os_mutex.src

uCOS-II_2.52在51上的移植程序

; .\OS_MUTEX.SRC generated from: OS_MUTEX.C
; COMPILER INVOKED BY:
;        C:\Keil\C51\BIN\C51.EXE OS_MUTEX.C LARGE BROWSE ORDER NOAREGS DEBUG OBJECTEXTEND SRC(.\OS_MUTEX.SRC)

$NOMOD51

NAME	OS_MUTEX

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TMOD	DATA	089H
TL0	DATA	08AH
TL1	DATA	08BH
TH0	DATA	08CH
TH1	DATA	08DH
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IP	DATA	0B8H
SCON	DATA	098H
SBUF	DATA	099H
CY	BIT	0D0H.7
AC	BIT	0D0H.6
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TR1	BIT	088H.6
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EX1	BIT	0A8H.2
ET0	BIT	0A8H.1
EX0	BIT	0A8H.0
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INT1	BIT	0B0H.3
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RXD	BIT	0B0H.0
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SM1	BIT	098H.6
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TI	BIT	098H.1
RI	BIT	098H.0
; /*
; *********************************************************************************************************
; *                                                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 "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 (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)
; {
;   
;     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)
; {
;    
;     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                          */