type linkLayerAddr struct {
		Type byte
		Nlen byte
		Alen byte
		Slen byte
	}
	lla := (*linkLayerAddr)(unsafe.Pointer(&b[0]))
	l := 4 + int(lla.Nlen) + int(lla.Alen) + int(lla.Slen)
	if len(b) < l {
		return nil, 0, EINVAL
	}
	b = b[4:]
	sa := &SockaddrDatalink{Type: lla.Type, Nlen: lla.Nlen, Alen: lla.Alen, Slen: lla.Slen}
	for i := 0; len(sa.Data) > i && i < l-4; i++ {
		sa.Data[i] = int8(b[i])
	}

//go:build unix

// Socket control messages

package syscall

import (
	"unsafe"
)

// CmsgLen returns the value to store in the Len field of the [Cmsghdr]
// structure, taking into account any necessary alignment.
func CmsgLen(datalen int) int {
	return cmsgAlignOf(SizeofCmsghdr) + datalen
}

// CmsgSpace returns the number of bytes an ancillary element with

// authentication.
func UnixCredentials(ucred *Ucred) []byte {
	b := make([]byte, CmsgSpace(SizeofUcred))
	h := (*Cmsghdr)(unsafe.Pointer(&b[0]))
	h.Level = SOL_SOCKET
	h.Type = SCM_CREDENTIALS
	h.SetLen(CmsgLen(SizeofUcred))
	*(*Ucred)(h.data(0)) = *ucred
	return b
}

// ParseUnixCredentials decodes a socket control message that contains
// credentials in a Ucred structure. To receive such a message, the

	offsetS390xHasVX = unsafe.Offsetof(cpu.S390X.HasVX)

	offsetPPC64HasPOWER9 = unsafe.Offsetof(cpu.PPC64.IsPOWER9)
)

// MaxLen is the maximum length of the string to be searched for (argument b) in Index.
// If MaxLen is not 0, make sure MaxLen >= 4.
var MaxLen int

// PrimeRK is the prime base used in Rabin-Karp algorithm.
const PrimeRK = 16777619

// HashStr returns the hash and the appropriate multiplicative

	// makeFuncImpl contains a stack map for use by the runtime
	_, _, abid := funcLayout(ftyp, nil)

	impl := &makeFuncImpl{
		makeFuncCtxt: makeFuncCtxt{
			fn:      code,
			stack:   abid.stackPtrs,
			argLen:  abid.stackCallArgsSize,
			regPtrs: abid.inRegPtrs,
		},
		ftyp: ftyp,
		fn:   fn,
	}

	return Value{t, unsafe.Pointer(impl), flag(Func)}
}

func summary(list []*CommentGroup) string {
	const maxLen = 40
	var buf bytes.Buffer

	// collect comments text
loop:
	for _, group := range list {
		// Note: CommentGroup.Text() does too much work for what we
		//       need and would only replace this innermost loop.
		//       Just do it explicitly.
		for _, comment := range group.List {
			if buf.Len() >= maxLen {
				break loop
			}

DATA ·poly1305Mask<>+0x08(SB)/8, $0x0FFFFFFC0FFFFFFC
GLOBL ·poly1305Mask<>(SB), RODATA, $16

// func update(state *[7]uint64, msg []byte)
TEXT ·update(SB), $0-32
	MOVD state+0(FP), R3
	MOVD msg_base+8(FP), R4
	MOVD msg_len+16(FP), R5

	MOVD 0(R3), R8   // h0
	MOVD 8(R3), R9   // h1
	MOVD 16(R3), R10 // h2
	MOVD 24(R3), R11 // r0
	MOVD 32(R3), R12 // r1

	CMP R5, $16
	BLT bytes_between_0_and_15

loop:

	if old != nil {
		*old = r
	}
}

func pipe2(flags int32) (r, w int32, errno int32)

//go:noescape
func setitimer(mode int32, new, old *itimerval)

//go:noescape
func sysctl(mib *uint32, miblen uint32, out *byte, size *uintptr, dst *byte, ndst uintptr) int32

// mmap calls the mmap system call. It is implemented in assembly.
// We only pass the lower 32 bits of file offset to the

	switch {
	case n == 0:
		return 0
	case n == 1:
		return IndexByte(s, substr[0])
	case n == len(s):
		if substr == s {
			return 0
		}
		return -1
	case n > len(s):
		return -1
	case n <= bytealg.MaxLen:
		// Use brute force when s and substr both are small
		if len(s) <= bytealg.MaxBruteForce {
			return bytealg.IndexString(s, substr)
		}
		c0 := substr[0]
		c1 := substr[1]
		i := 0
		t := len(s) - n + 1

	mc_es            uint16
	mc_ds            uint16
	mc_err           uint64
	mc_rip           uint64
	mc_cs            uint64
	mc_rflags        uint64
	mc_rsp           uint64
	mc_ss            uint64
	mc_len           uint64
	mc_fpformat      uint64
	mc_ownedfp       uint64
	mc_fpstate       [64]uint64
	mc_fsbase        uint64
	mc_gsbase        uint64
	mc_xfpustate     uint64
	mc_xfpustate_len uint64