/*
 * Copyright (c) 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 part of the Contiki operating system.
 * 
 * Author: Adam Dunkels <adam@sics.se>
 *
 * $Id: mt.c,v 1.3 2005/02/22 22:46:33 adamdunkels Exp $
 */

/**
 * \file
 * Implementation of the archtecture agnostic parts of the preemptive
 * multithreading library for Contiki.
 *
 * \author
 * Adam Dunkels <adam@sics.se>
 *
 */

#include "ek.h"
#include "mt.h"
#include "cc.h"

#define MT_STATE_READY   1
#define MT_STATE_RUNNING 2
#define MT_STATE_WAITING 3
#define MT_STATE_PEEK    4
#define MT_STATE_EXITED  5

static struct mt_thread *current;

/*--------------------------------------------------------------------------*/
void
mt_init(void)
{
  mtarch_init();
}
/*--------------------------------------------------------------------------*/
void
mt_remove(void)
{
  mtarch_remove();
}
/*--------------------------------------------------------------------------*/
void
mt_start(struct mt_thread *thread, void (* function)(void *), void *data)
{
  /* Call the architecture dependant function to set up the processor
     stack with the correct parameters. */
  mtarch_start(&thread->thread, function, data);

  thread->state = MT_STATE_READY;
}
/*--------------------------------------------------------------------------*/
void
mt_exec(struct mt_thread *thread)
{
  if(thread->state == MT_STATE_READY ||
     thread->state == MT_STATE_PEEK) {
    thread->state = MT_STATE_RUNNING;
    current = thread;
    /* Switch context to the thread. The function call will not return
       until the the thread has yielded, or is preempted. */
    mtarch_exec(&thread->thread);
  }
}
/*--------------------------------------------------------------------------*/
void
mt_exit(void)
{
  current->state = MT_STATE_EXITED;
  current = NULL;
  mtarch_yield();
}
/*--------------------------------------------------------------------------*/
void
mt_exec_event(struct mt_thread *thread, ek_event_t ev, ek_data_t data)
{
  if(thread->state == MT_STATE_WAITING ||
     thread->state == MT_STATE_PEEK) {
    *(thread->evptr) = ev;
    *(thread->dataptr) = data;
    thread->state = MT_STATE_RUNNING;
    current = thread;    
    /* Switch context to the thread. The function call will not return
       until the the thread has yielded, or is preempted. */
    mtarch_exec(&thread->thread);
  }
}
/*--------------------------------------------------------------------------*/
void
mt_yield(void)
{    
  mtarch_pstop();
  current->state = MT_STATE_READY;
  current = NULL;
  /* This function is called from the running thread, and we call the
     switch function in order to switch the thread to the main Contiki
     program instead. For us, the switch function will not return
     until the next time we are scheduled to run. */
  mtarch_yield();
  
}
/*--------------------------------------------------------------------------*/
void
mt_post(ek_id_t id, ek_event_t ev, ek_data_t data)
{  
  /* Turn off preemption to ensure mutual exclusion of kernel. */
  mtarch_pstop();

  ek_post(id, ev, data);
  
  /* Turn preemption on again. */  
  mtarch_pstart();  
}
/*--------------------------------------------------------------------------*/
void
mt_wait(ek_event_t *ev, ek_data_t *data)
{
  mtarch_pstop();
  current->evptr = ev;
  current->dataptr = data;
  current->state = MT_STATE_WAITING;
  current = NULL;
  mtarch_yield();
}
/*--------------------------------------------------------------------------*/
void
mt_peek(ek_event_t *ev, ek_data_t *data)
{
  mtarch_pstop();
  *ev = EK_EVENT_NONE;
  current->evptr = ev;
  current->dataptr = data;
  current->state = MT_STATE_PEEK;
  current = NULL;
  mtarch_yield();  
}
/*--------------------------------------------------------------------------*/
void
mtp_start(struct mtp_thread *t,
	  void (* function)(void *), void *data)
{
  mt_start(&t->t, function, data);
  ek_start(t->p);
}
/*--------------------------------------------------------------------------*/
void
mtp_exit(void)
{
  mtarch_pstop();
  mt_exit();
  mt_remove();
}
/*--------------------------------------------------------------------------*/
void
mtp_eventhandler(ek_event_t ev, ek_data_t data)
{
  struct mtp_thread *thread = (struct mtp_thread *)EK_PROC_STATE(EK_CURRENT());

  if(ev == EK_EVENT_REQUEST_EXIT) {
    ek_exit();
    LOADER_UNLOAD();
    
  } else if(ev == EK_EVENT_INIT) {
    
    ek_post(EK_PROC_ID(EK_CURRENT()), EK_EVENT_CONTINUE, NULL);
    
  } else if(ev == EK_EVENT_CONTINUE) {

    if(thread->t.state == MT_STATE_READY ||
       thread->t.state == MT_STATE_PEEK) {
      mt_exec(&thread->t);
      if(thread->t.state == MT_STATE_EXITED) {
	ek_exit();
	LOADER_UNLOAD();
      } else {
	ek_post(EK_PROC_ID(EK_CURRENT()), EK_EVENT_CONTINUE, NULL);
      }
    }
  } else {
    mt_exec_event(&thread->t, ev, data);
    if(thread->t.state == MT_STATE_EXITED) {
      ek_exit();
      LOADER_UNLOAD();
    } else if(thread->t.state == MT_STATE_READY ||
	      thread->t.state == MT_STATE_PEEK) {
      ek_post(EK_PROC_ID(EK_CURRENT()), EK_EVENT_CONTINUE, NULL);
    }
  }
}
/*--------------------------------------------------------------------------*/