From:	stanton AT haas DOT berkeley DOT edu (Richard Stanton)
Subject:	DLL help needed...
22 Dec 1997 13:33:58 -0800 :
Message-ID:	<199712222111.NAA04315.cygnus.gnu-win32@grether.haas.berkeley.edu>
Mime-Version:	1.0 (generated by SEMI MIME-Edit 0.92 - "Oyanagi")
To:	gnu-win32 AT cygnus DOT com

I'm getting close to creating working DLLs. With a lot of help from
Giandomenico De Sanctis, I've actually created a DLL file that
passes/returns short ints, and can be used in Excel 97, but I'm having
trouble when the functions pass/return double arguments. In fact, I'm
having trouble even in plain C.

Here's a simple example, which produces the following (odd looking)
output

[c:\projects\excel]exe
i 10.000000, j 11.000000, k -1.#IND00

When I pass everything as short instead of double, it all seems to
work OK. Any idea what I'm doing wrong? I attach all the necessary
files to get this to compile.

By the way, I'm compiling this using mingw32.

Thanks a lot.

Richard Stanton

------------------------------------------------------------------------

exe.c:

------------------------------------------------------------------------

#include <stdio.h>

double RHS (double x, double y) __attribute__((stdcall));

int main()
{
	double i, j, k;

	i = 10;
        j = 11;

	k = RHS(i,j);

	printf ("i %lf, j %lf, k %lf\n", i, j, k);
    
	return 0;
}

------------------------------------------------------------------------

dll.c:

------------------------------------------------------------------------

double RHS (double x, double y)
{
    return (x + y);
}

------------------------------------------------------------------------

dll.def:

------------------------------------------------------------------------

EXPORTS
RHS
RHS AT 16=RHS

------------------------------------------------------------------------

makefile:

------------------------------------------------------------------------

dll.dll:	dll.c dll.def
	dlltool --def dll.def --output-exp dll.exp --output-lib dll.a --dllname dll.dll -k
	gcc -g -o dll.dll dll.c dll.exp -Xlinker --image-base=0x40000000 -dll -mrtd -ggdb3

exe.exe:	exe.c dll.dll
	gcc exe.c dll.a -g -o exe.exe

------------------------------------------------------------------------

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