Stanislaus Eichstaedt
A simple Round Robin Task scheduler (a sub minimalistic Operating System) with no inter Task communication implemented (semaphores, mailboxes etc) nor task local varibales can be used. They have to be global (static). But, it's the first step up to an OS.
scheduler.cpp@0:9ce7c170cb66, 2010-06-11 (annotated)
- Committer:
- Stanislaus
- Date:
- Fri Jun 11 20:52:03 2010 +0000
- Revision:
- 0:9ce7c170cb66
Who changed what in which revision?
| User | Revision | Line number | New contents of line |
|---|---|---|---|
| Stanislaus | 0:9ce7c170cb66 | 1 | /*! \file scheduler.c \brief Simple Task Scheduler. */ |
| Stanislaus | 0:9ce7c170cb66 | 2 | //***************************************************************************** |
| Stanislaus | 0:9ce7c170cb66 | 3 | // |
| Stanislaus | 0:9ce7c170cb66 | 4 | // File Name : 'scheduler.c' |
| Stanislaus | 0:9ce7c170cb66 | 5 | // Title : Simple Task Scheduler |
| Stanislaus | 0:9ce7c170cb66 | 6 | // Author : Pascal Stang - Copyright (C) 2006 |
| Stanislaus | 0:9ce7c170cb66 | 7 | // Created : 2006.05.24 |
| Stanislaus | 0:9ce7c170cb66 | 8 | // Revised : 2006.05.26 |
| Stanislaus | 0:9ce7c170cb66 | 9 | // Version : 0.1 |
| Stanislaus | 0:9ce7c170cb66 | 10 | // Target MCU : Atmel AVR Series |
| Stanislaus | 0:9ce7c170cb66 | 11 | // Editor Tabs : 4 |
| Stanislaus | 0:9ce7c170cb66 | 12 | // |
| Stanislaus | 0:9ce7c170cb66 | 13 | // NOTE: This code is currently below version 1.0, and therefore is considered |
| Stanislaus | 0:9ce7c170cb66 | 14 | // to be lacking in some functionality or documentation, or may not be fully |
| Stanislaus | 0:9ce7c170cb66 | 15 | // tested. Nonetheless, you can expect most functions to work. |
| Stanislaus | 0:9ce7c170cb66 | 16 | // |
| Stanislaus | 0:9ce7c170cb66 | 17 | // This code is distributed under the GNU Public License |
| Stanislaus | 0:9ce7c170cb66 | 18 | // which can be found at http://www.gnu.org/licenses/gpl.txt |
| Stanislaus | 0:9ce7c170cb66 | 19 | // |
| Stanislaus | 0:9ce7c170cb66 | 20 | //***************************************************************************** |
| Stanislaus | 0:9ce7c170cb66 | 21 | |
| Stanislaus | 0:9ce7c170cb66 | 22 | #include "scheduler.h" |
| Stanislaus | 0:9ce7c170cb66 | 23 | |
| Stanislaus | 0:9ce7c170cb66 | 24 | // the task list |
| Stanislaus | 0:9ce7c170cb66 | 25 | struct task TaskList[TASKLIST_SIZE]; |
| Stanislaus | 0:9ce7c170cb66 | 26 | |
| Stanislaus | 0:9ce7c170cb66 | 27 | // functions |
| Stanislaus | 0:9ce7c170cb66 | 28 | void schedulerInit(void) |
| Stanislaus | 0:9ce7c170cb66 | 29 | { |
| Stanislaus | 0:9ce7c170cb66 | 30 | int i; |
| Stanislaus | 0:9ce7c170cb66 | 31 | |
