see a few example.

[Vortex]

Hi Onan,

Debugging is easy with PellesC, here is the debug version of my inline assembly example.

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[noman9607]

Vortex,
Thanks for the debug project, I just double clicked on the  project file and Pelle's ide came up then I clicked on debug and I was good to go in about 2 sec. One thing about the microsoft debugger I like when f8 or single stepping is that the register(s) that change state in that step are in red so you can catch something you are not specially looking for.

[GregL]

While trying out Pelles C 4.50, I updated Vortex's example posted above (Inline2.zip) to work with the new version. I had to rewrite the asm files, they now need to be in POASM format.



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[Vortex]

Hi Greg,

Thanks for updating the example, nice work :U

[OzzY]

Pelle's C compiler, pocc.exe accepts asm source files based on a variant of NASM syntax

I didn't know that. So , why Pelle is writting PoASM?

[Vortex]

Hi Ozzy,

Pelle released Poasm towards the end of 2005. He coded it to support his software development package. Poasm didn't exist when I created this topic.