os_flag.c

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/*
*********************************************************************************************************
*                                                uC/OS-II
*                                          The Real-Time Kernel
*                                         EVENT FLAG  MANAGEMENT
*
*                            (c) Copyright 2001, Jean J. Labrosse, Weston, FL
*                                           All Rights Reserved
*
* File : OS_FLAG.C
* By   : Jean J. Labrosse
*********************************************************************************************************
*/

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

#if (OS_VERSION >= 251) && (OS_FLAG_EN > 0) && (OS_MAX_FLAGS > 0)
/*
*********************************************************************************************************
*                                            LOCAL PROTOTYPES
*********************************************************************************************************
*/

static  void     OS_FlagBlock(OS_FLAG_GRP *pgrp, OS_FLAG_NODE *pnode, OS_FLAGS flags, INT8U wait_type, INT16U timeout);
static  BOOLEAN  OS_FlagTaskRdy(OS_FLAG_NODE *pnode, OS_FLAGS flags_rdy);

/*$PAGE*/
/*
*********************************************************************************************************
*                              CHECK THE STATUS OF FLAGS IN AN EVENT FLAG GROUP
*
* Description: This function is called to check the status of a combination of bits to be set or cleared
*              in an event flag group.  Your application can check for ANY bit to be set/cleared or ALL 
*              bits to be set/cleared.
*
*              This call does not block if the desired flags are not present.
*
* Arguments  : pgrp          is a pointer to the desired event flag group.
*
*              flags         Is a bit pattern indicating which bit(s) (i.e. flags) you wish to check.  
*                            The bits you want are specified by setting the corresponding bits in 
*                            'flags'.  e.g. if your application wants to wait for bits 0 and 1 then 
*                            'flags' would contain 0x03.
*
*              wait_type     specifies whether you want ALL bits to be set/cleared or ANY of the bits 
*                            to be set/cleared.
*                            You can specify the following argument:
*
*                            OS_FLAG_WAIT_CLR_ALL   You will check ALL bits in 'flags' to be clear (0)
*                            OS_FLAG_WAIT_CLR_ANY   You will check ANY bit  in 'flags' to be clear (0)
*                            OS_FLAG_WAIT_SET_ALL   You will check ALL bits in 'flags' to be set   (1)
*                            OS_FLAG_WAIT_SET_ANY   You will check ANY bit  in 'flags' to be set   (1)
*
*                            NOTE: Add OS_FLAG_CONSUME if you want the event flag to be 'consumed' by
*                                  the call.  Example, to wait for any flag in a group AND then clear
*                                  the flags that are present, set 'wait_type' to:
*
*                                  OS_FLAG_WAIT_SET_ANY + OS_FLAG_CONSUME
*
*              err           is a pointer to an error code and can be:
*                            OS_NO_ERR              No error
*                            OS_ERR_EVENT_TYPE      You are not pointing to an event flag group
*                            OS_FLAG_ERR_WAIT_TYPE  You didn't specify a proper 'wait_type' argument.
*                            OS_FLAG_INVALID_PGRP   You passed a NULL pointer instead of the event flag
*                                                   group handle.
*                            OS_FLAG_ERR_NOT_RDY    The desired flags you are waiting for are not 
*                                                   available.
*
* Returns    : The state of the flags in the event flag group.
*
* Called from: Task or ISR
*********************************************************************************************************
*/

#if OS_FLAG_ACCEPT_EN > 0
OS_FLAGS  OSFlagAccept (OS_FLAG_GRP *pgrp, OS_FLAGS flags, INT8U wait_type, INT8U *err)
{
#if OS_CRITICAL_METHOD == 3                                /* Allocate storage for CPU status register */
    OS_CPU_SR     cpu_sr;
#endif    
    OS_FLAGS      flags_cur;
    OS_FLAGS      flags_rdy;
    BOOLEAN       consume;


