net/rose/rose_out.c

   1 /*
   2  * This program is free software; you can redistribute it and/or modify
   3  * it under the terms of the GNU General Public License as published by
   4  * the Free Software Foundation; either version 2 of the License, or
   5  * (at your option) any later version.
   6  *
   7  * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
   8  */
   9 #include <linux/errno.h>
  10 #include <linux/types.h>
  11 #include <linux/socket.h>
  12 #include <linux/in.h>
  13 #include <linux/kernel.h>
  14 #include <linux/sched.h>
  15 #include <linux/timer.h>
  16 #include <linux/string.h>
  17 #include <linux/sockios.h>
  18 #include <linux/net.h>
  19 #include <net/ax25.h>
  20 #include <linux/inet.h>
  21 #include <linux/netdevice.h>
  22 #include <linux/skbuff.h>
  23 #include <net/sock.h>
  24 #include <asm/system.h>
  25 #include <linux/fcntl.h>
  26 #include <linux/mm.h>
  27 #include <linux/interrupt.h>
  28 #include <net/rose.h>
  29
  30 /*
  31  *      This procedure is passed a buffer descriptor for an iframe. It builds
  32  *      the rest of the control part of the frame and then writes it out.
  33  */
  34 static void rose_send_iframe(struct sock *sk, struct sk_buff *skb)
  35 {
  36         struct rose_sock *rose = rose_sk(sk);
  37
  38         if (skb == NULL)
  39                 return;
  40
  41         skb->data[2] |= (rose->vr << 5) & 0xE0;
  42         skb->data[2] |= (rose->vs << 1) & 0x0E;
  43
  44         rose_start_idletimer(sk);
  45
  46         rose_transmit_link(skb, rose->neighbour);
  47 }
  48
  49 void rose_kick(struct sock *sk)
  50 {
  51         struct rose_sock *rose = rose_sk(sk);
  52         struct sk_buff *skb, *skbn;
  53         unsigned short start, end;
  54
  55         if (rose->state != ROSE_STATE_3)
  56                 return;
  57
  58         if (rose->condition & ROSE_COND_PEER_RX_BUSY)
  59                 return;
  60
  61         if (!skb_peek(&sk->sk_write_queue))
  62                 return;
  63
  64         start = (skb_peek(&rose->ack_queue) == NULL) ? rose->va : rose->vs;
  65         end   = (rose->va + sysctl_rose_window_size) % ROSE_MODULUS;
  66
  67         if (start == end)
  68                 return;
  69
  70         rose->vs = start;
  71
  72         /*
  73          * Transmit data until either we're out of data to send or
  74          * the window is full.
  75          */
  76
  77         skb  = skb_dequeue(&sk->sk_write_queue);
  78
  79         do {
  80                 if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
  81                         skb_queue_head(&sk->sk_write_queue, skb);
  82                         break;
  83                 }
  84
  85                 skb_set_owner_w(skbn, sk);
  86
  87                 /*
  88                  * Transmit the frame copy.
  89                  */
  90                 rose_send_iframe(sk, skbn);
  91
  92                 rose->vs = (rose->vs + 1) % ROSE_MODULUS;
  93
  94                 /*
  95                  * Requeue the original data frame.
  96                  */
  97                 skb_queue_tail(&rose->ack_queue, skb);
  98
  99         } while (rose->vs != end &&
 100                  (skb = skb_dequeue(&sk->sk_write_queue)) != NULL);
 101
 102         rose->vl         = rose->vr;
 103         rose->condition &= ~ROSE_COND_ACK_PENDING;
 104
 105         rose_stop_timer(sk);
 106 }
 107
 108 /*
 109  * The following routines are taken from page 170 of the 7th ARRL Computer
 110  * Networking Conference paper, as is the whole state machine.
 111  */
 112
 113 void rose_enquiry_response(struct sock *sk)
 114 {
 115         struct rose_sock *rose = rose_sk(sk);
 116
 117         if (rose->condition & ROSE_COND_OWN_RX_BUSY)
 118                 rose_write_internal(sk, ROSE_RNR);
 119         else
 120                 rose_write_internal(sk, ROSE_RR);
 121
 122         rose->vl         = rose->vr;
 123         rose->condition &= ~ROSE_COND_ACK_PENDING;
 124
 125         rose_stop_timer(sk);
 126 }