Delphi HID in Delphi7 and Delphi XE2

Question

I made a small program in Delphi 7 to show some details of all attached HID devices. I only used system files like SetupAPI , Moduleloader and HID.pas . This works perfect. When I take the same code and compile it in Delphi XE2 or (2010 for that matter), it fails to produce the required output.

Probably this has something to do with pointer casting or so, but I cannot find the root cause.

Can anyone help.

This is my code:

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, 
  Graphics, Controls, Forms, Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Memo1: TMemo;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

Uses 
  SetUpAPI, HID;

{$R *.dfm}

Type
  THIDUSBDeviceInfo = Record   { contains interface level information of each device}
    SymLink            : String;
    BufferSize         : Word;
    Handle             : THandle;
    VID                : DWord;
    PID                : DWord;
    VersionNumber      : Word;
    ManufacturerString : String;
    ProductString      : String;
    SerialNumberString : String;
  end;
  THIDDeviceList = Array of THIDUSBDeviceInfo;

Const
  HIDUSB_COUNTOFINTERRUPTBUFFERS = 64;   // Count of buffers for interrupt data


Procedure ScanForHIDdevices( Var DeviceList : THIDDeviceList;
    TargetVID, TargetPID  : DWord);
Var
  HID_GUIid     : TGUID;
  spdid        : TSPDeviceInterfaceData;
  pSpDidd      : PSPDEVICEINTERFACEDETAILDATAA;
  spddd        : TSPDevInfoData;
  HIDinfo       : HDEVINFO;
  CurIdx       : Integer;
  dwSize       : DWord;
  SymbolicLink : String;
  DevHandle    : THandle;
  HidAttrs     : THIDDAttributes;
  FoundIdx     : Integer;
  Info         : THIDUSBDeviceInfo;

  Function GetHidDeviceInfo( Symlink : PChar) : THIDUSBDeviceInfo;
  Var
    pstr          : pWideChar;
    preparsedData : PHIDPPreparsedData;
    hidCaps       : THIDPCaps;
  Begin
    FillChar(Result, SizeOf( Result), 0);
    Result.SymLink := SymLink+ #0;
    GetMem( pstr, 512);
    DevHandle := CreateFile( Symlink,
                             GENERIC_READ or GENERIC_WRITE,
                             FILE_SHARE_READ or FILE_SHARE_WRITE,
                             nil,
                             OPEN_EXISTING,
                             0,
                             0);
    If DevHandle <> INVALID_HANDLE_VALUE then
    begin
      If HidD_GetAttributes( DevHandle,
                             HidAttrs) then
      begin
        result.VID           := HidAttrs.VendorID;
        result.PID           := HidAttrs.ProductID;
        result.VersionNumber := HidAttrs.VersionNumber;
      end;

      If HidD_GetManufacturerString( DevHandle, pstr, 512) then 
        Result.ManufacturerString := pStr;

      If HidD_GetProductString( DevHandle, pstr, 512) then 
        Result.ProductString := pStr;

      If HidD_GetSerialNumberString( DevHandle, pstr, 512) then 
        Result.SerialNumberString := pStr;

      { Set Input buffer size }
      HidD_SetNumInputBuffers( DevHandle,
                               HIDUSB_COUNTOFINTERRUPTBUFFERS);

      { Get capabilities }
      HidD_GetPreparsedData( DevHandle, preparsedData);
      if (preparsedData) then
      begin
        HidP_GetCaps( preparsedData, hidCaps);
        Result.BufferSize := hidCaps.OutputReportByteLength;
      end
      else 
       Result.BufferSize := 11;

      closeHandle( DevHandle);
    end;
    FreeMem( pStr);
  End;

