type suffixSaver struct {
	keep  int
	buf   []byte
	start int
	size  int64
}

func (ss *suffixSaver) Size() int64 { return ss.size }

var errDiscardedBytes = errors.New("ReadAt of discarded bytes")

func (ss *suffixSaver) ReadAt(p []byte, off int64) (n int, err error) {
	back := ss.size - off
	if back > int64(ss.keep) {
		return 0, errDiscardedBytes
	}
	suf := ss.Suffix()

	}
	r.i = int64(r.prevRune)
	r.prevRune = -1
	return nil
}

// Seek implements the [io.Seeker] interface.
func (r *Reader) Seek(offset int64, whence int) (int64, error) {
	r.prevRune = -1
	var abs int64
	switch whence {
	case io.SeekStart:
		abs = offset
	case io.SeekCurrent:
		abs = r.i + offset
	case io.SeekEnd:
		abs = int64(len(r.s)) + offset
	default:

			spb = append(strconv.AppendInt(spb, int64(len(spd)), 10), '\n')
			for _, s := range spd {
				hdr.Size += s.Length
				spb = append(strconv.AppendInt(spb, s.Offset, 10), '\n')
				spb = append(strconv.AppendInt(spb, s.Length, 10), '\n')
			}
			pad := blockPadding(int64(len(spb)))
			spb = append(spb, zeroBlock[:pad]...)
			hdr.Size += int64(len(spb)) // Accounts for encoded sparse map

	return 0
}

// positiveAtoi returns an int64 that must be >= 0.
func (p *Parser) positiveAtoi(str string) int64 {
	value, err := strconv.ParseInt(str, 0, 64)
	if err != nil {
		p.errorf("%s", err)
	}
	if value < 0 {
		p.errorf("%s overflows int64", str)
	}
	return value
}

func (p *Parser) atoi(str string) uint64 {
	value, err := strconv.ParseUint(str, 0, 64)
	if err != nil {

pkg math/bits, func Add64(uint64, uint64, uint64) (uint64, uint64)
pkg math/bits, func Div(uint, uint, uint) (uint, uint)
pkg math/bits, func Div32(uint32, uint32, uint32) (uint32, uint32)
pkg math/bits, func Div64(uint64, uint64, uint64) (uint64, uint64)
pkg math/bits, func Mul(uint, uint) (uint, uint)
pkg math/bits, func Mul32(uint32, uint32) (uint32, uint32)
pkg math/bits, func Mul64(uint64, uint64) (uint64, uint64)

import (
	. "bytes"
	"fmt"
	"io"
	"sync"
	"testing"
)

func TestReader(t *testing.T) {
	r := NewReader([]byte("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"},

		{"gopher.txt", "Gopher names:\nGeorge\nGeoffrey\nGonzo"},
		{"todo.txt", "Get animal handling license."},
	}
	for _, file := range files {
		hdr := &tar.Header{
			Name: file.Name,
			Mode: 0600,
			Size: int64(len(file.Body)),
		}
		if err := tw.WriteHeader(hdr); err != nil {
			log.Fatal(err)
		}
		if _, err := tw.Write([]byte(file.Body)); err != nil {
			log.Fatal(err)
		}
	}
	if err := tw.Close(); err != nil {

type int16 int16

// int32 is the set of all signed 32-bit integers.
// Range: -2147483648 through 2147483647.
type int32 int32

// int64 is the set of all signed 64-bit integers.
// Range: -9223372036854775808 through 9223372036854775807.
type int64 int64

// float32 is the set of all IEEE 754 32-bit floating-point numbers.
type float32 float32

// float64 is the set of all IEEE 754 64-bit floating-point numbers.

			minor |= uint32((dev & 0x00000ffffff00000) >> 12)
			h.Devmajor, h.Devminor = int64(major), int64(minor)
		case "darwin", "ios":
			// Copied from golang.org/x/sys/unix/dev_darwin.go.
			major := uint32((dev >> 24) & 0xff)
			minor := uint32(dev & 0xffffff)
			h.Devmajor, h.Devminor = int64(major), int64(minor)
		case "dragonfly":
			// Copied from golang.org/x/sys/unix/dev_dragonfly.go.

pkg sync/atomic, method (*Int32) Swap(int32) int32 #50860
pkg sync/atomic, method (*Int64) Add(int64) int64 #50860
pkg sync/atomic, method (*Int64) CompareAndSwap(int64, int64) bool #50860
pkg sync/atomic, method (*Int64) Load() int64 #50860
pkg sync/atomic, method (*Int64) Store(int64) #50860
pkg sync/atomic, method (*Int64) Swap(int64) int64 #50860
pkg sync/atomic, method (*Pointer[$0]) CompareAndSwap(*$0, *$0) bool #50860