LUFA/Scheduler/Scheduler.h

   1 /*
   2              LUFA Library
   3      Copyright (C) Dean Camera, 2009.
   4
   5   dean [at] fourwalledcubicle [dot] com
   6       www.fourwalledcubicle.com
   7 */
   8
   9 /*
  10   Copyright 2009  Dean Camera (dean [at] fourwalledcubicle [dot] com)
  11
  12   Permission to use, copy, modify, and distribute this software
  13   and its documentation for any purpose and without fee is hereby
  14   granted, provided that the above copyright notice appear in all
  15   copies and that both that the copyright notice and this
  16   permission notice and warranty disclaimer appear in supporting
  17   documentation, and that the name of the author not be used in
  18   advertising or publicity pertaining to distribution of the
  19   software without specific, written prior permission.
  20
  21   The author disclaim all warranties with regard to this
  22   software, including all implied warranties of merchantability
  23   and fitness.  In no event shall the author be liable for any
  24   special, indirect or consequential damages or any damages
  25   whatsoever resulting from loss of use, data or profits, whether
  26   in an action of contract, negligence or other tortious action,
  27   arising out of or in connection with the use or performance of
  28   this software.
  29 */
  30
  31 /** \file
  32  *
  33  *  Simple round-robbin cooperative scheduler for use in basic projects where non real-time tasks need
  34  *  to be executed. Each task is executed in sequence, and can be enabled or disabled individually or as a group.
  35  *
  36  *  For a task to yield it must return, thus each task should have persistent data marked with the static attribute.
  37  *
  38  *  Usage Example:
  39  *  \code
  40  *      #include <LUFA/Scheduler/Scheduler.h>
  41  *
  42  *      TASK(MyTask1);
  43  *      TASK(MyTask2);
  44  *
  45  *      TASK_LIST
  46  *      {
  47  *              { Task: MyTask1, TaskStatus: TASK_RUN, GroupID: 1  },
  48  *              { Task: MyTask2, TaskStatus: TASK_RUN, GroupID: 1  },
  49  *      }
  50  *
  51  *      int main(void)
  52  *      {
  53  *              Scheduler_Start();
  54  *      }
  55  *
  56  *      TASK(MyTask1)
  57  *      {
  58  *              // Implementation Here
  59  *      }
  60  *
  61  *      TASK(MyTask2)
  62  *      {
  63  *              // Implementation Here
  64  *      }
  65  *  \endcode
  66  */
  67
  68 #ifndef __SCHEDULER_H__
  69 #define __SCHEDULER_H__
  70
  71         /* Includes: */
  72                 #include <avr/io.h>
  73                 #include <stdbool.h>
  74
  75                 #include <util/atomic.h>
  76
  77                 #include "../Common/Common.h"
  78
  79         /* Enable C linkage for C++ Compilers: */
  80                 #if defined(__cplusplus)
  81                         extern "C" {
  82                 #endif
  83
  84         /* Public Interface - May be used in end-application: */
  85                 /* Macros: */
  86                         /** Creates a new scheduler task body or prototype. Should be used in the form:
  87                          *  \code
  88                          *      TASK(TaskName); // Prototype
  89                          *
  90                          *      TASK(TaskName)
  91                          *      {
  92                          *           // Task body
  93                          *      }
  94                          *  \endcode
  95                          */
  96                         #define TASK(name)                        void name (void)
  97
  98                         /** Defines a task list array, containing one or more task entries of the type TaskEntry_t. Each task list
  99                          *  should be encased in curly braces and ended with a comma.
 100                          *
 101                          *  Usage Example:
 102                          *  \code
 103                          *      TASK_LIST
 104                          *      {
 105                          *           { Task: MyTask1, TaskStatus: TASK_RUN, GroupID: 1 },
 106                          *           // More task entries here
 107                          *      }
 108                          *  \endcode
 109                          */
 110                         #define TASK_LIST                         extern TaskEntry_t Scheduler_TaskList[]; TaskEntry_t Scheduler_TaskList[] =
 111
 112                         /** Constant, giving the maximum delay in scheduler ticks which can be stored in a variable of type
 113                          *  SchedulerDelayCounter_t.
