Can you call a 32-bit dll from a 16-bit dll 
Author Message
 Can you call a 32-bit dll from a 16-bit dll

We have a 32bit Visual FoxPro system (VFP 6.0) which uses 32-bit dll's to
instantiate COM Datamanagers (Some written in VFP, some in VC).  The
datamanager gives other 32bit 3rd-party applications the ability to access
our data.  A client who has a 16-bit delphi application wishes to do the
same.  I haven't dealt with "cross-bit" development before.  So the question
is does one or more of the following possible implementations make any sense
and can it be implemented with a full head of hair:

1) Can I have the 16 bit application call the 32bit dll directly
or
2) Can the 16 bit application call a 16 bit dll which in turn calls the
existing 32 bit dll

Additionally, I assume that VFP 6.0 does not have the capacity to create a
16 bit dll, so I would be restricted to developing the 16 bit dll in VC,
yes?

Thanks.

- Tom -



Sat, 29 Sep 2001 03:00:00 GMT  
 Can you call a 32-bit dll from a 16-bit dll
Look in MSDN under thunk or thunking.

Quote:

>We have a 32bit Visual FoxPro system (VFP 6.0) which uses 32-bit dll's to
>instantiate COM Datamanagers (Some written in VFP, some in VC).  The
>datamanager gives other 32bit 3rd-party applications the ability to access
>our data.  A client who has a 16-bit delphi application wishes to do the
>same.  I haven't dealt with "cross-bit" development before.  So the
question
>is does one or more of the following possible implementations make any
sense
>and can it be implemented with a full head of hair:

>1) Can I have the 16 bit application call the 32bit dll directly
>or
>2) Can the 16 bit application call a 16 bit dll which in turn calls the
>existing 32 bit dll

>Additionally, I assume that VFP 6.0 does not have the capacity to create a
>16 bit dll, so I would be restricted to developing the 16 bit dll in VC,
>yes?

>Thanks.

>- Tom -



Sun, 30 Sep 2001 03:00:00 GMT  
 Can you call a 32-bit dll from a 16-bit dll
Tom,
At Rick Strahl's web site, he has a file that allows FPW2.x programs call
32-bit .DLLs. I believe it's based on a freeware VB 32-bit .DLL. The file is
CALL32.ZIP, at <http://www.west-wind.com/wwfp2pd.htm>.

Rick


Quote:
> We have a 32bit Visual FoxPro system (VFP 6.0) which uses 32-bit dll's to
> instantiate COM Datamanagers (Some written in VFP, some in VC).  The
> datamanager gives other 32bit 3rd-party applications the ability to access
> our data.  A client who has a 16-bit delphi application wishes to do the
> same.  I haven't dealt with "cross-bit" development before.  So the
question
> is does one or more of the following possible implementations make any
sense
> and can it be implemented with a full head of hair:

> 1) Can I have the 16 bit application call the 32bit dll directly
> or
> 2) Can the 16 bit application call a 16 bit dll which in turn calls the
> existing 32 bit dll

> Additionally, I assume that VFP 6.0 does not have the capacity to create a
> 16 bit dll, so I would be restricted to developing the 16 bit dll in VC,
> yes?

> Thanks.

> - Tom -



Sun, 30 Sep 2001 03:00:00 GMT  
 Can you call a 32-bit dll from a 16-bit dll

Quote:
>We have a 32bit Visual FoxPro system (VFP 6.0) which uses 32-bit dll's to
>instantiate COM Datamanagers (Some written in VFP, some in VC).  The
>datamanager gives other 32bit 3rd-party applications the ability to access
>our data.  A client who has a 16-bit delphi application wishes to do the
>same.

Tom,

I'm not familiar with FoxPro, Delphi, or "datamangers", however you do
mention COM, in which case you may be able to take advantage of the
standard OLE Automation marshaller which does support 16-32 bit
combinations. Have a look at Knowledge Base article Q139072 "Using OLE
Automation Marshaler for 16/16 & 16/32 COM Interface".

If that doesn't fit your needs, then I think things get rather messy
if you have to use thunks - see article Q125710 "PRB: Types of
Thunking Available in Win32 Platforms".

Dave
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Sun, 30 Sep 2001 03:00:00 GMT  
 
 [ 4 post ] 

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