priyanka Siddalingappa / SimpleScheduler

Very simple cooperative round-robin task scheduler. See examples.

Examples/example3.h@4:49652acb6806, 2011-03-04 (annotated)

Committer:
AjK
Date:
Fri Mar 04 13:55:15 2011 +0000
Revision:
4:49652acb6806
Parent:
1:f043501c4bed 
1.3 See ChangeLoh.h

Who changed what in which revision?

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AjK 1:f043501c4bed 1 /*
AjK 1:f043501c4bed 2 Copyright (c) 2011 Andy Kirkham
AjK 1:f043501c4bed 3
AjK 1:f043501c4bed 4 Permission is hereby granted, free of charge, to any person obtaining a copy
AjK 1:f043501c4bed 5 of this software and associated documentation files (the "Software"), to deal
AjK 1:f043501c4bed 6 in the Software without restriction, including without limitation the rights
AjK 1:f043501c4bed 7 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
AjK 1:f043501c4bed 8 copies of the Software, and to permit persons to whom the Software is
AjK 1:f043501c4bed 9 furnished to do so, subject to the following conditions:
AjK 1:f043501c4bed 10
AjK 1:f043501c4bed 11 The above copyright notice and this permission notice shall be included in
AjK 1:f043501c4bed 12 all copies or substantial portions of the Software.
AjK 1:f043501c4bed 13
AjK 1:f043501c4bed 14 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
AjK 1:f043501c4bed 15 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
AjK 1:f043501c4bed 16 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AjK 1:f043501c4bed 17 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
AjK 1:f043501c4bed 18 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
AjK 1:f043501c4bed 19 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
AjK 1:f043501c4bed 20 THE SOFTWARE.
AjK 1:f043501c4bed 21
AjK 1:f043501c4bed 22 @file example3.h
AjK 1:f043501c4bed 23 @purpose Simple round-robin cooperative scheduler example
AjK 1:f043501c4bed 24 @date Mar 2011
AjK 1:f043501c4bed 25 @author Andy Kirkham
AjK 1:f043501c4bed 26 */
AjK 1:f043501c4bed 27
AjK 1:f043501c4bed 28 /*
AjK 1:f043501c4bed 29 SimpleScheduler is a cooperative scheduler. What that means is YOU, the
AjK 1:f043501c4bed 30 programmer MUST cooperate with it. SimpleScheduler will call your task
AjK 1:f043501c4bed 31 functions based on the schedule you provide. However, it's not a guarenteed
AjK 1:f043501c4bed 32 scheduled time. It's on a "best effort". However, no tasks are called until
AjK 1:f043501c4bed 33 the currently executing task completes. What that means is your task function
AjK 1:f043501c4bed 34 must return before another task can be called.
AjK 1:f043501c4bed 35
AjK 1:f043501c4bed 36 Your tasks therefore should execute as fast as possible and return as soon as
AjK 1:f043501c4bed 37 they can. But when Mbed's wait API is used you stall your entire system. This
AjK 1:f043501c4bed 38 example shows how you can wait() in a task without actually waiting at all. In
AjK 1:f043501c4bed 39 order to do this we use the "Ton" (Timer ON) library. You will need to import
AjK 1:f043501c4bed 40 this library into your project to use this example:-
AjK 1:f043501c4bed 41
AjK 1:f043501c4bed 42 http://mbed.org/users/AjK/libraries/Ton/latest
AjK 1:f043501c4bed 43
AjK 1:f043501c4bed 44 What follows is basically example1. However, we are going to flash LED1 by
AjK 1:f043501c4bed 45 "waiting" 1second in the task.
AjK 1:f043501c4bed 46
AjK 1:f043501c4bed 47 */
AjK 1:f043501c4bed 48
AjK 1:f043501c4bed 49 #include "mbed.h"
AjK 1:f043501c4bed 50 #include "SimpleScheduler.h"
AjK 1:f043501c4bed 51 #include "Ton.h"
AjK 1:f043501c4bed 52
AjK 1:f043501c4bed 53 Ton t1(1000); // Timer ON delay of one second.
AjK 1:f043501c4bed 54
AjK 1:f043501c4bed 55 DigitalOut led1(LED1);
AjK 1:f043501c4bed 56 DigitalOut led2(LED2);
AjK 1:f043501c4bed 57 DigitalOut led3(LED3);
AjK 1:f043501c4bed 58 DigitalOut led4(LED4);
AjK 1:f043501c4bed 59
AjK 1:f043501c4bed 60 void f1(SimpleTask *task) {
AjK 4:49652acb6806 61 // wait(1);
AjK 4:49652acb6806 62 if (!t1.isRunning()) {
AjK 4:49652acb6806 63 t1 = Ton::On;
AjK 4:49652acb6806 64 // Code that should execute once before the wait() goes here.
AjK 4:49652acb6806 65 // ...
AjK 4:49652acb6806 66 }
AjK 1:f043501c4bed 67 if (t1) {
AjK 4:49652acb6806 68 // This code will be executed once the timer times out.
AjK 1:f043501c4bed 69 led1 = !led1;
AjK 1:f043501c4bed 70 t1.reset();
AjK 1:f043501c4bed 71 }
AjK 1:f043501c4bed 72 }
AjK 1:f043501c4bed 73 void f2(SimpleTask *task) { led2 = !led2; }
AjK 1:f043501c4bed 74 void f3(SimpleTask *task) { led3 = !led3; }
AjK 1:f043501c4bed 75 void f4(SimpleTask *task) { led4 = !led4; }
AjK 1:f043501c4bed 76
AjK 1:f043501c4bed 77 SimpleScheduler *scheduler;
AjK 1:f043501c4bed 78
AjK 1:f043501c4bed 79 int main() {
AjK 1:f043501c4bed 80
AjK 1:f043501c4bed 81 scheduler = new SimpleScheduler;
AjK 1:f043501c4bed 82
AjK 1:f043501c4bed 83 scheduler
AjK 1:f043501c4bed 84 ->addTask( new SimpleTask(0, f1) )
AjK 1:f043501c4bed 85 ->addTask( new SimpleTask(200, f2) )
AjK 1:f043501c4bed 86 ->addTask( new SimpleTask(300, f3) )
AjK 1:f043501c4bed 87 ->addTask( new SimpleTask(0.4, f4) )
AjK 1:f043501c4bed 88 ;
AjK 1:f043501c4bed 89
AjK 1:f043501c4bed 90 scheduler->run();
AjK 1:f043501c4bed 91 }
AjK 1:f043501c4bed 92