// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package sync

import "unsafe"

// defined in package runtime

// Semacquire waits until *s > 0 and then atomically decrements it.
// It is intended as a simple sleep primitive for use by the synchronization
// library and should not be used directly.
func runtime_Semacquire(s *uint32)

// Semrelease atomically increments *s and notifies a waiting goroutine
// if one is blocked in Semacquire.
// It is intended as a simple wakeup primitive for use by the synchronization
// library and should not be used directly.
func runtime_Semrelease(s *uint32)

// Approximation of notifyList in runtime/sema.go. Size and alignment must
// agree.
type notifyList struct {
	wait   uint32
	notify uint32
	lock   uintptr
	head   unsafe.Pointer
	tail   unsafe.Pointer
}

// See runtime/sema.go for documentation.
func runtime_notifyListAdd(l *notifyList) uint32

// See runtime/sema.go for documentation.
func runtime_notifyListWait(l *notifyList, t uint32)

// See runtime/sema.go for documentation.
func runtime_notifyListNotifyAll(l *notifyList)

// See runtime/sema.go for documentation.
func runtime_notifyListNotifyOne(l *notifyList)

// Ensure that sync and runtime agree on size of notifyList.
func runtime_notifyListCheck(size uintptr)
func init() {
	var n notifyList
	runtime_notifyListCheck(unsafe.Sizeof(n))
}

// Active spinning runtime support.
// runtime_canSpin returns true is spinning makes sense at the moment.
func runtime_canSpin(i int) bool

// runtime_doSpin does active spinning.
func runtime_doSpin()