al_sending.h

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/* AL_SENDING.H */

#ifndef _AL_SENDING_H_
#define _AL_SENDING_H_

#include "Buffer.h"
#include "arq.h"
#include "al.h"
#include "rcpc.h"

#define MAX_ARQ_BUFFER_SIZE 10
#define MAX_AL_BUFFER_SIZE 100000

typedef struct {

  al_type type;             /* AL type (AL1M, AL2M, etc.)           */
  int framed;               /* Frame with HDLC flags?               */
  int seq_num;              /* Prepend Sequence number?             */
  int rcpc_code;            /* Use RCPC coding?                     */
  int rcpc_rate;            /* RCPC coding rate                     */
  int arq_type;             /* ARQ Retransmission (0=None,1=typeI,2=typeII,3=typeI/II */
  int crc_bytes;            /* Number of CRC bytes to append        */

  int vs;                   /* Current Sequence number              */

  Buffer* al_sdus;          /* (byte) new SDU's to send             */
  Buffer* rcpcs;            /* (buf_rcpc) PDU's to be retransmitted */
  Buffer* forward_arq;      /* (arq_message) requests for retransmission from 
                             * corresponding remote al_receiving_entity 
                             * (ARQ on this channel)
                             */
  Buffer* backward_arq;     /* (arq_message) requests for retransmission from
                             * corresponding local al_receiving_entity 
                             * (ARQ for other channel)
                             */
} al_sending_entity;

/* function prototypes */

int al_send_request(al_sending_entity *which, bytes *al_sdu);
/*
 * Called by an AL user to send an SDU through a logical channel.  Data
 *   is put into the al_sending_entity buffer and will be made into an AL_PDU
 *   and sent when an AL_PDU is requested by the MUX.
 *
 * Returns 1 if succesful, 0 if unsuccesful (ie. buffer full)
 */

int al_send_byte(al_sending_entity *which, unsigned char b);
/*
 * Does the same as above, but for one byte only
 */

int al_request(al_sending_entity *which);
/*
 * This function is called by the MUX to see if an al_sending
 *   entity has data which needs to be sent
 */

int al_requested_size(al_sending_entity *which);
/*
 * This function is called by the MUX to see how big an ARQ packet needs
 *   to be sent.  It returns the AL-PDU length needed for the ARQ, or 0 if
 *   there are no forward ARQ's.
 */

int al_buffer_level(al_sending_entity *which);
/*
 * This function is called by the MUX to see how much NEW data this channel
 *   has waiting to send so that it can devise an appropriate multiplex
 *   code that assigns a block of data to the channel associated with this
 *   al_sending_entity.
 *
 * Also can be called by the al-user (sender) to perform rate control.
 *   The H.263 encoder does this to control its frame rate.
 */

void al_arq_request(al_sending_entity *which, arq_message *clone);
/*
 * This function is called by the corresponding al_receiving entity
 *   when it wants to request a retransmission of a particular AL_SDU
 */

void al_arq_received(al_sending_entity *which, arq_message *clone);
/*
 * This function is called by the corresponding al_receiving entity
 *   when it wants to report that a retransmission request has been
 *   received.  The al_sending_entity saves the incoming arq_message
 */

al_sending_entity *new_al_sending_entity(channel_info *nfo);
/*
 * Makes a new AL-Sending entity based on the channel_info struc
 */

void make_forward_control(bytes *forward_control,unsigned int snf, 
                          unsigned int pt,unsigned int rn);
/*
 * This function is only used in the old Annex A product
 */

void make_backward_control(bytes* backward_control,unsigned int snb, 
                           unsigned int sm);
/*
 * This function is only used in the old Annex A product
 */

int inc_sn(al_sending_entity *which);
/*
 * returns the current sequence number available from which, and
 * then increments it.
 */

bytes *get_al_pdu(al_sending_entity *which, int size);
/*
 * Constructs an AL-PDU of total size size (including headers,
 *   FEC, CRC if appropriate).
 *
 * If there is a forward retransmission request to send (and the size
 *   compatible) it shall send it.
 * If there is a backward_arq message for one or more AL sending entities,
 *   it shall include a backward control field.
 * (last 2 items: old h.223/a only)
 */


#endif

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