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675 lines
20 KiB
675 lines
20 KiB
/* X224.h
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*
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* Copyright (c) 1994-1995 by DataBeam Corporation, Lexington, KY
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*
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* Abstract:
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* This class represents the X.224 class 0 Transport functionality. This
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* is the highest layer in the T.123 specification. This layer is unique
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* in that it has direct access to the User. When data packets are
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* received from the remote site and reassembled by this class, they are
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* passed on to the user via a callback.
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*
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* This class has only limited functionality. It basically has a simple
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* link establishment procedure (which includes arbitration of maximum PDU
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* size). It is then responsible for transmitting and receiving user data.
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* Its maximum TSDU size is 8K, and its TPDU size can range from 128 bytes
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* to 2K. Its TSDU size is larger than its TPDU size, it must be able to
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* segment and reassemble the user packet.
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*
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* This layer ASSUMES that its lower layer has a packet interface rather
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* than a stream interface.
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*
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* This layer ASSUMES that the disconnect of a call is handled by the
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* Network layer (as specified in the X.224 class 0 document).
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*
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* Prior knowledge of the X.224 class 0 specification would help the user
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* understand the code.
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*
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* Caveats:
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* None.
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*
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* Authors:
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* James W. Lawwill
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*/
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#ifndef _X224_H_
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#define _X224_H_
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#include "tmemory2.h"
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/*
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** The following, are states that the class can be in.
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*/
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typedef enum
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{
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NO_CONNECTION,
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SENT_CONNECT_REQUEST_PACKET,
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SENT_CONNECT_CONFIRM_PACKET,
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SENT_DISCONNECT_REQUEST_PACKET,
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SENT_ERROR_PACKET,
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CONNECTION_ACTIVE,
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RECEIVED_CONNECT_REQUEST_PACKET,
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FAILED_TO_INITIALIZE
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}
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X224State;
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#define TRANSPORT_HASHING_BUCKETS 3
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/*
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** Packet types
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*/
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#define TPDU_CODE_MASK 0xf0
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#define TRANSPORT_NO_PACKET 0x00
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#define CONNECTION_REQUEST_PACKET 0xe0
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#define CONNECTION_CONFIRM_PACKET 0xd0
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#define DISCONNECT_REQUEST_PACKET 0x80
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#define ERROR_PACKET 0x70
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#define DATA_PACKET 0xf0
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#define TSAP_CALLING_IDENTIFIER 0xc1
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#define TSAP_CALLED_IDENTIFIER 0xc2
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#define TPDU_SIZE 0xc0
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/*
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** These defines are used for the ERROR packet
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*/
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#define INVALID_TPDU 0xc1
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/*
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** Packet size codes
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*/
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#define PACKET_SIZE_128 0x07
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#define PACKET_SIZE_256 0x08
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#define PACKET_SIZE_512 0x09
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#define PACKET_SIZE_1024 0x0a
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#define PACKET_SIZE_2048 0x0b
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/*
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** Miscellaneous definitions
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*/
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#define MAXIMUM_USER_DATA_SIZE 8192
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#define DATA_PACKET_HEADER_SIZE 3
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#define EOT_BIT 0x80
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#define CONNECT_REQUEST_HEADER_SIZE 6
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#define CONNECT_CONFIRM_HEADER_SIZE 6
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#define DISCONNECT_REQUEST_HEADER_SIZE 6
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#define ERROR_HEADER_SIZE 6
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#define TPDU_ARBITRATION_PACKET_SIZE 3
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#define DISCONNECT_REASON_NOT_SPECIFIED 0
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typedef SListClass DataRequestQueue;
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typedef SListClass PacketQueue;
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class CLayerX224 : public IProtocolLayer
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{
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public:
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CLayerX224(
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T123 *owner_object,
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CLayerQ922 *lower_layer,
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USHORT message_base,
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LogicalHandle logical_handle,
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ULONG identifier,
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USHORT data_indication_queue_size,
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USHORT default_PDU_size,
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PMemoryManager dr_memory_manager,
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BOOL *initialization_success);
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virtual ~CLayerX224(void);
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/*
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** Making and breaking links
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*/
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TransportError ConnectRequest (void);
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TransportError ConnectResponse (void);
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TransportError DisconnectRequest (void);
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/*
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** Functions overridden from the ProtocolLayer object
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*/
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ProtocolLayerError DataRequest (
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ULONG_PTR identifier,
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LPBYTE buffer_address,
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ULONG length,
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PULong bytes_accepted);
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ProtocolLayerError DataRequest (
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ULONG_PTR identifier,
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PMemory,
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PULong bytes_accepted);
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ProtocolLayerError DataIndication (
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LPBYTE buffer_address,
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ULONG length,
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PULong bytes_accepted);
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ProtocolLayerError RegisterHigherLayer (
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ULONG_PTR,
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PMemoryManager,
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IProtocolLayer *);
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ProtocolLayerError RemoveHigherLayer (
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ULONG_PTR);
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ProtocolLayerError PollTransmitter (
