[fpc-pascal] How can i detect what cause the problem

[Gabor Boros]

Hi,

I have a Symbol mobile device with an integrated barcode scanner.
The scanner's API in C and I cannot use every API calls.

An example: The problem appears in the 
ScanBuffer:=SCAN_AllocateBuffer(TRUE,dwScanSize);
line (see the test app below).
If I run in GDB the error message is:

warning: Prefetch Abort: Thread=8dcfe8dc Proc=8c329ab0 'project1.exe'
warning: AKY=00004001 PC=00000000 RA=00011338 BVA=00000000 FSR=000004f0

Program received signal SIGSEGV, Segmentation fault.
0x00000000 in ?? ()

The test app is:

program test;

{$apptype console}
{$PACKRECORDS C}

uses Windows, dynlibs;

const
   MAx_SRC=32;
   dwScanSize:DWORD=7095;	

type
   STRUCT_INFO=record
     dwAllocated:DWORD;
     dwUsed:DWORD;
   end;

   LABELTYPE = DWORD;

   LPSCAN_BUFFER = ^SCAN_BUFFER;
   SCAN_BUFFER=record
     StructInfo:STRUCT_INFO;
     dwDataBuffSize:DWORD;
     dwOffsetDataBuff:DWORD;
     dwDataLength:DWORD;
     dwTimeout:DWORD;
     dwStatus:DWORD;
     bText:BOOL;
     dwLabelType:LABELTYPE;
     dwRequestID:DWORD;
     TimeStamp:SYSTEMTIME;
     dwDirection:DWORD;
     szSource:array[0..MAx_SRC-1] of TCHAR;
     blsMultiPart:BOOL;
     dwScanID:DWORD;
     dwBarcodeID:DWORD;
     dwNumRemaining:DWORD;
     dwOffsetAuxDataBuff:DWORD;
     dwAuxDataLength:DWORD;
   end;

   T_SCAN_AllocateBuffer = function 
(bText:BOOL;dwSize:DWORD):LPSCAN_BUFFER; cdecl;

var
   SCAN_AllocateBuffer: T_SCAN_AllocateBuffer;
   DLL_Handle:TLibHandle;
   ScanBuffer:LPSCAN_BUFFER;

begin
   DLL_Handle:=LoadLibrary('SCNAPI32.DLL');
   Pointer(SCAN_AllocateBuffer):=GetProcedureAddress(DLL_Handle, 
'SCAN_AllocateBuffer');

   ScanBuffer:=SCAN_AllocateBuffer(TRUE,dwScanSize);

   UnloadLibrary(DLL_Handle);
end.


Thanks!

Gabor