/* ==== pthread.c ============================================================
 * Copyright (c) 1993, 1994 by Chris Provenzano, proven@mit.edu
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *  This product includes software developed by Chris Provenzano.
 * 4. The name of Chris Provenzano may not be used to endorse or promote 
 *	  products derived from this software without specific prior written
 *	  permission.
 *
 * THIS SOFTWARE IS PROVIDED BY CHRIS PROVENZANO ``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 CHRIS PROVENZANO 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.
 *
 * Description : Pthread functions.
 *
 *  1.00 93/07/26 proven
 *      -Started coding this file.
 */

#ifndef lint
static const char rcsid[] = "$Id: pthread.c,v 1.3 1994/02/07 22:04:22 proven Exp $ $provenid: pthread.c,v 1.16 1994/02/07 02:19:06 proven Exp $";
#endif

#include "pthread.h"
#include <signal.h>
#include <errno.h>

/*
 * These first functions really should not be called by the user.
 */

/* ==========================================================================
 * pthread_init()
 *
 * This function should be called in crt0.o before main() is called.
 * But on some systems It may not be possible to change crt0.o so currently
 * I'm requiring this function to be called first thing after main.
 * Actually I'm assuming it is, because I do no locking here.
 */
void pthread_init(void)
{
	struct machdep_pthread machdep_data = MACHDEP_PTHREAD_INIT;

	/* Initialize the first thread */
	if (pthread_initial = (pthread_t)malloc(sizeof(struct pthread))) {
		memcpy(&(pthread_initial->machdep_data), &machdep_data, sizeof(machdep_data));
		pthread_initial->state = PS_RUNNING;
		pthread_initial->queue = NULL;
		pthread_initial->next = NULL;
		pthread_initial->pll = NULL;

		pthread_initial->lock = SEMAPHORE_CLEAR;
		pthread_initial->error = 0;

		pthread_link_list = pthread_initial;
		pthread_run = pthread_initial;

		/* Initialize the signal handler. */
		sig_init();

		/* Initialize the fd table. */
		fd_init();

		return;
	}
	PANIC();
}

/* ==========================================================================
 * pthread_yield()
 */
void pthread_yield()
{
	sig_handler_fake(SIGVTALRM);
}

/* ======================================================================= */
/* ==========================================================================
 * pthread_self()
 */
pthread_t pthread_self()
{
	return(pthread_run);
}

/* ==========================================================================
 * pthread_equal()
 */
int pthread_equal(pthread_t t1, pthread_t t2)
{
	return(t1 == t2);
}

/* ==========================================================================
 * pthread_exit()
 */
void pthread_exit(void *status)
{
	semaphore *lock, *plock;
	pthread_t pthread;

	lock = &pthread_run->lock;
	if (SEMAPHORE_TEST_AND_SET(lock)) {
		pthread_yield();
	} 

	/* Save return value */
	pthread_run->ret = status;

	/* First execute all cleanup handlers */
	

	/*
	 * Are there any threads joined to this one,
	 * if so wake them and let them detach this thread.
	 */
	if (pthread = pthread_queue_get(&(pthread_run->join_queue))) {
		/* The current thread pthread_run can't be detached */
		plock = &(pthread->lock);
		while (SEMAPHORE_TEST_AND_SET(plock)) {
			pthread_yield();
		}
		(void)pthread_queue_deq(&(pthread_run->join_queue));
		pthread->state = PS_RUNNING;

		/* Thread will unlock itself in pthread_join() */
	}

	/* This thread will never run again */
	reschedule(PS_DEAD);
	PANIC();
}

/* ==========================================================================
 * pthread_create()
 *
 * After the new thread structure is allocated and set up, it is added to
 * pthread_run_next_queue, which requires a sig_prevent(),
 * sig_check_and_resume()
 */
int pthread_create(pthread_t *thread, const pthread_attr_t *attr,
  void * (*start_routine)(void *), void *arg)
{
	long nsec = 100000000;
	void *stack;

	if ((*thread) = (pthread_t)malloc(sizeof(struct pthread))) {

		if (! attr) { attr = &pthread_default_attr; }

		/* Get a stack, if necessary */
		if ((stack = attr->stackaddr_attr) ||
		  (stack = (void *)malloc(attr->stacksize_attr))) {

			machdep_pthread_create(&((*thread)->machdep_data),
			  start_routine, arg, 65536, stack, nsec);

			memcpy(&(*thread)->attr, attr, sizeof(pthread_attr_t));

			(*thread)->queue = NULL;
			(*thread)->next = NULL;

			(*thread)->lock = SEMAPHORE_CLEAR;
			(*thread)->error = 0;

			sig_prevent();

			/* Add to the link list of all threads. */
			(*thread)->pll = pthread_link_list;
			pthread_link_list = (*thread);

			(*thread)->state = PS_RUNNING;
			sig_check_and_resume();

			return(OK);
		}
		free((*thread));
	}
	return(ENOMEM);
}

/* ==========================================================================
 * pthread_cancel()
 *
 * This routine will also require a sig_prevent/sig_check_and_resume()
 */