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
  37 /** @defgroup Group_Scheduler Simple Task Scheduler - LUFA/Scheduler/Scheduler.h
  38  *
  39  *  \section Sec_Dependencies Module Source Dependencies
  40  *  The following files must be built with any user project that uses this module:
  41  *    - LUFA/Scheduler/Scheduler.c
  42  *
  43  *  \section Module Description
  44  *  Simple round-robbin cooperative scheduler for use in basic projects where non real-time tasks need
  45  *  to be executed. Each task is executed in sequence, and can be enabled or disabled individually or as a group.
  46  *
  47  *  For a task to yield it must return, thus each task should have persistent data marked with the static attribute.
  48  *
  49  *  Usage Example:
  50  *  \code
  51  *      #include <LUFA/Scheduler/Scheduler.h>
  52  *
  53  *      TASK(MyTask1);
  54  *      TASK(MyTask2);
  55  *
  56  *      TASK_LIST
  57  *      {
  58  *              { Task: MyTask1, TaskStatus: TASK_RUN, GroupID: 1  },
  59  *              { Task: MyTask2, TaskStatus: TASK_RUN, GroupID: 1  },
  60  *      }
  61  *
  62  *      int main(void)
  63  *      {
  64  *              Scheduler_Start();
  65  *      }
  66  *
  67  *      TASK(MyTask1)
  68  *      {
  69  *              // Implementation Here
  70  *      }
  71  *
  72  *      TASK(MyTask2)
  73  *      {
  74  *              // Implementation Here
  75  *      }
  76  *  \endcode
  77  *
  78  *  @{
  79  */
  80
  81 #ifndef __SCHEDULER_H__
  82 #define __SCHEDULER_H__
  83
  84         /* Includes: */
  85                 #include <avr/io.h>
  86                 #include <stdbool.h>
  87
  88                 #include <util/atomic.h>
  89
  90                 #include "../Common/Common.h"
  91
  92         /* Enable C linkage for C++ Compilers: */
  93                 #if defined(__cplusplus)
  94                         extern "C" {
  95                 #endif
  96
  97         /* Public Interface - May be used in end-application: */
  98                 /* Macros: */
  99                         /** Creates a new scheduler task body or prototype. Should be used in the form:
 100                          *  \code
 101                          *      TASK(TaskName); // Prototype
 102                          *
 103                          *      TASK(TaskName)
 104                          *      {
 105                          *           // Task body
 106                          *      }
 107                          *  \endcode
 108                          */
 109                         #define TASK(name)                        void name (void)
 110
 111                         /** Defines a task list array, containing one or more task entries of the type TaskEntry_t. Each task list
 112                          *  should be encased in curly braces and ended with a comma.
 113                          *
 114                          *  Usage Example:
 115                          *  \code
 116                          *      TASK_LIST
 117                          *      {
 118                          *           { Task: MyTask1, TaskStatus: TASK_RUN, GroupID: 1 },
 119                          *           // More task entries here
 120                          *      }
 121                          *  \endcode
 122                          */
 123                         #define TASK_LIST                         TaskEntry_t Scheduler_TaskList[] =
 124
 125                         /** Constant, giving the maximum delay in scheduler ticks which can be stored in a variable of type
 126                          *  SchedulerDelayCounter_t.
 127                          */
 128                         #define TASK_MAX_DELAY                    (MAX_DELAYCTR_COUNT - 1)
 129
 130                         /** Task status mode constant, for passing to Scheduler_SetTaskMode() or Scheduler_SetGroupTaskMode(). */
 131                         #define TASK_RUN                          true
 132
 133                         /** Task status mode constant, for passing to Scheduler_SetTaskMode() or Scheduler_SetGroupTaskMode(). */
 134                         #define TASK_STOP                         false
 135
 136                 /* Pseudo-Function Macros: */
 137                         #if defined(__DOXYGEN__)
 138                                 /** Starts the scheduler in its infinite loop, executing running tasks. This should be placed at the end
 139                                  *  of the user application's main() function, as it can never return to the calling function.
 140                                  */
 141                                 void Scheduler_Start(void);
 142
 143                                 /** Initializes the scheduler so that the scheduler functions can be called before the scheduler itself
 144                                  *  is started. This must be executed before any scheduler function calls other than Scheduler_Start(),
 145                                  *  and can be omitted if no such functions could be called before the scheduler is started.
 146                                  */
 147                                 void Scheduler_Init(void);
 148                         #else
 149                                 #define Scheduler_Start()                 Scheduler_GoSchedule(TOTAL_TASKS);
 150
 151                                 #define Scheduler_Init()                  Scheduler_InitScheduler(TOTAL_TASKS);
 152                         #endif
 153
 154                 /* Type Defines: */
 155                         /** Type define for a pointer to a scheduler task. */
 156                         typedef void (*TaskPtr_t)(void);
 157
 158                         /** Type define for a variable which can hold a tick delay value for the scheduler up to the maximum delay
 159                          *  possible.
 160                          */
 161                         typedef uint16_t SchedulerDelayCounter_t;
 162
 163                         /** Structure for holding a single task's information in the scheduler task list. */
 164                         typedef struct
 165                         {
 166                                 TaskPtr_t Task;       /**< Pointer to the task to execute. */
 167                                 bool      TaskStatus; /**< Status of the task (either TASK_RUN or TASK_STOP). */
 168                                 uint8_t   GroupID;    /**< Group ID of the task so that its status can be changed as a group. */
 169                         } TaskEntry_t;
 170
 171                 /* Global Variables: */
 172                         /** Task entry list, containing the scheduler tasks, task statuses and group IDs. Each entry is of type
 173                          *  TaskEntry_t and can be manipulated as desired, although it is preferential that the proper Scheduler
 174                          *  functions should be used instead of direct manipulation.
