Calling a PB DLL from VB

[Wayne Diamond]

Ive put together a little DLL in PB simply to create a CRC32 hash based on the CRC32 code floating around this forum. I can call it easily from PB, but I need to also call it from a VB app...
Here is the function exported from the PB DLL:

FUNCTION CRC32HASH (BYVAL ptrBuffer AS DWORD, BYVAL lenBuffer AS LONG, szReturn AS LONG) EXPORT AS LONG

Here is how I call it in PB:

#COMPILE EXE
#INCLUDE "win32api.inc"
  
DECLARE FUNCTION CRC32HASH Lib "pbcrc32.dll" ALIAS "CRC32HASH" (BYVAL ptrBuffer AS DWORD, BYVAL lenBuffer AS LONG, szReturn AS LONG) AS LONG
  
FUNCTION PBMAIN() AS LONG
ON ERROR RESUME NEXT
Dim MyString As String
Dim ResultCrc AS Long
MyString = "Test" & CHR$(0) & "Test"  'Note - cant use ASCIIZ, as string can have nullchars in it
Dim Result AS LONG
Result = CRC32HASH(STRPTR(MyString), LEN(MyString), ResultCrc)
MSGBOX "Result=" & STR$(Result) & ", CRC=" & HEX$(ResultCrc)   'Should return 45862144
END FUNCTION

Ive been trying for the last few hours to call it from VB, but none of my combinations have worked. It seems straight-forward enough, just need to crack the combination! Any ideas anyone?


[This message has been edited by Wayne Diamond (edited August 31, 2001).]

[Lance Edmonds]

What specific part are you having problems with? Parameter declaration problems, missing export, or...?

The BYVAL DWORD parameter should work fine provided you pass the string BYVAL from VB (The BYVAL of a dynamic string in VB forces VB to translate VB's internal UNICODE string to a null-terminated ANSI string, and it then passes a pointer to that).

Therefore, your BYVAL DWORD should receive the pointer address fine as long as you are passing BYVAL dynamicstring$.

Something like this:

DECLARE FUNCTION CRC32HASH LIB "pbcrc32.dll" _
  ALIAS "CRC32HASH" (BYVAL Buf AS STRING, _
  BYVAL lBuf AS LONG, Crc AS LONG) AS LONG

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Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>

[Wayne Diamond]

By george youve done it!!! first crack and all
I think i had tried every combination except that one, thats the only problem - me
This will definately come in handy over and over, thanks very much Lance - enjoy the weekend!


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