Begin
  FoundIdx   := 0;
  DeviceList := Nil;
  { Get GUID of hid class }
  HidD_GetHidGuid( HID_GUIid);
  { Get a list of devices belonging to HID class }
  HIDinfo := SetupDiGetClassDevs( @HID_GUIid,
                                  nil,
                                  GetDesktopWindow(),
                                  DIGCF_DEVICEINTERFACE or DIGCF_PRESENT);
  { Go through list of devices }
  If thandle(HIDinfo) <> INVALID_HANDLE_VALUE then
  begin
    CurIdx := 0;
    spdid.cbSize := SizeOf(spdid);
    While SetupDiEnumDeviceInterfaces( HIDinfo,
                                       nil,
                                       HID_GUIid,
                                       curIdx,
                                        spdid) do
    begin
      dwSize := 0;
      { Get device path for Createfile calls }
      SetupDiGetDeviceInterfaceDetail( HIDinfo,
                                       @spdid,
                                       nil,
                                       dwSize,
                                       @dwSize,
                                       nil);
      If dwSize > 0 then
      begin
        GetMem(pSpDidd, dwSize);
        pSpDidd^.cbSize := SizeOf( TSPDEVICEINTERFACEDETAILDATAA);
        spddd.cbSize    := SizeOf(spddd);
        If SetupDiGetDeviceInterfaceDetail( HIDinfo,
                                            @spdid,
                                            pSpDidd,
                                            dwSize,
                                            @dwSize,
                                            @spddd) then
        begin
          SymbolicLink := PChar( @(pSpDidd^.DevicePath));

          { Get information about the device (Vendor and 
            Product IDs, Strings, ...) }
          FillChar(info, SizeOf(Info), 0);
          Info        := GetHidDeviceInfo( @(pSpDidd^.DevicePath));
          Info.Handle := INVALID_HANDLE_VALUE;

          { check if VID/PID match targets }
          If (Info.VID = TargetVID) AND
             (Info.PID = TargetPID) then
          begin
            { Add Devices to result list }
            SetLength(DeviceList, FoundIdx + 1);
            DeviceList[foundIdx] := Info;
            Inc(FoundIdx);
          end
          else  // list all HID devices if no target is specified
            If (TargetVID = 0) AND (TargetPID = 0) then
            begin
              { Add Devices to result list }
              SetLength( DeviceList, FoundIdx + 1);
              DeviceList[FoundIdx] := Info;

              Inc(FoundIdx);
            end;
        end;

        FreeMem( pSpDidd);
      end;
      inc(CurIdx);
    end;
    SetupDiDestroyDeviceInfoList( HIDinfo);
  end;
End;

procedure TForm1.Button1Click(Sender: TObject);
Var
  DeviceList : THIDDeviceList;
  I          : Integer;
begin
  ScanForHIDdevices( DeviceList, 0, 0);
  Memo1.Lines.Clear;
  Memo1.Lines.Add(IntToStr(Length(DeviceList)) + ' device(s) found');
  If Length(DeviceList) > 0 then
    For I := 0 to Length(DeviceList)-1 do
      With DeviceList[I] do
      begin
        Memo1.Lines.Add('Device Number : '   + IntToStr(I));
        Memo1.Lines.Add('Symbolic link : '   + SymLink);
        Memo1.Lines.Add('Handle        : 0x' + IntToHex(Handle, 1));
        Memo1.Lines.Add('Buffer size   : '   + IntToStr(BufferSize));
        Memo1.Lines.Add('VID           : 0x' + IntToHex(VID, 4));
        Memo1.Lines.Add('PID           : 0x' + IntToHex(PID, 4));
        Memo1.Lines.Add('Version       : '   + IntToStr(VersionNumber));
        Memo1.Lines.Add('Manufacturer  : '   + ManufacturerString);
        Memo1.Lines.Add('Product name  : '   + ProductString);
        Memo1.Lines.Add('Serial number : '   + SerialNumberString);
        Memo1.Lines.Add(' ');
      end;
  Memo1.SetFocus;
end;

Answer 1

You have to load the DLL module before you call any of these functions:

LoadHid();
LoadSetupApi();

I suppose that we have to unload the DLL when finished with the program. Then use this code:

UnloadHid;
UnloadSetupApi