src/encoding/binary/binary.go - go - Git at Google

 // Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

 // Package binary implements simple translation between numbers and byte
 // sequences and encoding and decoding of varints.
 //
 // Numbers are translated by reading and writing fixed-size values.
 // A fixed-size value is either a fixed-size arithmetic
 // type (bool, int8, uint8, int16, float32, complex64, ...)
 // or an array or struct containing only fixed-size values.
 //
 // The varint functions encode and decode single integer values using
 // a variable-length encoding; smaller values require fewer bytes.
 // For a specification, see
 // https://developers.google.com/protocol-buffers/docs/encoding.
 //
 // This package favors simplicity over efficiency. Clients that require
 // high-performance serialization, especially for large data structures,
 // should look at more advanced solutions such as the encoding/gob
 // package or protocol buffers.
 package binary

 import (
 	"errors"
 	"io"
 	"math"
 	"reflect"
 	"sync"
 )

 // A ByteOrder specifies how to convert byte sequences into
 // 16-, 32-, or 64-bit unsigned integers.
 type ByteOrder interface {
 	Uint16([]byte) uint16
 	Uint32([]byte) uint32
 	Uint64([]byte) uint64
 	PutUint16([]byte, uint16)
 	PutUint32([]byte, uint32)
 	PutUint64([]byte, uint64)
 	String() string
 }

 // LittleEndian is the little-endian implementation of ByteOrder.
 var LittleEndian littleEndian

 // BigEndian is the big-endian implementation of ByteOrder.
 var BigEndian bigEndian

 type littleEndian struct{}

 func (littleEndian) Uint16(b []byte) uint16 {
 	_ = b[1] // bounds check hint to compiler; see golang.org/issue/14808
 	return uint16(b[0]) | uint16(b[1])<<8
 }

 func (littleEndian) PutUint16(b []byte, v uint16) {
 	_ = b[1] // early bounds check to guarantee safety of writes below
 	b[0] = byte(v)
 	b[1] = byte(v >> 8)
 }

 func (littleEndian) Uint32(b []byte) uint32 {
 	_ = b[3] // bounds check hint to compiler; see golang.org/issue/14808
 	return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24
 }

 func (littleEndian) PutUint32(b []byte, v uint32) {
 	_ = b[3] // early bounds check to guarantee safety of writes below
 	b[0] = byte(v)
 	b[1] = byte(v >> 8)
 	b[2] = byte(v >> 16)
 	b[3] = byte(v >> 24)
 }

 func (littleEndian) Uint64(b []byte) uint64 {
 	_ = b[7] // bounds check hint to compiler; see golang.org/issue/14808
 	return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
 		uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
 }

 func (littleEndian) PutUint64(b []byte, v uint64) {
 	_ = b[7] // early bounds check to guarantee safety of writes below
 	b[0] = byte(v)
 	b[1] = byte(v >> 8)
 	b[2] = byte(v >> 16)
 	b[3] = byte(v >> 24)
 	b[4] = byte(v >> 32)
 	b[5] = byte(v >> 40)
 	b[6] = byte(v >> 48)
 	b[7] = byte(v >> 56)
 }

 func (littleEndian) String() string { return "LittleEndian" }

 func (littleEndian) GoString() string { return "binary.LittleEndian" }

 type bigEndian struct{}

 func (bigEndian) Uint16(b []byte) uint16 {
 	_ = b[1] // bounds check hint to compiler; see golang.org/issue/14808
 	return uint16(b[1]) | uint16(b[0])<<8
 }

 func (bigEndian) PutUint16(b []byte, v uint16) {
 	_ = b[1] // early bounds check to guarantee safety of writes below
 	b[0] = byte(v >> 8)
 	b[1] = byte(v)
 }

 func (bigEndian) Uint32(b []byte) uint32 {
 	_ = b[3] // bounds check hint to compiler; see golang.org/issue/14808
 	return uint32(b[3]) | uint32(b[2])<<8 | uint32(b[1])<<16 | uint32(b[0])<<24
 }

 func (bigEndian) PutUint32(b []byte, v uint32) {
 	_ = b[3] // early bounds check to guarantee safety of writes below
 	b[0] = byte(v >> 24)
 	b[1] = byte(v >> 16)
 	b[2] = byte(v >> 8)
 	b[3] = byte(v)
 }

 func (bigEndian) Uint64(b []byte) uint64 {
 	_ = b[7] // bounds check hint to compiler; see golang.org/issue/14808
 	return uint64(b[7]) | uint64(b[6])<<8 | uint64(b[5])<<16 | uint64(b[4])<<24 |
 		uint64(b[3])<<32 | uint64(b[2])<<40 | uint64(b[1])<<48 | uint64(b[0])<<56
 }

 func (bigEndian) PutUint64(b []byte, v uint64) {
 	_ = b[7] // early bounds check to guarantee safety of writes below
 	b[0] = byte(v >> 56)
 	b[1] = byte(v >> 48)
 	b[2] = byte(v >> 40)
 	b[3] = byte(v >> 32)
 	b[4] = byte(v >> 24)
 	b[5] = byte(v >> 16)
 	b[6] = byte(v >> 8)
 	b[7] = byte(v)
 }

