cond.c

MANTIS是由科罗拉多大学开发的传感器网络嵌入式操作系统。 这是mantis的0.9.5版本的源码。

//  This file is part of MANTIS OS, Operating System
//  See http://mantis.cs.colorado.edu/
//
//  Copyright (C) 2003,2004,2005 University of Colorado, Boulder
//
//  This program is free software; you can redistribute it and/or
//  modify it under the terms of the mos license (see file LICENSE)

/** @file mos/kernel/avr/cond.c
 * @brief Basic condition variable support.
 *
 * THIS CODE HAS NOT BEEN TESTED
 * 
 * @author Lane Phillips
 * @date Created: 02/18/2005
 */
 
#include "mos.h"

#include "msched.h"
#include "tlist.h"
#include "mutex.h"
#include "cond.h"

void mos_cond_init(mos_cond_t *cond)
{
   mos_tlist_init(&cond->q);
}

void mos_cond_signal(mos_cond_t *cond)
{
   // If we have a waiting thread make it ready
   thread_t *next;
   if ((next = mos_tlist_remove(&cond->q)) != NULL) {
      mos_thread_resume(next);
   }
}

void mos_cond_broadcast(mos_cond_t *cond)
{
   // Wake up all waiting threads
   thread_t *next;
   while ((next = mos_tlist_remove(&cond->q)) != NULL) {
      mos_thread_resume(next);
   }
}

void mos_cond_wait(mos_cond_t *cond, mos_mutex_t *mt)
{
   // Get the current thread ID
   thread_t *id = mos_thread_current();
   // Disable interrupts so we can unlock and wait atomically
   handle_t int_handle = mos_disable_ints();
   // Unlock the mutex
   mos_mutex_unlock(mt);
   // Put us on the list for the condition variable
   mos_tlist_add(&cond->q, id);
   // Suspend us with interrupts already disabled
   mos_thread_suspend_noints(int_handle);
   // Lock the mutex again before returning
   mos_mutex_lock(mt);
}

// Not implemented yet
//int8_t mos_cond_timedwait(mos_cond_t *cond, mutex *mt,
//	const struct timespec *abstime)
//{
//}