main.cpp

00001 /* 21_ MUTEX a Guard at door - Basic program 
00002 MUTEX allow only one Thread / Function call inside CS, Mutex have ownership type locking mechanism.
00003 Procees /or Thread who locked block,only same process /or thread can unlock it.
00004 */
00005 
00006 
00007 //PROGRAM CREATED BY : JAYDEEP SHAH -- radheec@gmail.com
00008 //DATE : 25 JULY 20 ,VERSION 1.0
00009 
00010 //OUTPUT : USE SERIAL TERMINAL 9600    8-N-1
00011 
00012 
00013 #include "mbed.h"  //MBED LIBRARY 
00014 
00015 Mutex M_LOCK;  // Create MUTEX OBJECT  -class = MUTEX
00016 
00017 //Create Two Thread 
00018 
00019 Thread t2;  
00020 
00021 Thread t3; 
00022 
00023 
00024 //Here below section act as CS critical section
00025 
00026 void common_function(const char *name, int state)  //TWO ARGUMENTS 1) WHO CALLED THIS FUNCTION 2)STATE OF CALLER
00027 {
00028     printf("Thread arrive at door %s: %d\n\r", name, state);
00029     
00030     M_LOCK.lock();  //After arrive lock the code---------------------------LOCK THE BLOCK
00031     
00032     printf("This Thread lock the code %s: %d\n\r", name, state);
00033     wait(0.5); //sleep
00034     printf("Thread cross & unlock %s: %d\n\r", name, state); //OUTSIDE CODE BLOCK ---------   
00035     M_LOCK.unlock();  //After completing task unlock the code ------------- UNLOCK THE BLOCK
00036     
00037 //DO NOT WRITE any print statement after  unlock() it create missunderstanding ....
00038 /* print statement require more clk cycle,after  unlock the MUTEX Flag - schedular quickly schedule next thread before print the statement.*/
00039 }
00040 
00041 
00042 
00043 //Function -- We will connect more than one thread with this function
00044 //So because of context switching this Function become sharable between multiple process.
00045 void test_thread(void const *args)
00046 {
00047     while (true) {
00048         common_function((const char *)args, 0);
00049         ThisThread::sleep_for(500);
00050         common_function((const char *)args, 1);
00051         ThisThread::sleep_for(500);
00052     }
00053 }
00054 
00055 int main()
00056 {
00057     t2.start(callback(test_thread, (void *)"Th 2"));
00058     t3.start(callback(test_thread, (void *)"Th 3"));
00059 
00060     test_thread((void *)"Th 1");  // DIRECT CALL via main thread
00061 }