 func (bigEndian) String() string { return "BigEndian" }

 func (bigEndian) GoString() string { return "binary.BigEndian" }

 // Read reads structured binary data from r into data.
 // Data must be a pointer to a fixed-size value or a slice
 // of fixed-size values.
 // Bytes read from r are decoded using the specified byte order
 // and written to successive fields of the data.
 // When decoding boolean values, a zero byte is decoded as false, and
 // any other non-zero byte is decoded as true.
 // When reading into structs, the field data for fields with
 // blank (_) field names is skipped; i.e., blank field names
 // may be used for padding.
 // When reading into a struct, all non-blank fields must be exported
 // or Read may panic.
 //
 // The error is EOF only if no bytes were read.
 // If an EOF happens after reading some but not all the bytes,
 // Read returns ErrUnexpectedEOF.
 func Read(r io.Reader, order ByteOrder, data interface{}) error {
 	// Fast path for basic types and slices.
 	if n := intDataSize(data); n != 0 {
 		bs := make([]byte, n)
 		if _, err := io.ReadFull(r, bs); err != nil {
 			return err
 		}
 		switch data := data.(type) {
 		case *bool:
 			*data = bs[0] != 0
 		case *int8:
 			*data = int8(bs[0])
 		case *uint8:
 			*data = bs[0]
 		case *int16:
 			*data = int16(order.Uint16(bs))
 		case *uint16:
 			*data = order.Uint16(bs)
 		case *int32:
 			*data = int32(order.Uint32(bs))
 		case *uint32:
 			*data = order.Uint32(bs)
 		case *int64:
 			*data = int64(order.Uint64(bs))
 		case *uint64:
 			*data = order.Uint64(bs)
 		case []bool:
 			for i, x := range bs { // Easier to loop over the input for 8-bit values.
 				data[i] = x != 0
 			}
 		case []int8:
 			for i, x := range bs {
 				data[i] = int8(x)
 			}
 		case []uint8:
 			copy(data, bs)
 		case []int16:
 			for i := range data {
 				data[i] = int16(order.Uint16(bs[2*i:]))
 			}
 		case []uint16:
 			for i := range data {
 				data[i] = order.Uint16(bs[2*i:])
 			}
 		case []int32:
 			for i := range data {
 				data[i] = int32(order.Uint32(bs[4*i:]))
 			}
 		case []uint32:
 			for i := range data {
 				data[i] = order.Uint32(bs[4*i:])
 			}
 		case []int64:
 			for i := range data {
 				data[i] = int64(order.Uint64(bs[8*i:]))
 			}
 		case []uint64:
 			for i := range data {
 				data[i] = order.Uint64(bs[8*i:])
 			}
 		}
 		return nil
 	}

 	// Fallback to reflect-based decoding.
 	v := reflect.ValueOf(data)
 	size := -1
 	switch v.Kind() {
 	case reflect.Ptr:
 		v = v.Elem()
 		size = dataSize(v)
 	case reflect.Slice:
 		size = dataSize(v)
 	}
 	if size < 0 {
 		return errors.New("binary.Read: invalid type " + reflect.TypeOf(data).String())
 	}
 	d := &decoder{order: order, buf: make([]byte, size)}
 	if _, err := io.ReadFull(r, d.buf); err != nil {
 		return err
 	}
 	d.value(v)
 	return nil
 }

 // Write writes the binary representation of data into w.
 // Data must be a fixed-size value or a slice of fixed-size
 // values, or a pointer to such data.
 // Boolean values encode as one byte: 1 for true, and 0 for false.
 // Bytes written to w are encoded using the specified byte order
 // and read from successive fields of the data.
 // When writing structs, zero values are written for fields
 // with blank (_) field names.
 func Write(w io.Writer, order ByteOrder, data interface{}) error {
 	// Fast path for basic types and slices.
 	if n := intDataSize(data); n != 0 {
 		bs := make([]byte, n)
 		switch v := data.(type) {
 		case *bool:
 			if *v {
 				bs[0] = 1
 			} else {
 				bs[0] = 0
 			}
 		case bool:
 			if v {
 				bs[0] = 1
 			} else {
 				bs[0] = 0
 			}
 		case []bool:
 			for i, x := range v {
 				if x {
 					bs[i] = 1
 				} else {
 					bs[i] = 0
 				}
 			}
 		case *int8:
 			bs[0] = byte(*v)
 		case int8:
 			bs[0] = byte(v)
 		case []int8:
 			for i, x := range v {
 				bs[i] = byte(x)
 			}
 		case *uint8:
 			bs[0] = *v
 		case uint8:
 			bs[0] = v
 		case []uint8:
 			bs = v // TODO(josharian): avoid allocating bs in this case?
 		case *int16:
 			order.PutUint16(bs, uint16(*v))
 		case int16:
 			order.PutUint16(bs, uint16(v))
 		case []int16:
 			for i, x := range v {
 				order.PutUint16(bs[2*i:], uint16(x))
 			}
 		case *uint16:
 			order.PutUint16(bs, *v)
 		case uint16:
 			order.PutUint16(bs, v)
 		case []uint16:
 			for i, x := range v {
 				order.PutUint16(bs[2*i:], x)
 			}
 		case *int32:
 			order.PutUint32(bs, uint32(*v))
 		case int32:
 			order.PutUint32(bs, uint32(v))
 		case []int32:
 			for i, x := range v {
 				order.PutUint32(bs[4*i:], uint32(x))
 			}
 		case *uint32:
 			order.PutUint32(bs, *v)
 		case uint32:
 			order.PutUint32(bs, v)
 		case []uint32:
 			for i, x := range v {
 				order.PutUint32(bs[4*i:], x)
 			}
 		case *int64:
 			order.PutUint64(bs, uint64(*v))
 		case int64:
 			order.PutUint64(bs, uint64(v))
 		case []int64:
 			for i, x := range v {
 				order.PutUint64(bs[8*i:], uint64(x))
 			}
 		case *uint64:
 			order.PutUint64(bs, *v)
 		case uint64:
 			order.PutUint64(bs, v)
 		case []uint64:
 			for i, x := range v {
 				order.PutUint64(bs[8*i:], x)
 			}
 		}
 		_, err := w.Write(bs)
 		return err
 	}

