; .\OS_MBOX.SRC generated from: SOURCE\OS_MBOX.C
; COMPILER INVOKED BY:
;        D:\tools\Keil\C51\BIN\C51.EXE SOURCE\OS_MBOX.C LARGE OPTIMIZE(SIZE) REGFILE(.\OS_AT89C55WD.ORC) BROWSE NOINTPROMOTE INCDIR(D:\MY\empolder\uCOS-II\MCS-51\AT89C55WD\Keil 7_5\) DEBUG OBJECTEXTEND NOPRINT SRC(.\OS_MBOX.SRC)

$NOMOD51

NAME	OS_MBOX

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; /*
; *********************************************************************************************************
; *                                                uC/OS-II
; *                                          The Real-Time Kernel
; *                                       MESSAGE MAILBOX MANAGEMENT
; *
; *                          (c) Copyright 1992-2002, Jean J. Labrosse, Weston, FL
; *                                           All Rights Reserved
; *
; * File : OS_MBOX.C
; * By   : Jean J. Labrosse
; *********************************************************************************************************
; */
; 
; #ifndef  OS_MASTER_FILE
; #include "includes.h"
; #endif
; 
; #if OS_MBOX_EN > 0
; /*
; *********************************************************************************************************
; *                                     ACCEPT MESSAGE FROM MAILBOX
; *
; * Description: This function checks the mailbox to see if a message is available.  Unlike OSMboxPend(),
; *              OSMboxAccept() does not suspend the calling task if a message is not available.
; *
; * Arguments  : pevent        is a pointer to the event control block
; *
; * Returns    : != (void *)0  is the message in the mailbox if one is available.  The mailbox is cleared
; *                            so the next time OSMboxAccept() is called, the mailbox will be empty.
; *              == (void *)0  if the mailbox is empty or,
; *                            if 'pevent' is a NULL pointer or,
; *                            if you didn't pass the proper event pointer.
; *********************************************************************************************************
; */
; 
; #if OS_MBOX_ACCEPT_EN > 0
; void  *OSMboxAccept (OS_EVENT *pevent)LG_REENTRANT
; {
; #if OS_CRITICAL_METHOD == 3                      /* Allocate storage for CPU status register           */
;     OS_CPU_SR  cpu_sr;
; #endif    
;     void      *msg;
; 
; 
; #if OS_ARG_CHK_EN > 0
;     if (pevent == (OS_EVENT *)0) {                        /* Validate 'pevent'                         */
;         return ((void *)0);
;     }
;     if (pevent->OSEventType != OS_EVENT_TYPE_MBOX) {      /* Validate event block type                 */
;         return ((void *)0);
;     }
; #endif
;     OS_ENTER_CRITICAL();
;     msg                = pevent->OSEventPtr;
;     pevent->OSEventPtr = (void *)0;                       /* Clear the mailbox                         */
;     OS_EXIT_CRITICAL();
;     return (msg);                                         /* Return the message received (or NULL)     */
; }
; #endif
; /*$PAGE*/
; /*
; *********************************************************************************************************
; *                                        CREATE A MESSAGE MAILBOX
; *
; * Description: This function creates a message mailbox if free event control blocks are available.
; *
; * Arguments  : msg           is a pointer to a message that you wish to deposit in the mailbox.  If
; *                            you set this value to the NULL pointer (i.e. (void *)0) then the mailbox
; *                            will be considered empty.
; *
; * Returns    : != (OS_EVENT *)0  is a pointer to the event control clock (OS_EVENT) associated with the
; *                                created mailbox
; *              == (OS_EVENT *)0  if no event control blocks were available
; *********************************************************************************************************
; */
; 
; OS_EVENT  *OSMboxCreate (void *msg)LG_REENTRANT
; {
; #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 ...                         */
;         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) {
;         pevent->OSEventType = OS_EVENT_TYPE_MBOX;
;         pevent->OSEventCnt  = 0;
;         pevent->OSEventPtr  = msg;               /* Deposit message in event control block             */
;         OS_EventWaitListInit(pevent);
;     }
;     return (pevent);                             /* Return pointer to event control block              */
; }
; /*$PAGE*/
; /*
; *********************************************************************************************************
; *                                         DELETE A MAIBOX
; *
; * Description: This function deletes a mailbox and readies all tasks pending on the mailbox.
; *
; * Arguments  : pevent        is a pointer to the event control block associated with the desired
; *                            mailbox.
; *
; *              opt           determines delete options as follows:
; *                            opt == OS_DEL_NO_PEND   Delete the mailbox ONLY if no task pending
; *                            opt == OS_DEL_ALWAYS    Deletes the mailbox 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 mailbox was deleted
; *                            OS_ERR_DEL_ISR          If you attempted to delete the mailbox from an ISR
; *                            OS_ERR_INVALID_OPT      An invalid option was specified
; *                            OS_ERR_TASK_WAITING     One or more tasks were waiting on the mailbox
; *                            OS_ERR_EVENT_TYPE       If you didn't pass a pointer to a mailbox
; *                            OS_ERR_PEVENT_NULL      If 'pevent' is a NULL pointer.
; *
; * Returns    : pevent        upon error
; *              (OS_EVENT *)0 if the mailbox was successfully deleted.
; *
; * Note(s)    : 1) This function must be used with care.  Tasks that would normally expect the presence of
; *                 the mailbox MUST check the return code of OSMboxPend().
; *              2) OSMboxAccept() callers will not know that the intended mailbox has been deleted!
; *              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 mailbox.
; *              4) Because ALL tasks pending on the mailbox will be readied, you MUST be careful in
; *                 applications where the mailbox is used for mutual exclusion because the resource(s)
; *                 will no longer be guarded by the mailbox.
; *********************************************************************************************************
; */
; 
; #if OS_MBOX_DEL_EN > 0
; OS_EVENT  *OSMboxDel (OS_EVENT *pevent, INT8U opt, INT8U *err)LG_REENTRANT
; {
; #if OS_CRITICAL_METHOD == 3                                /* Allocate storage for CPU status register */
;     OS_CPU_SR  cpu_sr;
; #endif    
;     BOOLEAN    tasks_waiting;
; 
; 
;     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 (pevent);
;     }
;     if (pevent->OSEventType != OS_EVENT_TYPE_MBOX) {       /* 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 mailbox      */
;         tasks_waiting = TRUE;                              /* Yes                                      */
;     } else {
;         tasks_waiting = FALSE;                             /* No                                       */
;     }
;     switch (opt) {
;         case OS_DEL_NO_PEND:                               /* Delete mailbox only if no task waiting   */
;              if (tasks_waiting == FALSE) {
;                  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();
;                  *err = OS_NO_ERR;
;                  return ((OS_EVENT *)0);                   /* Mailbox has been deleted                 */
;              } else {
;                  OS_EXIT_CRITICAL();
;                  *err = OS_ERR_TASK_WAITING;
;                  return (pevent);
;              }
; 
;         case OS_DEL_ALWAYS:                                /* Always delete the mailbox                */
;              while (pevent->OSEventGrp != 0x00) {          /* Ready ALL tasks waiting for mailbox      */
;                  OS_EventTaskRdy(pevent, (void *)0, OS_STAT_MBOX);
;              }
;              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  */