if uint64(oldlen+len(out.heap)) > filesize {
		panic("mmap size too small")
	}
	copy(out.buf[oldlen:], out.heap)
	out.heap = out.heap[:0]
	return nil
}

func (out *OutBuf) munmap() {
	if out.buf == nil {
		return
	}
	syscall.Munmap(out.buf)
	out.buf = nil

//go:build aix || darwin || dragonfly || freebsd || openbsd || solaris || zos

package unix

var mapper = &mmapper{
	active: make(map[*byte][]byte),
	mmap:   mmap,
	munmap: munmap,

}

// Mmap maps the given file into memory.
// When remapping a file, pass the most recently returned Data.
func Mmap(f *os.File, data *Data) (Data, error) {
	return mmapFile(f, data)
}

// Munmap unmaps the given file from memory.
func Munmap(d *Data) error {
	// d.f.Close() on Windows still gets an error
	return munmapFile(*d)

	}
	return Data{f, data[:n], nil}, nil
}

func munmapFile(d Data) error {
	if len(d.Data) == 0 {
		return nil
	}
	err := syscall.Munmap(d.Data)
	if err != nil {
		return &fs.PathError{Op: "munmap", Path: d.f.Name(), Err: err}
	}
	return nil

// The err result is an OS error code such as ENOMEM.
func mmap(addr unsafe.Pointer, n uintptr, prot, flags, fd int32, off uint32) (p unsafe.Pointer, err int)

// munmap calls the munmap system call. It is implemented in assembly.
func munmap(addr unsafe.Pointer, n uintptr)

func nanotime1() int64

//go:noescape
func sigaltstack(new, old *stackt)

func fcntl(fd, cmd, arg int32) (ret int32, errno int32)

	oldheap := out.heap
	if filesize < uint64(len(oldheap)) {
		panic("mmap size too small")
	}
	out.heap = make([]byte, filesize)
	copy(out.heap, oldheap)
	return nil
}

	closefd(fd)
	newP := uintptr(addr)
	if mmapErr != 0 {
		newP = ^uintptr(0)
	}
	if !atomic.Casuintptr(&hpetDevMap[idx], 0, newP) && mmapErr == 0 {
		munmap(addr, physPageSize)
	}
}

//go:nosplit
func (th *vdsoTimehands) getTimecounter() (uint32, bool) {
	switch th.algo {
	case _VDSO_TH_ALGO_X86_TSC:
		return th.getTSCTimecounter(), true

	return
}

var mapper = &mmapper{
	active: make(map[*byte][]byte),
	mmap:   mmap,
	munmap: munmap,
}

func Mmap(fd int, offset int64, length int, prot int, flags int) (data []byte, err error) {
	return mapper.Mmap(fd, offset, length, prot, flags)
}

func Munmap(b []byte) (err error) {
	return mapper.Munmap(b)
}

func Utimes(path string, tv []Timeval) error {
	if len(tv) != 2 {
		return EINVAL

	mmap:   mmap,
	munmap: munmap,
}

//sys	mmap(addr uintptr, length uintptr, prot int, flag int, fd int, pos int64) (ret uintptr, err error)
//sys	munmap(addr uintptr, length uintptr) (err error)

func Mmap(fd int, offset int64, length int, prot int, flags int) (data []byte, err error) {
	return mapper.Mmap(fd, offset, length, prot, flags)
}

func Munmap(b []byte) (err error) {
	return mapper.Munmap(b)

	KeepAlive(addr) // Just for consistency. Hopefully addr is not a Go address.
	return args.ret1, args.ret2
}
func mmap_trampoline()

//go:nosplit
//go:cgo_unsafe_args
func munmap(addr unsafe.Pointer, n uintptr) {
	libcCall(unsafe.Pointer(abi.FuncPCABI0(munmap_trampoline)), unsafe.Pointer(&addr))
	KeepAlive(addr) // Just for consistency. Hopefully addr is not a Go address.
}
func munmap_trampoline()