 175                          */
 176                         extern          TaskEntry_t               Scheduler_TaskList[];
 177
 178                         /** Contains the total number of tasks in the task list, irrespective of if the task's status is set to
 179                          *  TASK_RUN or TASK_STOP.
 180                          *
 181                          *  \note This value should be treated as read-only, and never altered in user-code.
 182                          */
 183                         extern volatile uint8_t                   Scheduler_TotalTasks;
 184
 185                         /**  Contains the current scheduler tick count, for use with the delay functions. If the delay functions
 186                          *   are used in the user code, this should be incremented each tick period so that the delays can be
 187                          *   calculated.
 188                          */
 189                         extern volatile SchedulerDelayCounter_t   Scheduler_TickCounter;
 190
 191                 /* Inline Functions: */
 192                         /** Resets the delay counter value to the current tick count. This should be called to reset the period
 193                          *  for a delay in a task which is dependant on the current tick value.
 194                          *
 195                          *  \param DelayCounter  Counter which is storing the starting tick count for a given delay.
 196                          */
 197                         static inline void Scheduler_ResetDelay(SchedulerDelayCounter_t* const DelayCounter)
 198                                                                 ATTR_NON_NULL_PTR_ARG(1) ATTR_ALWAYS_INLINE;
 199                         static inline void Scheduler_ResetDelay(SchedulerDelayCounter_t* const DelayCounter)
 200                         {
 201                                 ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
 202                                 {
 203                                         *DelayCounter = Scheduler_TickCounter;
 204                                 }
 205                         }
 206
 207                 /* Function Prototypes: */
 208                         /** Determines if the given tick delay has elapsed, based on the given .
 209                          *
 210                          *  \param Delay         The delay to test for, measured in ticks
 211                          *  \param DelayCounter  The counter which is storing the starting tick value for the delay
 212                          *
 213                          *  \return Boolean true if the delay has elapsed, false otherwise
 214                          *
 215                          *  Usage Example:
 216                          *  \code
 217                          *      static SchedulerDelayCounter_t DelayCounter = 10000; // Force immediate run on start-up
 218                          *
 219                          *      // Task runs every 10000 ticks, 10 seconds for this demo
 220                          *      if (Scheduler_HasDelayElapsed(10000, &DelayCounter))
 221                          *      {
 222                          *           // Code to execute after delay interval elapsed here
 223                          *      }
 224                          *  \endcode
 225                          */
 226                         bool Scheduler_HasDelayElapsed(const uint16_t Delay,
 227                                                        SchedulerDelayCounter_t* const DelayCounter)
 228                                                                                    ATTR_WARN_UNUSED_RESULT ATTR_NON_NULL_PTR_ARG(2);
 229
 230                         /** Sets the task mode for a given task.
 231                          *
 232                          *  \param Task        Name of the task whose status is to be changed
 233                          *  \param TaskStatus  New task status for the task (TASK_RUN or TASK_STOP)
 234                          */
 235                         void Scheduler_SetTaskMode(const TaskPtr_t Task, const bool TaskStatus);
 236
 237                         /** Sets the task mode for a given task group ID, allowing for an entire group of tasks to have their
 238                          *  statuses changed at once.
 239                          *
 240                          *  \param GroupID     Value of the task group ID whose status is to be changed
 241                          *  \param TaskStatus  New task status for tasks in the specified group (TASK_RUN or TASK_STOP)
 242                          */
 243                         void Scheduler_SetGroupTaskMode(const uint8_t GroupID, const bool TaskStatus);
 244
 245         /* Private Interface - For use in library only: */
 246         #if !defined(__DOXYGEN__)
 247                 /* Macros: */
 248                         #define TOTAL_TASKS                       (sizeof(Scheduler_TaskList) / sizeof(TaskEntry_t))
 249                         #define MAX_DELAYCTR_COUNT                0xFFFF
 250
 251                 /* Inline Functions: */
 252                         static inline void Scheduler_InitScheduler(const uint8_t TotalTasks) ATTR_ALWAYS_INLINE;
 253                         static inline void Scheduler_InitScheduler(const uint8_t TotalTasks)
 254                         {
 255                                 Scheduler_TotalTasks = TotalTasks;
 256                         }
 257
 258                         static inline void Scheduler_GoSchedule(const uint8_t TotalTasks) ATTR_NO_RETURN ATTR_ALWAYS_INLINE;
 259                         static inline void Scheduler_GoSchedule(const uint8_t TotalTasks)
 260                         {
 261                                 Scheduler_InitScheduler(TotalTasks);
 262
 263                                 for (;;)
 264                                 {
 265                                         TaskEntry_t* CurrTask = &Scheduler_TaskList[0];
 266
 267                                         while (CurrTask != &Scheduler_TaskList[TotalTasks])
 268                                         {
 269                                                 if (CurrTask->TaskStatus == TASK_RUN)
 270                                                   CurrTask->Task();
 271
 272                                                 CurrTask++;
 273                                         }
 274                                 }
 275                         }
 276         #endif
 277
 278         /* Disable C linkage for C++ Compilers: */
 279                 #if defined(__cplusplus)
 280                         }
 281                 #endif
 282
 283 #endif
 284
 285 /** @} */