#pragma implementation "Timer.h"
#include "Timer.h"
#include <unistd.h>
#include <sys/times.h>
#include <sys/time.h>

static tms cpu;
static Timer *timerChain = 0;

#ifdef m68k
double const Timer::hz = 60;
#else
double const Timer::hz = sysconf(_SC_CLK_TCK);
#endif

void Timer::wait(struct timeval &to) {
  if (!timerChain) return;
  long t = ticks();
  if (timerChain) {
    t = timerChain->target - t;
    to.tv_sec = (long)(t / hz);
    long m = (long)(to.tv_sec * hz);
    if (t < m) {
      if (to.tv_sec == 0) {
	to.tv_sec = 0;
	to.tv_usec = 1;
	return;
      }
      m = (long)(--to.tv_sec * hz);
    }
    to.tv_usec = (long)((t - m) / hz * 1000000L);
  }
}

unsigned long Timer::ticks() {
  unsigned long lastclk = times(&cpu);
  for (Timer *p = timerChain; p && p->before(lastclk); p = timerChain) {
    timerChain = p->nextTimer;
    p->timerEvent();	// might alter timerChain, so we reload p
  }
  return lastclk;
}

void Timer::timer(unsigned long tval) {
  // remove from timerChain
  if (active) {
    for (Timer **p = &timerChain; *p; p = &(*p)->nextTimer) {
      if (*p == this) {
	*p = nextTimer;
	break;
      }
    }
    active = 0;
  }
  // add to timerChain
  if (tval) {
    target = ticks() + tval;
    Timer **p;
    for (p = &timerChain; *p; p = &(*p)->nextTimer) {
      if (before((*p)->target)) break;
    }
    nextTimer = *p;
    *p = this;
    active = 1;
  }
}