os_mutex.c - This C code implements a mutex (mutual exclusi…

/src/compiler/ucos-vs2008/UCOS_SIM/src/ucosii/os_mutex.c

http://ftk.googlecode.com/ · C · 603 lines · 390 code · 34 blank · 179 comment · 94 complexity · 09fbeec509c78b1996a94780188c5569 MD5 · raw file

/*

*********************************************************************************************************

*                                                uC/OS-II

*                                          The Real-Time Kernel

*                                  MUTUAL EXCLUSION SEMAPHORE MANAGEMENT

*

*                          (c) Copyright 1992-2005, Jean J. Labrosse, Weston, FL

*                                           All Rights Reserved

*

* File    : OS_MUTEX.C

* By      : Jean J. Labrosse

* Version : V2.80

*********************************************************************************************************

*/



#ifndef  OS_MASTER_FILE

#include <ucos_ii.h>

#endif



/*

*********************************************************************************************************

*                                            LOCAL CONSTANTS

*********************************************************************************************************

*/



#define  OS_MUTEX_KEEP_LOWER_8   0x00FFu

#define  OS_MUTEX_KEEP_UPPER_8   0xFF00u



#define  OS_MUTEX_AVAILABLE      0x00FFu





#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 = 0;

#endif







#if OS_ARG_CHK_EN > 0

    if (err == (INT8U *)0) {                           /* Validate 'err'                               */

        return (0);

    }

    if (pevent == (OS_EVENT *)0) {                     /* Validate 'pevent'                            */

        *err = OS_ERR_PEVENT_NULL;

        return (0);

    }

#endif

    if (pevent->OSEventType != OS_EVENT_TYPE_MUTEX) {  /* Validate event block type                    */

        *err = OS_ERR_EVENT_TYPE;

        return (0);

    }

    if (OSIntNesting > 0) {                            /* Make sure it's not called from an ISR        */

        *err = OS_ERR_PEND_ISR;

        return (0);

    }

    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 OS_CRITICAL_METHOD == 3                                /* Allocate storage for CPU status register */

    OS_CPU_SR  cpu_sr = 0;

#endif







#if OS_ARG_CHK_EN > 0

    if (err == (INT8U *)0) {                               /* Validate 'err'                           */

        return ((OS_EVENT *)0);

    }

    if (prio >= OS_LOWEST_PRIO) {                          /* Validate PIP                             */

        *err = OS_PRIO_INVALID;

        return ((OS_EVENT *)0);

    }

#endif

    if (OSIntNesting > 0) {                                /* See if called from ISR ...               */

        *err = OS_ERR_CREATE_ISR;                          /* ... can't CREATE mutex from an ISR       */

        return ((OS_EVENT *)0);

    }

    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     = (INT16U)((INT16U)prio << 8) | OS_MUTEX_AVAILABLE; /* Resource is avail.   */

    pevent->OSEventPtr     = (void *)0;                                 /* No task owning the mutex    */

#if OS_EVENT_NAME_SIZE > 1

    pevent->OSEventName[0] = '?';

    pevent->OSEventName[1] = OS_ASCII_NUL;

#endif

    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;

    OS_EVENT  *pevent_return;

    INT8U      pip;

#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 (err == (INT8U *)0) {                               /* Validate 'err'                           */

        return ((OS_EVENT *)0);

    }

    if (pevent == (OS_EVENT *)0) {                         /* Validate 'pevent'                        */

        *err = OS_ERR_PEVENT_NULL;

        return ((OS_EVENT *)0);

    }

#endif

    if (pevent->OSEventType != OS_EVENT_TYPE_MUTEX) {      /* Validate event block type                */

        *err = OS_ERR_EVENT_TYPE;

        return (pevent);

    }

    if (OSIntNesting > 0) {                                /* See if called from ISR ...               */

        *err = 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 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) {

#if OS_EVENT_NAME_SIZE > 1

                 pevent->OSEventName[0] = '?';             /* Unknown name                             */

                 pevent->OSEventName[1] = OS_ASCII_NUL;

#endif

                 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  */

                 pevent->OSEventCnt  = 0;

