/*
   * Copyright (C) 2015 Kaspar Schleiser <kaspar@schleiser.de>
   * Copyright (C) 2016 Eistec AB
   *
   * This file is subject to the terms and conditions of the GNU Lesser
   * General Public License v2.1. See the file LICENSE in the top level
   * directory for more details.
   */
  
  /**
   * @ingroup xtimer
   * @{
   * @file
   * @brief xtimer convenience functionality
   * @author Kaspar Schleiser <kaspar@schleiser.de>
   * @author Joakim Nohlgård <joakim.nohlgard@eistec.se>
   * @}
   */
  
  #include <assert.h>
  #include <stdint.h>
  #include <string.h>
  
  #include "xtimer.h"
  #include "mutex.h"
  #include "thread.h"
  #include "irq.h"
  #include "div.h"
  
  #include "timex.h"
  
  #define ENABLE_DEBUG 0
  #include "debug.h"
  
  static void _callback_unlock_mutex(void* arg)
  {
      mutex_t *mutex = (mutex_t *) arg;
      mutex_unlock(mutex);
  }
  
  void _xtimer_tsleep(uint32_t offset, uint32_t long_offset)
  {
      if (irq_is_in()) {
          assert(!long_offset);
          _xtimer_spin(offset);
          return;
      }
  
      xtimer_t timer;
      mutex_t mutex = MUTEX_INIT;
  
      timer.callback = _callback_unlock_mutex;
      timer.arg = (void*) &mutex;
      timer.target = timer.long_target = 0;
  
      mutex_lock(&mutex);
      _xtimer_set64(&timer, offset, long_offset);
      mutex_lock(&mutex);
  }
  
  void _xtimer_periodic_wakeup(uint32_t *last_wakeup, uint32_t period) {
      xtimer_t timer;
      mutex_t mutex = MUTEX_INIT;
  
      timer.callback = _callback_unlock_mutex;
      timer.arg = (void*) &mutex;
  
      uint32_t target = (*last_wakeup) + period;
      uint32_t now = _xtimer_now();
      /* make sure we're not setting a value in the past */
      if (now < (*last_wakeup)) {
          /* base timer overflowed between last_wakeup and now */
          if (!((now < target) && (target < (*last_wakeup)))) {
              /* target time has already passed */
              goto out;
          }
      }
      else {
          /* base timer did not overflow */
          if ((((*last_wakeup) <= target) && (target <= now))) {
              /* target time has already passed */
              goto out;
          }
      }
  
      /*
       * For large offsets, set an absolute target time.
       * As that might cause an underflow, for small offsets, set a relative
       * target time.
       * For very small offsets, spin.
       */
      /*
       * Note: last_wakeup _must never_ specify a time in the future after
       * _xtimer_periodic_sleep returns.
       * If this happens, last_wakeup may specify a time in the future when the
       * next call to _xtimer_periodic_sleep is made, which in turn will trigger
       * the overflow logic above and make the next timer fire too early, causing
       * last_wakeup to point even further into the future, leading to a chain
       * reaction.
       *
       * tl;dr Don't return too early!
       */
      uint32_t offset = target - now;
      DEBUG("xps, now: %9" PRIu32 ", tgt: %9" PRIu32 ", off: %9" PRIu32 "\n", now, target, offset);
      if (offset < XTIMER_PERIODIC_SPIN) {
          _xtimer_spin(offset);
      }
      else {
          if (offset < XTIMER_PERIODIC_RELATIVE) {
              /* NB: This will overshoot the target by the amount of time it took
               * to get here from the beginning of xtimer_periodic_wakeup()
               *
               * Since interrupts are normally enabled inside this function, this time may
               * be undeterministic. */
              target = _xtimer_now() + offset;
          }
          mutex_lock(&mutex);
          DEBUG("xps, abs: %" PRIu32 "\n", target);
          _xtimer_set_absolute(&timer, target);
          mutex_lock(&mutex);
      }
  out:
      *last_wakeup = target;
  }
  
  static void _callback_msg(void* arg)
  {
      msg_t *msg = (msg_t*)arg;
      msg_send_int(msg, msg->sender_pid);
  }
  
  static inline void _setup_msg(xtimer_t *timer, msg_t *msg, kernel_pid_t target_pid)
  {
      timer->callback = _callback_msg;
      timer->arg = (void*) msg;
  
      /* use sender_pid field to get target_pid into callback function */
      msg->sender_pid = target_pid;
  }
  
  void _xtimer_set_msg(xtimer_t *timer, uint32_t offset, msg_t *msg, kernel_pid_t target_pid)
  {
      _setup_msg(timer, msg, target_pid);
      _xtimer_set(timer, offset);
  }
  
  void _xtimer_set_msg64(xtimer_t *timer, uint64_t offset, msg_t *msg, kernel_pid_t target_pid)
  {
      _setup_msg(timer, msg, target_pid);
      _xtimer_set64(timer, offset, offset >> 32);
  }
  
  static void _callback_wakeup(void* arg)
  {
      thread_wakeup((kernel_pid_t)((intptr_t)arg));
  }
  
  void _xtimer_set_wakeup(xtimer_t *timer, uint32_t offset, kernel_pid_t pid)
  {
      timer->callback = _callback_wakeup;
      timer->arg = (void*) ((intptr_t)pid);
  
      _xtimer_set(timer, offset);
  }
  
  void _xtimer_set_wakeup64(xtimer_t *timer, uint64_t offset, kernel_pid_t pid)
  {
      timer->callback = _callback_wakeup;
      timer->arg = (void*) ((intptr_t)pid);
  
      _xtimer_set64(timer, offset, offset >> 32);
  }
  
  void xtimer_now_timex(timex_t *out)
  {
      uint64_t now = xtimer_usec_from_ticks64(xtimer_now64());
  
      out->seconds = div_u64_by_1000000(now);
      out->microseconds = now - (out->seconds * SEC_IN_USEC);
  }
  
  /* Prepares the message to trigger the timeout.
   * Additionally, the xtimer_t struct gets initialized.
   */
  static void _setup_timer_msg(msg_t *m, xtimer_t *t)
  {
      m->type = MSG_XTIMER;
      m->content.ptr = m;
  
      t->target = t->long_target = 0;
  }
  
  /* Waits for incoming message or timeout. */
  static int _msg_wait(msg_t *m, msg_t *tmsg, xtimer_t *t)
  {
      msg_receive(m);
      if (m->type == MSG_XTIMER && m->content.ptr == tmsg) {
          /* we hit the timeout */
          return -1;
      }
      else {
          xtimer_remove(t);
          return 1;
      }
  }
  
  int _xtimer_msg_receive_timeout64(msg_t *m, uint64_t timeout_ticks) {
      msg_t tmsg;
      xtimer_t t;
      _setup_timer_msg(&tmsg, &t);
      _xtimer_set_msg64(&t, timeout_ticks, &tmsg, sched_active_pid);
      return _msg_wait(m, &tmsg, &t);
  }
  
  int _xtimer_msg_receive_timeout(msg_t *msg, uint32_t timeout_ticks)
  {
      msg_t tmsg;
      xtimer_t t;
      _setup_timer_msg(&tmsg, &t);
      _xtimer_set_msg(&t, timeout_ticks, &tmsg, sched_active_pid);
      return _msg_wait(msg, &tmsg, &t);
  }