 	// Fallback to reflect-based encoding.
 	v := reflect.Indirect(reflect.ValueOf(data))
 	size := dataSize(v)
 	if size < 0 {
 		return errors.New("binary.Write: invalid type " + reflect.TypeOf(data).String())
 	}
 	buf := make([]byte, size)
 	e := &encoder{order: order, buf: buf}
 	e.value(v)
 	_, err := w.Write(buf)
 	return err
 }

 // Size returns how many bytes Write would generate to encode the value v, which
 // must be a fixed-size value or a slice of fixed-size values, or a pointer to such data.
 // If v is neither of these, Size returns -1.
 func Size(v interface{}) int {
 	return dataSize(reflect.Indirect(reflect.ValueOf(v)))
 }

 var structSize sync.Map // map[reflect.Type]int

 // dataSize returns the number of bytes the actual data represented by v occupies in memory.
 // For compound structures, it sums the sizes of the elements. Thus, for instance, for a slice
 // it returns the length of the slice times the element size and does not count the memory
 // occupied by the header. If the type of v is not acceptable, dataSize returns -1.
 func dataSize(v reflect.Value) int {
 	switch v.Kind() {
 	case reflect.Slice:
 		if s := sizeof(v.Type().Elem()); s >= 0 {
 			return s * v.Len()
 		}
 		return -1

 	case reflect.Struct:
 		t := v.Type()
 		if size, ok := structSize.Load(t); ok {
 			return size.(int)
 		}
 		size := sizeof(t)
 		structSize.Store(t, size)
 		return size

 	default:
 		return sizeof(v.Type())
 	}
 }

 // sizeof returns the size >= 0 of variables for the given type or -1 if the type is not acceptable.
 func sizeof(t reflect.Type) int {
 	switch t.Kind() {
 	case reflect.Array:
 		if s := sizeof(t.Elem()); s >= 0 {
 			return s * t.Len()
 		}

 	case reflect.Struct:
 		sum := 0
 		for i, n := 0, t.NumField(); i < n; i++ {
 			s := sizeof(t.Field(i).Type)
 			if s < 0 {
 				return -1
 			}
 			sum += s
 		}
 		return sum

 	case reflect.Bool,
 		reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64,
 		reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
 		reflect.Float32, reflect.Float64, reflect.Complex64, reflect.Complex128:
 		return int(t.Size())
 	}

 	return -1
 }

 type coder struct {
 	order  ByteOrder
 	buf    []byte
 	offset int
 }

 type decoder coder
 type encoder coder

 func (d *decoder) bool() bool {
 	x := d.buf[d.offset]
 	d.offset++
 	return x != 0
 }

 func (e *encoder) bool(x bool) {
 	if x {
 		e.buf[e.offset] = 1
 	} else {
 		e.buf[e.offset] = 0
 	}
 	e.offset++
 }

 func (d *decoder) uint8() uint8 {
 	x := d.buf[d.offset]
 	d.offset++
 	return x
 }

 func (e *encoder) uint8(x uint8) {
 	e.buf[e.offset] = x
 	e.offset++
 }

 func (d *decoder) uint16() uint16 {
 	x := d.order.Uint16(d.buf[d.offset : d.offset+2])
 	d.offset += 2
 	return x
 }

 func (e *encoder) uint16(x uint16) {
 	e.order.PutUint16(e.buf[e.offset:e.offset+2], x)
 	e.offset += 2
 }

 func (d *decoder) uint32() uint32 {
 	x := d.order.Uint32(d.buf[d.offset : d.offset+4])
 	d.offset += 4
 	return x
 }

 func (e *encoder) uint32(x uint32) {
 	e.order.PutUint32(e.buf[e.offset:e.offset+4], x)
 	e.offset += 4
 }

 func (d *decoder) uint64() uint64 {
 	x := d.order.Uint64(d.buf[d.offset : d.offset+8])
 	d.offset += 8
 	return x
 }

 func (e *encoder) uint64(x uint64) {
 	e.order.PutUint64(e.buf[e.offset:e.offset+8], x)
 	e.offset += 8
 }

 func (d *decoder) int8() int8 { return int8(d.uint8()) }

 func (e *encoder) int8(x int8) { e.uint8(uint8(x)) }

 func (d *decoder) int16() int16 { return int16(d.uint16()) }

 func (e *encoder) int16(x int16) { e.uint16(uint16(x)) }

 func (d *decoder) int32() int32 { return int32(d.uint32()) }

 func (e *encoder) int32(x int32) { e.uint32(uint32(x)) }

 func (d *decoder) int64() int64 { return int64(d.uint64()) }

 func (e *encoder) int64(x int64) { e.uint64(uint64(x)) }

 func (d *decoder) value(v reflect.Value) {
 	switch v.Kind() {
 	case reflect.Array:
 		l := v.Len()
 		for i := 0; i < l; i++ {
 			d.value(v.Index(i))
 		}

