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/**

 * @file

 * lwIP Operating System abstraction

 *

 */

/*

 * 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. The name of the author may not be used to endorse or promote products

 *    derived from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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 part of the lwIP TCP/IP stack.

 *

 * Author: Adam Dunkels <adam@sics.se>

 *

 */

#include "lwip/opt.h"

#if (NO_SYS == 0) /* don't build if not configured for use in lwipopts.h */

#include "lwip/sys.h"

#include "lwip/def.h"

#include "lwip/memp.h"

#include "lwip/tcpip.h"

/**

 * Struct used for sys_sem_wait_timeout() to tell wether the time

 * has run out or the semaphore has really become available.

 */

struct sswt_cb

{

  s16_t timeflag;

  sys_sem_t *psem;

};

/**

 * Wait (forever) for a message to arrive in an mbox.

 * While waiting, timeouts (for this thread) are processed.

 *

 * @param mbox the mbox to fetch the message from

 * @param msg the place to store the message

 */

void

sys_mbox_fetch(sys_mbox_t mbox, void **msg)

{

  u32_t time;

  struct sys_timeouts *timeouts;

  struct sys_timeo *tmptimeout;

  sys_timeout_handler h;

  void *arg;

 again:

  timeouts = sys_arch_timeouts();

  if (!timeouts || !timeouts->next) {

    UNLOCK_TCPIP_CORE();

    time = sys_arch_mbox_fetch(mbox, msg, 0);

    LOCK_TCPIP_CORE();

  } else {

    if (timeouts->next->time > 0) {

      UNLOCK_TCPIP_CORE();

      time = sys_arch_mbox_fetch(mbox, msg, timeouts->next->time);

      LOCK_TCPIP_CORE();

    } else {

      time = SYS_ARCH_TIMEOUT;

    }

    if (time == SYS_ARCH_TIMEOUT) {

      /* If time == SYS_ARCH_TIMEOUT, a timeout occured before a message

         could be fetched. We should now call the timeout handler and

         deallocate the memory allocated for the timeout. */

      tmptimeout = timeouts->next;

      timeouts->next = tmptimeout->next;

      h   = tmptimeout->h;

      arg = tmptimeout->arg;

      memp_free(MEMP_SYS_TIMEOUT, tmptimeout);

      if (h != NULL) {

        LWIP_DEBUGF(SYS_DEBUG, ("smf calling h=%p(%p)\n", (void*)&h, arg));

        h(arg);

      }

      /* We try again to fetch a message from the mbox. */

      goto again;

    } else {

      /* If time != SYS_ARCH_TIMEOUT, a message was received before the timeout

         occured. The time variable is set to the number of

         milliseconds we waited for the message. */

      if (time < timeouts->next->time) {

        timeouts->next->time -= time;

      } else {

        timeouts->next->time = 0;

      }

    }

  }

}

/**

 * Wait (forever) for a semaphore to become available.

 * While waiting, timeouts (for this thread) are processed.

 *

 * @param sem semaphore to wait for

 */

void

sys_sem_wait(sys_sem_t sem)

{

  u32_t time;

  struct sys_timeouts *timeouts;

  struct sys_timeo *tmptimeout;

  sys_timeout_handler h;

  void *arg;

 again:

  timeouts = sys_arch_timeouts();

  if (!timeouts || !timeouts->next) {

    sys_arch_sem_wait(sem, 0);

  } else {

    if (timeouts->next->time > 0) {

      time = sys_arch_sem_wait(sem, timeouts->next->time);

    } else {

      time = SYS_ARCH_TIMEOUT;

    }

    if (time == SYS_ARCH_TIMEOUT) {

      /* If time == SYS_ARCH_TIMEOUT, a timeout occured before a message

        could be fetched. We should now call the timeout handler and

        deallocate the memory allocated for the timeout. */

      tmptimeout = timeouts->next;

      timeouts->next = tmptimeout->next;

      h = tmptimeout->h;

      arg = tmptimeout->arg;

      memp_free(MEMP_SYS_TIMEOUT, tmptimeout);

      if (h != NULL) {

        LWIP_DEBUGF(SYS_DEBUG, ("ssw h=%p(%p)\n", (void*)&h, (void *)arg));

        h(arg);

      }

      /* We try again to fetch a message from the mbox. */

      goto again;

    } else {

      /* If time != SYS_ARCH_TIMEOUT, a message was received before the timeout

         occured. The time variable is set to the number of

         milliseconds we waited for the message. */

      if (time < timeouts->next->time) {

        timeouts->next->time -= time;

      } else {

        timeouts->next->time = 0;

      }

    }

  }

}

/**

 * Create a one-shot timer (aka timeout). Timeouts are processed in the

 * following cases:

 * - while waiting for a message using sys_mbox_fetch()

 * - while waiting for a semaphore using sys_sem_wait() or sys_sem_wait_timeout()

