Vb5 & PowerBasic..

[Tyrone W. Lee]

I am having trouble linking a .DLL I've compiled with PB2.0 with VB5..
Every time I attempt to use a function in the .DLL is says the DLL isn't
found. When I give the FULL path in the DECLARE statement, the VB
application still doesn't see the .DLL

Any idea why?

It is a 16bit .DLL but I can't understand why VB5 won't recognize it..
Does it need to be registered? If so, how do I register a custom
stand alone .DLL in VB5?



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Explorations v3.0 RPG Development System
http://www.explore-rpg.com

[Edwin Knoppert]

You 'can't' use 16bit dlls from VB5 because VB5 is 32bits.
You need to use a flat thunk wich is VERY hard (Forget it)
(Under NT a problem)

Vice versa, using a generic thunk from lets say VB3 (16bit) using a 32bit DLL is easy.

I posted some code in the source section as example ~ a month ago..

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[John McWilliams]

Read Chapter 4 in the PBDLL 2.0 manual. There is a supplied
THUNK layer (direct32.dll). It's been so long since I've done
this that i can't remember the details but it's well explained
in the docs.

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[Tyrone W. Lee]

Ok.. I've given up on the 16bit call from vb5.. Instead, I am trying
to use VB5 to call a 32Bit .DLL..

The HELP File tells me the LibMain function will be called by Windows
and The LibMain() returns a 1, the OS will accept the .DLL..
Anything else, and Windows will auto-matically unload the .DLL.

I am running on Windows NT 2000 and my .DLL is automatically unloading
when my .DLL is initialized. Does anyone know what Win2000NT is expecting
my LibMain() to return?



------------------
Explorations v3.0 RPG Development System
http://www.explore-rpg.com

[Tom Hanlin]

I don't remember thunking from 32-bit code to 16-bit code as being all that
difficult under Win95-based OSes, although it's been a few years. It's said
to be more of a problem under NT-based systems.

DIRECT32.DLL doesn't work that well with current OSes and VB versions, but
it's certainly worth a try.


------------------
Tom Hanlin
PowerBASIC Staff

[Tyrone W. Lee]

Well I am home and I am running Windows ME.. I can't get VB5 to see
a PowerBasic 32Bit .DLL

Heres is my code..

#DIM ALL

#COMPILE DLL "DISTANCE.DLL"
#INCLUDE "WIN32API.INC"
GLOBAL ghLibTest AS LONG
GLOBAL gReason AS LONG
GLOBAL gReserved AS LONG
GLOBAL gNumOfTimes AS DWORD
GLOBAL gNumOfCheck AS DWORD

FUNCTION LibMain(BYVAL hInstance AS LONG, _
BYVAL fwdReason AS LONG, _
BYVAL lpvReserved AS LONG) EXPORT AS LONG

ghLibTest = hInstance
gReason = fwdReason
gReserved = lpvReserved
INCR gNumOfTimes

SELECT CASE fwdReason

CASE %DLL_PROCESS_ATTACH
gNumOfCheck = 1234
MSGBOX "%DLL_PROCESS_ATTACH" + CHR$(13,10) + "ghLibTest = " + FORMAT$(ghLibTest) + CHR$(13,10) + "gNumOfCheck = " + FORMAT$(gNumOfCheck) + CHR$(13,10) + "gNumOfTimes = " + FORMAT$(gNumOfTimes) + CHR$(13,10) + "gReserved = " + _
FORMAT$(gReserved)
LibMain = 1 'success!
'LibMain = 0 'failure!
EXIT FUNCTION
CASE %DLL_PROCESS_DETACH

MSGBOX "%DLL_PROCESS_DETACH" + CHR$(13,10) + "ghLibTest = " + FORMAT$(ghLibTest) + CHR$(13,10) + "gNumOfCheck = " + FORMAT$(gNumOfCheck) + CHR$(13,10) + "gNumOfTimes = " + FORMAT$(gNumOfTimes) + CHR$(13,10) + _
"gReserved = " + FORMAT$(gReserved)
EXIT FUNCTION
CASE %DLL_THREAD_ATTACH
MSGBOX "%DLL_THREAD_ATTACH" + CHR$(13,10) + "ghLibTest = " + FORMAT$(ghLibTest) + CHR$(13,10) + "gNumOfCheck = " + FORMAT$(gNumOfCheck) + CHR$(13,10) + "gNumOfTimes = " + FORMAT$(gNumOfTimes) + CHR$(13,10) + _
"gReserved = " + FORMAT$(gReserved)
EXIT FUNCTION
CASE %DLL_THREAD_DETACH
MSGBOX "%DLL_THREAD_DETACH" + CHR$(13,10) + "ghLibTest = " + FORMAT$(ghLibTest) + CHR$(13,10) + "gNumOfCheck = " + FORMAT$(gNumOfCheck) + CHR$(13,10) + "gNumOfTimes = " + FORMAT$(gNumOfTimes) + CHR$(13,10) + _
"gReserved = " + FORMAT$(gReserved)
EXIT FUNCTION
END SELECT
MSGBOX "Lib Main" + CHR$(13,10) + "ghLibTest = " + FORMAT$(ghLibTest) + CHR$(13,10) + "gNumOfCheck = " + FORMAT$(gNumOfCheck) + CHR$(13,10) + "gNumOfTimes = " + FORMAT$(gNumOfTimes) + CHR$(13,10) + _
"gReason = " + FORMAT$(gReason) + CHR$(13,10) + "gReserved = " + FORMAT$(gReserved)
'LibMain = 0 'failure!

