/*
    ChibiOS/RT - Copyright (C) 2006-2007 Giovanni Di Sirio.

    This file is part of ChibiOS/RT.

    ChibiOS/RT is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 3 of the License, or
    (at your option) any later version.

    ChibiOS/RT is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

/**
 * @file chsys.c
 * @brief System related code.
 * @addtogroup System
 * @{
 */

#include <ch.h>

static WORKING_AREA(idle_thread_wa, IDLE_THREAD_STACK_SIZE);

/**
 * @brief This function implements the idle thread infinite loop.
 * @details The function puts the processor in the lowest power mode capable
 *          to serve interrupts.<br>
 *          The priority is internally set to the minimum system value so
 *          that this thread is executed only if there are no other ready
 *          threads in the system.
 *
 * @param[in] p the thread parameter, unused in this scenario
 */
static void idle_thread(void *p) {

  while (TRUE) {
    port_wait_for_interrupt();
    IDLE_LOOP_HOOK();
  }
}

/**
 * @brief ChibiOS/RT initialization.
 * @details After executing this function the current instructions stream
 *          becomes the main thread.
 *
 * @note Interrupts should be still disabled when @p chSysInit() is invoked
 *       and are internally enabled.
 * @note The main thread is created with priority @p NORMALPRIO.
 */
void chSysInit(void) {
  static Thread mainthread;

  port_init();
  scheduler_init();
  vt_init();
#if CH_USE_HEAP
  heap_init();
#endif
#if CH_DBG_ENABLE_TRACE
  trace_init();
#endif

  /*
   * Now this instructions flow becomes the main thread.
   */
  (currp = init_thread(&mainthread, NORMALPRIO))->p_state = PRCURR;
  chSysEnable();

  /*
   * This thread has the lowest priority in the system, its role is just to
   * serve interrupts in its context while keeping the lowest energy saving
   * mode compatible with the system status.
   */
  chThdCreateStatic(idle_thread_wa, sizeof(idle_thread_wa), IDLEPRIO,
                    (tfunc_t)idle_thread, NULL);
}

/**
 * @brief Handles time ticks for round robin preemption and timer increments.
 * @details Decrements the remaining time quantum of the running thread
 *          and preempts it when the quantum is used up. Increments system
 *          time and manages the timers.
 *
 * @note The frequency of the timer determines the system tick granularity and,
 *       together with the @p CH_TIME_QUANTUM macro, the round robin interval.
 */
void chSysTimerHandlerI(void) {

#if CH_USE_ROUNDROBIN
  /* running thread has not used up quantum yet? */
  if (rlist.r_preempt > 0)
    /* decrement remaining quantum */
    rlist.r_preempt--;
#endif
#if CH_DBG_THREADS_PROFILING
  currp->p_time++;
#endif
  chVTDoTickI();
}

#if CH_USE_NESTED_LOCKS && !CH_OPTIMIZE_SPEED
void chSysLock(void) {

  chDbgAssert(currp->p_locks >= 0,
              "chSysLock(), #1",
              "negative nesting counter");
  if (currp->p_locks++ == 0)
    port_lock();
}

void chSysUnlock(void) {

  chDbgAssert(currp->p_locks > 0,
              "chSysUnlock(), #1",
              "non-positive nesting counter");
  if (--currp->p_locks == 0)
    port_unlock();
}
#endif /* CH_USE_NESTED_LOCKS && !CH_OPTIMIZE_SPEED */

/** @} */