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ULONG_PTR identifier,
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USHORT data_to_transmit,
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USHORT * pending_data,
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USHORT * holding_data);
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ProtocolLayerError PollReceiver(void);
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ProtocolLayerError GetParameters (
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USHORT *,
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USHORT *,
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USHORT *);
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void ShutdownReceiver (void);
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void EnableReceiver (void);
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void ShutdownTransmitter (void);
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void PurgeRequest (void);
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void CheckUserBuffers (void);
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static ULONG GetMaxTPDUSize (
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ULONG max_lower_layer_pdu);
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private:
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BOOL AllocateBuffers (void);
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void ErrorPacket (
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LPBYTE packet_address,
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USHORT packet_length);
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private:
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DataRequestQueue Data_Request_Queue;
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PacketQueue Data_Indication_Queue;
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PacketQueue Data_Indication_Memory_Pool;
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PTMemory Active_Data_Indication;
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T123 *m_pT123; // owner object
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CLayerQ922 *m_pQ922; // lower layer;
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USHORT m_nMsgBase;
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USHORT Default_PDU_Size;
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USHORT Maximum_PDU_Size;
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USHORT Arbitrated_PDU_Size;
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ULONG Identifier;
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PMemoryManager Data_Request_Memory_Manager;
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USHORT Lower_Layer_Prepend;
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USHORT Lower_Layer_Append;
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ULONG User_Data_Pending;
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USHORT Data_Indication_Queue_Size;
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BOOL Data_Indication_Reassembly_Active;
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X224State State;
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USHORT Packet_Pending;
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UChar Reject_Cause;
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BOOL Packet_Size_Respond;
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BOOL Shutdown_Receiver;
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BOOL Shutdown_Transmitter;
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LPBYTE Error_Buffer;
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USHORT Error_Buffer_Length;
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LogicalHandle m_nLocalLogicalHandle;
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LogicalHandle m_nRemoteLogicalHandle;
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};
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#endif
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/*
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* Documentation for Public class members
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*/
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/*
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* Transport::Transport (
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* PTransportResources transport_resources,
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* IObject * owner_object,
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* IProtocolLayer * lower_layer,
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* USHORT message_base,
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* USHORT logical_handle,
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* USHORT identifier,
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* USHORT data_request_queue_size,
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* USHORT data_indication_queue_size,
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* USHORT default_PDU_size,
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* PMemoryManager dr_memory_manager,
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* BOOL * initialization_success);
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*
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* Functional Description
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* This is the class constructor. During construction, this object
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* registers itself with its lower layer and allocates buffer space for
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* sending and receiving data.
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*
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* Formal Parameters
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* transport_resources (i) - Pointer to TransportResources structure.
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* owner_object (i) - Address of owner object. We use this
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* address for owner callbacks.
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* lower_layer (i) - Address of the lower layer that we will use
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* for data reception and transmission. This
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* layer must inherit from ProtocolLayer.
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* message_base (i) - Message base for messages used for owner
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* callbacks.
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* logical_handle (i) - This identification must be passed back to
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* the owner during owner callbacks to identify
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* itself.
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* identifier (i) - This identifier is passed to the lower layer
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* to identify itself (in case the lower layer
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* is doing multiplexing.
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* data_request_queue_size (i) - Number of buffers to be used for data
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* requests from user.
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* data_indication_queue_size (i) - Number of buffers to be used for
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* data requests from user.
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* default_PDU_size (i) - If the remote site does not support packet
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* size arbitration, this is the default
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* dr_memory_manager (i) - Data Request memory manager
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* initialization_success (o) - Return TRUE if initialization was
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* successful
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*
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* Return Value
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* None
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*
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* Side Effects
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* None
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*
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* Caveats
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* None
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*
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*/
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/*
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* Transport::~Transport (void)
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*
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* Functional Description
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* This is the destructor for the class. It does all cleanup
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*
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* Formal Parameters
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* None
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*
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* Return Value
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* None
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*
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* Side Effects
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* None
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*
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* Caveats
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* None
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*
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*/
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/*
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* TransportError Transport::ConnectRequest (void);
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*
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* Functional Description
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* This function is called to initiate the connection. As a result the
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* owner will either receive a TRANSPORT_CONNECT_CONFIRM or a
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* TRANSPORT_DISCONNECT_INDICATION message on completion of arbitration.
