[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
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