if fi := ldr.FuncInfo(s); !fi.Valid() {
			continue
		}
		uw := ldr.SEHUnwindSym(s)
		if uw == 0 {
			continue
		}
		name := ctxt.SymName(uw)
		off, cached := uwcache[name]
		if !cached {
			off = xdata.Size()
			uwcache[name] = off
			xdata.AddBytes(ldr.Data(uw))
			// The SEH unwind data can contain relocations,
			// make sure those are copied over.
			rels := ldr.Relocs(uw)

	iovecs := bytes2iovec(iovs)
	n, err = readv(fd, iovecs)
	return n, err
}

//sys	preadv(fd int, iovs []Iovec, off int64) (n int, err error)

func Preadv(fd int, iovs [][]byte, off int64) (n int, err error) {
	iovecs := bytes2iovec(iovs)
	n, err = preadv(fd, iovecs, off)
	return n, err
}

//sys	writev(fd int, iovs []Iovec) (n int, err error)

func Writev(fd int, iovs [][]byte) (n int, err error) {

	for off := uintptr(0); off < 3<<30; off += 65536 {
		_, _, errno := syscall.Syscall6(syscall.SYS_MMAP,
			base+off, 65536, syscall.PROT_READ|syscall.PROT_WRITE, syscall.MAP_SHARED|syscall.MAP_FIXED, tmp.Fd(), 0)
		if errno != 0 {
			t.Skipf("could not map a page at requested 0x%x: %s", base+off, errno)
		}
		defer syscall.Syscall(syscall.SYS_MUNMAP, base+off, 65536, 0)
	}

	next = m.load32(off + 12)
	v = (*atomic.Uint64)(unsafe.Pointer(&m.mapping.Data[off]))
	return name, next, v, true
}

func (m *mappedFile) writeEntryAt(off uint32, name string) (next *atomic.Uint32, v *atomic.Uint64, ok bool) {
	if off < m.hdrLen+hashOff || int64(off)+16+int64(len(name)) > int64(len(m.mapping.Data)) {
		return nil, nil, false
	}
	copy(m.mapping.Data[off+16:], name)

// Don't extend before storing
(MOVWstore [off] {sym} ptr (MOVWreg x) mem) => (MOVWstore [off] {sym} ptr x mem)
(MOVHstore [off] {sym} ptr (MOVHreg x) mem) => (MOVHstore [off] {sym} ptr x mem)
(MOVBstore [off] {sym} ptr (MOVBreg x) mem) => (MOVBstore [off] {sym} ptr x mem)
(MOVWstore [off] {sym} ptr (MOVWZreg x) mem) => (MOVWstore [off] {sym} ptr x mem)
(MOVHstore [off] {sym} ptr (MOVHZreg x) mem) => (MOVHstore [off] {sym} ptr x mem)

// Returns the offset code corresponding to a specific offset.
func offsetCode(off uint32) uint32 {
	if off < uint32(len(offsetCodes)) {
		return offsetCodes[off]
	}
	if off>>7 < uint32(len(offsetCodes)) {
		return offsetCodes[off>>7] + 14
	}
	return offsetCodes[off>>14] + 28

		return true
	}
	// match: (LEAQ2 [off] {sym} x (MOVQconst [scale]))
	// cond: is32Bit(int64(off)+int64(scale)*2)
	// result: (LEAQ [off+int32(scale)*2] {sym} x)
	for {
		off := auxIntToInt32(v.AuxInt)
		sym := auxToSym(v.Aux)
		x := v_0
		if v_1.Op != OpAMD64MOVQconst {
			break
		}
		scale := auxIntToInt64(v_1.AuxInt)
		if !(is32Bit(int64(off) + int64(scale)*2)) {
			break
		}

	r := strings.NewReader("0123456789")
	tests := []struct {
		off     int64
		seek    int
		n       int
		want    string
		wantpos int64
		readerr error
		seekerr string
	}{
		{seek: io.SeekStart, off: 0, n: 20, want: "0123456789"},
		{seek: io.SeekStart, off: 1, n: 1, want: "1"},
		{seek: io.SeekCurrent, off: 1, wantpos: 3, n: 2, want: "34"},
		{seek: io.SeekStart, off: -1, seekerr: "strings.Reader.Seek: negative position"},

  protected void update(byte[] b) {
    update(b, 0, b.length);
  }

  /** Updates this hasher with {@code len} bytes starting at {@code off} in the given buffer. */
  protected void update(byte[] b, int off, int len) {
    for (int i = off; i < off + len; i++) {
      update(b[i]);
    }
  }

  /** Updates this hasher with bytes from the given buffer. */
  protected void update(ByteBuffer b) {

	return 0
}

func makeBuf(d *Data, format dataFormat, name string, off Offset, data []byte) buf {
	return buf{d, d.order, format, name, off, data, nil}
}

func (b *buf) uint8() uint8 {
	if len(b.data) < 1 {
		b.error("underflow")
		return 0
	}
	val := b.data[0]
	b.data = b.data[1:]
	b.off++
	return val
}

func (b *buf) bytes(n int) []byte {
	if n < 0 || len(b.data) < n {