os_sem.lst

ucos移植学习

C51 COMPILER V7.02a   OS_SEM                                                               10/16/2006 15:27:51 PAGE 1   


C51 COMPILER V7.02a, COMPILATION OF MODULE OS_SEM
OBJECT MODULE PLACED IN .\OS_SEM.obj
COMPILER INVOKED BY: d:\Keil\C51\BIN\C51.EXE ..\uc_os_II\OS_SEM.C BROWSE DEBUG OBJECTEXTEND PRINT(.\OS_SEM.lst) OBJECT(.
                    -\OS_SEM.obj)

stmt level    source

   1          /*
   2          *********************************************************************************************************
   3          *                                                uC/OS-II
   4          *                                          The Real-Time Kernel
   5          *                                          SEMAPHORE MANAGEMENT
   6          *
   7          *                        (c) Copyright 1992-1998, Jean J. Labrosse, Plantation, FL
   8          *                                           All Rights Reserved
   9          *
  10          *                                                  V2.00
  11          *
  12          * File : OS_SEM.C
  13          * By   : Jean J. Labrosse
  14          *********************************************************************************************************
  15          */
  16          
  17          #ifndef  OS_MASTER_FILE
  18          #include "includes.h"
  19          #endif
  20          
  21          #if OS_SEM_EN
  22          /*
  23          *********************************************************************************************************
  24          *                                           ACCEPT SEMAPHORE
  25          *
  26          * Description: This function checks the semaphore to see if a resource is available or, if an event
  27          *              occurred.  Unlike OSSemPend(), OSSemAccept() does not suspend the calling task if the
  28          *              resource is not available or the event did not occur.
  29          *
  30          * Arguments  : pevent     is a pointer to the event control block
  31          *
  32          * Returns    : >  0       if the resource is available or the event did not occur the semaphore is
  33          *                         decremented to obtain the resource.
  34          *              == 0       if the resource is not available or the event did not occur or,
  35          *                         you didn't pass a pointer to a semaphore
  36          *********************************************************************************************************
  37          */
  38          
  39          INT16U OSSemAccept (OS_EVENT DT_XDATA *pevent) REENTRANT
  40          {
  41   1          INT16U cnt;
  42   1      
  43   1      
  44   1          OS_ENTER_CRITICAL();
  45   1          if (pevent->OSEventType != OS_EVENT_TYPE_SEM) {   /* Validate event block type                     */
  46   2              OS_EXIT_CRITICAL();
  47   2              return (0);
  48   2          }
  49   1          cnt = pevent->OSEventCnt;
  50   1          if (cnt > 0) {                                    /* See if resource is available                  */
  51   2              pevent->OSEventCnt--;                         /* Yes, decrement semaphore and notify caller    */
  52   2          }
  53   1          OS_EXIT_CRITICAL();
  54   1          return (cnt);                                     /* Return semaphore count                        */
C51 COMPILER V7.02a   OS_SEM                                                               10/16/2006 15:27:51 PAGE 2   

  55   1      }
  56          
  57          /*$PAGE*/
  58          /*
  59          *********************************************************************************************************
  60          *                                           CREATE A SEMAPHORE
  61          *
  62          * Description: This function creates a semaphore.
  63          *
  64          * Arguments  : cnt           is the initial value for the semaphore.  If the value is 0, no resource is
  65          *                            available (or no event has occurred).  You initialize the semaphore to a 
  66          *                            non-zero value to specify how many resources are available (e.g. if you have
  67          *                            10 resources, you would initialize the semaphore to 10).
  68          *
  69          * Returns    : != (void *)0  is a pointer to the event control clock (OS_EVENT) associated with the
  70          *                            created semaphore
  71          *              == (void *)0  if no event control blocks were available
  72          *********************************************************************************************************
  73          */
  74          
  75          OS_EVENT DT_XDATA *OSSemCreate (INT16U cnt) REENTRANT
  76          {
  77   1          OS_EVENT DT_XDATA *pevent;
  78   1      
  79   1      
  80   1          OS_ENTER_CRITICAL();
  81   1          pevent = OSEventFreeList;                              /* Get next free event control block        */
  82   1          if (OSEventFreeList != (OS_EVENT DT_XDATA *)0) {                /* See if pool of free ECB pool was em
             -pty   */
  83   2              OSEventFreeList = (OS_EVENT DT_XDATA *)OSEventFreeList->OSEventPtr;
  84   2          }
  85   1          OS_EXIT_CRITICAL();
  86   1          if (pevent != (OS_EVENT DT_XDATA *)0) {                         /* Get an event control block         
             -      */
  87   2              pevent->OSEventType = OS_EVENT_TYPE_SEM;
  88   2              pevent->OSEventCnt  = cnt;                         /* Set semaphore value                      */
  89   2              OSEventWaitListInit(pevent);
  90   2          }
  91   1          return (pevent);
  92   1      }
  93          
  94          /*$PAGE*/
  95          /*
  96          *********************************************************************************************************
  97          *                                           PEND ON SEMAPHORE
  98          *
  99          * Description: This function waits for a semaphore.
 100          *
 101          * Arguments  : pevent        is a pointer to the event control block associated with the desired 
 102          *                            semaphore.
 103          *
 104          *              timeout       is an optional timeout period (in clock ticks).  If non-zero, your task will
 105          *                            wait for the resource up to the amount of time specified by this argument.  
 106          *                            If you specify 0, however, your task will wait forever at the specified 
 107          *                            semaphore or, until the resource becomes available (or the event occurs).
 108          *
 109          *              err           is a pointer to where an error message will be deposited.  Possible error
 110          *                            messages are:
 111          *
 112          *                            OS_NO_ERR          The call was successful and your task owns the resource 
 113          *                                               or, the event you are waiting for occurred.
 114          *                            OS_TIMEOUT         The semaphore was not received within the specified 
C51 COMPILER V7.02a   OS_SEM                                                               10/16/2006 15:27:51 PAGE 3   

 115          *                                               timeout.
 116          *                            OS_ERR_EVENT_TYPE  If you didn't pass a pointer to a semaphore.
 117          *                            OS_ERR_PEND_ISR    If you called this function from an ISR and the result
 118          *                                               would lead to a suspension.
 119          *
 120          * Returns    : none