DLL C++ import functions to Delphi

Question

How do I access the functions of a C++ DLL in Delphi

 #define CCONV _stdcall 
  typedef struct{ 
    unsigned long BaudRate; 
    unsigned char PortNumber; 
    ..... 
  }SSP_COMMAND;

NOMANGLE int CCONV OpenSSPComPort (SSP_COMMAND * cmd);

In documentation: OpenSSPComPort

Parameters: Pointer to SSP_COMMAND structure

Returns: WORD 0 for fail, 1 for success

I suspect I am wrong about this Pointer.

In Delphi I am attempting this:

type
  SSP_COMMAND=class
   BaudRate:integer;
   PortNumber:integer;
end;

type
 TOpenSSPComPort = function (sspc:SSP_COMMAND):Integer;stdcall;

    var nv11 : THandle;
    OpenSSPComPort:TOpenSSPComPort;

    procedure TForm1.FormCreate(Sender: TObject);
    begin

    if nv11 = 0 then
    begin
      nv11 := LoadLibrary(pchar('ITLSSPProc.dll'));
      @OpenSSPComPort:=GetProcAddress(nv11, 'OpenSSPComPort');

      ss_cmd := SSP_COMMAND.create;

    end;
  end;

  procedure TForm1.Button1Click(Sender: TObject);
  begin
    ss_cmd.BaudRate := 9600;
    ss_cmd.PortNumber :=8;

   If OpenSSPComPort(ss_cmd)=0 Then
   Memo1.lines.add('Error OpenSSPComPort')
   else
   Memo1.lines.add('OpenSSPComPort - OK');

  end;

So result is : COM0 - Can't open this port but I sent 8 this means then SSP_COMMAND was sent incorrectly

Answer 1

According to the C definition from the link you provided, you would need to change the following:

type
  SSP_FULL_KEY = packed record
    FixedKey : UINT64;
    EncryptKey : UINT64;
end;  

type
  SSP_COMMAND=packed record
    key : SSP_FULL_KEY;
    BaudRate:integer;
    PortNumber:integer;
    SSPAddress : byte;
    RetryLevel : byte; 
    EncryptionStatus : byte;
    CommandDataLength : byte;
    CommandData : Array[0..254] of byte;
    ResponseStatus : byte;
    ResponseDataLength : byte;
    ResponseData : Array[0..254] of byte;
  end;
  PSSP_COMMAND = ^SSP_COMMAND;

type
  TOpenSSPComPort = function (sspc:PSSP_COMMAND):Integer;stdcall;

procedure TForm1.Button1Click(Sender: TObject);
var
  ss_cmd : SSP_COMMAND; 
begin 
  FillChar(ss_cmd, sizeof(ss_cmd), 0);
  ss_cmd.BaudRate := 9600;
  ss_cmd.PortNumber :=8;

  If OpenSSPComPort(@ss_cmd)=0 Then
    Memo1.lines.add('Error OpenSSPComPort')
  else
    Memo1.lines.add('OpenSSPComPort - OK');
end;