force specific calling convention on C

Sun, 27 Dec 2009 20:18:51 -0700

Hi guys, I am developing bootloader and met with a need to force C compiler to output the calling function in a specific way.

Due to program requirement, I am passing function parameter to function called ProcName function from code segment like following:
I am also declaring all functions far.

jmp skipData
param1 db 00h, 001h

skipData:
push cs
push offset word ptr cs:param1 ; pushed seg:ofs address of param1
push cs
push offset word ptr cs:retAddr ; pushed return address.
dw eah
dw ProcName
dw CS_SEG ; far jump to CS_SEG:ProcName

retAddr:

ProcName PROC FAR

Now the problem is I declare ProcName in C file and calling ProcName function from C like following way:

extern void far ProcName(char far *);
.....
ProcName("12345");

Problem is it is not working because, C compiler compiles it as follows:
push ds
push offset word ptr ds:paramInC

because string '12345' is created in data segment. But upon program entry I am using ds for something else not for DATA segment.

Finally the question is is there way to force C compiler to create 12345 string in code segment and pass CS and OFFSET CS:12345 to ProcName. Thanks!

Re: force specific calling convention on C

Mon, 01 Mar 2010 13:51:49 -0700

By default, unless you specify the convention, the compiler will probably default to __cdecl?

extern void far ProcName(char far *);

is probably defaulting to

extern void __cdecl far ProcName(char far *);

I think you might be wanting to do this if your compiler supports it.

Naked function calls

http://msdn.microsoft.com/en-us/library/5ekezyy2%28VS.71%29.aspx

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force specific calling convention on C

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