 114                          */
 115                         #define TASK_MAX_DELAY                    (MAX_DELAYCTR_COUNT - 1)
 116
 117                         /** Task status mode constant, for passing to Scheduler_SetTaskMode() or Scheduler_SetGroupTaskMode(). */
 118                         #define TASK_RUN                          true
 119
 120                         /** Task status mode constant, for passing to Scheduler_SetTaskMode() or Scheduler_SetGroupTaskMode(). */
 121                         #define TASK_STOP                         false
 122
 123                         /** Starts the scheduler in its infinite loop, executing running tasks. This should be placed at the end
 124                          *  of the user application's main() function, as it can never return to the calling function.
 125                          */
 126                         #define Scheduler_Start()                 Scheduler_GoSchedule(TOTAL_TASKS);
 127
 128                         /** Initializes the scheduler so that the scheduler functions can be called before the scheduler itself
 129                          *  is started. This must be executed before any scheduler function calls other than Scheduler_Start(),
 130                          *  and can be omitted if no such functions could be called before the scheduler is started.
 131                          */
 132                         #define Scheduler_Init()                  Scheduler_InitScheduler(TOTAL_TASKS);
 133
 134                 /* Type Defines: */
 135                         /** Type define for a pointer to a scheduler task. */
 136                         typedef void (*TaskPtr_t)(void);
 137
 138                         /** Type define for a variable which can hold a tick delay value for the scheduler up to the maximum delay
 139                          *  possible.
 140                          */
 141                         typedef uint16_t SchedulerDelayCounter_t;
 142
 143                         /** Structure for holding a single task's information in the scheduler task list. */
 144                         typedef struct
 145                         {
 146                                 TaskPtr_t Task;       /**< Pointer to the task to execute. */
 147                                 bool      TaskStatus; /**< Status of the task (either TASK_RUN or TASK_STOP). */
 148                                 uint8_t   GroupID;    /**< Group ID of the task so that its status can be changed as a group. */
 149                         } TaskEntry_t;
 150
 151                 /* Global Variables: */
 152                         /** Task entry list, containing the scheduler tasks, task statuses and group IDs. Each entry is of type
 153                          *  TaskEntry_t and can be manipulated as desired, although it is preferential that the proper Scheduler
 154                          *  functions should be used instead of direct manipulation.
 155                          */
 156                         extern          TaskEntry_t               Scheduler_TaskList[];
 157
 158                         /** Contains the total number of tasks in the task list, irrespective of if the task's status is set to
 159                          *  TASK_RUN or TASK_STOP.
 160                          *
 161                          *  \note This value should be treated as read-only, and never altered in user-code.
 162                          */
 163                         extern volatile uint8_t                   Scheduler_TotalTasks;
 164
 165                         /**  Contains the current scheduler tick count, for use with the delay functions. If the delay functions
 166                          *   are used in the user code, this should be incremented each tick period so that the delays can be
 167                          *   calculated.
 168                          */
 169                         extern volatile SchedulerDelayCounter_t   Scheduler_TickCounter;
 170
 171                 /* Inline Functions: */
 172                         /** Resets the delay counter value to the current tick count. This should be called to reset the period
 173                          *  for a delay in a task which is dependant on the current tick value.
 174                          *
 175                          *  \param DelayCounter  Counter which is storing the starting tick count for a given delay.
