i := uint32(1)
	b := (*[4]byte)(unsafe.Pointer(&i))
	if b[0] == 1 {
		nativeEndian = littleEndian
	} else {
		nativeEndian = bigEndian
	}
	// might get overridden in probeRoutingStack
	rtmVersion = syscall.RTM_VERSION
	kernelAlign, wireFormats = probeRoutingStack()
}

func roundup(l int) int {
	if l == 0 {
		return kernelAlign
	}
	return (l + kernelAlign - 1) &^ (kernelAlign - 1)
}

type wireFormat struct {

func (m *InterfaceMessage) Sys() []Sys {
	return []Sys{
		&InterfaceMetrics{
			Type: int(m.raw[m.extOff]),
			MTU:  int(nativeEndian.Uint32(m.raw[m.extOff+8 : m.extOff+12])),
		},
	}
}

func probeRoutingStack() (int, map[int]*wireFormat) {
	rtm := &wireFormat{extOff: 40, bodyOff: sizeofRtMsghdrNetBSD7}
	rtm.parse = rtm.parseRouteMessage
	ifm := &wireFormat{extOff: 16, bodyOff: sizeofIfMsghdrNetBSD7}

func (m *InterfaceMessage) Sys() []Sys {
	return []Sys{
		&InterfaceMetrics{
			Type: int(m.raw[m.extOff]),
			MTU:  int(nativeEndian.Uint32(m.raw[m.extOff+8 : m.extOff+12])),
		},
	}
}

func probeRoutingStack() (int, map[int]*wireFormat) {
	var p uintptr
	rtm := &wireFormat{extOff: 40, bodyOff: sizeofRtMsghdrDragonFlyBSD4}
	rtm.parse = rtm.parseRouteMessage
	ifm := &wireFormat{extOff: 16, bodyOff: sizeofIfMsghdrDragonFlyBSD4}

func (m *InterfaceMessage) Sys() []Sys {
	return []Sys{
		&InterfaceMetrics{
			Type: int(m.raw[m.extOff]),
			MTU:  int(nativeEndian.Uint32(m.raw[m.extOff+8 : m.extOff+12])),
		},
	}
}

func probeRoutingStack() (int, map[int]*wireFormat) {
	rtm := &wireFormat{extOff: 36, bodyOff: sizeofRtMsghdrDarwin15}
	rtm.parse = rtm.parseRouteMessage
	rtm2 := &wireFormat{extOff: 36, bodyOff: sizeofRtMsghdr2Darwin15}

func (m *InterfaceMessage) Sys() []Sys {
	return []Sys{
		&InterfaceMetrics{
			Type: int(m.raw[24]),
			MTU:  int(nativeEndian.Uint32(m.raw[28:32])),
		},
	}
}

func probeRoutingStack() (int, map[int]*wireFormat) {
	var p uintptr
	rtm := &wireFormat{extOff: -1, bodyOff: -1}
	rtm.parse = rtm.parseRouteMessage
	ifm := &wireFormat{extOff: -1, bodyOff: -1}
	ifm.parse = ifm.parseInterfaceMessage

		&InterfaceMetrics{
			Type: int(m.raw[m.extOff]),
			MTU:  int(nativeEndian.Uint32(m.raw[m.extOff+8 : m.extOff+12])),
		},
	}
}

var compatFreeBSD32 bool // 386 emulation on amd64

func probeRoutingStack() (int, map[int]*wireFormat) {
	var p uintptr
	wordSize := int(unsafe.Sizeof(p))
	align := wordSize
	// In the case of kern.supported_archs="amd64 i386", we need