 	case reflect.Struct:
 		t := v.Type()
 		l := v.NumField()
 		for i := 0; i < l; i++ {
 			// Note: Calling v.CanSet() below is an optimization.
 			// It would be sufficient to check the field name,
 			// but creating the StructField info for each field is
 			// costly (run "go test -bench=ReadStruct" and compare
 			// results when making changes to this code).
 			if v := v.Field(i); v.CanSet() || t.Field(i).Name != "_" {
 				d.value(v)
 			} else {
 				d.skip(v)
 			}
 		}

 	case reflect.Slice:
 		l := v.Len()
 		for i := 0; i < l; i++ {
 			d.value(v.Index(i))
 		}

 	case reflect.Bool:
 		v.SetBool(d.bool())

 	case reflect.Int8:
 		v.SetInt(int64(d.int8()))
 	case reflect.Int16:
 		v.SetInt(int64(d.int16()))
 	case reflect.Int32:
 		v.SetInt(int64(d.int32()))
 	case reflect.Int64:
 		v.SetInt(d.int64())

 	case reflect.Uint8:
 		v.SetUint(uint64(d.uint8()))
 	case reflect.Uint16:
 		v.SetUint(uint64(d.uint16()))
 	case reflect.Uint32:
 		v.SetUint(uint64(d.uint32()))
 	case reflect.Uint64:
 		v.SetUint(d.uint64())

 	case reflect.Float32:
 		v.SetFloat(float64(math.Float32frombits(d.uint32())))
 	case reflect.Float64:
 		v.SetFloat(math.Float64frombits(d.uint64()))

 	case reflect.Complex64:
 		v.SetComplex(complex(
 			float64(math.Float32frombits(d.uint32())),
 			float64(math.Float32frombits(d.uint32())),
 		))
 	case reflect.Complex128:
 		v.SetComplex(complex(
 			math.Float64frombits(d.uint64()),
 			math.Float64frombits(d.uint64()),
 		))
 	}
 }

 func (e *encoder) value(v reflect.Value) {
 	switch v.Kind() {
 	case reflect.Array:
 		l := v.Len()
 		for i := 0; i < l; i++ {
 			e.value(v.Index(i))
 		}

 	case reflect.Struct:
 		t := v.Type()
 		l := v.NumField()
 		for i := 0; i < l; i++ {
 			// see comment for corresponding code in decoder.value()
 			if v := v.Field(i); v.CanSet() || t.Field(i).Name != "_" {
 				e.value(v)
 			} else {
 				e.skip(v)
 			}
 		}

 	case reflect.Slice:
 		l := v.Len()
 		for i := 0; i < l; i++ {
 			e.value(v.Index(i))
 		}

 	case reflect.Bool:
 		e.bool(v.Bool())

 	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
 		switch v.Type().Kind() {
 		case reflect.Int8:
 			e.int8(int8(v.Int()))
 		case reflect.Int16:
 			e.int16(int16(v.Int()))
 		case reflect.Int32:
 			e.int32(int32(v.Int()))
 		case reflect.Int64:
 			e.int64(v.Int())
 		}

 	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
 		switch v.Type().Kind() {
 		case reflect.Uint8:
 			e.uint8(uint8(v.Uint()))
 		case reflect.Uint16:
 			e.uint16(uint16(v.Uint()))
 		case reflect.Uint32:
 			e.uint32(uint32(v.Uint()))
 		case reflect.Uint64:
 			e.uint64(v.Uint())
 		}

 	case reflect.Float32, reflect.Float64:
 		switch v.Type().Kind() {
 		case reflect.Float32:
 			e.uint32(math.Float32bits(float32(v.Float())))
 		case reflect.Float64:
 			e.uint64(math.Float64bits(v.Float()))
 		}

 	case reflect.Complex64, reflect.Complex128:
 		switch v.Type().Kind() {
 		case reflect.Complex64:
 			x := v.Complex()
 			e.uint32(math.Float32bits(float32(real(x))))
 			e.uint32(math.Float32bits(float32(imag(x))))
 		case reflect.Complex128:
 			x := v.Complex()
 			e.uint64(math.Float64bits(real(x)))
 			e.uint64(math.Float64bits(imag(x)))
 		}
 	}
 }

 func (d *decoder) skip(v reflect.Value) {
 	d.offset += dataSize(v)
 }

 func (e *encoder) skip(v reflect.Value) {
 	n := dataSize(v)
 	zero := e.buf[e.offset : e.offset+n]
 	for i := range zero {
 		zero[i] = 0
 	}
 	e.offset += n
 }

 // intDataSize returns the size of the data required to represent the data when encoded.
 // It returns zero if the type cannot be implemented by the fast path in Read or Write.
 func intDataSize(data interface{}) int {
 	switch data := data.(type) {
 	case bool, int8, uint8, *bool, *int8, *uint8:
 		return 1
 	case []bool:
 		return len(data)
 	case []int8:
 		return len(data)
 	case []uint8:
 		return len(data)
 	case int16, uint16, *int16, *uint16:
 		return 2
 	case []int16:
 		return 2 * len(data)
 	case []uint16:
 		return 2 * len(data)
 	case int32, uint32, *int32, *uint32:
 		return 4
 	case []int32:
 		return 4 * len(data)
 	case []uint32:
 		return 4 * len(data)
 	case int64, uint64, *int64, *uint64:
 		return 8
 	case []int64:
 		return 8 * len(data)
 	case []uint64:
 		return 8 * len(data)
 	}
 	return 0
 }
	// Copyright 2009 The Go Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file.