 176                          */
 177                         static inline void Scheduler_ResetDelay(SchedulerDelayCounter_t* const DelayCounter)
 178                                                                 ATTR_NON_NULL_PTR_ARG(1) ATTR_ALWAYS_INLINE;
 179                         static inline void Scheduler_ResetDelay(SchedulerDelayCounter_t* const DelayCounter)
 180                         {
 181                                 ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
 182                                 {
 183                                         *DelayCounter = Scheduler_TickCounter;
 184                                 }
 185                         }
 186
 187                 /* Function Prototypes: */
 188                         /** Determines if the given tick delay has elapsed, based on the given .
 189                          *
 190                          *  \param Delay         The delay to test for, measured in ticks
 191                          *  \param DelayCounter  The counter which is storing the starting tick value for the delay
 192                          *
 193                          *  \return Boolean true if the delay has elapsed, false otherwise
 194                          *
 195                          *  Usage Example:
 196                          *  \code
 197                          *      static SchedulerDelayCounter_t DelayCounter = 10000; // Force immediate run on start-up
 198                          *
 199                          *      // Task runs every 10000 ticks, 10 seconds for this demo
 200                          *      if (Scheduler_HasDelayElapsed(10000, &DelayCounter))
 201                          *      {
 202                          *           // Code to execute after delay interval elapsed here
 203                          *      }
 204                          *  \endcode
 205                          */
 206                         bool Scheduler_HasDelayElapsed(const uint16_t Delay,
 207                                                        SchedulerDelayCounter_t* const DelayCounter)
 208                                                                                    ATTR_WARN_UNUSED_RESULT ATTR_NON_NULL_PTR_ARG(2);
 209
 210                         /** Sets the task mode for a given task.
 211                          *
 212                          *  \param Task        Name of the task whose status is to be changed
 213                          *  \param TaskStatus  New task status for the task (TASK_RUN or TASK_STOP)
 214                          */
 215                         void Scheduler_SetTaskMode(const TaskPtr_t Task, const bool TaskStatus);
 216
 217                         /** Sets the task mode for a given task group ID, allowing for an entire group of tasks to have their
 218                          *  statuses changed at once.
 219                          *
 220                          *  \param GroupID     Value of the task group ID whose status is to be changed
 221                          *  \param TaskStatus  New task status for tasks in the specified group (TASK_RUN or TASK_STOP)
 222                          */
 223                         void Scheduler_SetGroupTaskMode(const uint8_t GroupID, const bool TaskStatus);
 224
 225         /* Private Interface - For use in library only: */
 226         #if !defined(__DOXYGEN__)
 227                 /* Macros: */
 228                         #define TOTAL_TASKS                       (sizeof(Scheduler_TaskList) / sizeof(TaskEntry_t))
 229                         #define MAX_DELAYCTR_COUNT                0xFFFF
 230
 231                 /* Inline Functions: */
 232                         static inline void Scheduler_InitScheduler(const uint8_t TotalTasks) ATTR_ALWAYS_INLINE;
 233                         static inline void Scheduler_InitScheduler(const uint8_t TotalTasks)
 234                         {
 235                                 Scheduler_TotalTasks = TotalTasks;
 236                         }
 237
 238                         static inline void Scheduler_GoSchedule(const uint8_t TotalTasks) ATTR_NO_RETURN ATTR_ALWAYS_INLINE;
 239                         static inline void Scheduler_GoSchedule(const uint8_t TotalTasks)
 240                         {
 241                                 Scheduler_InitScheduler(TotalTasks);
 242
 243                                 for (;;)
 244                                 {
 245                                         TaskEntry_t* CurrTask = &Scheduler_TaskList[0];
 246
 247                                         while (CurrTask != &Scheduler_TaskList[TotalTasks])
 248                                         {
 249                                                 if (CurrTask->TaskStatus == TASK_RUN)
 250                                                   CurrTask->Task();
 251
 252                                                 CurrTask++;
 253                                         }
 254                                 }
 255                         }
 256         #endif
 257
 258         /* Disable C linkage for C++ Compilers: */
 259                 #if defined(__cplusplus)
 260                         }
 261                 #endif
 262
 263 #endif