'LibMain = 1 'success!
END FUNCTION


FUNCTION distance(BYVAL x1%,BYVAL y1%,BYVAL x2%,BYVAL y2%) EXPORT AS INTEGER

distance = SQR((x2%-x1%)^2 +(y2%-y1%)^2)

END FUNCTION


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

I copied the LibMain straight from the Help file and I made my own
distance calculation call that I wanted to test..

When I declare the function in VB5, the system will ATTACH the .DLL
and then immediatelyt DETACH it.. Anyone know why?

------------------
Explorations v3.0 RPG Development System
http://www.explore-rpg.com

[Tom Hanlin]

To see if it's the LIBMAIN, comment out the whole LIBMAIN procedure and rely
on PB's default LIBMAIN handling.

Chances are, though, your problem is mismatched symbol case. PB/DLL exports
in uppercase by default. VB uses the specified case as a default. To make sure
both sides agree, use the ALIAS clause. For example:

FUNCTION Foo ALIAS "Foo" (BYVAL ork AS LONG) AS LONG  ' PB

Declare Function Foo Lib "whatever.dll" Alias "Foo" (ByVal ork As Long) As Long  ' VB

------------------
Tom Hanlin
PowerBASIC Staff

[Don Dickinson]

Your function should look like this:

FUNCTION distance Alias "distance" (BYVAL x1%,BYVAL y1%,BYVAL x2%,BYVAL y2%) EXPORT AS INTEGER

If you don't put in the alias, your VB declare MUST be in all upper case or your function won't be found.

--Don


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www.basicguru.com/dickinson

[Tyrone W. Lee]

I've tried removing the LibMain and I get the error "CANT FIND DLL entry point distance in C:\DISTANCE.DLL"

My Code is below..

#DIM ALL

#COMPILE DLL "DISTANCE.DLL"
#INCLUDE "WIN32API.INC"

FUNCTION distance (BYVAL x1 AS LONG,BYVAL y1 AS LONG,BYVAL x2 AS LONG,BYVAL y2 AS LONG) EXPORT AS LONG

distance = SQR((x2-x1)^2 +(y2-y1)^2)

END FUNCTION


VB DECLARE:

Declare Function DISTANCE Lib "C:\DISTANCE.DLL" Alias "distance" (ByVal x1 As Long, ByVal y1 As Long, ByVal x2 As Long, ByVal y2 As Long) As Long



------------------
Explorations v3.0 RPG Development System
http://www.explore-rpg.com

[Tyrone W. Lee]

Ok guys .. I figured it out.. But someone should document this somewhere...

#DIM ALL

#COMPILE DLL "C:\DISTANCE.DLL"
#INCLUDE "WIN32API.INC"

FUNCTION DISTANCE ALIAS "Distance" (BYVAL x1 AS LONG,BYVAL y1 AS LONG,BYVAL x2 AS LONG,BYVAL y2 AS LONG) EXPORT AS LONG

DISTANCE = SQR((x2-x1)^2 +(y2-y1)^2)

END FUNCTION


In VB5 you must declare it like this..

Declare Function distance Lib "C:\DISTANCE.DLL" Alias "Distance" (ByVal x1 As Long, ByVal y1 As Long, ByVal x2 As Long, ByVal y2 As Long) As Long

or

Declare Function DISTANCE Lib "C:\DISTANCE.DLL" Alias "Distance" (ByVal x1 As Long, ByVal y1 As Long, ByVal x2 As Long, ByVal y2 As Long) As Long


The function is matched up by the Alias " " not by the actual functionname.
So PowerBasic EXPORTED Functions must have an Alias in order to be seen
by VB5? Why? Older versions could EXPORT functions without the use of an Alias?




------------------
Explorations v3.0 RPG Development System
http://www.explore-rpg.com

[Tom Hanlin]

16-bit Windows expected uppercase symbols. 32-bit Windows allows case-sensitive
symbols. PowerBASIC (16-bit or 32-bit) always exports and imports using uppercase
by default. 32-bit versions of Visual Basic use the symbol as typed by the user
by default.

So, if you don't want to use ALIAS, you can always enter the symbol as DISTANCE
in the VB version, and it will work fine until someone comes along and
decides to change the case on you. After all, symbols are not normally case-sensitive
in VB code, so people don't think twice about changing it to suit themselves...

It is most prudent to use ALIAS on both the PB and VB sides to make sure that
you're getting just what you expect.

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Tom Hanlin
PowerBASIC Staff