os_mbox.src

在51单片机上移植成功的UCOS-II操作系统源代码,包括源代码及相关注释

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

$NOMOD51

NAME	OS_MBOX

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; /*
; *********************************************************************************************************
; *                                                uC/OS-II
; *                                          The Real-Time Kernel
; *                                       MESSAGE MAILBOX MANAGEMENT
; *
; *                        (c) Copyright 1992-1998, Jean J. Labrosse, Plantation, FL
; *                                           All Rights Reserved
; *
; *                                                  V2.00
; *
; * File : OS_MBOX.C
; * By   : Jean J. Labrosse
; *********************************************************************************************************
; */
; 
; #ifndef  OS_MASTER_FILE
; #include "includes.h"
; #endif
; 
; #if OS_MBOX_EN
; /*
; *********************************************************************************************************
; *                                     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 you didn't pass the proper event pointer.
; *********************************************************************************************************
; */
; 
; void *OSMboxAccept (OS_EVENT *pevent) reentrant
; {
;     void  *msg;
; 
; 
;     OS_ENTER_CRITICAL();
;     if (pevent->OSEventType != OS_EVENT_TYPE_MBOX) {      /* Validate event block type                 */
;         OS_EXIT_CRITICAL();
;         return ((void *)0);
;     }
;     msg = pevent->OSEventPtr; 
;     if (msg != (void *)0) {                               /* See if there is already a message         */
;         pevent->OSEventPtr = (void *)0;                   /* Clear the mailbox                         */
;     }
;     OS_EXIT_CRITICAL();
;     return (msg);                                         /* Return the message received (or NULL)     */
; }
; /*$PAGE*/
; /*
; *********************************************************************************************************
; *                                        CREATE A MESSAGE MAILBOX
; *
; * Description: This function creates a message mailbox if free event control blocks are available.
; *
; * Arguments  : msg           is a pointer to a message that you wish to deposit in the mailbox.  If
; *                            you set this value to the NULL pointer (i.e. (void *)0) then the mailbox
; *                            will be considered empty.
; *
; * Returns    : != (void *)0  is a pointer to the event control clock (OS_EVENT) associated with the
; *                            created mailbox
; *              == (void *)0  if no event control blocks were available
; *********************************************************************************************************
; */
; 
; OS_EVENT *OSMboxCreate (void *msg) reentrant
; {
;     OS_EVENT *pevent;
; 
; 
;     OS_ENTER_CRITICAL();
;     pevent = OSEventFreeList;                    /* Get next free event control block                  */
;     if (OSEventFreeList != (OS_EVENT *)0) {      /* See if pool of free ECB pool was empty             */
;         OSEventFreeList = (OS_EVENT *)OSEventFreeList->OSEventPtr;
;     }
;     OS_EXIT_CRITICAL();
;     if (pevent != (OS_EVENT *)0) {
;         pevent->OSEventType = OS_EVENT_TYPE_MBOX;
;         pevent->OSEventPtr  = msg;               /* Deposit message in event control block             */
;         OSEventWaitListInit(pevent);
;     }
;     return (pevent);                             /* Return pointer to event control block              */
; }
; /*$PAGE*/
; /*
; *********************************************************************************************************
; *                                      PEND ON MAILBOX FOR A MESSAGE
; *
; * Description: This function waits for a message to be sent to a mailbox
; *
; * Arguments  : pevent        is a pointer to the event control block associated with the desired mailbox
; *
; *              timeout       is an optional timeout period (in clock ticks).  If non-zero, your task will
; *                            wait for a message to arrive at the mailbox up to the amount of time 
; *                            specified by this argument.  If you specify 0, however, your task will wait 
; *                            forever at the specified mailbox or, until a message arrives.
; *
; *              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 received a message.
; *                            OS_TIMEOUT        A message was not received within the specified timeout
; *                            OS_ERR_EVENT_TYPE Invalid event type
; *                            OS_ERR_PEND_ISR   If you called this function from an ISR and the result
; *                                              would lead to a suspension.
; *
; * Returns    : != (void *)0  is a pointer to the message received
; *              == (void *)0  if no message was received or you didn't pass the proper pointer to the
; *                            event control block.
; *********************************************************************************************************
; */
; 
; void *OSMboxPend (OS_EVENT *pevent, INT16U timeout, INT8U *err) reentrant
; {
;     void  *msg;
; 
; 
;     OS_ENTER_CRITICAL();
;     if (pevent->OSEventType != OS_EVENT_TYPE_MBOX) {  /* Validate event block type                     */
;         OS_EXIT_CRITICAL();
;         *err = OS_ERR_EVENT_TYPE;
;         return ((void *)0);
;     }
;     msg = pevent->OSEventPtr;
;     if (msg != (void *)0) {                           /* See if there is already a message             */
;         pevent->OSEventPtr = (void *)0;               /* Clear the mailbox                             */
;         OS_EXIT_CRITICAL();
;         *err = OS_NO_ERR;