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*
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* Formal Parameters
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* None
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*
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* Return Value
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* TRANSPORT_NO_ERROR - No error occured
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* TRANSPORT_ERROR - Error
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*
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* Side Effects
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* None
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*
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* Caveats
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* None
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*
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*/
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/*
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* TransportError Transport::ConnectResponse (void);
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*
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* Functional Description
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* This function is called in response to a TRANSPORT_CONNECT_INDICATION
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* message issued by this class. By calling this function, the user is
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* accepting the transport connection.
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*
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* Formal Parameters
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* None
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*
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* Return Value
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* TRANSPORT_NO_ERROR - No error occured
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* TRANSPORT_ERROR - Error
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*
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* Side Effects
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* None
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*
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* Caveats
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* None
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*
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*/
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/*
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* TransportError Transport::DisconnectRequest (void);
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*
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* Functional Description
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* This function is called in response to a TRANSPORT_CONNECT_INDICATION
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* message issued by this class. By calling this function, the user is
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* not accepting the transport connection.
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*
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* Formal Parameters
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* None
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*
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* Return Value
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* TRANSPORT_NO_ERROR - No error occured
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* TRANSPORT_ERROR - Error
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*
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* Side Effects
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* None
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*
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* Caveats
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* None
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*
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*/
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/*
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* ProtocolLayerError Transport::DataRequest (
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* USHORT identifier,
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* LPBYTE buffer_address,
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* USHORT length,
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* USHORT * bytes_accepted);
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*
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* Functional Description
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* This function is called by a higher layer to request transmission of
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* a packet.
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*
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* Formal Parameters
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* identifier (i) - Identifier of the higher layer
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* buffer_address (i) - Buffer address
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* length (i) - Length of packet to transmit
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* bytes_accepted (o) - Number of bytes accepted by the Transport.
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* This value will either be 0 or the packet
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* length since this layer is a packet to byte
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* converter.
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*
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* Return Value
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* PROTOCOL_LAYER_NO_ERROR - No error occured
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*
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* Side Effects
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* None
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*
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* Caveats
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* None
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*
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*/
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/*
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* ProtocolLayerError Transport::DataIndication (
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* LPBYTE buffer_address,
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* USHORT length,
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* USHORT * bytes_accepted);
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*
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* Functional Description
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* This function is called by the lower layer when it has data to pass up
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*
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* Formal Parameters
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* buffer_address (i) - Buffer address
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* length (i) - Number of bytes available
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* bytes_accepted (o) - Number of bytes accepted
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*
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* Return Value
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* PROTOCOL_LAYER_NO_ERROR - No error occured
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*
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* Side Effects
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* None
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*
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* Caveats
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* None
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*
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*/
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/*
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* ProtocolLayerError Transport::RegisterHigherLayer (
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* USHORT,
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* IProtocolLayer *);
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*
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* Functional Description
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* This function is called by the higher layer to register its identifier
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* and its address. This function is not used by this class. It is only
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* in here because this class inherits from ProtocolLayer and this function
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* is a pure virtual function.
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*
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* Formal Parameters
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* None used
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*
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* Return Value
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* PROTOCOL_LAYER_NO_ERROR - No error occured
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*
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* Side Effects
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* None
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*
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* Caveats
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* None
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*
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*/
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/*
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* ProtocolLayerError Transport::RemoveHigherLayer (
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* USHORT);
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*
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* Functional Description
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* This function is called by the higher layer to remove its identifier
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* and its address. This function is not used by this class. It is only
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* in here because this class inherits from ProtocolLayer and this function
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* is a pure virtual function.
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*
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* Formal Parameters
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* None used
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*
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* Return Value
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* PROTOCOL_LAYER_NO_ERROR - No error occured
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*
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* Side Effects
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* None
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*
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* Caveats
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* None
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*/
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/*
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* ProtocolLayerError Transport::PollTransmitter (
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* USHORT,
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* USHORT data_to_transmit,
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* USHORT * pending_data,
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* USHORT *)
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*
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* Functional Description
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* This function is called to give the Transport a chance transmit data
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* in its Data_Request buffer.
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*
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* Formal Parameters
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* identifier (i) - Not used
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* data_to_transmit (i) - This is a mask that tells us to send Control
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* data, User data, or both. Since the
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* Transport does not differentiate between
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* data types it transmits any data it has
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* pending_data (o) - Return value to indicate which data is left
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* to be transmitted.
