os_sem.c

MCB2300_ucgui_LCD320240.rar LPC2368的uc/gui的移植

/*
*********************************************************************************************************
*   											 uC/OS-II
*   									   The Real-Time Kernel
*   									   SEMAPHORE MANAGEMENT
*
*   					   (c) Copyright 1992-2007, Jean J. Labrosse, Weston, FL
*   										All Rights Reserved
*
* File    : OS_SEM.C
* By	  : Jean J. Labrosse
* Version : V2.85
*
* LICENSING TERMS:
* ---------------
*   uC/OS-II is provided in source form for FREE evaluation, for educational use or for peaceful research.  
* If you plan on using  uC/OS-II  in a commercial product you need to contact Micri祄 to properly license 
* its use in your product. We provide ALL the source code for your convenience and to help you experience 
* uC/OS-II.   The fact that the  source is provided does  NOT  mean that you can use it without  paying a 
* licensing fee.
*********************************************************************************************************
*/

#ifndef  OS_MASTER_FILE
#include <ucos_ii.h>
#endif

#if OS_SEM_EN > 0
/*$PAGE*/
/*
*********************************************************************************************************
*   										ACCEPT SEMAPHORE
*
* Description: This function checks the semaphore to see if a resource is available or, if an event
*   		   occurred.  Unlike OSSemPend(), OSSemAccept() 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
*
* Returns    : >  0 	  if the resource is available or the event did not occur the semaphore is
*   					  decremented to obtain the resource.
*   		   == 0 	  if the resource is not available or the event did not occur or,
*   					  if 'pevent' is a NULL pointer or,
*   					  if you didn't pass a pointer to a semaphore
*********************************************************************************************************
*/

#if OS_SEM_ACCEPT_EN > 0
INT16U OSSemAccept(OS_EVENT *pevent)
{
	INT16U     cnt;
#if OS_CRITICAL_METHOD == 3 						  /* Allocate storage for CPU status register      */
	OS_CPU_SR  cpu_sr = 0;
#endif



#if OS_ARG_CHK_EN > 0
	if (pevent == (OS_EVENT *) 0)
	{
		/* Validate 'pevent'							 */
		return (0);
	}
#endif
	if (pevent->OSEventType != OS_EVENT_TYPE_SEM)
	{
		/* Validate event block type					 */
		return (0);
	}
	OS_ENTER_CRITICAL();
	cnt = pevent->OSEventCnt;
	if (cnt > 0)
	{
		/* See if resource is available 				 */
		pevent->OSEventCnt--;   					  /* Yes, decrement semaphore and notify caller    */
	}
	OS_EXIT_CRITICAL();
	return (cnt);   								  /* Return semaphore count 					   */
}
#endif

/*$PAGE*/
/*
*********************************************************************************************************
*   										CREATE A SEMAPHORE
*
* Description: This function creates a semaphore.
*
* Arguments  : cnt  		 is the initial value for the semaphore.  If the value is 0, no resource is
*   						 available (or no event has occurred).  You initialize the semaphore to a
*   						 non-zero value to specify how many resources are available (e.g. if you have
*   						 10 resources, you would initialize the semaphore to 10).
*
* Returns    : != (void *)0  is a pointer to the event control block (OS_EVENT) associated with the
*   						 created semaphore
*   		   == (void *)0  if no event control blocks were available
*********************************************************************************************************
*/

OS_EVENT * OSSemCreate(INT16U cnt)
{
	OS_EVENT  *pevent;
#if OS_CRITICAL_METHOD == 3 							   /* Allocate storage for CPU status register */
	OS_CPU_SR  cpu_sr = 0;
#endif



	if (OSIntNesting > 0)
	{
		/* See if called from ISR ...   			*/
		return ((OS_EVENT *) 0);							/* ... can't CREATE from an ISR             */
	}
	OS_ENTER_CRITICAL();
	pevent = OSEventFreeList;   						   /* Get next free event control block 	   */
	if (OSEventFreeList != (OS_EVENT *) 0)
	{
		/* See if pool of free ECB pool was empty   */
		OSEventFreeList = (OS_EVENT *) OSEventFreeList->OSEventPtr;
	}
	OS_EXIT_CRITICAL();
	if (pevent != (OS_EVENT *) 0)
	{
		/* Get an event control block   			*/
		pevent->OSEventType = OS_EVENT_TYPE_SEM;
		pevent->OSEventCnt = cnt;   				   /* Set semaphore value   				   */
		pevent->OSEventPtr = (void *) 0;				/* Unlink from ECB free list				*/
#if OS_EVENT_NAME_SIZE > 1
		pevent->OSEventName[0] = '?';   				   /* Unknown name  						   */
		pevent->OSEventName[1] = OS_ASCII_NUL;
#endif
		OS_EventWaitListInit(pevent);   				   /* Initialize to 'nobody waiting' on sem.   */
	}
	return (pevent);
}

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

#if OS_SEM_DEL_EN > 0
OS_EVENT * OSSemDel(OS_EVENT *pevent, INT8U opt, INT8U *perr)
{
	BOOLEAN    tasks_waiting;
	OS_EVENT  *pevent_return;
#if OS_CRITICAL_METHOD == 3 							   /* Allocate storage for CPU status register */
	OS_CPU_SR  cpu_sr = 0;
#endif



