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/* Mplex.h
* * Copyright (c) 1994-1995 by DataBeam Corporation, Lexington, KY * * Abstract: * This is the multiplexer class. It inherits from the ProtocolLayer * class which means it is one of the layers in a Transport stack. This * class has these capabilities: * * 1. It takes stream data from the lower layer and packetizes it. * If the lower layer gives us data in a stream format, we run it * through a packet framer to build up a packet. This class uses * a framer object passed in by the constructor. When data is * received from the lower layer, the data is given to the framer * object. The framer notifies us of a complete packet. The * framer could be any type of framer (i.e RFC1006, flagged data * with bit or byte stuffing, ...). If no framer is passed in by * the constructor, we assume that the data is being received in * packets. * * A packet received from the higher layer is run through the * framer to encode the data. It is then fed to the lower layer * in a stream fashion. * * 2. It multiplexes multiple higher layers. It currently assumes the * incoming packets are in Q.922 packet format. Each higher layer * is identified by its DLCI. This class is capable of looking at * the packet and determining the DLCI and thus where to route it. * * Since this is a multiplexer, we receive packets for many * different stacks and we do not buffer them if the higher layer * is not ready for them. If it attempts to send the packet to the * higher layer and it does not accept it, it may trash it. This * must be done in order to maintain the other transport * connections. If necessary, in the future, we could buffer * packets at this layer. * * 3. This class receives a CRC object during construction (if it is * NULL, no CRC is necessary). The object runs a packet thru the * CRC generator and attaches it to the end of the packet. On the * reception of a packet from a lower layer, we check the CRC for * validity. * * Caveats: * 1. If a framer exists, it assumes the packet is in Q.922 format * 2. This class is currently Q.922 oriented as far as finding the * packet identifier (DLCI). This will be fixed in the future. * * Authors: * James W. Lawwill */#ifndef _MULTIPLEXER_H_
#define _MULTIPLEXER_H_
#include "q922.h"
#define MULTIPLEXER_MAXIMUM_PACKET_SIZE 1024
#define TRANSPORT_HASHING_BUCKETS 3
/*
** If the identifier (DLCI) contained by the packet is not legal, the following ** identifier is returned */#define ILLEGAL_DLCI 0xffff
/*
** Multiplexer return codes */typedef enum{ MULTIPLEXER_NO_ERROR} MultiplexerError;
typedef struct{ IProtocolLayer *q922; PMemoryManager data_request_memory_manager;} MPlexStruct, * PMPlexStruct;
class Multiplexer : public IProtocolLayer{public:
Multiplexer(T123 *owner_object, ComPort *lower_layer, PhysicalHandle lower_layer_identifier, USHORT message_base, PPacketFrame framer, PCRC crc, BOOL *initialized); virtual ~Multiplexer(void);
MultiplexerError ConnectRequest (void); MultiplexerError DisconnectRequest (void);
/*
** Functions overridden from the ProtocolLayer object */ ProtocolLayerError DataRequest ( ULONG_PTR dlci, LPBYTE buffer_address, ULONG length, PULong bytes_accepted); ProtocolLayerError DataRequest ( ULONG_PTR dlci, PMemory memory, PULong bytes_accepted); ProtocolLayerError DataIndication ( LPBYTE buffer_address, ULONG length, PULong bytes_accepted); ProtocolLayerError RegisterHigherLayer ( ULONG_PTR dlci, PMemoryManager memory_manager, IProtocolLayer * higher_layer); ProtocolLayerError RemoveHigherLayer ( ULONG_PTR dlci); ProtocolLayerError PollTransmitter ( ULONG_PTR dlci, USHORT data_to_transmit, USHORT * pending_data, USHORT * holding_data); ProtocolLayerError PollReceiver(void); ProtocolLayerError GetParameters ( USHORT * max_packet_size, USHORT * prepend_bytes, USHORT * append_bytes);
private:
void SendDataToHigherLayer ( LPBYTE buffer_address, USHORT buffer_length); DLCI GetDLCI ( LPBYTE buffer_address, USHORT buffer_size);
private:
DictionaryClass Q922_Layers;
T123 *m_pT123; // owner object
ComPort *m_pComPort; // lower layer
PhysicalHandle m_hCommLink; // physical handle
USHORT m_nMsgBase; USHORT Maximum_Packet_Size; USHORT Packet_Size;
LPBYTE Data_Request_Buffer; PMemory Data_Request_Memory_Object; DLCI Data_Request_DLCI; USHORT Data_Request_Length; USHORT Data_Request_Offset;
LPBYTE Data_Indication_Buffer; USHORT Data_Indication_Length; BOOL Data_Indication_Ready;
PPacketFrame Framer; PCRC CRC; USHORT CRC_Size;
BOOL Decode_In_Progress; BOOL Disconnect;};
#endif
/*
* Documentation for Public class members */
/*
* Multiplexer::Multiplexer ( * IObject * object_owner, * IProtocolLayer * lower_layer, * ULONG identifier, * USHORT message_base, * PPacketFrame framer, * PCRC crc, * BOOL * initialized); * * Functional Description * This is the constructor for the Multiplexer layer * * Formal Parameters * object_owner - (i) Address of owner object. * lower_layer - (i) Address of the layer below the multiplexer * identifier - (i) A lower layer identifier that is passed to the * lower layer with each call to it. The * identifier tells the lower layer which "channel" * to use. * message_base - (i) Message identifier that is passed back to the * owner object during a callback * framer - (i) Address of a framer object * crc - (i) Address of a crc object * initialized - (o) Set to TRUE if the multiplexer initialized OK * * Return Value * None * * Side Effects * None * * Caveats * None * */
/*
