//
// Hitting this target resolution is easy in the nanotime case: just pick a
// division of 64. In the cputicks case it's a bit more complex.
//
// For x86, on a 3 GHz machine, we'd want to divide by 3*64 to hit our target.
// To keep the division operation efficient, we round that up to 4*64, or 256.
// Given what cputicks represents, we use this on all other platforms except
// for PowerPC.

// See go.dev/issue/67401.

// Notable members of the hall of shame include:
//   - github.com/dgraph-io/ristretto
//   - github.com/outcaste-io/ristretto
//   - github.com/clubpay/ronykit
//go:linkname cputicks

// Notable members of the hall of shame include:
//   - gvisor.dev/gvisor (from assembly)

	_HPET_MAIN_COUNTER = 0xf0 /* Main counter register */

	hpetDevPath = "/dev/hpetX\x00"
)

var hpetDevMap [_HPET_DEV_MAP_MAX]uintptr

//go:nosplit
func (th *vdsoTimehands) getTSCTimecounter() uint32 {
	tsc := cputicks()
	if th.x86_shift > 0 {
		tsc >>= th.x86_shift
	}
	return uint32(tsc)
}

//go:nosplit
func (th *vdsoTimehands) getHPETTimecounter() (uint32, bool) {
	idx := int(th.x86_hpet_idx)

//
// Must not run concurrently with ticksPerSecond.
func (t *ticksType) init() {
	lock(&ticks.lock)
	t.startTime = nanotime()
	t.startTicks = cputicks()
	unlock(&ticks.lock)
}

// minTimeForTicksPerSecond is the minimum elapsed time we require to consider our ticksPerSecond
// measurement to be of decent enough quality for profiling.
//

	throw("too many writes on closed pipe")
}

//go:linkname syscall_now syscall.now
func syscall_now() (sec int64, nsec int32) {
	sec, nsec, _ = time_now()
	return
}

//go:nosplit
func cputicks() int64 {
	// runtime·nanotime() is a poor approximation of CPU ticks that is enough for the profiler.
	return nanotime()
}

// gsignalStack is unused on js.
type gsignalStack struct{}

	t0 := int64(0)
	s.releasetime = 0
	s.acquiretime = 0
	s.ticket = 0
	if profile&semaBlockProfile != 0 && blockprofilerate > 0 {
		t0 = cputicks()
		s.releasetime = -1
	}
	if profile&semaMutexProfile != 0 && mutexprofilerate > 0 {
		if t0 == 0 {
			t0 = cputicks()
		}
		s.acquiretime = t0
	}
	for {
		lockWithRank(&root.lock, lockRankRoot)
		// Add ourselves to nwait to disable "easy case" in semrelease.

	// chanrecv() and closechan() to update this thread's view of c.closed and full().
	if !block && c.closed == 0 && full(c) {
		return false
	}

	var t0 int64
	if blockprofilerate > 0 {
		t0 = cputicks()
	}

	lock(&c.lock)

	if c.closed != 0 {
		unlock(&c.lock)
		panic(plainError("send on closed channel"))
	}

	if sg := c.recvq.dequeue(); sg != nil {

					// The test imposes a delay with usleep, verified with calls to
					// nanotime. Compare against the runtime/metrics package's view
					// (based on nanotime) rather than runtime/pprof's view (based
					// on cputicks).
					t.Errorf("runtime/metrics reported less than the known minimum contention duration (%fs < %fs)", have, want)
				}
			})
			if have, want := n, int64(len(mus)); have != want {

		pcs = pc1[:ncases:ncases]
	}
	casePC := func(casi int) uintptr {
		if pcs == nil {
			return 0
		}
		return pcs[casi]
	}

	var t0 int64
	if blockprofilerate > 0 {
		t0 = cputicks()
	}

	// The compiler rewrites selects that statically have
	// only 0 or 1 cases plus default into simpler constructs.
	// The only way we can end up with such small sel.ncase

// call with "if dlogEnabled".
//
//go:nosplit
//go:nowritebarrierrec
func dlog() *dlogger {
	if !dlogEnabled {
		return nil
	}

	// Get the time.
	tick, nano := uint64(cputicks()), uint64(nanotime())

	// Try to get a cached logger.
	l := getCachedDlogger()

	// If we couldn't get a cached logger, try to get one from the
	// global pool.
	if l == nil {