OpalHandle OPAL_EXPORT OpalInitialise(unsigned * version, const char * options);

Public Declare Function OpalInitialise Lib "opal.dll" (ByVal version As Integer, ByVal options As String) As Long

#ifdef _WIN32
  #define OPAL_EXPORT __stdcall

OpalHandle OPAL_EXPORT OpalInitialise(unsigned * version, const char * options)
typedef struct OpalHandleStruct * OpalHandle;
struct OpalHandleStruct
{
  OpalHandleStruct(unsigned version, const PCaselessString & options)
    : process(options)
    , manager(version)
  {
  }

  PProcess_C     process;
  OpalManager_C  manager;
};

Public Declare Function OpalInitialise Lib "opal.dll" (ByVal version As Integer, ByVal options As String) As Long
Public Declare Function OpalShutDown Lib "opal.dll" (ByVal handle As Long) As Long
'-----
Dim L As Long
Private Sub Command1_Click()
    L = OpalInitialise( 0 , "sip")
    MsgBox L
End Sub

Private Sub Command2_Click()
    Dim S As Long
    S = OpalShutDown(L)
    MsgBox S
End Sub

 void OPAL_EXPORT OpalShutDown(OpalHandle handle)
  {
    delete handle;
  }

  OpalMessage * OPAL_EXPORT OpalGetMessage(OpalHandle handle, unsigned timeout)
  {
    return handle == NULL ? NULL : handle->manager.GetMessage(timeout);
  }


  OpalMessage * OPAL_EXPORT OpalSendMessage(OpalHandle handle, const OpalMessage * message)
  {
    return handle == NULL ? NULL : handle->manager.SendMessage(message);
  }

Public Declare Function OpalGetMessage Lib "opal.dll" (ByVal handle As Long, ByVal timeout As Integer) As OpalMessage
Public Declare Function OpalSendMessage Lib "opal.dll" (ByVal handle As Long, ByVal message As OpalMessage) As OpalMessage

struct OpalMessage {
  OpalMessageType m_type;   ///< Type of message
  union {
    const char *             m_commandError;       ///< Used by OpalIndCommandError
    OpalParamGeneral         m_general;            ///< Used by OpalCmdSetGeneralParameters
    OpalParamProtocol        m_protocol;           ///< Used by OpalCmdSetProtocolParameters
    OpalParamRegistration    m_registrationInfo;   ///< Used by OpalCmdRegistration
    OpalStatusRegistration   m_registrationStatus; ///< Used by OpalIndRegistrationStatus
    OpalParamSetUpCall       m_callSetUp;          ///< Used by   } m_param;
...
};
typedef struct OpalParamSetUpCall {
  const char * m_partyA;      /**< A-Party for call.
  const char * m_partyB;      /**< B-Party for call. This is typically a remote host URL
 ...

    L = OpalInitialise( 16 , "sip")

#define OPAL_C_API_VERSION  16 

struct OpalMessage {
  OpalMessageType m_type;   ///< Type of message
  union {
    const char *             m_commandError;       ///< Used by OpalIndCommandError
    OpalParamGeneral         m_general;            ///< Used by OpalCmdSetGeneralParameters
    OpalParamProtocol        m_protocol;           ///< Used by OpalCmdSetProtocolParameters
........
  } m_param;
};

Public Type OpalMessage
    m_type As OpalMessageType
    m_param As 'WHAT?????
    m_general As OpalParamGeneral
    .....
End Type
Public Enum OpalMessageType
    OpalIndCommandError =  0 
    OpalCmdSetGeneralParameters =  1 
    OpalCmdSetProtocolParameters =  2 
.....
End Enum
Public Type OpalParamGeneral
  m_audioRecordDevice As String
  m_audioPlayerDevice As String
....
End Type
'и т.д.до бесконечности по тексту пока все не сведется к понятным String-Long

struct OpalMessage {
  OpalMessageType m_type;   ///< Type of message
  union {
    const char *             m_commandError;       ///< Used by OpalIndCommandError
    OpalParamGeneral         m_general;            ///< Used by OpalCmdSetGeneralParameters
    OpalParamProtocol        m_protocol;           ///< Used by OpalCmdSetProtocolParameters
........
  } m_param;
};

Private Type OpalMessage
    m_type As OpalMessageType
    m_param As MyUnionTipe
End Type
Private Enum OpalMessageType
    OpalIndCommandError =  0 
    OpalCmdSetGeneralParameters =  1 
    OpalCmdSetProtocolParameters =  2 
...
End Enum
Private Type MyUnionTipe
    m_commandError As String                       '< Used by OpalIndCommandError
    m_general As OpalParamGeneral                  '< Used by OpalCmdSetGeneralParameters
    m_protocol As OpalParamProtocol                '< Used by OpalCmdSetProtocolParameters
...
End Type

Message2.m_type= 1    'OpalCmdSetGeneralParameters
Message2.m_param.m_general.m_stunServer = "myserver.com"

Public Declare Function OpalInitialise Lib "opal.dll" (ByRef version As Long, ByVal options As String) As Long
Public Declare Function OpalShutDown Lib "opal.dll" (ByVal handle As Long) As Long
Public Declare Function OpalGetMessage Lib "opal.dll" (ByVal handle As Long, ByRef timeout As Long) As OpalMessage
Public Declare Function OpalSendMessage Lib "opal.dll" (ByVal handle As Long, ByRef Message As OpalMessage) As OpalMessage
Public Declare Function OpalFreeMessage Lib "opal.dll" (ByRef Message As OpalMessage) As Long

    Dim NewMes As OpalMessage
    Dim BackMes As OpalMessage
    NewMes.m_type = ...
    NewMes.m_param....
    NewMes.m_param....

    BackMes = OpalSendMessage(L, NewMes) 

OpalSendMessage L, NewMes

   Example:
      void SendCommand(OpalMessage * command)
      {
        OpalMessage * response;
        if ((response = OpalSendMessage(hOPAL, command)) == NULL) {
          puts("OPAL not initialised.");
        else if (response->m_type != OpalIndCommandError)
          HandleResponse(response);
        else if (response->m_param.m_commandError == NULL || *response->m_param.m_commandError == '\0')
          puts("OPAL error.");
        else
          printf("OPAL error: %s\n", response->m_param.m_commandError);

        FreeMessageFunction(response);
      }
  */
OpalMessage * OPAL_EXPORT OpalSendMessage(OpalHandle opal, const OpalMessage * message);

/** String representation of the OpalSendMessage() which may be used for late
    binding to the library.
 */
typedef OpalMessage * (OPAL_EXPORT *OpalSendMessageFunction)(OpalHandle opal, const OpalMessage * message);

/** Typedef representation of the pointer to the OpalSendMessage() function which
    may be used for late binding to the library.