os_mutex.c

lpc2368-keil环境下的ucos的移植例程

/*
*********************************************************************************************************
*   											 uC/OS-II
*   									   The Real-Time Kernel
*   							   MUTUAL EXCLUSION SEMAPHORE MANAGEMENT
*
*   					   (c) Copyright 1992-2002, Jean J. Labrosse, Weston, FL
*   										All Rights Reserved
*
* File : OS_MUTEX.C
* By   : Jean J. Labrosse
*********************************************************************************************************
*/

#ifndef  OS_MASTER_FILE
#include "..\APP\includes.h"
#endif

/*
*********************************************************************************************************
*   										 LOCAL CONSTANTS
*********************************************************************************************************
*/

#define  OS_MUTEX_KEEP_LOWER_8   0x00FF
#define  OS_MUTEX_KEEP_UPPER_8   0xFF00

#define  OS_MUTEX_AVAILABLE 	 0x00FF


#if OS_MUTEX_EN > 0
/*
*********************************************************************************************************
*   								ACCEPT MUTUAL EXCLUSION SEMAPHORE
*
* Description: This  function checks the mutual exclusion semaphore to see if a resource is available.
*   		   Unlike OSMutexPend(), OSMutexAccept() does not suspend the calling task if the resource is
*   		   not available or the event did not occur.
*
* Arguments  : pevent     is a pointer to the event control block
*
*   		   err  	  is a pointer to an error code which will be returned to your application:
*   						 OS_NO_ERR  		if the call was successful.
*   						 OS_ERR_EVENT_TYPE  if 'pevent' is not a pointer to a mutex
*   						 OS_ERR_PEVENT_NULL 'pevent' is a NULL pointer
*   						 OS_ERR_PEND_ISR	 if you called this function from an ISR
*
* Returns    : == 1 	  if the resource is available, the mutual exclusion semaphore is acquired
*   		   == 0 	  a) if the resource is not available
*   					  b) you didn't pass a pointer to a mutual exclusion semaphore
*   					  c) you called this function from an ISR
*
* Warning(s) : This function CANNOT be called from an ISR because mutual exclusion semaphores are
*   		   intended to be used by tasks only.
*********************************************************************************************************
*/

#if OS_MUTEX_ACCEPT_EN > 0
INT8U OSMutexAccept(OS_EVENT *pevent, INT8U *err)
{
#if OS_CRITICAL_METHOD == 3 						   /* Allocate storage for CPU status register     */
	OS_CPU_SR  cpu_sr;
#endif    


	if (OSIntNesting > 0)
	{
		/* Make sure it's not called from an ISR        */
		*err = OS_ERR_PEND_ISR;
		return (0);
	}
#if OS_ARG_CHK_EN > 0
	if (pevent == (OS_EVENT *) 0)
	{
		/* Validate 'pevent'							*/
		*err = OS_ERR_PEVENT_NULL;
		return (0);
	}
	if (pevent->OSEventType != OS_EVENT_TYPE_MUTEX)
	{
		/* Validate event block type					*/
		*err = OS_ERR_EVENT_TYPE;
		return (0);
	}
#endif  												   
	OS_ENTER_CRITICAL();							   /* Get value (0 or 1) of Mutex   			   */
	if ((pevent->OSEventCnt & OS_MUTEX_KEEP_LOWER_8) == OS_MUTEX_AVAILABLE)
	{
		pevent->OSEventCnt &= OS_MUTEX_KEEP_UPPER_8;   /*      Mask off LSByte (Acquire Mutex)  	   */
		pevent->OSEventCnt |= OSTCBCur->OSTCBPrio;     /*      Save current task priority in LSByte    */
		pevent->OSEventPtr = (void *) OSTCBCur; 	   /*      Link TCB of task owning Mutex		   */
		OS_EXIT_CRITICAL();
		*err = OS_NO_ERR;
		return (1);
	}
	OS_EXIT_CRITICAL();
	*err = OS_NO_ERR;
	return (0);
}
#endif  												   

