Calling an exe from a dll

[Todd Wasson]

I found this on the subject:

http://powerbasic.com/support/pbforums/showthread.php?p=21166&highlight=calling+executable+function+from+dll#post21166

It's from 2001 though. Is this still the way to go about calling an exe function from a dll rather than the other way around? The exe functions will be in a C++ exe called by a PB DLL it's already using. Not sure if that would make things any different than a PB to PB thing, which I don't know how to do either. I assume CALL DWORD would be used in the dll after receiving the exe function's addresses from other calls at program initialization. This would work just peachy for our purposes. Anyone know of any other examples?

The exe function doesn't need to return a value to the dll if that simplifies things. It also does not need to be a separate thread or callback function. Just a simple F_Add_Value(BYVAL a AS SINGLE) AS LONG type of thing would suffice. Anyone know what I should be searching for or have a simple example handy?

Thanks

[Todd Wasson]

Nevermind. Figured it out:


EXE code:

#COMPILE EXE "Parent.exe"

DECLARE FUNCTION DLL_Receive_EXE_Function_Address LIB "CHILD_DLL.DLL" ALIAS "DLL_Receive_EXE_Function_Address" (BYVAL Address AS DWORD) AS LONG
DECLARE FUNCTION DLL_Run LIB "CHILD_DLL.DLL" ALIAS "DLL_Run" AS LONG

FUNCTION Send_Address_Of_EXE_Function (BYVAL Address AS DWORD) AS DWORD
  DLL_Receive_EXE_Function_Address Address
END FUNCTION

FUNCTION EXE_Function(BYVAL InputValue1 AS LONG) AS LONG
TEXT$ = "EXE_Function has been called by the dll " + $CRLF+_
        "The value " + FORMAT$(InputValue1,"# ") + "has been received."
  MSGBOX TEXT$,,"This is the EXE talking"
END FUNCTION

FUNCTION PBMAIN
  Send_Address_Of_EXE_Function CODEPTR(EXE_Function)
  DLL_Run
END FUNCTION

DLL code

#COMPILE DLL "Child_DLL"
                        
DECLARE FUNCTION EXE_Function(BYVAL InputValue1 AS LONG) AS LONG

GLOBAL GLOBAL_EXE_Function_Address AS DWORD

FUNCTION DLL_Receive_EXE_Function_Address ALIAS "DLL_Receive_EXE_Function_Address" (BYVAL Address AS DWORD) EXPORT AS LONG
  GLOBAL_EXE_Function_Address = Address
  TEXT$ = "Address received is " + FORMAT$(Address,"#")
  MSGBOX TEXT$,,"This is the DLL talking"
END FUNCTION
                                                      
FUNCTION DLL_Run ALIAS "DLL_Run" EXPORT AS LONG
  LOCAL Value_To_Send_To_Exe AS LONG
  Value_To_Send_To_Exe = 4
  TEXT$ = "DLL_Run has been called by the exe.  Sending value " + FORMAT$(Value_To_Send_To_Exe,"# ") + "to EXE_Function"
  MSGBOX TEXT$,,"This is the DLL talking"
  CALL DWORD GLOBAL_EXE_Function_Address USING EXE_Function(Value_To_Send_To_Exe)
END FUNCTION

Thanks anyway

[Edwin Knoppert]

As long the exe loads your dll you can perfectly use ordinary declares.
Of course the name of the exe should be static (but no folder required)
I do this myself.

[Michael Mattias]

Passing an address like this instead of DECLAREing an external is IMNSHO good technique.

Besides, you are probably already familiar with passing a code address from using the WinAPI "Enumxxxx" functions.

If you are really curious, here's a demo I created a long time ago on the same subject...

PB/WIN: Write your own ENUM functions to callback September 23, 2002