#if OS_ARG_CHK_EN > 0
	if (perr == (INT8U *) 0)
	{
		/* Validate 'perr'  						*/
		return (pevent);
	}
	if (pevent == (OS_EVENT *) 0)
	{
		/* Validate 'pevent'						*/
		*perr = OS_ERR_PEVENT_NULL;
		return (pevent);
	}
#endif
	if (pevent->OSEventType != OS_EVENT_TYPE_SEM)
	{
		/* Validate event block type				*/
		*perr = OS_ERR_EVENT_TYPE;
		return (pevent);
	}
	if (OSIntNesting > 0)
	{
		/* See if called from ISR ...   			*/
		*perr = OS_ERR_DEL_ISR; 							/* ... can't DELETE from an ISR             */
		return (pevent);
	}
	OS_ENTER_CRITICAL();
	if (pevent->OSEventGrp != 0)
	{
		/* See if any tasks waiting on semaphore	*/
		tasks_waiting = OS_TRUE;						   /* Yes   								   */
	}
	else
	{
		tasks_waiting = OS_FALSE;   					   /* No									   */
	}
	switch (opt)
	{
		case OS_DEL_NO_PEND:
			/* Delete semaphore only if no task waiting */
			if (tasks_waiting == OS_FALSE)
			{
#if OS_EVENT_NAME_SIZE > 1
				pevent->OSEventName[0] = '?';   		  /* Unknown name   						  */
				pevent->OSEventName[1] = OS_ASCII_NUL;
#endif
				pevent->OSEventType = OS_EVENT_TYPE_UNUSED;
				pevent->OSEventPtr = OSEventFreeList; /* Return Event Control Block to free list  */
				pevent->OSEventCnt = 0;
				OSEventFreeList = pevent;   	   /* Get next free event control block 	   */
				OS_EXIT_CRITICAL();
				*perr = OS_ERR_NONE;
				pevent_return = (OS_EVENT *) 0;   /* Semaphore has been deleted 			  */
			}
			else
			{
				OS_EXIT_CRITICAL();
				*perr = OS_ERR_TASK_WAITING;
				pevent_return = pevent;
			}
			break;

		case OS_DEL_ALWAYS:
			/* Always delete the semaphore  			*/
			while (pevent->OSEventGrp != 0)
			{
				/* Ready ALL tasks waiting for semaphore	*/
				(void) OS_EventTaskRdy(pevent, (void *) 0, OS_STAT_SEM, OS_STAT_PEND_OK);
			}
#if OS_EVENT_NAME_SIZE > 1
			pevent->OSEventName[0] = '?';   			  /* Unknown name   						  */
			pevent->OSEventName[1] = OS_ASCII_NUL;
#endif
			pevent->OSEventType = OS_EVENT_TYPE_UNUSED;
			pevent->OSEventPtr = OSEventFreeList;     /* Return Event Control Block to free list  */
			pevent->OSEventCnt = 0;
			OSEventFreeList = pevent;   		   /* Get next free event control block 	   */
			OS_EXIT_CRITICAL();
			if (tasks_waiting == OS_TRUE)
			{
				/* Reschedule only if task(s) were waiting  */
				OS_Sched(); 							  /* Find highest priority task ready to run  */
			}
			*perr = OS_ERR_NONE;
			pevent_return = (OS_EVENT *) 0; 	  /* Semaphore has been deleted 			  */
			break;

		default:
			OS_EXIT_CRITICAL();
			*perr = OS_ERR_INVALID_OPT;
			pevent_return = pevent;
			break;
	}
	return (pevent_return);
}
#endif

/*$PAGE*/
/*
*********************************************************************************************************
*   										PEND ON SEMAPHORE
*
* Description: This function waits for a semaphore.
*
* Arguments  : pevent   	 is a pointer to the event control block associated with the desired
*   						 semaphore.
*
*   		   timeout  	 is an optional timeout period (in clock ticks).  If non-zero, your task will
*   						 wait for the resource up to the amount of time specified by this argument.
*   						 If you specify 0, however, your task will wait forever at the specified
*   						 semaphore or, until the resource becomes available (or the event occurs).
*
*   		   perr 		 is a pointer to where an error message will be deposited.  Possible error
*   						 messages are:
*
*   						 OS_ERR_NONE		 The call was successful and your task owns the resource
*   											 or, the event you are waiting for occurred.
*   						 OS_ERR_TIMEOUT 	 The semaphore was not received within the specified
*   											 'timeout'.
*   						 OS_ERR_PEND_ABORT   The wait on the semaphore was aborted.
*   						 OS_ERR_EVENT_TYPE   If you didn't pass a pointer to a semaphore.
*   						 OS_ERR_PEND_ISR	 If you called this function from an ISR and the result
*   											 would lead to a suspension.
*   						 OS_ERR_PEVENT_NULL  If 'pevent' is a NULL pointer.
*   						 OS_ERR_PEND_LOCKED  If you called this function when the scheduler is locked
*
* Returns    : none
*********************************************************************************************************
*/

void OSSemPend(OS_EVENT *pevent, INT16U timeout, INT8U *perr)
{
	INT8U      pend_stat;
#if OS_CRITICAL_METHOD == 3 						  /* Allocate storage for CPU status register      */
	OS_CPU_SR  cpu_sr = 0;
#endif



#if OS_ARG_CHK_EN > 0
	if (perr == (INT8U *) 0)
	{
		/* Validate 'perr'  							 */
		return;
	}
	if (pevent == (OS_EVENT *) 0)
	{
		/* Validate 'pevent'							 */
		*perr = OS_ERR_PEVENT_NULL;
		return;
	}
#endif
	if (pevent->OSEventType != OS_EVENT_TYPE_SEM)
	{
		/* Validate event block type					 */
		*perr = OS_ERR_EVENT_TYPE;
		return;
	}
	if (OSIntNesting > 0)
	{
		/* See if called from ISR ...   				 */
		*perr = OS_ERR_PEND_ISR;					  /* ... can't PEND from an ISR                    */
		return;
	}
	if (OSLockNesting > 0)
	{