unsigned int timer_1;   // Countdown value for Timer-1
unsigned int timer_2;   // Countdown value for Timer-2
unsigned int timer_3;   // Countdown value for Timer-3
                        // etc...

void timer_isr( void )   // Hardware timer interrupt handler
                         // use appropriate compiler-specific syntax!
{
   if( timer_1 )
   {  
      // The countdown is running
      if( --timer_1 == 0 )
      {
         // The countdown has reached zero; ie, the timer has expired
         // Set flags and/or call functions as appropriate
      }
   }

   if( timer_2 )
   {  
      // The countdown is running
      if( --timer_2 == 0 )
      {
         // The countdown has reached zero; ie, the timer has expired
         // Set flags and/or call functions as appropriate
      }
   }

   if( timer_3 )
   {  
      // The countdown is running
      if( --timer_3 == 0 )
      {
         // The countdown has reached zero; ie, the timer has expired
         // Set flags and/or call functions as appropriate
      }
   }

   // etc, etc,...
}