                 OSEventFreeList     = pevent;

                 OS_EXIT_CRITICAL();

                 *err                = OS_NO_ERR;

                 pevent_return       = (OS_EVENT *)0;      /* Mutex has been deleted                   */

             } else {

                 OS_EXIT_CRITICAL();

                 *err                = OS_ERR_TASK_WAITING;

                 pevent_return       = pevent;

             }

             break;



        case OS_DEL_ALWAYS:                                /* Always delete the mutex                  */

             while (pevent->OSEventGrp != 0) {             /* Ready ALL tasks waiting for mutex        */

                 (void)OS_EventTaskRdy(pevent, (void *)0, OS_STAT_MUTEX);

             }

#if OS_EVENT_NAME_SIZE > 1

             pevent->OSEventName[0] = '?';                 /* Unknown name                             */

             pevent->OSEventName[1] = OS_ASCII_NUL;

#endif

             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  */

             pevent->OSEventCnt  = 0;

             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;

             pevent_return = (OS_EVENT *)0;                /* Mutex has been deleted                   */

             break;



        default:

             OS_EXIT_CRITICAL();

             *err          = OS_ERR_INVALID_OPT;

             pevent_return = pevent;

             break;

    }

    return (pevent_return);

}

#endif



/*$PAGE*/

/*

*********************************************************************************************************

*                                  PEND ON MUTUAL EXCLUSION SEMAPHORE

*

* Description: This function waits for a mutual exclusion semaphore.

*

* Arguments  : pevent        is a pointer to the event control block associated with the desired

*                            mutex.

*

*              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

*                            mutex or, until the resource becomes available.

*

*              err           is a pointer to where an error message will be deposited.  Possible error

*                            messages are:

*                               OS_NO_ERR          The call was successful and your task owns the mutex

*                               OS_TIMEOUT         The mutex was not available within the specified time.

*                               OS_ERR_EVENT_TYPE  If you didn't pass 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 and the result

*                                                  would lead to a suspension.

*                               OS_ERR_PIP_LOWER   If the priority of the task that owns the Mutex is

*                                                  HIGHER (i.e. a lower number) than the PIP.  This error

*                                                  indicates that you did not set the PIP higher (lower

*                                                  number) than ALL the tasks that compete for the Mutex.

*                                                  Unfortunately, this is something that could not be

*                                                  detected when the Mutex is created because we don't know

*                                                  what tasks will be using the Mutex.

*

* Returns    : none

*

* Note(s)    : 1) The task that owns the Mutex MUST NOT pend on any other event while it owns the mutex.

*              2) You MUST NOT change the priority of the task that owns the mutex

*********************************************************************************************************

*/

void  OSMutexPend (OS_EVENT *pevent, INT16U timeout, INT8U *err)

{

    INT8U      pip;                                        /* Priority Inheritance Priority (PIP)      */

    INT8U      mprio;                                      /* Mutex owner priority                     */

    BOOLEAN    rdy;                                        /* Flag indicating task was ready           */

    OS_TCB    *ptcb;

    OS_EVENT  *pevent2;

    INT8U      y;

#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 (err == (INT8U *)0) {                               /* Validate 'err'                           */

        return;

    }

    if (pevent == (OS_EVENT *)0) {                         /* Validate 'pevent'                        */

        *err = OS_ERR_PEVENT_NULL;

        return;

    }

#endif

    if (pevent->OSEventType != OS_EVENT_TYPE_MUTEX) {      /* Validate event block type                */

        *err = OS_ERR_EVENT_TYPE;

        return;

    }

    if (OSIntNesting > 0) {                                /* See if called from ISR ...               */

        *err = OS_ERR_PEND_ISR;                            /* ... can't PEND from an ISR               */

        return;

    }

    OS_ENTER_CRITICAL();								

    pip = (INT8U)(pevent->OSEventCnt >> 8);                /* Get PIP from mutex                       */

