Embedded System Programming

The following code example executes four tasks (scheduled in ISR that is not presented). Now suppose that execution time of TASK2 is 3 milliseconds and TASK1 should be executed with time interval of 1 ms. TASK2 is a passive task requiring no synchronization with TASK1.

Which is the problem and which are the alternative ways to fix the problem? (Code is not needed, just write explanations.)

#define NUM_OF_TASKS 4

#define TASK1 0

#define TASK2 1

#define TASK3 2

#define TASK4 3

struct tasks {

unsigned short timcount; /* Count value */

unsigned short timval; /* interval in milliseconds */

unsigned char disabled; /* set as not schedulable */

unsigned char taskrunning; /* already running */

unsigned char runtask; /* mark to be redy for execution */

};

void init_tasks ( void ){

uint8_t ii; task[0].timval=1; task[1].timval=10; task[2].timval=30; task[3].timval=40;

for(ii=0;ii

task[ii].timcount=task[ii].timval;

task[ii].taskrunning=0;

task[ii].runtask=0;

task[ii].disabled=0;

}

}

// in main we have the following code

while(1) {

for(i=0;i

if(task[i].runtask ) {

task[i].runtask=0;

task[i].taskrunning=1;

switch(i)

{

case 0: run_task1();break;

case 1: run_task2();break;

case 2: run_task3();break;

case 3: run_task4();break;

}

}

}