🚀 go-pugleaf

I am trying to interface with a .dll written in vb. 

The instructions are as follows : 
SHA1_StringHexHash 
SHA1_StringHexHash creates a SHA-1 message digest in hexadecimal format from a message of String type. 
Syntax 
Public Declare Function SHA1_StringHexHash Lib "diCrHash.dll" (ByVal sDigest As String, ByVal sMessage As String) As Long 
iRet = SHA1_StringHexHash(sDigest, sMessage) 

Parameters 
sDigest String to receive message digest. 
sMessage String containing the message to be hashed. 

Returns 
Long: If successful, the return value is 0; otherwise it returns a non-zero error code. 
Remarks 
sDigest must be at least 40 characters long (41 characters in a C program). 
Example 
Dim iRet As Long 
Dim sDigest As String 
' Set sDigest to be 40 chars 
sDigest = String(40, " ") 
iRet = SHA1_StringHexHash(sDigest, "abc") 
Debug.Print sDigest 

iRet = SHA1_StringHexHash(sDigest, _ 
"abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq") 
Debug.Print sDigest 

This should result in output as follows: 
a9993e364706816aba3e25717850c26c9cd0d89d 
84983e441c3bd26ebaae4aa1f95129e5e54670f1 


How do I translate this into a Delphi form? 

My current example below does not return a result : 

unit main_Frm; 

interface 

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

type 
// encryption parameters 
// TSHA1_StringHexHash = function ( s : string; t : string ): string; 
TSHA1_StringHexHash = procedure(s : string; t : string); stdcall; // VERY NB! Stdcall must be used here, not cdecl 
TMainFrm = class(TForm) 
BitBtn1: TBitBtn; 
Edit1: TEdit; 
procedure BitBtn1Click(Sender: TObject); 
private 
{ Private declarations } 
public 
{ Public declarations } 
// variables to used for encryption below 
hndDLLHandle: THandle; 
// hash_res: TACBencfile; 
// param_ptr : string; 
SHA1_StringHexHash : TSHA1_StringHexHash; 
// SHA1_StringHexHashfunc : TSHA1_StringHexHashfunc; 
end; 

var 
MainFrm: TMainFrm; 

implementation 

{$R *.dfm} 

procedure TMainFrm.BitBtn1Click(Sender: TObject); 
var 
sdigest : string[41]; 
result : string[41]; 

begin 
// load dll in dynamic type(mode) 
hndDLLHandle := loadLibrary ( 'diCrHash.dll' ); 
if hndDLLHandle <> 0 then 
begin 
// get function address 
@SHA1_StringHexHash := getProcAddress ( hndDLLHandle, 'SHA1_StringHexHash' ); 
if addr(SHA1_StringHexHash) <> nil then 
begin 
// Procedure called 
@SHA1_StringHexHash := getProcAddress ( hndDLLHandle, 'SHA1_StringHexHash' ); 
SHA1_StringHexHash(sDigest, 'abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq'); 
result := sDigest; 
end 
else 
begin 
MessageDlg('procudure not able to be called', mtInformation,[mbOk], 0); 
end; 
end 
else 
begin 
MessageDlg('function not able to be called', mtInformation,[mbOk], 0); 
end; 

edit1.Text := result; 

end; 

end.