                                                           /* Is Mutex available?                      */

    if ((INT8U)(pevent->OSEventCnt & OS_MUTEX_KEEP_LOWER_8) == OS_MUTEX_AVAILABLE) {

        pevent->OSEventCnt &= OS_MUTEX_KEEP_UPPER_8;       /* Yes, Acquire the resource                */

        pevent->OSEventCnt |= OSTCBCur->OSTCBPrio;         /*      Save priority of owning task        */

        pevent->OSEventPtr  = (void *)OSTCBCur;            /*      Point to owning task's OS_TCB       */

        if (OSTCBCur->OSTCBPrio <= pip) {                  /*      PIP 'must' have a SMALLER prio ...  */

            OS_EXIT_CRITICAL();                            /*      ... than current task!              */

            *err  = OS_ERR_PIP_LOWER;

        } else {

            OS_EXIT_CRITICAL();

            *err  = OS_NO_ERR;

        }

        return;

    }

    mprio = (INT8U)(pevent->OSEventCnt & OS_MUTEX_KEEP_LOWER_8);  /* No, Get priority of mutex owner   */

    ptcb  = (OS_TCB *)(pevent->OSEventPtr);                       /*     Point to TCB of mutex owner   */

    if (ptcb->OSTCBPrio > pip) {                                  /*     Need to promote prio of owner?*/

        if (mprio > OSTCBCur->OSTCBPrio) {

            y = ptcb->OSTCBY;

            if ((OSRdyTbl[y] & ptcb->OSTCBBitX) != 0) {           /*     See if mutex owner is ready   */

                OSRdyTbl[y] &= ~ptcb->OSTCBBitX;                  /*     Yes, Remove owner from Rdy ...*/

                if (OSRdyTbl[y] == 0) {                           /*          ... list at current prio */

                    OSRdyGrp &= ~ptcb->OSTCBBitY;

                }

                rdy = TRUE;

            } else {

                pevent2 = ptcb->OSTCBEventPtr;

                if (pevent2 != (OS_EVENT *)0) {                   /* Remove from event wait list       */

                    if ((pevent2->OSEventTbl[ptcb->OSTCBY] &= ~ptcb->OSTCBBitX) == 0) {

                        pevent2->OSEventGrp &= ~ptcb->OSTCBBitY;

                    }

                }

                rdy = FALSE;                               /* No                                       */

            }

            ptcb->OSTCBPrio = pip;                         /* Change owner task prio to PIP            */

#if OS_LOWEST_PRIO <= 63

            ptcb->OSTCBY    =  ptcb->OSTCBPrio >> 3;

            ptcb->OSTCBX    =  ptcb->OSTCBPrio & 0x07;

#else

            ptcb->OSTCBY    = (ptcb->OSTCBPrio >> 4) & 0xFF;

            ptcb->OSTCBX    =  ptcb->OSTCBPrio & 0x0F;

#endif

            ptcb->OSTCBBitY = 1 << ptcb->OSTCBY;

            ptcb->OSTCBBitX = 1 << ptcb->OSTCBX;

            if (rdy == TRUE) {                             /* If task was ready at owner's priority ...*/

                OSRdyGrp               |= ptcb->OSTCBBitY; /* ... make it ready at new priority.       */

                OSRdyTbl[ptcb->OSTCBY] |= ptcb->OSTCBBitX;

            } else {

                pevent2 = ptcb->OSTCBEventPtr;

                if (pevent2 != (OS_EVENT *)0) {            /* Remove from event wait list              */

                    pevent2->OSEventGrp               |= ptcb->OSTCBBitY;

                    pevent2->OSEventTbl[ptcb->OSTCBY] |= ptcb->OSTCBBitX;

                }

            }

            OSTCBPrioTbl[pip] = ptcb;

        }

    }

    OSTCBCur->OSTCBStat   |= OS_STAT_MUTEX;           /* Mutex not available, pend current task        */

    OSTCBCur->OSTCBPendTO  = FALSE;

    OSTCBCur->OSTCBDly     = timeout;                 /* Store timeout in current task's TCB           */

    OS_EventTaskWait(pevent);                         /* Suspend task until event or timeout occurs    */

    OS_EXIT_CRITICAL();

    OS_Sched();                                       /* Find next highest priority task ready         */

    OS_ENTER_CRITICAL();

    if (OSTCBCur->OSTCBPendTO == TRUE) {              /* See if we timed out during the pend           */