* Multiplexer::~Multiplexer (void) * * Functional Description * This is the destructor for the Multiplexer layer. It removes itself * from the lower layer and frees all buffers and filters (i.e. framer) * * Formal Parameters * None * * Return Value * None * * Side Effects * None * * Caveats * None * */
/*
* MultiplexerError Multiplexer::ConnectRequest (void); * * Functional Description * This function issues an immediate NEW_CONNECTION message to the owner * of this object. If this was a more sophisticated layer, it would * communicate with the remote multiplexer layer to establish itself. * * Formal Parameters * None * * Return Value * None * * Side Effects * None * * Caveats * None * */
/*
* MultiplexerError Multiplexer::DisconnectRequest (void); * * Functional Description * This function removes its connection with the lower layer and does * a BROKEN_CONNECTION callback to the owner object * * Formal Parameters * None * * Return Value * None * * Side Effects * None * * Caveats * None * */
/*
* ProtocolLayerError Multiplexer::DataRequest ( * ULONG identifier, * LPBYTE buffer_address, * USHORT length, * USHORT * bytes_accepted); * * Functional Description * This function is called by a higher layer to request transmission of * a packet. * * Formal Parameters * identifier (i) - Identifier of the higher layer * buffer_address (i) - Buffer address * length (i) - Length of packet to transmit * bytes_accepted (o) - Number of bytes accepted by the Multiplexer. * This value will either be 0 or the packet * length since this layer is a packet to byte * converter. * * Return Value * PROTOCOL_LAYER_NO_ERROR - No error occured * * Side Effects * None * * Caveats * None * */
/*
* ProtocolLayerError Multiplexer::DataRequest ( * ULONG identifier, * PMemory memory, * PULong bytes_accepted); * * Functional Description * This function is called by a higher layer to request transmission of * a packet. * * Formal Parameters * identifier (i) - Identifier of the higher layer * memory (o) - Pointer to memory object holding the packet * bytes_accepted (o) - Number of bytes accepted by the Multiplexer. * This value will either be 0 or the packet * length since this layer is a packet to byte * converter. * * Return Value * PROTOCOL_LAYER_NO_ERROR - No error occured * * Side Effects * None * * Caveats * None * */
/*
* ProtocolLayerError Multiplexer::DataIndication ( * LPBYTE buffer_address, * USHORT length, * USHORT * bytes_accepted); * * Functional Description * This function is called by the lower layer when it has data to pass up * * Formal Parameters * buffer_address (i) - Buffer address * length (i) - Number of bytes available * bytes_accepted (o) - Number of bytes accepted * * Return Value * PROTOCOL_LAYER_NO_ERROR - No error occured * * Side Effects * None * * Caveats * None * */
/*
* ProtocolLayerError Multiplexer::RegisterHigherLayer ( * ULONG identifier, * IProtocolLayer * higher_layer); * * Functional Description * This function is called by the higher layer to register its identifier * and its address. In some cases, the identifier is the DLCI number in * the packet. If this multiplexer is being used as a stream to packet * converter only, the identifer is not used and all data is passed to the * higher layer. * * Formal Parameters * identifier (i) - Identifier used to identify the higher layer * higher_layer (i) - Address of higher layer * * Return Value * PROTOCOL_LAYER_NO_ERROR - No error occured * PROTOCOL_LAYER_REGISTRATION_ERROR - Illegal identifier * * Side Effects * None * * Caveats * None * */
/*
* ProtocolLayerError Multiplexer::RemoveHigherLayer ( * ULONG identifier); * * Functional Description * This function is called by the higher layer to remove the higher layer. * If any more data is received with its identifier on it, it will be * trashed. * * Formal Parameters * identifier (i) - Identifier used to identify the higher layer * * Return Value * PROTOCOL_LAYER_NO_ERROR - No error occured * PROTOCOL_LAYER_REGISTRATION_ERROR - Illegal identifier * * Side Effects * None * * Caveats * None * */
/*
* ProtocolLayerError Multiplexer::PollTransmitter ( * ULONG identifier, * USHORT data_to_transmit, * USHORT * pending_data); * * Functional Description * This function is called to give the Multiplexer a chance transmit data * in its Data_Request buffer. * * Formal Parameters * identifier (i) - Not used * data_to_transmit (i) - This is a mask that tells us to send Control * data, User data, or both. Since the * Multiplexer does not differentiate between * data types it transmits any data it has * pending_data (o) - Return value to indicat which data is left * to be transmitted. * * Return Value * PROTOCOL_LAYER_NO_ERROR - No error occured * * Side Effects * None * * Caveats * None * */
/*
* ProtocolLayerError Multiplexer::PollReceiver ( * ULONG identifier); * * Functional Description * This function is called to give the Multiplexer a chance pass packets * to higher layers * * Formal Parameters * identifier (i) - Not used * * Return Value * PROTOCOL_LAYER_NO_ERROR - No error occured * * Side Effects * None * * Caveats * None * */
/*
* ProtocolLayerError Multiplexer::GetParameters ( * ULONG identifier, * USHORT * max_packet_size, * USHORT * prepend_bytes, * USHORT * append_bytes); * * Functional Description * This function is called to get the maximum packet size * * Formal Parameters * identifier (i) - Not used * max_packet_size (o) - Returns the maximum packet size * prepend_bytes (o) - Returns the Number of bytes prepended by * this layer * append_bytes (o) - Returns the Number of bytes appended by * this layer * * Return Value * PROTOCOL_LAYER_NO_ERROR - No error occured * * Side Effects * None * * Caveats * None * */
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