;     } else if (OSIntNesting > 0) {                    /* See if called from ISR ...                    */
;         OS_EXIT_CRITICAL();                           /* ... can't PEND from an ISR                    */
;         *err = OS_ERR_PEND_ISR;
;     } else {
;         OSTCBCur->OSTCBStat |= OS_STAT_MBOX;          /* Message not available, task will pend         */
;         OSTCBCur->OSTCBDly   = timeout;               /* Load timeout in TCB                           */
;         OSEventTaskWait(pevent);                      /* Suspend task until event or timeout occurs    */
;         OS_EXIT_CRITICAL();
;         OSSched();                                    /* Find next highest priority task ready to run  */
;         OS_ENTER_CRITICAL();
;         if ((msg = OSTCBCur->OSTCBMsg) != (void *)0) {     /* See if we were given the message         */
;             OSTCBCur->OSTCBMsg      = (void *)0;           /* Yes, clear message received              */
;             OSTCBCur->OSTCBStat     = OS_STAT_RDY;
;             OSTCBCur->OSTCBEventPtr = (OS_EVENT *)0;       /* No longer waiting for event              */
;             OS_EXIT_CRITICAL();
;             *err                    = OS_NO_ERR;
;         } else if (OSTCBCur->OSTCBStat & OS_STAT_MBOX) {   /* If status is not OS_STAT_RDY, timed out  */
;             OSEventTO(pevent);                             /* Make task ready                          */
;             OS_EXIT_CRITICAL();
;             msg                     = (void *)0;           /* Set message contents to NULL             */
;             *err                    = OS_TIMEOUT;          /* Indicate that a timeout occured          */
;         } else {
;             msg                     = pevent->OSEventPtr;  /* Message received                         */
;             pevent->OSEventPtr      = (void *)0;           /* Clear the mailbox                        */
;             OSTCBCur->OSTCBEventPtr = (OS_EVENT *)0;
;             OS_EXIT_CRITICAL();
;             *err                    = OS_NO_ERR;
;         }
;     }
;     return (msg);                                          /* Return the message received (or NULL)    */
; }
; /*$PAGE*/
; /*
; *********************************************************************************************************
; *                                       POST MESSAGE TO A MAILBOX
; *
; * Description: This function sends a message to a mailbox
; *
; * Arguments  : pevent        is a pointer to the event control block associated with the desired mailbox
; *
; *              msg           is a pointer to the message to send.  You MUST NOT send a NULL pointer.  
; *
; * Returns    : OS_NO_ERR          The call was successful and the message was sent
; *              OS_MBOX_FULL       If the mailbox already contains a message.  You can can only send one
; *                                 message at a time and thus, the message MUST be consumed before you are
; *                                 allowed to send another one.
; *              OS_ERR_EVENT_TYPE  If you are attempting to post to a non mailbox.
; *********************************************************************************************************
; */
; 
; INT8U OSMboxPost (OS_EVENT *pevent, void *msg) reentrant
; {
;     OS_ENTER_CRITICAL();
;     if (pevent->OSEventType != OS_EVENT_TYPE_MBOX) {  /* Validate event block type                     */
;         OS_EXIT_CRITICAL();
;         return (OS_ERR_EVENT_TYPE);
;     }
;     if (pevent->OSEventGrp) {                         /* See if any task pending on mailbox            */
;         OSEventTaskRdy(pevent, msg, OS_STAT_MBOX);    /* Ready highest priority task waiting on event  */
;         OS_EXIT_CRITICAL();
;         OSSched();                                    /* Find highest priority task ready to run       */
;         return (OS_NO_ERR);
;     } else {
;         if (pevent->OSEventPtr != (void *)0) {        /* Make sure mailbox doesn't already have a msg  */
;             OS_EXIT_CRITICAL();
;             return (OS_MBOX_FULL);
;         } else {
;             pevent->OSEventPtr = msg;                 /* Place message in mailbox                      */
;             OS_EXIT_CRITICAL();
;             return (OS_NO_ERR);
;         }
;     }
; }
; /*$PAGE*/
; /*
; *********************************************************************************************************
; *                                        QUERY A MESSAGE MAILBOX
; *
; * Description: This function obtains information about a message mailbox.
; *
; * Arguments  : pevent        is a pointer to the event control block associated with the desired mailbox
; *
; *              pdata         is a pointer to a structure that will contain information about the message
; *                            mailbox.
; *
; * Returns    : OS_NO_ERR          The call was successful and the message was sent
; *              OS_ERR_EVENT_TYPE  If you are attempting to obtain data from a non mailbox.
; *********************************************************************************************************
; */
; 
; INT8U OSMboxQuery (OS_EVENT *pevent, OS_MBOX_DATA *ppdata) reentrant
; {
;     INT8U  i;
;     INT8U *psrc;
;     INT8U *pdest;
;     
;     
;     OS_ENTER_CRITICAL();
;     if (pevent->OSEventType != OS_EVENT_TYPE_MBOX) {       /* Validate event block type                */
;         OS_EXIT_CRITICAL();
;         return (OS_ERR_EVENT_TYPE);
;     }
;     ppdata->OSEventGrp = pevent->OSEventGrp;                /* Copy message mailbox wait list           */
;     psrc              = &pevent->OSEventTbl[0];
;     pdest             = &ppdata->OSEventTbl[0];
;     for (i = 0; i < OS_EVENT_TBL_SIZE; i++) {
;         *pdest++ = *psrc++;   
;     }
;     ppdata->OSMsg = pevent->OSEventPtr;                     /* Get message from mailbox                 */
;     OS_EXIT_CRITICAL();
;     return (OS_NO_ERR);
; }
; #endif
; *** sync lost ***
; *** sync lost ***
; *** sync lost ***
	END