        OS_EventTO(pevent);

        OS_EXIT_CRITICAL();

        *err = OS_TIMEOUT;                            /* Indicate that we didn't get mutex within TO   */

        return;

    }

    OSTCBCur->OSTCBEventPtr = (OS_EVENT *)0;

    OS_EXIT_CRITICAL();

    *err = OS_NO_ERR;

}

/*$PAGE*/

/*

*********************************************************************************************************

*                                  POST TO A MUTUAL EXCLUSION SEMAPHORE

*

* Description: This function signals a mutual exclusion semaphore

*

* Arguments  : pevent              is a pointer to the event control block associated with the desired

*                                  mutex.

*

* Returns    : OS_NO_ERR               The call was successful and the mutex was signaled.

*              OS_ERR_EVENT_TYPE       If you didn't pass a pointer to a mutex

*              OS_ERR_PEVENT_NULL      'pevent' is a NULL pointer

*              OS_ERR_POST_ISR         Attempted to post from an ISR (not valid for MUTEXes)

*              OS_ERR_NOT_MUTEX_OWNER  The task that did the post is NOT the owner of the MUTEX.

*********************************************************************************************************

*/



INT8U  OSMutexPost (OS_EVENT *pevent)

{

    INT8U      pip;                                   /* Priority inheritance priority                 */

    INT8U      prio;

    INT8U      y;

#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_ERR_POST_ISR);                     /* ... can't POST mutex from an ISR              */

    }

#if OS_ARG_CHK_EN > 0

    if (pevent == (OS_EVENT *)0) {                    /* Validate 'pevent'                             */

        return (OS_ERR_PEVENT_NULL);

    }

#endif

    if (pevent->OSEventType != OS_EVENT_TYPE_MUTEX) { /* Validate event block type                     */

        return (OS_ERR_EVENT_TYPE);

    }

    OS_ENTER_CRITICAL();

    pip  = (INT8U)(pevent->OSEventCnt >> 8);          /* Get priority inheritance priority of mutex    */

    prio = (INT8U)(pevent->OSEventCnt & OS_MUTEX_KEEP_LOWER_8);  /* Get owner's original priority      */

    if (OSTCBCur != (OS_TCB *)pevent->OSEventPtr) {   /* See if posting task owns the MUTEX            */

        OS_EXIT_CRITICAL();

        return (OS_ERR_NOT_MUTEX_OWNER);

    }

    if (OSTCBCur->OSTCBPrio == pip) {                 /* Did we have to raise current task's priority? */

        y            = OSTCBCur->OSTCBY;              /* Yes, Return to original priority              */

        OSRdyTbl[y] &= ~OSTCBCur->OSTCBBitX;          /*      Remove owner from ready list at 'pip'    */

        if (OSRdyTbl[y] == 0) {

            OSRdyGrp &= ~OSTCBCur->OSTCBBitY;

        }

        OSTCBCur->OSTCBPrio         = prio;

#if OS_LOWEST_PRIO <= 63

        OSTCBCur->OSTCBY            = prio >> 3;

        OSTCBCur->OSTCBX            = prio & 0x07;

#else

        OSTCBCur->OSTCBY            = (prio >> 4) & 0xFF;

        OSTCBCur->OSTCBX            = prio & 0x0F;

#endif

        OSTCBCur->OSTCBBitY         = 1 << OSTCBCur->OSTCBY;

        OSTCBCur->OSTCBBitX         = 1 << OSTCBCur->OSTCBX;

        OSRdyGrp                   |= OSTCBCur->OSTCBBitY;

        OSRdyTbl[OSTCBCur->OSTCBY] |= OSTCBCur->OSTCBBitX;

        OSTCBPrioTbl[prio]          = OSTCBCur;

    }

    OSTCBPrioTbl[pip] = (OS_TCB *)1;                  /* Reserve table entry                           */

    if (pevent->OSEventGrp != 0) {                    /* Any task waiting for the mutex?               */