 * - while sleeping using the inbuilt sys_msleep()

 *

 * @param msecs time in milliseconds after that the timer should expire

 * @param h callback function to call when msecs have elapsed

 * @param arg argument to pass to the callback function

 */

void

sys_timeout(u32_t msecs, sys_timeout_handler h, void *arg)

{

  struct sys_timeouts *timeouts;

  struct sys_timeo *timeout, *t;

  timeout = memp_malloc(MEMP_SYS_TIMEOUT);

  if (timeout == NULL) {

    LWIP_ASSERT("sys_timeout: timeout != NULL", timeout != NULL);

    return;

  }

  timeout->next = NULL;

  timeout->h = h;

  timeout->arg = arg;

  timeout->time = msecs;

  timeouts = sys_arch_timeouts();

  LWIP_DEBUGF(SYS_DEBUG, ("sys_timeout: %p msecs=%"U32_F" h=%p arg=%p\n",

    (void *)timeout, msecs, (void*)&h, (void *)arg));

  if (timeouts == NULL) {

    LWIP_ASSERT("sys_timeout: timeouts != NULL", timeouts != NULL);

    return;

  }

  if (timeouts->next == NULL) {

    timeouts->next = timeout;

    return;

  }

  if (timeouts->next->time > msecs) {

    timeouts->next->time -= msecs;

    timeout->next = timeouts->next;

    timeouts->next = timeout;

  } else {

    for(t = timeouts->next; t != NULL; t = t->next) {

      timeout->time -= t->time;

      if (t->next == NULL || t->next->time > timeout->time) {

        if (t->next != NULL) {

          t->next->time -= timeout->time;

        }

        timeout->next = t->next;

        t->next = timeout;

        break;

      }

    }

  }

}

/**

 * Go through timeout list (for this task only) and remove the first matching

 * entry, even though the timeout has not triggered yet.

 *

 * @note This function only works as expected if there is only one timeout

 * calling 'h' in the list of timeouts.

 *

 * @param h callback function that would be called by the timeout

 * @param arg callback argument that would be passed to h

*/

void

sys_untimeout(sys_timeout_handler h, void *arg)

{

  struct sys_timeouts *timeouts;

  struct sys_timeo *prev_t, *t;

  timeouts = sys_arch_timeouts();

  if (timeouts == NULL) {

    LWIP_ASSERT("sys_untimeout: timeouts != NULL", timeouts != NULL);

    return;

  }

  if (timeouts->next == NULL) {

    return;

  }

  for (t = timeouts->next, prev_t = NULL; t != NULL; prev_t = t, t = t->next) {

    if ((t->h == h) && (t->arg == arg)) {

      /* We have a match */

      /* Unlink from previous in list */

      if (prev_t == NULL)

        timeouts->next = t->next;

      else

        prev_t->next = t->next;

      /* If not the last one, add time of this one back to next */

      if (t->next != NULL)

        t->next->time += t->time;

      memp_free(MEMP_SYS_TIMEOUT, t);

      return;

    }

  }

  return;

}

/**

 * Timeout handler function for sys_sem_wait_timeout()

 *

 * @param arg struct sswt_cb* used to signal a semaphore and end waiting.

 */

static void

sswt_handler(void *arg)

{

  struct sswt_cb *sswt_cb = (struct sswt_cb *) arg;

  /* Timeout. Set flag to TRUE and signal semaphore */

  sswt_cb->timeflag = 1;

  sys_sem_signal(*(sswt_cb->psem));

}

/**

 * Wait for a semaphore with timeout (specified in ms)

 *

 * @param sem semaphore to wait

 * @param timeout timeout in ms (0: wait forever)

 * @return 0 on timeout, 1 otherwise

 */

int

sys_sem_wait_timeout(sys_sem_t sem, u32_t timeout)

{

  struct sswt_cb sswt_cb;

  sswt_cb.psem = &sem;

  sswt_cb.timeflag = 0;

  /* If timeout is zero, then just wait forever */

  if (timeout > 0) {

    /* Create a timer and pass it the address of our flag */

    sys_timeout(timeout, sswt_handler, &sswt_cb);

  }

  sys_sem_wait(sem);

  /* Was it a timeout? */

  if (sswt_cb.timeflag) {

    /* timeout */

    return 0;

  } else {

    /* Not a timeout. Remove timeout entry */

    sys_untimeout(sswt_handler, &sswt_cb);

    return 1;

  }

}

/**

 * Sleep for some ms. Timeouts are processed while sleeping.

 *

 * @param ms number of milliseconds to sleep

 */

void

sys_msleep(u32_t ms)

{

  sys_sem_t delaysem = sys_sem_new(0);

  sys_sem_wait_timeout(delaysem, ms);

  sys_sem_free(delaysem);

}

#endif /* NO_SYS */