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/**

 * @file

 * SLIP Interface

 *

 */

/*

 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 * 3. Neither the name of the Institute nor the names of its contributors

 *    may be used to endorse or promote products derived from this software

 *    without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND

 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE

 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS

 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY

 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

 * SUCH DAMAGE.

 *

 * This file is built upon the file: src/arch/rtxc/netif/sioslip.c

 *

 * Author: Magnus Ivarsson <magnus.ivarsson(at)volvo.com>

 */

/*

 * This is an arch independent SLIP netif. The specific serial hooks must be

 * provided by another file. They are sio_open, sio_recv and sio_send

 */

#include "netif/slipif.h"

#include "lwip/opt.h"

#include "lwip/def.h"

#include "lwip/pbuf.h"

#include "lwip/sys.h"

#include "lwip/stats.h"

#include "lwip/snmp.h"

#include "lwip/sio.h"

#define SLIP_END     0300 /* 0xC0 */

#define SLIP_ESC     0333 /* 0xDB */

#define SLIP_ESC_END 0334 /* 0xDC */

#define SLIP_ESC_ESC 0335 /* 0xDD */

#define MAX_SIZE     1500

/**

 * Send a pbuf doing the necessary SLIP encapsulation

 *

 * Uses the serial layer's sio_send()

 *

 * @param netif the lwip network interface structure for this slipif

 * @param p the pbuf chaing packet to send

 * @param ipaddr the ip address to send the packet to (not used for slipif)

 * @return always returns ERR_OK since the serial layer does not provide return values

 */

err_t

slipif_output(struct netif *netif, struct pbuf *p, struct ip_addr *ipaddr)

{

  struct pbuf *q;

  u16_t i;

  u8_t c;

  LWIP_ASSERT("netif != NULL", (netif != NULL));

  LWIP_ASSERT("netif->state != NULL", (netif->state != NULL));

  LWIP_ASSERT("p != NULL", (p != NULL));

  LWIP_UNUSED_ARG(ipaddr);

  /* Send pbuf out on the serial I/O device. */

  sio_send(SLIP_END, netif->state);

  for (q = p; q != NULL; q = q->next) {

    for (i = 0; i < q->len; i++) {

      c = ((u8_t *)q->payload)[i];

      switch (c) {

      case SLIP_END:

        sio_send(SLIP_ESC, netif->state);

        sio_send(SLIP_ESC_END, netif->state);

        break;

      case SLIP_ESC:

        sio_send(SLIP_ESC, netif->state);

        sio_send(SLIP_ESC_ESC, netif->state);

        break;

      default:

        sio_send(c, netif->state);

        break;

      }

    }

  }

  sio_send(SLIP_END, netif->state);

  return ERR_OK;

}

/**

 * Handle the incoming SLIP stream character by character

 *

 * Poll the serial layer by calling sio_recv()

 *

 * @param netif the lwip network interface structure for this slipif

 * @return The IP packet when SLIP_END is received

 */

static struct pbuf *

slipif_input(struct netif *netif)

{

  u8_t c;

  /* q is the whole pbuf chain for a packet, p is the current pbuf in the chain */

  struct pbuf *p, *q;

  u16_t recved;

  u16_t i;

  LWIP_ASSERT("netif != NULL", (netif != NULL));

  LWIP_ASSERT("netif->state != NULL", (netif->state != NULL));

  q = p = NULL;

  recved = i = 0;

  c = 0;

  while (1) {

    c = sio_recv(netif->state);

    switch (c) {

    case SLIP_END:

      if (recved > 0) {

        /* Received whole packet. */

        /* Trim the pbuf to the size of the received packet. */

        pbuf_realloc(q, recved);

        LINK_STATS_INC(link.recv);

        LWIP_DEBUGF(SLIP_DEBUG, ("slipif: Got packet\n"));

        return q;

      }

      break;

    case SLIP_ESC:

      c = sio_recv(netif->state);

      switch (c) {

      case SLIP_ESC_END:

        c = SLIP_END;

        break;

      case SLIP_ESC_ESC:

        c = SLIP_ESC;

        break;

      }

      /* FALLTHROUGH */

    default:

      /* byte received, packet not yet completely received */

      if (p == NULL) {

        /* allocate a new pbuf */

        LWIP_DEBUGF(SLIP_DEBUG, ("slipif_input: alloc\n"));

        p = pbuf_alloc(PBUF_LINK, PBUF_POOL_BUFSIZE, PBUF_POOL);

        if (p == NULL) {

          LINK_STATS_INC(link.drop);

          LWIP_DEBUGF(SLIP_DEBUG, ("slipif_input: no new pbuf! (DROP)\n"));

          /* don't process any further since we got no pbuf to receive to */

          break;

        }

        if (q != NULL) {

          /* 'chain' the pbuf to the existing chain */

          pbuf_cat(q, p);

        } else {

          /* p is the first pbuf in the chain */

          q = p;

        }

      }

      /* this automatically drops bytes if > MAX_SIZE */

      if ((p != NULL) && (recved <= MAX_SIZE)) {

        ((u8_t *)p->payload)[i] = c;

        recved++;

        i++;

        if (i >= p->len) {

          /* on to the next pbuf */

          i = 0;

          if (p->next != NULL && p->next->len > 0) {

            /* p is a chain, on to the next in the chain */

            p = p->next;

          } else {

            /* p is a single pbuf, set it to NULL so next time a new

             * pbuf is allocated */

            p = NULL;

          }

        }

      }

      break;

    }

  }

  return NULL;

}

#if !NO_SYS

/**

 * The SLIP input thread.

 *

 * Feed the IP layer with incoming packets

 *

 * @param nf the lwip network interface structure for this slipif

 */

static void

slipif_loop(void *nf)

{

  struct pbuf *p;

  struct netif *netif = (struct netif *)nf;

  while (1) {

    p = slipif_input(netif);

    if (p != NULL) {

      if (netif->input(p, netif) != ERR_OK) {

        pbuf_free(p);

        p = NULL;

      }

    }

  }

}

#endif /* !NO_SYS */

/**

 * SLIP netif initialization

 *

 * Call the arch specific sio_open and remember

 * the opened device in the state field of the netif.

 *

 * @param netif the lwip network interface structure for this slipif

 * @return ERR_OK if serial line could be opened,

 *         ERR_IF is serial line couldn't be opened

 *

 * @note netif->num must contain the number of the serial port to open

 *       (0 by default)

 */

err_t

slipif_init(struct netif *netif)

{

  LWIP_DEBUGF(SLIP_DEBUG, ("slipif_init: netif->num=%"U16_F"\n", (u16_t)netif->num));

  netif->name[0] = 's';

  netif->name[1] = 'l';

  netif->output = slipif_output;

  netif->mtu = MAX_SIZE;

  netif->flags = NETIF_FLAG_POINTTOPOINT;

  /* Try to open the serial port (netif->num contains the port number). */

  netif->state = sio_open(netif->num);

  if (!netif->state) {

    /* Opening the serial port failed. */

    return ERR_IF;

  }

  /* initialize the snmp variables and counters inside the struct netif

   * ifSpeed: no assumption can be made without knowing more about the

   * serial line!

   */

  NETIF_INIT_SNMP(netif, snmp_ifType_slip, 0);

  /* Create a thread to poll the serial line. */

  sys_thread_new(SLIPIF_THREAD_NAME, slipif_loop, netif, SLIPIF_THREAD_STACKSIZE, SLIPIF_THREAD_PRIO);

  return ERR_OK;

}