| Stanislaus | 0:9ce7c170cb66 | 32 | // reset task list |
| Stanislaus | 0:9ce7c170cb66 | 33 | for(i=0; i<TASKLIST_SIZE; i++) |
| Stanislaus | 0:9ce7c170cb66 | 34 | { |
| Stanislaus | 0:9ce7c170cb66 | 35 | // initialize task list |
| Stanislaus | 0:9ce7c170cb66 | 36 | TaskList[i].runtime = 0; |
| Stanislaus | 0:9ce7c170cb66 | 37 | TaskList[i].funcptr = 0; |
| Stanislaus | 0:9ce7c170cb66 | 38 | } |
| Stanislaus | 0:9ce7c170cb66 | 39 | } |
| Stanislaus | 0:9ce7c170cb66 | 40 | |
| Stanislaus | 0:9ce7c170cb66 | 41 | void schedulerRun(int systime) |
| Stanislaus | 0:9ce7c170cb66 | 42 | { |
| Stanislaus | 0:9ce7c170cb66 | 43 | int i; |
| Stanislaus | 0:9ce7c170cb66 | 44 | |
| Stanislaus | 0:9ce7c170cb66 | 45 | // locate active task slots |
| Stanislaus | 0:9ce7c170cb66 | 46 | for(i=0; i<TASKLIST_SIZE; i++) |
| Stanislaus | 0:9ce7c170cb66 | 47 | { |
| Stanislaus | 0:9ce7c170cb66 | 48 | if(TaskList[i].funcptr) |
| Stanislaus | 0:9ce7c170cb66 | 49 | { |
| Stanislaus | 0:9ce7c170cb66 | 50 | // check systime against runtime |
| Stanislaus | 0:9ce7c170cb66 | 51 | if(systime >= TaskList[i].runtime) |
| Stanislaus | 0:9ce7c170cb66 | 52 | { |
| Stanislaus | 0:9ce7c170cb66 | 53 | // run task, then update it |
| Stanislaus | 0:9ce7c170cb66 | 54 | TaskList[i].funcptr(i,systime); |
| Stanislaus | 0:9ce7c170cb66 | 55 | |
| Stanislaus | 0:9ce7c170cb66 | 56 | if(TaskList[i].nrepeat) |
| Stanislaus | 0:9ce7c170cb66 | 57 | { |
| Stanislaus | 0:9ce7c170cb66 | 58 | TaskList[i].runtime += TaskList[i].interval; |
| Stanislaus | 0:9ce7c170cb66 | 59 | TaskList[i].nrepeat--; |
| Stanislaus | 0:9ce7c170cb66 | 60 | // task has expired, remove it now |
| Stanislaus | 0:9ce7c170cb66 | 61 | if(!TaskList[i].nrepeat) |
| Stanislaus | 0:9ce7c170cb66 | 62 | schedulerRemoveTask(i); |
| Stanislaus | 0:9ce7c170cb66 | 63 | } |
| Stanislaus | 0:9ce7c170cb66 | 64 | else |
| Stanislaus | 0:9ce7c170cb66 | 65 | { |
| Stanislaus | 0:9ce7c170cb66 | 66 | // nrepeat==0 means run forever |
| Stanislaus | 0:9ce7c170cb66 | 67 | TaskList[i].runtime += TaskList[i].interval; |
| Stanislaus | 0:9ce7c170cb66 | 68 | } |
| Stanislaus | 0:9ce7c170cb66 | 69 | |
| Stanislaus | 0:9ce7c170cb66 | 70 | } |
| Stanislaus | 0:9ce7c170cb66 | 71 | } |
| Stanislaus | 0:9ce7c170cb66 | 72 | } |
| Stanislaus | 0:9ce7c170cb66 | 73 | |
| Stanislaus | 0:9ce7c170cb66 | 74 | // increment scheduler timer |
| Stanislaus | 0:9ce7c170cb66 | 75 | //SchedulerTimer++; |
| Stanislaus | 0:9ce7c170cb66 | 76 | } |
| Stanislaus | 0:9ce7c170cb66 | 77 | |
| Stanislaus | 0:9ce7c170cb66 | 78 | int schedulerAddTask(int runtime, int nrepeat, int interval, taskfuncptr taskfunc) |
| Stanislaus | 0:9ce7c170cb66 | 79 | { |
| Stanislaus | 0:9ce7c170cb66 | 80 | int i; |
