mutex.c

来自「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」· C语言 代码 · 共 93 行

//  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)

/*
  Project Mantis
  File: mutex.c
  Author: Jeff Rose
  Date: 1-20-03

  Basic mutex support.
*/

#include "mos.h"
#include "mutex.h"

void mos_mutex_init(mos_mutex_t *mt)
{
   mt->owner = NULL;
   mos_tlist_init(&mt->q);
}

void mos_mutex_lock(mos_mutex_t *mt)
{
   thread_t *id;
   handle_t int_handle;

   id = mos_thread_current(); // Get the current thread ID

   int_handle = mos_disable_ints();
   
   // If its locked then add the thread to the queue and block
   if(mt->owner) {
      mos_tlist_add(&mt->q, id);
      mos_thread_suspend_noints(int_handle);
   } else { // If its free then lock it and save the id
      mt->owner = id;
      mos_enable_ints(int_handle);
   }
}

void mos_mutex_unlock(mos_mutex_t *mt)
{
   thread_t *next;
   thread_t *id;
   handle_t int_handle;
   
   id = mos_thread_current(); // Get the current thread ID

   int_handle = mos_disable_ints();
   
   // Make sure the current thread is the owner before unlocking
   if(mt->owner != id) {
     mos_enable_ints(int_handle);
     return;
   }
   // Now if we have a waiting thread make them ready
   if((next = mos_tlist_remove(&mt->q))) {
      mt->owner = next;
      //mos_thread_resume_noints_nodispatch(next, int_handle);
      //mos_enable_ints(int_handle);
      mos_thread_resume_noints(next, int_handle);
   } else { // Just unlock the mutex and clear the owner
      mt->owner = NULL;
      mos_enable_ints(int_handle);
   }
}

int8_t mos_mutex_try_lock(mos_mutex_t *mt)
{
   thread_t *id;
   handle_t int_handle;
   id = mos_thread_current(); // Get the current thread ID

   int_handle = mos_disable_ints();
   
   // If its locked then return a zero
   if(mt->owner) {
      mos_enable_ints(int_handle);
      return MUTEX_LOCKED;
   } else { // If its free then lock it and save the id
      mt->owner = id;
   }

   mos_enable_ints(int_handle);

   return MUTEX_OK;
}