How to build without CRT ?

[bitcoin]

Hello, I write some simple program with option "ignore standart places " (no crt).

In Linker section I add entry_point as ep. In code I write

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int ep(void)

but this fails. Also fails , if write in linker section _ep, _ep@4 and other.

But if I write in code

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int ep()
it works , but I have warnings "old style"

[Vortex]

Hi bitcoin,

The entry point should be ep as you mentioned.

Attached is a quick example for you.

[bitcoin]

Thank you Vortex, your sample works good..save it as template )

[TimoVJL]

In Pelle's C help is a topic  Program startup: the true story

linker knows these:
mainCRTStartup
wmainCRTStartup
WinMainCRTStartup
wWinMainCRTStartup
DllMainCRTStartup

[Vortex]

Hi bitcoin,

You are welcome. Here is how to build the project with a batch file.

After running \PellesC\Bin\povars32.bat :

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pocc.exe /Ze /Zx -Tx86-coff CustEntryPoint.c

pocc.exe /Ze /Zx -Tx86-coff StdOut.c

pocc.exe /Ze /Zx -Tx86-coff StrLen.c

polink /SUBSYSTEM:CONSOLE /ENTRY:ep /LIBPATH:\Pellesc\Lib\Win CustEntryPoint.obj StdOut.obj StrLen.obj kernel32.lib user32.lib

[TimoVJL]

For lazy programmer, to sourcecode:

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#pragma comment(linker, "/SUBSYSTEM:CONSOLE /ENTRY:ep")

[frankie]

Hello, I write some simple program with option "ignore standart places " (no crt).

In Linker section I add entry_point as ep. In code I write

Code Select Expand

int ep(void)

but this fails. Also fails , if write in linker section _ep, _ep@4 and other.

But if I write in code

Code Select Expand

int ep()
it works , but I have warnings "old style"

Probably you compiled your code with MS extensions on and __stdcall as default.
The entry point name can be the base name or the underscore decorated if compiling as __cdecl your function, that automatically happen when you declare it as 'int ep()'.
So you have 2 options declare your function as:

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int __cdecl ep(void)
and the entry point as 'ep' or '_ep', or if you compile the function as __stdcall use the entry point '_ep@0' with full decorations.

[bitcoin]

Yes, if change to _cdecl, all works also.

Thanks all for the answers!

[TimoVJL]

A NoCrt library is also usually needed, as compiler needs support library, like SEH in x86 mode.

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#include <excpt.h>

void __stdcall ExitProcess(int);
int __cdecl main(void);
void __cdecl mainCRTStartup(void) { ExitProcess(main()); }

int __cdecl main(void)
{
__try
{
char *p = 0;
*p = 0; /* force a null-pointer exception */
}
__except(EXCEPTION_EXECUTE_HANDLER)
{
//printf("An exception occurred - the code is %x\n", exception_code());
}
return 0;
}
map-file

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0001:00000078       __except_handler3          00401078 f   crt:seh2.obj
0001:00000150       __seh_longjmp_unwind@4     00401150 f   crt:seh2.obj
0001:00000170       __global_unwind2           00401170 f   crt:seh1.obj
0001:00000190       __unwind_handler           00401190 f   crt:seh1.obj
0001:000001c0       __local_unwind2            004011c0 f   crt:seh1.obj
0001:0000021f       __NLG_Return2              0040121f     crt:seh1.obj
0001:00000230       __abnormal_termination     00401230 f   crt:seh1.obj
0001:00000260       __NLG_Notify1              00401260     crt:seh1.obj
0001:00000269       __NLG_Notify               00401269     crt:seh1.obj
0001:0000027d       __NLG_Dispatch             0040127d     crt:seh1.obj
0002:00000010       __load_config_used         00402010     crt:_loadcfg.obj
0003:00000068       __NLG_Destination          00403068     crt:seh1.obj


https://forum.pellesc.de/index.php?topic=7264.msg27613#msg27613