os_mutex.c

一个简单易用的可裁减的小型实时操作系统 移植非常简单

/*
 *******************************************************************************
 *
 * MicroROS
 *
 * Copyright (C) 2007 <[e-mail]>			
 *
 * Description	: 互斥型信号量
 *
 * File			: os_mutex.c
 * Author		: amwox
 * Edition		: V0.10
 * History		: 2007-11-18  created 
 *				  2008-01-28  增加事件列表指针,并对处理方式作了相应的变化
 *******************************************************************************
 */
#include "..\include\MicroROS.h"
#include "..\include\os_cpu.h"

#if MUTEX_EN > 0

/* 
 * Description	: 
 * Arguments	:
 * Returns		:
 */
void OS_MutexCreate(pMUTEX pMutex, BYTE priority)
{
	pMutex->pLockMutex = NULL;
#if EVENT_BLOCK_COUNT > 0
	pMutex->BlockCnt = 0;
#endif
	pMutex->Priority = priority;
	pMutex->LockPriority = priority;
}

/* 
 * Description	: 申请一个互斥体
 * Arguments	:
 * Returns		:
 */
BYTE OS_MutexLock(pMUTEX pMutex,WORD timeout)
{
	CPU_SREG cpu_sreg;
	BYTE err = NO_ERROR;
	
	OS_ENTER_CRITICAL();
	pPID pTmp = os_kernel.pRunning;	
	if (pMutex->pLockMutex == NULL) {					/*互斥体处于解锁状态*/
		pMutex->pLockMutex = pTmp;						/*锁定当前进程*/
		pMutex->LockPriority = pTmp->Priority;
	}
	else {	
		pPID plock = pMutex->pLockMutex;
		//检查:是否发生优先级反转
		if (plock->Priority > pTmp->Priority) {			/*互斥体已被一个低优先级的进程锁定*/ 											/*提升优先级*/
			plock->Priority = pMutex->Priority;			/*按优先级天花板协议提升*/
		}											
		_AppendEvent(&pMutex->pLockMutex,pTmp);
		pTmp->TimerCnt = timeout;
		pTmp->State |= BV(PID_MUTEX);					/*等待信号量状态*/	
#if EVENT_BLOCK_COUNT > 0
		pMutex->BlockCnt ++;
#endif
		err = TIME_OUT;
		while (pTmp->TimerCnt) {		
			OS_TaskSuspend(pTmp);
			if (pTmp->TimerCnt != LIMITLESS) {
				_QueueTimer(pTmp);
			}
			OS_EXIT_CRITICAL();
			_Schedule();
			OS_ENTER_CRITICAL();
			if (pMutex->pLockMutex == pTmp) {			/*已解锁*/ 
				pMutex->LockPriority = pTmp->Priority;
				break;
			}
		}
#if EVENT_BLOCK_COUNT > 0
		pMutex->BlockCnt --;
#endif
		_RemoveEvent(&pMutex->pLockMutex,pTmp);
		pTmp->State &= ~BV(PID_MUTEX);
	}
	OS_EXIT_CRITICAL();
	return err;
}

/* 
 * Description	: 释放一个互斥体
 * Arguments	:
 * Returns		:
 */
void OS_MutexUnLock(pMUTEX pMutex)
{
	if (pMutex->pLockMutex == NULL) {
		return;
	}
	if (pMutex->pLockMutex != os_kernel.pRunning) {			/*锁定的不是当前进程,原因TIMEOUT*/
		return;
	}
	os_kernel.pRunning->Priority = pMutex->LockPriority;	/*恢复优先级*/
	pMutex->pLockMutex = pMutex->pLockMutex->pEventNext;
	os_kernel.pRunning->pEventNext = NULL;
	if (pMutex->pLockMutex != NULL) {
		CPU_SREG cpu_sreg;
		OS_ENTER_CRITICAL();
		if (pMutex->pLockMutex->TimerCnt != LIMITLESS)
			_RemoveTimer(pMutex->pLockMutex);
		OS_TaskResume(pMutex->pLockMutex);
		OS_EXIT_CRITICAL(); 
		_Schedule();
	}
}

#endif