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*
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* Return Value
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* PROTOCOL_LAYER_NO_ERROR - No error occured
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*
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* Side Effects
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* None
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*
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* Caveats
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* None
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*
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*/
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|
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/*
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* ProtocolLayerError Transport::PollReceiver (
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* USHORT identifier);
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*
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* Functional Description
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* This function is called to give the Transport a chance pass packets
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* to higher layers
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*
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* Formal Parameters
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* identifier (i) - Not used
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*
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* Return Value
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* PROTOCOL_LAYER_NO_ERROR - No error occured
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*
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* Side Effects
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* None
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*
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* Caveats
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* None
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*/
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|
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/*
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* ProtocolLayerError Transport::GetParameters (
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* USHORT identifier,
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* USHORT * max_packet_size,
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* USHORT * prepend,
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* USHORT * append);
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*
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* Functional Description:
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* This function is not used by this class. It is only in here because
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* this class inherits from ProtocolLayer and this function
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* is a pure virtual function.
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*
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* Formal Parameters
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* None used
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*
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* Return Value
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* PROTOCOL_LAYER_NO_ERROR - No error occured
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*
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* Side Effects
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* None
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*
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* Caveats
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* None
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*/
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/*
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* void Transport::ShutdownReceiver ();
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*
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* Functional Description:
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* This function tells the object to stop accepting packets from the
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* lower layer
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*
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* Formal Parameters
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* None used
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*
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* Return Value
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* None
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*
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* Side Effects
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* None
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*
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* Caveats
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* None
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*/
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/*
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* void Transport::EnableReceiver (void);
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*
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* Functional Description:
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* This function tells the object to start sending packets up to the user
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* again. If the X224 object ever issues a DATA_INDICATION and it fails,
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* we shutdown the receiver. We wait for this call to be issued before
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* we start sending up packets again.
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*
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* Formal Parameters
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* None used
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*
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* Return Value
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* None
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*
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* Side Effects
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* None
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*
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* Caveats
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* None
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*/
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/*
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* void Transport::ShutdownTransmitter (void);
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*
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* Functional Description:
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* This function tells the object to stop accepting packets from
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* higher layers.
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*
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|
* Formal Parameters
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|
* None used
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*
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* Return Value
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* None
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*
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* Side Effects
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* None
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*
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* Caveats
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* None
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*/
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/*
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* void Transport::PurgeRequest (void);
|
|
*
|
|
* Functional Description:
|
|
* This function removes all packets from the Transport's outbound queue
|
|
*
|
|
* Formal Parameters
|
|
* None used
|
|
*
|
|
* Return Value
|
|
* None
|
|
*
|
|
* Side Effects
|
|
* None
|
|
*
|
|
* Caveats
|
|
* None
|
|
*/
|
|
|
|
/*
|
|
* void Transport::CheckUserBuffers (void);
|
|
*
|
|
* Functional Description:
|
|
* This function determines if the user has recently failed to pass a
|
|
* packet down to the Transport because we didn't have enough memory
|
|
* available to handle it. If he did and we NOW have space for that
|
|
* packet, we will issue a TRANSPORT_BUFFER_EMPTY_INDICATION callback
|
|
* to the user, to notify him that we can accept it.
|
|
*
|
|
* Formal Parameters
|
|
* None used
|
|
*
|
|
* Return Value
|
|
* None
|
|
*
|
|
* Side Effects
|
|
* None
|
|
*
|
|
* Caveats
|
|
* None
|
|
*/
|
|
|
|
/*
|
|
* static ULONG Transport::GetMaxTPDUSize (
|
|
* ULONG max_lower_layer_pdu)
|
|
*
|
|
* Public
|
|
*
|
|
* Functional Description:
|
|
* This function accepts a value for the lower layer max. PDU size
|
|
* and returns the max. PDU size that this Transport can support
|
|
* based on it. X224 only suports max PDU sizes of 128, 256, 512,
|
|
* 1024, and 2048. So, if the max_lower_layer_pdu is 260, the
|
|
* Transport can only have a max pdu size of 256.
|
|
*
|
|
* Formal Parameters
|
|
* max_lower_layer_pdu - Since we pass data to the lower layer,
|
|
* we must conform to its max packet size.
|
|
*
|
|
* Return Value
|
|
* The largest TPDU that we will send based on the max_lower_layer_pdu.
|
|
*
|
|
* Side Effects
|
|
* None
|
|
*
|
|
* Caveats
|
|
* None
|
|
*/
|
|
|