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

$NOMOD51

NAME	OS_Q

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; /*
; *********************************************************************************************************
; *                                                uC/OS-II
; *                                          The Real-Time Kernel
; *                                        MESSAGE QUEUE MANAGEMENT
; *
; *                        (c) Copyright 1992-1998, Jean J. Labrosse, Plantation, FL
; *                                           All Rights Reserved
; *
; *                                                  V2.00
; *
; * File : OS_Q.C
; * By   : Jean J. Labrosse
; *********************************************************************************************************
; */
; 
; #ifndef  OS_MASTER_FILE
; #include "includes.h"
; #endif
; 
; #if OS_Q_EN && (OS_MAX_QS >= 2)
; /*
; *********************************************************************************************************
; *                                           LOCAL DATA TYPES  
; *********************************************************************************************************
; */
; 
; typedef struct os_q {                  /* QUEUE CONTROL BLOCK                                          */
;     struct os_q   *OSQPtr;             /* Link to next queue control block in list of free blocks      */
;     void         **OSQStart;           /* Pointer to start of queue data                               */
;     void         **OSQEnd;             /* Pointer to end   of queue data                               */
;     void         **OSQIn;              /* Pointer to where next message will be inserted  in   the Q   */
;     void         **OSQOut;             /* Pointer to where next message will be extracted from the Q   */
;     INT16U         OSQSize;            /* Size of queue (maximum number of entries)                    */
;     INT16U         OSQEntries;         /* Current number of entries in the queue                       */
; } OS_Q;
; 
; /*
; *********************************************************************************************************
; *                                         LOCAL GLOBAL VARIABLES
; *********************************************************************************************************
; */
; 
; static  OS_Q        *OSQFreeList;              /* Pointer to list of free QUEUE control blocks         */
; static  OS_Q         OSQTbl[OS_MAX_QS];        /* Table of QUEUE control blocks                        */
; 
; /*$PAGE*/
; /*
; *********************************************************************************************************
; *                                      ACCEPT MESSAGE FROM QUEUE
; *
; * Description: This function checks the queue to see if a message is available.  Unlike OSQPend(),
; *              OSQAccept() 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 queue if one is available.  The message is removed
; *                            from the so the next time OSQAccept() is called, the queue will contain
; *                            one less entry.
; *              == (void *)0  if the queue is empty
; *                            if you passed an invalid event type
; *********************************************************************************************************
; */
; 
; void *OSQAccept (OS_EVENT *pevent) reentrant
; {
;     void  *msg;
;     OS_Q  *pq;
; 
; 
;     OS_ENTER_CRITICAL();
;     if (pevent->OSEventType != OS_EVENT_TYPE_Q) {     /* Validate event block type                     */
;         OS_EXIT_CRITICAL();
;         return ((void *)0);
;     }
;     pq = pevent->OSEventPtr;                     /* Point at queue control block                       */
;     if (pq->OSQEntries != 0) {                   /* See if any messages in the queue                   */
;         msg = *pq->OSQOut++;                     /* Yes, extract oldest message from the queue         */
;         pq->OSQEntries--;                        /* Update the number of entries in the queue          */
;         if (pq->OSQOut == pq->OSQEnd) {          /* Wrap OUT pointer if we are at the end of the queue */
;             pq->OSQOut = pq->OSQStart;
;         }
;     } else {
;         msg = (void *)0;                         /* Queue is empty                                     */
;     }
;     OS_EXIT_CRITICAL();
;     return (msg);                                /* Return message received (or NULL)                  */
; }
; /*$PAGE*/
; /*
; *********************************************************************************************************
; *                                        CREATE A MESSAGE QUEUE
; *
; * Description: This function creates a message queue if free event control blocks are available.
; *
; * Arguments  : start         is a pointer to the base address of the message queue storage area.  The
; *                            storage area MUST be declared as an array of pointers to 'void' as follows
; *
; *                            void *MessageStorage[size]
; *
; *              size          is the number of elements in the storage area
; *
; * Returns    : != (void *)0  is a pointer to the event control clock (OS_EVENT) associated with the
; *                            created queue
; *              == (void *)0  if no event control blocks were available
; *********************************************************************************************************
; */
; 
; OS_EVENT *OSQCreate (void **start, INT16U size) reentrant
; {
;     OS_EVENT *pevent;
;     OS_Q     *pq;
; 
; 
;     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) {               /* See if we have an event control block              */
;         OS_ENTER_CRITICAL();                     /* Get a free queue control block                     */
;         pq = OSQFreeList;
;         if (OSQFreeList != (OS_Q *)0) {
;             OSQFreeList = OSQFreeList->OSQPtr;
;         }
;         OS_EXIT_CRITICAL();
;         if (pq != (OS_Q *)0) {                   /* See if we were able to get a queue control block   */
;             pq->OSQStart        = start;         /* Yes, initialize the queue                          */
;             pq->OSQEnd          = &start[size];
;             pq->OSQIn           = start;
;             pq->OSQOut          = start;
;             pq->OSQSize         = size;
;             pq->OSQEntries      = 0;
;             pevent->OSEventType = OS_EVENT_TYPE_Q;
;             pevent->OSEventPtr  = pq;
;             OSEventWaitListInit(pevent);
;         } else {                                 /* No,  since we couldn't get a queue control block   */
;             OS_ENTER_CRITICAL();                 /* Return event control block on error                */
;             pevent->OSEventPtr = (void *)OSEventFreeList;
;             OSEventFreeList    = pevent;
;             OS_EXIT_CRITICAL();
;             pevent = (OS_EVENT *)0;
;         }
;     }
;     return (pevent);
; }
; /*$PAGE*/
; /*
; *********************************************************************************************************
; *                                           FLUSH QUEUE
; *
; * Description : This function is used to flush the contents of the message queue.
; *
; * Arguments   : none
; *
; * Returns     : OS_NO_ERR          upon success
; *               OS_ERR_EVENT_TYPE  If you didn't pass a pointer to a queue
; *********************************************************************************************************
; */
; 
; INT8U OSQFlush (OS_EVENT *pevent) reentrant
; {
;     OS_Q  *pq;
;     
; 
;     OS_ENTER_CRITICAL();
;     if (pevent->OSEventType != OS_EVENT_TYPE_Q) {     /* Validate event block type                     */
;         OS_EXIT_CRITICAL();
;         return (OS_ERR_EVENT_TYPE);
;     }
;     pq             = pevent->OSEventPtr;              /* Point to queue storage structure              */
;     pq->OSQIn      = pq->OSQStart;
;     pq->OSQOut     = pq->OSQStart;
;     pq->OSQEntries = 0;
;     OS_EXIT_CRITICAL();
;     return (OS_NO_ERR);
; }
; 
; /*$PAGE*/
; /*
; *********************************************************************************************************
; *                                      QUEUE MODULE INITIALIZATION
; *
; * Description : This function is called by uC/OS-II to initialize the message queue module.  Your