| Stanislaus | 0:9ce7c170cb66 | 81 | |
| Stanislaus | 0:9ce7c170cb66 | 82 | // locate empty scheduler slot |
| Stanislaus | 0:9ce7c170cb66 | 83 | for(i=0; i<TASKLIST_SIZE; i++) |
| Stanislaus | 0:9ce7c170cb66 | 84 | { |
| Stanislaus | 0:9ce7c170cb66 | 85 | //CRITICAL_SECTION_BEGIN; |
| Stanislaus | 0:9ce7c170cb66 | 86 | if(!TaskList[i].funcptr) |
| Stanislaus | 0:9ce7c170cb66 | 87 | { |
| Stanislaus | 0:9ce7c170cb66 | 88 | // setup entry |
| Stanislaus | 0:9ce7c170cb66 | 89 | TaskList[i].funcptr = taskfunc; |
| Stanislaus | 0:9ce7c170cb66 | 90 | TaskList[i].runtime = runtime; |
| Stanislaus | 0:9ce7c170cb66 | 91 | TaskList[i].nrepeat = nrepeat; |
| Stanislaus | 0:9ce7c170cb66 | 92 | TaskList[i].interval = interval; |
| Stanislaus | 0:9ce7c170cb66 | 93 | |
| Stanislaus | 0:9ce7c170cb66 | 94 | // return task handle |
| Stanislaus | 0:9ce7c170cb66 | 95 | return i; |
| Stanislaus | 0:9ce7c170cb66 | 96 | } |
| Stanislaus | 0:9ce7c170cb66 | 97 | //CRITICAL_SECTION_END; |
| Stanislaus | 0:9ce7c170cb66 | 98 | } |
| Stanislaus | 0:9ce7c170cb66 | 99 | // error - no task slots left |
| Stanislaus | 0:9ce7c170cb66 | 100 | return -1; |
| Stanislaus | 0:9ce7c170cb66 | 101 | } |
| Stanislaus | 0:9ce7c170cb66 | 102 | |
| Stanislaus | 0:9ce7c170cb66 | 103 | int schedulerRemoveTask(int taskhandle) |
| Stanislaus | 0:9ce7c170cb66 | 104 | { |
| Stanislaus | 0:9ce7c170cb66 | 105 | // clear the task entry |
| Stanislaus | 0:9ce7c170cb66 | 106 | TaskList[taskhandle].runtime = 0; |
| Stanislaus | 0:9ce7c170cb66 | 107 | TaskList[taskhandle].interval = 0; |
| Stanislaus | 0:9ce7c170cb66 | 108 | TaskList[taskhandle].nrepeat = 0; |
| Stanislaus | 0:9ce7c170cb66 | 109 | TaskList[taskhandle].funcptr = 0; |
| Stanislaus | 0:9ce7c170cb66 | 110 | |
| Stanislaus | 0:9ce7c170cb66 | 111 | return taskhandle; |
| Stanislaus | 0:9ce7c170cb66 | 112 | } |
| Stanislaus | 0:9ce7c170cb66 | 113 | |
| Stanislaus | 0:9ce7c170cb66 | 114 | int schedulerRemoveTaskFunc(taskfuncptr funcptr) |
| Stanislaus | 0:9ce7c170cb66 | 115 | { |
| Stanislaus | 0:9ce7c170cb66 | 116 | int i; |
| Stanislaus | 0:9ce7c170cb66 | 117 | int taskhandle = -1; |
| Stanislaus | 0:9ce7c170cb66 | 118 | |
| Stanislaus | 0:9ce7c170cb66 | 119 | // locate the task |
| Stanislaus | 0:9ce7c170cb66 | 120 | for(i=0; i<TASKLIST_SIZE; i++) |
| Stanislaus | 0:9ce7c170cb66 | 121 | { |
| Stanislaus | 0:9ce7c170cb66 | 122 | // on match, disable the task |
| Stanislaus | 0:9ce7c170cb66 | 123 | if(TaskList[i].funcptr == funcptr) taskhandle = schedulerRemoveTask(i); |
| Stanislaus | 0:9ce7c170cb66 | 124 | } |
| Stanislaus | 0:9ce7c170cb66 | 125 | return taskhandle; |
| Stanislaus | 0:9ce7c170cb66 | 126 | } |