#if OS_ARG_CHK_EN > 0
    if (pgrp == (OS_FLAG_GRP *)0) {                        /* Validate 'pgrp'                          */
        *err = OS_FLAG_INVALID_PGRP;
        return ((OS_FLAGS)0);
    }
    if (pgrp->OSFlagType != OS_EVENT_TYPE_FLAG) {          /* Validate event block type                */
        *err = OS_ERR_EVENT_TYPE;
        return ((OS_FLAGS)0);
    }
#endif
    if (wait_type & OS_FLAG_CONSUME) {                     /* See if we need to consume the flags      */
        wait_type &= ~OS_FLAG_CONSUME;
        consume    = TRUE;
    } else {
        consume    = FALSE;
    }
/*$PAGE*/
    *err = OS_NO_ERR;                                      /* Assume NO error until proven otherwise.  */
    OS_ENTER_CRITICAL();
    switch (wait_type) {
        case OS_FLAG_WAIT_SET_ALL:                         /* See if all required flags are set        */
             flags_rdy = pgrp->OSFlagFlags & flags;        /* Extract only the bits we want            */
             if (flags_rdy == flags) {                     /* Must match ALL the bits that we want     */
                 if (consume == TRUE) {                    /* See if we need to consume the flags      */
                     pgrp->OSFlagFlags &= ~flags_rdy;      /* Clear ONLY the flags that we wanted      */
                 }
             } else {
                 *err  = OS_FLAG_ERR_NOT_RDY;
             }
             flags_cur = pgrp->OSFlagFlags;                /* Will return the state of the group       */
             OS_EXIT_CRITICAL();
             break;

        case OS_FLAG_WAIT_SET_ANY:
             flags_rdy = pgrp->OSFlagFlags & flags;        /* Extract only the bits we want            */
             if (flags_rdy != (OS_FLAGS)0) {               /* See if any flag set                      */
                 if (consume == TRUE) {                    /* See if we need to consume the flags      */
                     pgrp->OSFlagFlags &= ~flags_rdy;      /* Clear ONLY the flags that we got         */
                 }
             } else {
                 *err  = OS_FLAG_ERR_NOT_RDY;
             }
             flags_cur = pgrp->OSFlagFlags;                /* Will return the state of the group       */
             OS_EXIT_CRITICAL();
             break;

#if OS_FLAG_WAIT_CLR_EN > 0
        case OS_FLAG_WAIT_CLR_ALL:                         /* See if all required flags are cleared    */
             flags_rdy = ~pgrp->OSFlagFlags & flags;       /* Extract only the bits we want            */
             if (flags_rdy == flags) {                     /* Must match ALL the bits that we want     */
                 if (consume == TRUE) {                    /* See if we need to consume the flags      */
                     pgrp->OSFlagFlags |= flags_rdy;       /* Set ONLY the flags that we wanted        */
                 }
             } else {
                 *err  = OS_FLAG_ERR_NOT_RDY;
             }
             flags_cur = pgrp->OSFlagFlags;                /* Will return the state of the group       */
             OS_EXIT_CRITICAL();
             break;

        case OS_FLAG_WAIT_CLR_ANY:
             flags_rdy = ~pgrp->OSFlagFlags & flags;       /* Extract only the bits we want            */
             if (flags_rdy != (OS_FLAGS)0) {               /* See if any flag cleared                  */
                 if (consume == TRUE) {                    /* See if we need to consume the flags      */
                     pgrp->OSFlagFlags |= flags_rdy;       /* Set ONLY the flags that we got           */
                 }
             } else {
                 *err  = OS_FLAG_ERR_NOT_RDY;
             }
             flags_cur = pgrp->OSFlagFlags;                /* Will return the state of the group       */
             OS_EXIT_CRITICAL();
             break;
#endif

        default:
             OS_EXIT_CRITICAL();
             flags_cur = (OS_FLAGS)0;
             *err      = OS_FLAG_ERR_WAIT_TYPE;
             break;
    }
    return (flags_cur);
}
#endif    

/*$PAGE*/
/*
*********************************************************************************************************
*                                           CREATE AN EVENT FLAG
*
* Description: This function is called to create an event flag group.
*
* Arguments  : flags         Contains the initial value to store in the event flag group.
*
*              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 an Event Flag from an 
*                                                        ISR.
*                               OS_FLAG_GRP_DEPLETED     if there are no more event flag groups
*
* Returns    : A pointer to an event flag group or a NULL pointer if no more groups are available.
*
* Called from: Task ONLY
*********************************************************************************************************
*/

