======Project: Timers n' signals======

A project for Systems Programming by Brandon Kennedy during the fall 2011 semester.

This project was begun on 12-15-2011 and is anticipated to take 4 hours. 
=====Objectives=====
By undertaking this project I hope to refresh myself on the use of timers and signal handling. I am going to review a previous program and reformat it to be an alarm clock(soundless).
=====Prerequisites=====
In order to successfully accomplish/perform this project, the listed resources/experiences need to be consulted/achieved:

  * wikipedia and the c programming guide on timers and signals
  * c pocket reference
  * matt Hass (back in september

=====Background=====
The idea of this project is to use timers and signals to create a nagging alarm clock. I am hoping that by reviewing and re-implementing this program that I can brush up on timers and signal handling enough to be able to implement this concept in other programs.
=====Attributes=====
State and justify the attributes you'd like to receive upon successful approval and completion of this project.

  * attribute1: Signals -> this program handles signals
  * attribute2: timers -> this program implements a timer as an alarm clock

=====Code=====
Upon completion of the project, if there is an applicable collection of created code, place a copy of your finished code within <nowiki><code> </code></nowiki> blocks here.

<code c>
//signal.c
//An alarm function by brandon kennedy for systems programming
//This function implements timers and signals as an alarm clock
//
//written in september of 2011
//Now being reused as a project for systems programming on 12-15-2011
//this file was created on 12-15-2011

#include <stdlib.h>
#include <stdio.h>
#include <signal.h>
#include <sys/time.h>

#define INTERVAL 5

int howmany = 0;

void alarm_wakeup (int i)
{
   struct itimerval tout_val;

   signal(SIGALRM,alarm_wakeup);

   howmany += INTERVAL;

   printf("\n%d sec up, time to Wakeup!!!\n",howmany);
   tout_val.it_interval.tv_sec = 0;
   tout_val.it_interval.tv_usec = 0;
   tout_val.it_value.tv_sec = INTERVAL; /* 10 seconds timer */
   tout_val.it_value.tv_usec = 0;

   setitimer(ITIMER_REAL, &tout_val,0);

}
void exit_func (int i)
{
    signal(SIGINT,exit_func);
    printf("\nYour up! Bye!!!\n");
    exit(0);
}

int main ()
{
  struct itimerval tout_val;

  tout_val.it_interval.tv_sec = 0;
  tout_val.it_interval.tv_usec = 0;
  tout_val.it_value.tv_sec = INTERVAL; /* 10 seconds timer */
  tout_val.it_value.tv_usec = 0;
  setitimer(ITIMER_REAL, &tout_val,0);

  signal(SIGALRM,alarm_wakeup); /* set the Alarm signal capture */
  signal(SIGINT,exit_func);

  while(1)
  {
     //printf("!");
  }
  return 0;
}
</code>

=====Execution=====
Again, if there is associated code with the project, and you haven't already indicated how to run it, provide a sample run of your code:

<cli>

lab46:~/src/SysProg/signals$ ./signal

5 sec up, time to Wakeup!!!

10 sec up, time to Wakeup!!!

15 sec up, time to Wakeup!!!

20 sec up, time to Wakeup!!!

25 sec up, time to Wakeup!!!
^C
Your up! Bye!!!
lab46:~/src/SysProg/signals$

</cli>

=====Reflection=====
Timers rock! I can deffinitely see a future for timers in my programming. As for signals, I could play some pretty sweet tricks on people with those bad boys, talk about a runaway program :)
=====References=====
In performing this project, the following resources were referenced:

  * wiki page of timers and signal
  * the c programming guide of timers
  * matt haas
  * manual pages for signal and setitimer