type
  TNewLispCall = function(string1: PChar): PChar; stdcall;

VAR     DllCall     : TNewLispCall;
...
...
           Handle := 0;
           Handle := LoadLibrary( Pchar( 'newlisp.dll' ));
           if Handle <> 0 then
              Begin
              @DllCall := GetProcAddress( Handle, PChar( 'dllEvalStr' ) );
              if Assigned( DllCall ) then
                begin
                  RetStr := NIL;
                  RetStr := DllCall( PChar( DllParam1 ) );
                end;
              end;

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    Edit1 : TEdit;
    Button3: TButton;
    Edit2: TEdit;
    Button4: TButton;
    Edit3: TEdit;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
    procedure Button4Click(Sender: TObject);
  private
    { Private-Deklarationen } 
  public
    { Public-Deklarationen } 
    // This is the procedure that I call from newLisp.
    procedure xRefresh1(param1 : PChar); stdcall;
    procedure xRefresh2(param1,param2 : PChar); stdcall;
    procedure xRefresh3(param1,param2,param3 : PChar); stdcall;
  end;

var
  Form1: TForm1;
  DllNewLisp : THandle;
  newLispEvalStr : function(argExpression: pchar): pchar; stdcall;

implementation

{$R *.DFM} 

procedure openNewLispLibrary;
begin
  DllNewLisp := LoadLibrary('newlisp.dll');
  if (DllNewLisp < HINSTANCE_ERROR) then
    raise Exception.Create('newlisp.dll' + ' library can not be loaded or not found. ' + SysErrorMessage(GetLastError));
  try
    { load an address of required procedure} 
    @newLispEvalStr := GetProcAddress(DllNewLisp, 'newlispEvalStr');
  finally
    {unload a library} 
  end;
end;

procedure TForm1.xRefresh1(param1 : PChar); stdcall;
begin
  showmessage(param1);
  showmessage(IntToStr(Strlen(param1)));
end;

procedure TForm1.xRefresh2(param1, param2 : PChar); stdcall;
begin
  showmessage(param1+' / '+param2);
  showmessage(IntToStr(Strlen(param1))+' / '+IntToStr(Strlen(param2)));
end;

procedure TForm1.xRefresh3(param1, param2, param3 : PChar); stdcall;
begin
  showmessage(param1+' / '+param2+' / '+param3);
  showmessage(IntToStr(Strlen(param1))+' / '+IntToStr(Strlen(param2))+' / '+IntToStr(Strlen(param3)));
end;

procedure registerAndCall1(txtparam : String);
var
  newlispstr: string;
begin
  // I'm using Lutz code to link Pascal function to be used in newLisp.
  newlispstr := '(set ''foo print)' +
                '(cpymem (pack "ld" 265) (first (dump foo)) 4)' +
                '(cpymem (pack "ld" ' +
                IntToStr(integer(@TForm1.xRefresh1)) + ') (+ (first (dump foo)) 12) 4)' +
                '(cpymem (pack "ld" "foo") (+ (first (dump foo)) 8) 4)';
  newLispEvalStr(pchar(newlispstr));

  newlispstr := '(foo nil "'+ txtparam + ' is the String from the edit-field")';
  newLispEvalStr(pchar(newlispstr));
end;

procedure registerAndCall2(txtparam1, txtparam2 : String);
var
  newlispstr: string;
begin
  // I'm using Lutz code to link Pascal function to be used in newLisp.
  newlispstr := '(set ''foo1 print)' +
                '(cpymem (pack "ld" 265) (first (dump foo1)) 4)' +
                '(cpymem (pack "ld" ' +
                IntToStr(integer(@TForm1.xRefresh2)) + ') (+ (first (dump foo1)) 12) 4)' +
                '(cpymem (pack "ld" "foo1") (+ (first (dump foo1)) 8) 4)';
  newLispEvalStr(pchar(newlispstr));

  newlispstr := '(foo1 nil "'+ txtparam1 + ' is the String from the edit-field" "Test2:'+ txtparam2 + '")';
  newLispEvalStr(pchar(newlispstr));
end;

procedure registerAndCall3(txtparam1, txtparam2, txtparam3 : String);
var
  newlispstr: string;
begin
  // I'm using Lutz code to link Pascal function to be used in newLisp.
  newlispstr := '(set ''foo2 print)' +
                '(cpymem (pack "ld" 265) (first (dump foo2)) 4)' +
                '(cpymem (pack "ld" ' +
                IntToStr(integer(@TForm1.xRefresh3)) + ') (+ (first (dump foo2)) 12) 4)' +
                '(cpymem (pack "ld" "foo2") (+ (first (dump foo2)) 8) 4)';
  newLispEvalStr(pchar(newlispstr));

  newlispstr := '(foo2 nil "'+ txtparam1 + ' is the String from the edit-field" "Param2:'+ txtparam2 + '" "Param3:'+ txtparam3 + '")';
  newLispEvalStr(pchar(newlispstr));
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
   openNewLispLibrary;
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
  registerAndCall1(Edit1.Text);
end;

procedure TForm1.Button3Click(Sender: TObject);
begin
  registerAndCall2(Edit1.Text, Edit2.Text);
end;

procedure TForm1.Button4Click(Sender: TObject);
begin
  registerAndCall3(Edit1.Text, Edit2.Text, Edit3.Text);
end;

end.