OS_FLAG_GRP  *OSFlagCreate (OS_FLAGS flags, INT8U *err)
{
#if OS_CRITICAL_METHOD == 3                         /* Allocate storage for CPU status register        */
    OS_CPU_SR    cpu_sr;
#endif    
    OS_FLAG_GRP *pgrp;


    if (OSIntNesting > 0) {                         /* See if called from ISR ...                      */
        *err = OS_ERR_CREATE_ISR;                   /* ... can't CREATE from an ISR                    */
        return ((OS_FLAG_GRP *)0);               
    }
    OS_ENTER_CRITICAL();
    pgrp = OSFlagFreeList;                          /* Get next free event flag                        */
    if (pgrp != (OS_FLAG_GRP *)0) {                 /* See if we have event flag groups available      */
                                                    /* Adjust free list                                */
        OSFlagFreeList       = (OS_FLAG_GRP *)OSFlagFreeList->OSFlagWaitList;
        pgrp->OSFlagType     = OS_EVENT_TYPE_FLAG;  /* Set to event flag group type                    */
        pgrp->OSFlagFlags    = flags;               /* Set to desired initial value                    */
        pgrp->OSFlagWaitList = (void *)0;           /* Clear list of tasks waiting on flags            */
        OS_EXIT_CRITICAL();
        *err                 = OS_NO_ERR;
    } else {
        OS_EXIT_CRITICAL();
        *err                 = OS_FLAG_GRP_DEPLETED;
    }
    return (pgrp);                                  /* Return pointer to event flag group              */
}

/*$PAGE*/
/*
*********************************************************************************************************
*                                     DELETE AN EVENT FLAG GROUP
*
* Description: This function deletes an event flag group and readies all tasks pending on the event flag
*              group.
*
* Arguments  : pgrp          is a pointer to the desired event flag group.
*
*              opt           determines delete options as follows:
*                            opt == OS_DEL_NO_PEND   Deletes the event flag group ONLY if no task pending
*                            opt == OS_DEL_ALWAYS    Deletes the event flag group 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 event flag group was 
*                                                    deleted
*                            OS_ERR_DEL_ISR          If you attempted to delete the event flag group from 
*                                                    an ISR
*                            OS_FLAG_INVALID_PGRP    If 'pgrp' is a NULL pointer.
*                            OS_ERR_EVENT_TYPE       You are not pointing to an event flag group
*                            OS_ERR_EVENT_TYPE       If you didn't pass a pointer to an event flag group
*                            OS_ERR_INVALID_OPT      An invalid option was specified
*                            OS_ERR_TASK_WAITING     One or more tasks were waiting on the event flag 
*                                                    group.
*
* 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 event flag group MUST check the return code of OSFlagAccept() and OSFlagPend().
*              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 event flag group.
*********************************************************************************************************
*/

#if OS_FLAG_DEL_EN > 0
OS_FLAG_GRP  *OSFlagDel (OS_FLAG_GRP *pgrp, INT8U opt, INT8U *err)
{
#if OS_CRITICAL_METHOD == 3                                /* Allocate storage for CPU status register */
    OS_CPU_SR     cpu_sr;
#endif    
    BOOLEAN       tasks_waiting;
    OS_FLAG_NODE *pnode;


    if (OSIntNesting > 0) {                                /* See if called from ISR ...               */
        *err = OS_ERR_DEL_ISR;                             /* ... can't DELETE from an ISR             */
        return (pgrp);
    }
#if OS_ARG_CHK_EN > 0
    if (pgrp == (OS_FLAG_GRP *)0) {                        /* Validate 'pgrp'                          */
        *err = OS_FLAG_INVALID_PGRP;
        return (pgrp);
    }
    if (pgrp->OSFlagType != OS_EVENT_TYPE_FLAG) {          /* Validate event group type                */
        *err = OS_ERR_EVENT_TYPE;
        return (pgrp);
    }
#endif
    OS_ENTER_CRITICAL();
    if (pgrp->OSFlagWaitList != (void *)0) {               /* See if any tasks waiting on event flags  */
        tasks_waiting = TRUE;                              /* Yes                                      */
    } else {
        tasks_waiting = FALSE;                             /* No                                       */
    }
    switch (opt) {
        case OS_DEL_NO_PEND:                               /* Delete group if no task waiting          */
             if (tasks_waiting == FALSE) {
                 pgrp->OSFlagType     = OS_EVENT_TYPE_UNUSED;
                 pgrp->OSFlagWaitList = (void *)OSFlagFreeList; /* Return group to free list           */
                 OSFlagFreeList       = pgrp;
                 OS_EXIT_CRITICAL();
                 *err                 = OS_NO_ERR;
                 return ((OS_FLAG_GRP *)0);                /* Event Flag Group has been deleted        */
             } else {