	// Package binary implements simple translation between numbers and byte
	// sequences and encoding and decoding of varints.
	//
	// Numbers are translated by reading and writing fixed-size values.
	// A fixed-size value is either a fixed-size arithmetic
	// type (bool, int8, uint8, int16, float32, complex64, ...)
	// or an array or struct containing only fixed-size values.
	//
	// The varint functions encode and decode single integer values using
	// a variable-length encoding; smaller values require fewer bytes.
	// For a specification, see
	// https://developers.google.com/protocol-buffers/docs/encoding.
	//
	// This package favors simplicity over efficiency. Clients that require
	// high-performance serialization, especially for large data structures,
	// should look at more advanced solutions such as the encoding/gob
	// package or protocol buffers.
	package binary

	import (
	"errors"
	"io"
	"math"
	"reflect"
	"sync"
	)

	// A ByteOrder specifies how to convert byte sequences into
	// 16-, 32-, or 64-bit unsigned integers.
	type ByteOrder interface {
	Uint16([]byte) uint16
	Uint32([]byte) uint32
	Uint64([]byte) uint64
	PutUint16([]byte, uint16)
	PutUint32([]byte, uint32)
	PutUint64([]byte, uint64)
	String() string
	}

	// LittleEndian is the little-endian implementation of ByteOrder.
	var LittleEndian littleEndian

	// BigEndian is the big-endian implementation of ByteOrder.
	var BigEndian bigEndian

	type littleEndian struct{}

	func (littleEndian) Uint16(b []byte) uint16 {
	_ = b[1] // bounds check hint to compiler; see golang.org/issue/14808
	return uint16(b[0]) \| uint16(b[1])<<8
	}

	func (littleEndian) PutUint16(b []byte, v uint16) {
	_ = b[1] // early bounds check to guarantee safety of writes below
	b[0] = byte(v)
	b[1] = byte(v >> 8)
	}

	func (littleEndian) Uint32(b []byte) uint32 {
	_ = b[3] // bounds check hint to compiler; see golang.org/issue/14808
	return uint32(b[0]) \| uint32(b[1])<<8 \| uint32(b[2])<<16 \| uint32(b[3])<<24
	}

	func (littleEndian) PutUint32(b []byte, v uint32) {
	_ = b[3] // early bounds check to guarantee safety of writes below
	b[0] = byte(v)
	b[1] = byte(v >> 8)
	b[2] = byte(v >> 16)
	b[3] = byte(v >> 24)
	}

	func (littleEndian) Uint64(b []byte) uint64 {
	_ = b[7] // bounds check hint to compiler; see golang.org/issue/14808
	return uint64(b[0]) \| uint64(b[1])<<8 \| uint64(b[2])<<16 \| uint64(b[3])<<24 \|
	uint64(b[4])<<32 \| uint64(b[5])<<40 \| uint64(b[6])<<48 \| uint64(b[7])<<56
	}

	func (littleEndian) PutUint64(b []byte, v uint64) {
	_ = b[7] // early bounds check to guarantee safety of writes below
	b[0] = byte(v)
	b[1] = byte(v >> 8)
	b[2] = byte(v >> 16)
	b[3] = byte(v >> 24)
	b[4] = byte(v >> 32)
	b[5] = byte(v >> 40)
	b[6] = byte(v >> 48)
	b[7] = byte(v >> 56)
	}

	func (littleEndian) String() string { return "LittleEndian" }

	func (littleEndian) GoString() string { return "binary.LittleEndian" }

	type bigEndian struct{}

	func (bigEndian) Uint16(b []byte) uint16 {
	_ = b[1] // bounds check hint to compiler; see golang.org/issue/14808
	return uint16(b[1]) \| uint16(b[0])<<8
	}

	func (bigEndian) PutUint16(b []byte, v uint16) {
	_ = b[1] // early bounds check to guarantee safety of writes below
	b[0] = byte(v >> 8)
	b[1] = byte(v)
	}

	func (bigEndian) Uint32(b []byte) uint32 {
	_ = b[3] // bounds check hint to compiler; see golang.org/issue/14808
	return uint32(b[3]) \| uint32(b[2])<<8 \| uint32(b[1])<<16 \| uint32(b[0])<<24
	}

	func (bigEndian) PutUint32(b []byte, v uint32) {
	_ = b[3] // early bounds check to guarantee safety of writes below
	b[0] = byte(v >> 24)
	b[1] = byte(v >> 16)
	b[2] = byte(v >> 8)
	b[3] = byte(v)
	}

	func (bigEndian) Uint64(b []byte) uint64 {
	_ = b[7] // bounds check hint to compiler; see golang.org/issue/14808
	return uint64(b[7]) \| uint64(b[6])<<8 \| uint64(b[5])<<16 \| uint64(b[4])<<24 \|
	uint64(b[3])<<32 \| uint64(b[2])<<40 \| uint64(b[1])<<48 \| uint64(b[0])<<56
	}

