#include <io.h>
#include <interrupt.h>


typedef unsigned char  u8;
typedef   signed char  s8;
typedef unsigned short u16;
typedef   signed short s16;
typedef unsigned long  u32;
typedef   signed long  s32;


u32 t2_soft;


ISR( TIMER2_OVF_vect )
{
  t2_soft += 256;
}


void t2_init( void )
{
  t2_soft = 0;
  TCCR2 = 1<<CS21;	// mode 0, prescaler 8
  TIMSK |= 1<<TOIE2;	// enable overflow interrupt
}


u32 get_ticks( void )			  // read T2 as 32 bit timer
{
  u32 val;
  u8 tifr;

  cli();
  val = t2_soft + TCNT2;
  tifr = TIFR;				  // read interrupt flags
  sei();
  if( (tifr & 1<<TOV2) && !(val & 0x80) ) // overflow prior reading TCNT2 ?
    val += 256;				  // then add overflow

  return val;
}


int main( void )
{
  u32 timerticks;

  t2_init();
  sei();

  for(;;){
    timerticks = get_ticks();
  }
}