/*$PAGE*/
/*
*********************************************************************************************************
*   							   CREATE A MUTUAL EXCLUSION SEMAPHORE
*
* Description: This function creates a mutual exclusion semaphore.
*
* Arguments  : prio 		 is the priority to use when accessing the mutual exclusion semaphore.  In
*   						 other words, when the semaphore is acquired and a higher priority task
*   						 attempts to obtain the semaphore then the priority of the task owning the
*   						 semaphore is raised to this priority.  It is assumed that you will specify
*   						 a priority that is LOWER in value than ANY of the tasks competing for the
*   						 mutex.
*
*   		   err  		 is a pointer to an error code which will be returned to your application:
*   							OS_NO_ERR   		if the call was successful.
*   							OS_ERR_CREATE_ISR   if you attempted to create a MUTEX from an ISR
*   							OS_PRIO_EXIST   	if a task at the priority inheritance priority
*   												already exist.
*   							OS_ERR_PEVENT_NULL  No more event control blocks available.
*   							OS_PRIO_INVALID 	if the priority you specify is higher that the 
*   												maximum allowed (i.e. > OS_LOWEST_PRIO)
*
* Returns    : != (void *)0  is a pointer to the event control clock (OS_EVENT) associated with the
*   						 created mutex.
*   		   == (void *)0  if an error is detected.
*
* Note(s)    : 1) The LEAST significant 8 bits of '.OSEventCnt' are used to hold the priority number
*   			  of the task owning the mutex or 0xFF if no task owns the mutex.
*   		   2) The MOST  significant 8 bits of '.OSEventCnt' are used to hold the priority number
*   			  to use to reduce priority inversion.
*********************************************************************************************************
*/

OS_EVENT * OSMutexCreate(INT8U prio, INT8U *err)
{
#if OS_CRITICAL_METHOD == 3 							   /* Allocate storage for CPU status register */
	OS_CPU_SR  cpu_sr;
#endif    
	OS_EVENT  *pevent;


	if (OSIntNesting > 0)
	{
		/* See if called from ISR ...   			*/
		*err = OS_ERR_CREATE_ISR;   					   /* ... can't CREATE mutex from an ISR       */
		return ((OS_EVENT *) 0);
	}
#if OS_ARG_CHK_EN > 0
	if (prio >= OS_LOWEST_PRIO)
	{
		/* Validate PIP 							*/
		*err = OS_PRIO_INVALID;
		return ((OS_EVENT *) 0);
	}
#endif
	OS_ENTER_CRITICAL();
	if (OSTCBPrioTbl[prio] != (OS_TCB *) 0)
	{
		/* Mutex priority must not already exist	*/
		OS_EXIT_CRITICAL(); 							   /* Task already exist at priority ...	   */
		*err = OS_PRIO_EXIST;   						   /* ... inheritance priority  			   */
		return ((OS_EVENT *) 0);
	}
	OSTCBPrioTbl[prio] = (OS_TCB *) 1;  					/* Reserve the table entry  				*/
	pevent = OSEventFreeList;   			   /* Get next free event control block 	   */
	if (pevent == (OS_EVENT *) 0)
	{
		/* See if an ECB was available  			*/
		OSTCBPrioTbl[prio] = (OS_TCB *) 0;  				/* No, Release the table entry  			*/
		OS_EXIT_CRITICAL();
		*err = OS_ERR_PEVENT_NULL;  		 /* No more event control blocks			 */
		return (pevent);
	}
	OSEventFreeList = (OS_EVENT *) OSEventFreeList->OSEventPtr;   /* Adjust the free list   		*/
	OS_EXIT_CRITICAL();
	pevent->OSEventType = OS_EVENT_TYPE_MUTEX;
	pevent->OSEventCnt = (prio << 8) | OS_MUTEX_AVAILABLE;/* Resource is available  				  */
	pevent->OSEventPtr = (void *) 0;					   /* No task owning the mutex  			   */
	OS_EventWaitListInit(pevent);
	*err = OS_NO_ERR;
	return (pevent);
}

