al_receiving.h

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/* AL_RECEIVING.H */

#ifndef _AL_RECEIVING_H_
#define _AL_RECEIVING_H_

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

typedef struct {
  int logical_channel;             /* channel number it receives from         */
  al_type type;                    /* one of AL1M, AL2M, AL3M, etc.           */
  int framed;                      /* Frame SDU with HDLC flags?              */
  int seq_num;                     /* Packets contain sequence number (FCF)   */
  int rcpc_code;                   /* PDU Payload is RCPC coded?              */
  int rcpc_rate;                   /* Rate Payload was coded at               */
  int arq_type;                    /* what type of arq (type 1,2,3)           */
  int crc_bytes;                   /* how many CRC bytes to use               */
  int last_recd;                   /* seq_num of last new packet received     */
  int last_written;                /* seq_num of last packet written out      */
  list *outlist;                   /* output buffer (linked list)             */
  int initialized;                 /* if output buffer is intialized          */
  int old_threshold;               /* Threshold to determine if packet is old */
  int max_arq;                     /* Max number of retransmit requests.      */
  
  Buffer *outgoing_data;           /* (byte) buffer */
  Buffer *incoming_data;           /* (byte) buffer */
  Buffer *rcpcs;                   /* buffer of rcpc info (old H.223/a)       */

  al_sending_entity *back_channel; /* al_sending entity to send arq's through (old
                                      h.223/a) */
  int bad_payloads;                /* number of times the payload crc failed  */
} al_receiving_entity;

/* function prototypes */

al_receiving_entity *new_al_receiving_entity(channel_info *nfo);
/*
 * this function creates a new al_receiving_entity based on the 
 *   given channel_info structure
 */

void send_to_al(al_receiving_entity *which, byte b);
/*
 * writes byte b to the incoming data buffer of the
 *   al_receiving entity
 */

int al_indication(al_receiving_entity *which);
/*
 * Called by AL user (receiver) to check if there is any data
 *   waiting for it in the receiver buffer.  
 * 
 *   Returns 1 if data is there, 0 if not
 */

byte al_receive(al_receiving_entity *which);
/*
 * Called by al_user, reads data out of the incoming buffer
 */

void send_closing_flag(al_receiving_entity *which);
/*
 * called by mux to signal the end of an AL-PDU.
 *
 * check the crc on the data in incoming buffer (incoming_data).  if it
 * is good, transfers the data to the outgoing buffer (outgoing_data).
 */

#endif

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