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Date: Sun, 20 Jan 2002 12:01:46 -0600
From: Tim <tjbynum AT swbell DOT net>
Subject: Re: DLL And Visual Basic
To: cygwin AT cygwin DOT com
Message-id: <007401c1a1dc$86c1a800$fa34fea9@rineco.com>
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Ok, I've gotten a little further in my endeavors and am stumped again.
Actually this is pretty much where I was stumped in the beginning, but I
have made some moderate headway.

I have successfully created a dl that can be called (successfully mind you)
from Visual Basic, but unfortunately only once.  ;-)  Any attempt to run the
app again without first shutting it down will result in the following:
VB6 caused an invalid page fault in
module CYGWIN1.DLL at 0177:610066e2.
Registers:
EAX=00000000 CS=0177 EIP=610066e2 EFLGS=00010202
EBX=00000000 SS=017f ESP=045ffc08 EBP=045ffc20
ECX=63c40000 DS=017f ESI=610a47c0 FS=7797
EDX=00000001 ES=017f EDI=00000000 GS=0000
Bytes at CS:EIP:
8b 43 2c 85 c0 7f 1b 68 80 66 00 61 68 b4 66 00
Stack dump:
00000001 63c40000 00000000 7ff420db 7ff20000 00000002 045ffc40 61006bf7
610a47c0 00000000 00000000 00000000 00000000 00000000 045ffc70 63c410ba

What it is that I have or have not done to prevent this, is beyond me, but
perhaps someone could point me in the right direction.  ;-)

I found some examples here and there and put together the following:
--- MyTest.c --
#include <windows.h>

int WINAPI testit (int i)
{
   return(i+1);
}


-- MyTest.def --
EXPORTS
testit=testit AT 4


-- MyMakeTestDLL.sh --
#!/bin/sh
gcc -nostartfiles -c -DBUILD_DLL MyTest.c
dllwrap --def=MyTest.def --output-lib=libtstdll.a --dllname=MyTest.dll --dri
ver-name=gcc MyTest.o

I then copied MyTest.dll \windows\system

Added the following to VB:
Private Declare Function doit Lib "bar.dll" (ByVal myNumber As Long) As Long

Private Sub Form_Load()
Dim i As Long

    i = doit(100)
End Sub

Calling doit returns 101.....so far so good.  Now I run it again w/out
closing down the app and  *POOF*  ,VB tanks!!!

What am I missing here?  Am I doing something wrong, or is this what I'm in
for?

I also had to copy /usr/bin/cygwin1.dll to \windows\system in order to even
attempt to use the newly created DLL.  I thought I read something somewhere
where you could created a DLL that wouldn't require this, but then again I
could be wrong b/c I can't find it now.  Anyhow, I suppose that's not as
important to me right now as much as figuring out why it's crashing VB after
I run it twice.

Any and all help/comments/flames/suggestions always welcome.

Best Regards,
-tim


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