	func (bigEndian) PutUint64(b []byte, v uint64) {
	_ = b[7] // early bounds check to guarantee safety of writes below
	b[0] = byte(v >> 56)
	b[1] = byte(v >> 48)
	b[2] = byte(v >> 40)
	b[3] = byte(v >> 32)
	b[4] = byte(v >> 24)
	b[5] = byte(v >> 16)
	b[6] = byte(v >> 8)
	b[7] = byte(v)
	}

	func (bigEndian) String() string { return "BigEndian" }

	func (bigEndian) GoString() string { return "binary.BigEndian" }

	// Read reads structured binary data from r into data.
	// Data must be a pointer to a fixed-size value or a slice
	// of fixed-size values.
	// Bytes read from r are decoded using the specified byte order
	// and written to successive fields of the data.
	// When decoding boolean values, a zero byte is decoded as false, and
	// any other non-zero byte is decoded as true.
	// When reading into structs, the field data for fields with
	// blank (_) field names is skipped; i.e., blank field names
	// may be used for padding.
	// When reading into a struct, all non-blank fields must be exported
	// or Read may panic.
	//
	// The error is EOF only if no bytes were read.
	// If an EOF happens after reading some but not all the bytes,
	// Read returns ErrUnexpectedEOF.
	func Read(r io.Reader, order ByteOrder, data interface{}) error {
	// Fast path for basic types and slices.
	if n := intDataSize(data); n != 0 {
	bs := make([]byte, n)
	if _, err := io.ReadFull(r, bs); err != nil {
	return err
	}
	switch data := data.(type) {
	case *bool:
	*data = bs[0] != 0
	case *int8:
	*data = int8(bs[0])
	case *uint8:
	*data = bs[0]
	case *int16:
	*data = int16(order.Uint16(bs))
	case *uint16:
	*data = order.Uint16(bs)
	case *int32:
	*data = int32(order.Uint32(bs))
	case *uint32:
	*data = order.Uint32(bs)
	case *int64:
	*data = int64(order.Uint64(bs))
	case *uint64:
	*data = order.Uint64(bs)
	case []bool:
	for i, x := range bs { // Easier to loop over the input for 8-bit values.
	data[i] = x != 0
	}
	case []int8:
	for i, x := range bs {
	data[i] = int8(x)
	}
	case []uint8:
	copy(data, bs)
	case []int16:
	for i := range data {
	data[i] = int16(order.Uint16(bs[2*i:]))
	}
	case []uint16:
	for i := range data {
	data[i] = order.Uint16(bs[2*i:])
	}
	case []int32:
	for i := range data {
	data[i] = int32(order.Uint32(bs[4*i:]))
	}
	case []uint32:
	for i := range data {
	data[i] = order.Uint32(bs[4*i:])
	}
	case []int64:
	for i := range data {
	data[i] = int64(order.Uint64(bs[8*i:]))
	}
	case []uint64:
	for i := range data {
	data[i] = order.Uint64(bs[8*i:])
	}
	}
	return nil
	}

	// Fallback to reflect-based decoding.
	v := reflect.ValueOf(data)
	size := -1
	switch v.Kind() {
	case reflect.Ptr:
	v = v.Elem()
	size = dataSize(v)
	case reflect.Slice:
	size = dataSize(v)
	}
	if size < 0 {
	return errors.New("binary.Read: invalid type " + reflect.TypeOf(data).String())
	}
	d := &decoder{order: order, buf: make([]byte, size)}
	if _, err := io.ReadFull(r, d.buf); err != nil {
	return err
	}
	d.value(v)
	return nil
	}

	// Write writes the binary representation of data into w.
	// Data must be a fixed-size value or a slice of fixed-size
	// values, or a pointer to such data.
	// Boolean values encode as one byte: 1 for true, and 0 for false.
	// Bytes written to w are encoded using the specified byte order
	// and read from successive fields of the data.
	// When writing structs, zero values are written for fields
	// with blank (_) field names.
	func Write(w io.Writer, order ByteOrder, data interface{}) error {
	// Fast path for basic types and slices.
	if n := intDataSize(data); n != 0 {
	bs := make([]byte, n)
	switch v := data.(type) {
	case *bool:
	if *v {
	bs[0] = 1
	} else {
	bs[0] = 0
	}
	case bool:
	if v {
	bs[0] = 1
	} else {
	bs[0] = 0
	}
	case []bool:
	for i, x := range v {
	if x {
	bs[i] = 1
	} else {
	bs[i] = 0
	}
	}
	case *int8:
	bs[0] = byte(*v)
	case int8:
	bs[0] = byte(v)
	case []int8:
	for i, x := range v {
	bs[i] = byte(x)
	}
	case *uint8:
	bs[0] = *v
	case uint8:
	bs[0] = v
	case []uint8:
	bs = v // TODO(josharian): avoid allocating bs in this case?
	case *int16:
	order.PutUint16(bs, uint16(*v))
	case int16:
	order.PutUint16(bs, uint16(v))
	case []int16:
	for i, x := range v {
	order.PutUint16(bs[2*i:], uint16(x))
	}
	case *uint16:
	order.PutUint16(bs, *v)
	case uint16:
	order.PutUint16(bs, v)
	case []uint16:
	for i, x := range v {
	order.PutUint16(bs[2*i:], x)
	}
	case *int32:
	order.PutUint32(bs, uint32(*v))
	case int32:
	order.PutUint32(bs, uint32(v))
	case []int32:
	for i, x := range v {
	order.PutUint32(bs[4*i:], uint32(x))
	}
	case *uint32:
	order.PutUint32(bs, *v)
	case uint32:
	order.PutUint32(bs, v)
	case []uint32:
	for i, x := range v {
	order.PutUint32(bs[4*i:], x)
	}
	case *int64:
	order.PutUint64(bs, uint64(*v))
	case int64:
	order.PutUint64(bs, uint64(v))
	case []int64:
	for i, x := range v {
	order.PutUint64(bs[8*i:], uint64(x))
	}
	case *uint64:
	order.PutUint64(bs, *v)
	case uint64:
	order.PutUint64(bs, v)
	case []uint64:
	for i, x := range v {
	order.PutUint64(bs[8*i:], x)
	}
	}
	_, err := w.Write(bs)
	return err
	}

