poll_.c

#include <poll.h>
#include <unistd.h>
#include <stdio.h>
#include <pthread.h>
#include <wiringPi.h>
#include <stdlib.h>
#include <string.h>


volatile int flag=0;
char cstr[100];
int iret,ret,p[2];
void *thread_1(void *ptr);
char str[] = "start";
char str1[] = "end";
struct pollfd fds[1];
 
int main(){
	fds->fd=p[0];
	fds->events=POLLIN;
	
if (pipe(p)==-1)
    {
        printf("Pipe Failed" );
        return 1;
    }

if(wiringPiSetup()==-1){
		exit(0);}
		pinMode(15,OUTPUT);
		char *led1="15";

pthread_t t1;
iret = pthread_create( &t1, NULL, thread_1,(void*)led1);
if(iret<0){
     printf("Error starting thread 1");}
 char c;  
   
 while(1){
 printf("enter\n");    
 scanf("%c",&c);
 switch(c){
	 case '1': write(p[1], str, strlen(str)+1);
	 break;
	 case '2':write(p[1], str1, strlen(str1)+1);
			  pthread_join( t1, NULL);
			  printf("Thread stopped");
			  delay(5000);
			  exit(0);
			  break;
	 default:break;
	 
	 
	 }    }
     
     
     
     
return 0;}     
     
 
void *thread_1( void *ptr)
{
	int pin=atoi(ptr);
	while(1){
		ret=poll(fds, 1, 0);
	if(fds->revents && POLLIN){
		
        read(p[0], cstr, 6);
		}
	if(strncmp(cstr,str,6)==0){flag=1;}
	else if (strncmp(cstr,str1,3)==0){pthread_exit(NULL);}
	
	if(flag==1){		
	digitalWrite(pin,1);
	delay(100);
	digitalWrite(pin,0);
	delay(100);
}
} 
}