/*$PAGE*/
/*
*********************************************************************************************************
*   									   DELETE A MUTEX
*
* Description: This function deletes a mutual exclusion semaphore and readies all tasks pending on the it.
*
* Arguments  : pevent   	 is a pointer to the event control block associated with the desired mutex.
*
*   		   opt  		 determines delete options as follows:
*   						 opt == OS_DEL_NO_PEND   Delete mutex ONLY if no task pending
*   						 opt == OS_DEL_ALWAYS    Deletes the mutex even if tasks are waiting.
*   												 In this case, all the tasks pending will be readied.
*
*   		   err  		 is a pointer to an error code that can contain one of the following values:
*   						 OS_NO_ERR  			 The call was successful and the mutex was deleted
*   						 OS_ERR_DEL_ISR 		 If you attempted to delete the MUTEX from an ISR
*   						 OS_ERR_INVALID_OPT 	 An invalid option was specified
*   						 OS_ERR_TASK_WAITING	 One or more tasks were waiting on the mutex
*   						 OS_ERR_EVENT_TYPE  	 If you didn't pass a pointer to a mutex
*   						 OS_ERR_PEVENT_NULL 	 If 'pevent' is a NULL pointer.
*
* Returns    : pevent   	 upon error
*   		   (OS_EVENT *)0 if the mutex was successfully deleted.
*
* Note(s)    : 1) This function must be used with care.  Tasks that would normally expect the presence of
*   			  the mutex MUST check the return code of OSMutexPend().
*   		   2) This call can potentially disable interrupts for a long time.  The interrupt disable
*   			  time is directly proportional to the number of tasks waiting on the mutex.
*   		   3) Because ALL tasks pending on the mutex will be readied, you MUST be careful because the
*   			  resource(s) will no longer be guarded by the mutex.
*********************************************************************************************************
*/

#if OS_MUTEX_DEL_EN
OS_EVENT * OSMutexDel(OS_EVENT *pevent, INT8U opt, INT8U *err)
{
#if OS_CRITICAL_METHOD == 3 					 /* Allocate storage for CPU status register		   */
	OS_CPU_SR  cpu_sr;
#endif    
	BOOLEAN    tasks_waiting;
	INT8U      pip;


	if (OSIntNesting > 0)
	{
		/* See if called from ISR ...   			*/
		*err = OS_ERR_DEL_ISR;  						   /* ... can't DELETE from an ISR             */
		return (pevent);
	}
#if OS_ARG_CHK_EN > 0
	if (pevent == (OS_EVENT *) 0)
	{
		/* Validate 'pevent'						*/
		*err = OS_ERR_PEVENT_NULL;
		return ((OS_EVENT *) 0);
	}
	if (pevent->OSEventType != OS_EVENT_TYPE_MUTEX)
	{
		/* Validate event block type				*/
		*err = OS_ERR_EVENT_TYPE;
		return (pevent);
	}
#endif
	OS_ENTER_CRITICAL();
	if (pevent->OSEventGrp != 0x00)
	{
		/* See if any tasks waiting on mutex		*/
		tasks_waiting = TRUE;   						   /* Yes   								   */
	}
	else
	{
		tasks_waiting = FALSE;  						   /* No									   */
	}
	switch (opt)
	{
		case OS_DEL_NO_PEND:
			/* Delete mutex only if no task waiting 	*/
			if (tasks_waiting == FALSE)
			{
				pip = (INT8U) (pevent->OSEventCnt >> 8);
				OSTCBPrioTbl[pip] = (OS_TCB *) 0;   	 /* Free up the PIP 						 */
				pevent->OSEventType = OS_EVENT_TYPE_UNUSED;
				pevent->OSEventPtr = OSEventFreeList;    /* Return Event Control Block to free list  */
				OSEventFreeList = pevent;
				OS_EXIT_CRITICAL();
				*err = OS_NO_ERR;
				return ((OS_EVENT *) 0);				   /* Mutex has been deleted				   */
			}
			else
			{
				OS_EXIT_CRITICAL();
				*err = OS_ERR_TASK_WAITING;
				return (pevent);
			}

		case OS_DEL_ALWAYS:
			/* Always delete the mutex  				*/
			while (pevent->OSEventGrp != 0x00)
			{
				/* Ready ALL tasks waiting for mutex		*/
				OS_EventTaskRdy(pevent, (void *) 0, OS_STAT_MUTEX);
			}
			pip = (INT8U) (pevent->OSEventCnt >> 8);
			OSTCBPrioTbl[pip] = (OS_TCB *) 0;   		 /* Free up the PIP 						 */
			pevent->OSEventType = OS_EVENT_TYPE_UNUSED;
			pevent->OSEventPtr = OSEventFreeList;   	 /* Return Event Control Block to free list  */
			OSEventFreeList = pevent;   			  /* Get next free event control block  	  */
			OS_EXIT_CRITICAL();
			if (tasks_waiting == TRUE)
			{
				/* Reschedule only if task(s) were waiting  */
				OS_Sched(); 							  /* Find highest priority task ready to run  */
			}
			*err = OS_NO_ERR;
			return ((OS_EVENT *) 0);					   /* Mutex has been deleted				   */

		default:
			OS_EXIT_CRITICAL();
			*err = OS_ERR_INVALID_OPT;
			return (pevent);
	}
}
#endif