	// Fallback to reflect-based encoding.
	v := reflect.Indirect(reflect.ValueOf(data))
	size := dataSize(v)
	if size < 0 {
	return errors.New("binary.Write: invalid type " + reflect.TypeOf(data).String())
	}
	buf := make([]byte, size)
	e := &encoder{order: order, buf: buf}
	e.value(v)
	_, err := w.Write(buf)
	return err
	}

	// Size returns how many bytes Write would generate to encode the value v, which
	// must be a fixed-size value or a slice of fixed-size values, or a pointer to such data.
	// If v is neither of these, Size returns -1.
	func Size(v interface{}) int {
	return dataSize(reflect.Indirect(reflect.ValueOf(v)))
	}

	var structSize sync.Map // map[reflect.Type]int

	// dataSize returns the number of bytes the actual data represented by v occupies in memory.
	// For compound structures, it sums the sizes of the elements. Thus, for instance, for a slice
	// it returns the length of the slice times the element size and does not count the memory
	// occupied by the header. If the type of v is not acceptable, dataSize returns -1.
	func dataSize(v reflect.Value) int {
	switch v.Kind() {
	case reflect.Slice:
	if s := sizeof(v.Type().Elem()); s >= 0 {
	return s * v.Len()
	}
	return -1

	case reflect.Struct:
	t := v.Type()
	if size, ok := structSize.Load(t); ok {
	return size.(int)
	}
	size := sizeof(t)
	structSize.Store(t, size)
	return size

	default:
	return sizeof(v.Type())
	}
	}

	// sizeof returns the size >= 0 of variables for the given type or -1 if the type is not acceptable.
	func sizeof(t reflect.Type) int {
	switch t.Kind() {
	case reflect.Array:
	if s := sizeof(t.Elem()); s >= 0 {
	return s * t.Len()
	}

	case reflect.Struct:
	sum := 0
	for i, n := 0, t.NumField(); i < n; i++ {
	s := sizeof(t.Field(i).Type)
	if s < 0 {
	return -1
	}
	sum += s
	}
	return sum

	case reflect.Bool,
	reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64,
	reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
	reflect.Float32, reflect.Float64, reflect.Complex64, reflect.Complex128:
	return int(t.Size())
	}

	return -1
	}

	type coder struct {
	order ByteOrder
	buf []byte
	offset int
	}

	type decoder coder
	type encoder coder

	func (d *decoder) bool() bool {
	x := d.buf[d.offset]
	d.offset++
	return x != 0
	}

	func (e *encoder) bool(x bool) {
	if x {
	e.buf[e.offset] = 1
	} else {
	e.buf[e.offset] = 0
	}
	e.offset++
	}

	func (d *decoder) uint8() uint8 {
	x := d.buf[d.offset]
	d.offset++
	return x
	}

	func (e *encoder) uint8(x uint8) {
	e.buf[e.offset] = x
	e.offset++
	}

	func (d *decoder) uint16() uint16 {
	x := d.order.Uint16(d.buf[d.offset : d.offset+2])
	d.offset += 2
	return x
	}

	func (e *encoder) uint16(x uint16) {
	e.order.PutUint16(e.buf[e.offset:e.offset+2], x)
	e.offset += 2
	}

	func (d *decoder) uint32() uint32 {
	x := d.order.Uint32(d.buf[d.offset : d.offset+4])
	d.offset += 4
	return x
	}

	func (e *encoder) uint32(x uint32) {
	e.order.PutUint32(e.buf[e.offset:e.offset+4], x)
	e.offset += 4
	}

	func (d *decoder) uint64() uint64 {
	x := d.order.Uint64(d.buf[d.offset : d.offset+8])
	d.offset += 8
	return x
	}

	func (e *encoder) uint64(x uint64) {
	e.order.PutUint64(e.buf[e.offset:e.offset+8], x)
	e.offset += 8
	}

	func (d *decoder) int8() int8 { return int8(d.uint8()) }

	func (e *encoder) int8(x int8) { e.uint8(uint8(x)) }

	func (d *decoder) int16() int16 { return int16(d.uint16()) }

	func (e *encoder) int16(x int16) { e.uint16(uint16(x)) }

	func (d *decoder) int32() int32 { return int32(d.uint32()) }

	func (e *encoder) int32(x int32) { e.uint32(uint32(x)) }

	func (d *decoder) int64() int64 { return int64(d.uint64()) }

	func (e *encoder) int64(x int64) { e.uint64(uint64(x)) }

	func (d *decoder) value(v reflect.Value) {
	switch v.Kind() {
	case reflect.Array:
	l := v.Len()
	for i := 0; i < l; i++ {
	d.value(v.Index(i))
	}