                                                      /* Yes, Make HPT waiting for mutex ready         */

        prio                = OS_EventTaskRdy(pevent, (void *)0, OS_STAT_MUTEX);

        pevent->OSEventCnt &= OS_MUTEX_KEEP_UPPER_8;  /*      Save priority of mutex's new owner       */

        pevent->OSEventCnt |= prio;

        pevent->OSEventPtr  = OSTCBPrioTbl[prio];     /*      Link to mutex owner's OS_TCB             */

        OS_EXIT_CRITICAL();

        OS_Sched();                                   /*      Find highest priority task ready to run  */

        return (OS_NO_ERR);

    }

    pevent->OSEventCnt |= OS_MUTEX_AVAILABLE;         /* No,  Mutex is now available                   */

    pevent->OSEventPtr  = (void *)0;

    OS_EXIT_CRITICAL();

    return (OS_NO_ERR);

}

/*$PAGE*/

/*

*********************************************************************************************************

*                                     QUERY A MUTUAL EXCLUSION SEMAPHORE

*

* Description: This function obtains information about a mutex

*

* Arguments  : pevent          is a pointer to the event control block associated with the desired mutex

*

*              p_mutex_data    is a pointer to a structure that will contain information about the mutex

*

* Returns    : OS_NO_ERR            The call was successful and the message was sent

*              OS_ERR_QUERY_ISR     If you called this function from an ISR

*              OS_ERR_PEVENT_NULL   If 'pevent'       is a NULL pointer

*              OS_ERR_PDATA_NULL    If 'p_mutex_data' is a NULL pointer

*              OS_ERR_EVENT_TYPE    If you are attempting to obtain data from a non mutex.

*********************************************************************************************************

*/



#if OS_MUTEX_QUERY_EN > 0

INT8U  OSMutexQuery (OS_EVENT *pevent, OS_MUTEX_DATA *p_mutex_data)

{

    INT8U      i;

#if OS_LOWEST_PRIO <= 63

    INT8U     *psrc;

    INT8U     *pdest;

#else

    INT16U    *psrc;

    INT16U    *pdest;

#endif

#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_ERR_QUERY_ISR);                         /* ... can't QUERY mutex from an ISR        */

    }

#if OS_ARG_CHK_EN > 0

    if (pevent == (OS_EVENT *)0) {                         /* Validate 'pevent'                        */

        return (OS_ERR_PEVENT_NULL);

    }

    if (p_mutex_data == (OS_MUTEX_DATA *)0) {              /* Validate 'p_mutex_data'                  */

        return (OS_ERR_PDATA_NULL);

    }

#endif

    if (pevent->OSEventType != OS_EVENT_TYPE_MUTEX) {      /* Validate event block type                */

        return (OS_ERR_EVENT_TYPE);

    }

    OS_ENTER_CRITICAL();

    p_mutex_data->OSMutexPIP  = (INT8U)(pevent->OSEventCnt >> 8);

    p_mutex_data->OSOwnerPrio = (INT8U)(pevent->OSEventCnt & OS_MUTEX_KEEP_LOWER_8);

    if (p_mutex_data->OSOwnerPrio == 0xFF) {

        p_mutex_data->OSValue = 1;

    } else {

        p_mutex_data->OSValue = 0;

    }

    p_mutex_data->OSEventGrp  = pevent->OSEventGrp;        /* Copy wait list                           */

    psrc                      = &pevent->OSEventTbl[0];

    pdest                     = &p_mutex_data->OSEventTbl[0];

    for (i = 0; i < OS_EVENT_TBL_SIZE; i++) {

        *pdest++ = *psrc++;

    }

    OS_EXIT_CRITICAL();

    return (OS_NO_ERR);

}

#endif                                                     /* OS_MUTEX_QUERY_EN                        */

#endif                                                     /* OS_MUTEX_EN                              */
Summary ✨

This C code implements a mutex (mutual exclusion) system for synchronization between threads. It provides functions to create, destroy, and query a mutex, as well as wait on a mutex. The code uses event tables to manage waiting tasks and priority inheritance to ensure that the mutex is always acquired by the highest-priority task.
Alerts (2)

Complexity hotspot; lines 405 to 406 (total complexity: 4)
405 406