[Mingw-users] [mingw - StupidTechiQuestions] RE: MinGW calling conventions

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By: adah

> In the standard C calling convention (__cdecl), the parameters are pushed
> from right to left, and the caller must clear the stack after the call.
> In the other calling conventions (__stdcall, __pascal, etc), the parameters
> are pushed from left to right, and the called routine removes arguments from
> the stack.

No, that is not right. According to

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vccore98/html/_
core___stdcall.asp

__stdcall pushes arguments from right to left. The difference between __cdecl
is who in responsible for pop up the arguments.


> (And my program should crash if there is a mismatch between the calling and
> the called conventions !)

The program did not crash on mismatch because the ESP is restored from EBP when
the function returns. You will not be so lucky when the -fomit-frame-pointer
optimization is used.


> void __pascal push() {}
> typedef void (__pascal * PUSHLONG)( long );
> PUSHLONG pushFn = (PUSHLONG) push;
> pushFn( a );
> pushFn( b );
> // a & b are now on the stack
> lResult = FnPtr(); // or (* FnPtr)()
> 
> With MinGW, no argument is passed to the called routine ! (while it is OK
> with other compilers)

__pascal is simply defined to __stdcall. And I guess the stack trick did not
work because of the same reason why you program did not crash.


Please do not mail to me personally. Thanks.

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