C51 COMPILER V8.01   SCH51                                                                 07/13/2008 18:02:06 PAGE 1   


C51 COMPILER V8.01, COMPILATION OF MODULE SCH51
OBJECT MODULE PLACED IN SCH51.OBJ
COMPILER INVOKED BY: C:\Keil\C51\BIN\C51.EXE SCH51.C OPTIMIZE(6,SIZE) BROWSE DEBUG OBJECTEXTEND

line level    source

   1          /*------------------------------------------------------------------*-
   2          
   3             SCH51.C (v1.00) 
   4          
   5            ------------------------------------------------------------------
   6          
   7             *** THESE ARE THE CORE SCHEDULER FUNCTIONS ***
   8             --- These functions may be used with all 8051 devices ---
   9          
  10             *** SCH_MAX_TASKS *must* be set by the user ***
  11             --- see "Sch51.H" ---
  12          
  13             *** Includes (optional) power-saving mode ***
  14             --- You must ensure that the power-down mode is adapted ---
  15             --- to match your chosen device (or disabled altogether) ---
  16          
  17          
  18             COPYRIGHT
  19             ---------
  20          
  21             This code is from the book:
  22          
  23             PATTERNS FOR TIME-TRIGGERED EMBEDDED SYSTEMS by Michael J. Pont 
  24             [Pearson Education, 2001; ISBN: 0-201-33138-1].
  25          
  26             This code is copyright (c) 2001 by Michael J. Pont.
  27           
  28             See book for copyright details and other information.
  29          
  30          -*------------------------------------------------------------------*/
  31          
  32          #include "Main.h"
  33          #include "Port.h"
  34          
  35          #include "Sch51.h"
  36          
  37          // ------ Public variable definitions ------------------------------
  38          
  39          // The array of tasks
  40          sTask SCH_tasks_G[SCH_MAX_TASKS];
  41          
  42          // Used to display the error code
  43          // See Main.H for details of error codes
  44          // See Port.H for details of the error port
  45          tByte Error_code_G = 0;
  46          
  47          // ------ Private function prototypes ------------------------------
  48          
  49          static void SCH_Go_To_Sleep(void);
  50          
  51          // ------ Private variables ----------------------------------------
  52          
  53          // Keeps track of time since last error was recorded (see below)
  54          static tWord Error_tick_count_G;
  55          
C51 COMPILER V8.01   SCH51                                                                 07/13/2008 18:02:06 PAGE 2   

  56          // The code of the last error (reset after ~1 minute)
  57          static tByte Last_error_code_G;
  58          
  59          
  60          /*------------------------------------------------------------------*-
  61          
  62            SCH_Dispatch_Tasks()
  63          
  64            This is the 'dispatcher' function.  When a task (function)
  65            is due to run, SCH_Dispatch_Tasks() will run it.
  66            This function must be called (repeatedly) from the main loop.
  67          
  68          -*------------------------------------------------------------------*/
  69          void SCH_Dispatch_Tasks(void) 
  70             {
  71   1         tByte Index;
  72   1      
  73   1         // Dispatches (runs) the next task (if one is ready)
  74   1         for (Index = 0; Index < SCH_MAX_TASKS; Index++)
  75   1            {
  76   2            if (SCH_tasks_G[Index].RunMe > 0) 
  77   2               {
  78   3               (*SCH_tasks_G[Index].pTask)();  // Run the task
  79   3      
  80   3               SCH_tasks_G[Index].RunMe -= 1;   // Reset / reduce RunMe flag
  81   3      
  82   3               // Periodic tasks will automatically run again
  83   3               // - if this is a 'one shot' task, remove it from the array
  84   3               if (SCH_tasks_G[Index].Period == 0)
  85   3                  {
  86   4                  SCH_Delete_Task(Index);
  87   4                  }
  88   3               }
  89   2            }
  90   1      
  91   1         // Report system status
  92   1         SCH_Report_Status();  
  93   1      
  94   1         // The scheduler enters idle mode at this point 
  95   1         SCH_Go_To_Sleep();          
  96   1         }
  97          
  98          /*------------------------------------------------------------------*-
  99          
 100            SCH_Add_Task()
 101          
 102            Causes a task (function) to be executed at regular intervals 
 103            or after a user-defined delay
 104          
 105            Fn_P   - The name of the function which is to be scheduled.
 106                     NOTE: All scheduled functions must be 'void, void' -
 107                     that is, they must take no parameters, and have 
 108                     a void return type. 
 109                             
 110            DELAY  - The interval (TICKS) before the task is first executed
 111          
 112            PERIOD - If 'PERIOD' is 0, the function is only called once,
 113                     at the time determined by 'DELAY'.  If PERIOD is non-zero,
 114                     then the function is called repeatedly at an interval
 115                     determined by the value of PERIOD (see below for examples
 116                     which should help clarify this).
 117          
C51 COMPILER V8.01   SCH51                                                                 07/13/2008 18:02:06 PAGE 3   

 118          
 119            RETURN VALUE:  
 120          
 121            Returns the position in the task array at which the task has been 
 122            added.  If the return value is SCH_MAX_TASKS then the task could 
 123            not be added to the array (there was insufficient space).  If the
 124            return value is < SCH_MAX_TASKS, then the task was added 
 125            successfully.  
 126          
 127            Note: this return value may be required, if a task is
 128            to be subsequently deleted - see SCH_Delete_Task().
 129          
 130            EXAMPLES:
 131          
 132            Task_ID = SCH_Add_Task(Do_X,1000,0);
 133            Causes the function Do_X() to be executed once after 1000 sch ticks.            
 134          
 135            Task_ID = SCH_Add_Task(Do_X,0,1000);
 136            Causes the function Do_X() to be executed regularly, every 1000 sch ticks.            
 137          
 138            Task_ID = SCH_Add_Task(Do_X,300,1000);
 139            Causes the function Do_X() to be executed regularly, every 1000 ticks.
 140            Task will be first executed at T = 300 ticks, then 1300, 2300, etc.            
 141           
 142          -*------------------------------------------------------------------*/
 143          tByte SCH_Add_Task(void (code * pFunction)(), 
 144                             const tWord DELAY, 
 145                             const tWord PERIOD)    
 146             {
 147   1         tByte Index = 0;
 148   1         
 149   1         // First find a gap in the array (if there is one) //注意在這里 MAIN（）運行了SCH_Delete_Task(const tBy
             -te TASK_INDEX) 
 150   1         //就把所有的任務     的函數指針SCH_tasks_G[Index].pTask清零了，所以如果沒有添加的任務，SCH_tasks_G[Index].p
             -Task == 0
 151   1         while ((SCH_tasks_G[Index].pTask != 0) && (Index < SCH_MAX_TASKS))
 152   1            {
 153   2            Index++;
 154   2            } 
 155   1         
 156   1         // Have we reached the end of the list?   
 157   1         if (Index == SCH_MAX_TASKS)
 158   1            {