	case reflect.Struct:
	t := v.Type()
	l := v.NumField()
	for i := 0; i < l; i++ {
	// Note: Calling v.CanSet() below is an optimization.
	// It would be sufficient to check the field name,
	// but creating the StructField info for each field is
	// costly (run "go test -bench=ReadStruct" and compare
	// results when making changes to this code).
	if v := v.Field(i); v.CanSet() \|\| t.Field(i).Name != "_" {
	d.value(v)
	} else {
	d.skip(v)
	}
	}

	case reflect.Slice:
	l := v.Len()
	for i := 0; i < l; i++ {
	d.value(v.Index(i))
	}

	case reflect.Bool:
	v.SetBool(d.bool())

	case reflect.Int8:
	v.SetInt(int64(d.int8()))
	case reflect.Int16:
	v.SetInt(int64(d.int16()))
	case reflect.Int32:
	v.SetInt(int64(d.int32()))
	case reflect.Int64:
	v.SetInt(d.int64())

	case reflect.Uint8:
	v.SetUint(uint64(d.uint8()))
	case reflect.Uint16:
	v.SetUint(uint64(d.uint16()))
	case reflect.Uint32:
	v.SetUint(uint64(d.uint32()))
	case reflect.Uint64:
	v.SetUint(d.uint64())

	case reflect.Float32:
	v.SetFloat(float64(math.Float32frombits(d.uint32())))
	case reflect.Float64:
	v.SetFloat(math.Float64frombits(d.uint64()))

	case reflect.Complex64:
	v.SetComplex(complex(
	float64(math.Float32frombits(d.uint32())),
	float64(math.Float32frombits(d.uint32())),
	))
	case reflect.Complex128:
	v.SetComplex(complex(
	math.Float64frombits(d.uint64()),
	math.Float64frombits(d.uint64()),
	))
	}
	}

	func (e *encoder) value(v reflect.Value) {
	switch v.Kind() {
	case reflect.Array:
	l := v.Len()
	for i := 0; i < l; i++ {
	e.value(v.Index(i))
	}

	case reflect.Struct:
	t := v.Type()
	l := v.NumField()
	for i := 0; i < l; i++ {
	// see comment for corresponding code in decoder.value()
	if v := v.Field(i); v.CanSet() \|\| t.Field(i).Name != "_" {
	e.value(v)
	} else {
	e.skip(v)
	}
	}

	case reflect.Slice:
	l := v.Len()
	for i := 0; i < l; i++ {
	e.value(v.Index(i))
	}

	case reflect.Bool:
	e.bool(v.Bool())

	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
	switch v.Type().Kind() {
	case reflect.Int8:
	e.int8(int8(v.Int()))
	case reflect.Int16:
	e.int16(int16(v.Int()))
	case reflect.Int32:
	e.int32(int32(v.Int()))
	case reflect.Int64:
	e.int64(v.Int())
	}

	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
	switch v.Type().Kind() {
	case reflect.Uint8:
	e.uint8(uint8(v.Uint()))
	case reflect.Uint16:
	e.uint16(uint16(v.Uint()))
	case reflect.Uint32:
	e.uint32(uint32(v.Uint()))
	case reflect.Uint64:
	e.uint64(v.Uint())
	}

	case reflect.Float32, reflect.Float64:
	switch v.Type().Kind() {
	case reflect.Float32:
	e.uint32(math.Float32bits(float32(v.Float())))
	case reflect.Float64:
	e.uint64(math.Float64bits(v.Float()))
	}

	case reflect.Complex64, reflect.Complex128:
	switch v.Type().Kind() {
	case reflect.Complex64:
	x := v.Complex()
	e.uint32(math.Float32bits(float32(real(x))))
	e.uint32(math.Float32bits(float32(imag(x))))
	case reflect.Complex128:
	x := v.Complex()
	e.uint64(math.Float64bits(real(x)))
	e.uint64(math.Float64bits(imag(x)))
	}
	}
	}

	func (d *decoder) skip(v reflect.Value) {
	d.offset += dataSize(v)
	}

	func (e *encoder) skip(v reflect.Value) {
	n := dataSize(v)
	zero := e.buf[e.offset : e.offset+n]
	for i := range zero {
	zero[i] = 0
	}
	e.offset += n
	}

	// intDataSize returns the size of the data required to represent the data when encoded.
	// It returns zero if the type cannot be implemented by the fast path in Read or Write.
	func intDataSize(data interface{}) int {
	switch data := data.(type) {
	case bool, int8, uint8, bool, int8, *uint8:
	return 1
	case []bool:
	return len(data)
	case []int8:
	return len(data)
	case []uint8:
	return len(data)
	case int16, uint16, int16, uint16:
	return 2
	case []int16:
	return 2 * len(data)
	case []uint16:
	return 2 * len(data)
	case int32, uint32, int32, uint32:
	return 4
	case []int32:
	return 4 * len(data)
	case []uint32:
	return 4 * len(data)
	case int64, uint64, int64, uint64:
	return 8
	case []int64:
	return 8 * len(data)
	case []uint64:
	return 8 * len(data)
	}
	return 0
	}