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path: root/src/encoding/binary/binary.go
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-rw-r--r--src/encoding/binary/binary.go634
1 files changed, 634 insertions, 0 deletions
diff --git a/src/encoding/binary/binary.go b/src/encoding/binary/binary.go
new file mode 100644
index 000000000..466bf97c9
--- /dev/null
+++ b/src/encoding/binary/binary.go
@@ -0,0 +1,634 @@
+// 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 (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
+// http://code.google.com/apis/protocolbuffers/docs/encoding.html.
+//
+// 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"
+)
+
+// 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 { return uint16(b[0]) | uint16(b[1])<<8 }
+
+func (littleEndian) PutUint16(b []byte, v uint16) {
+ b[0] = byte(v)
+ b[1] = byte(v >> 8)
+}
+
+func (littleEndian) Uint32(b []byte) uint32 {
+ return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24
+}
+
+func (littleEndian) PutUint32(b []byte, v uint32) {
+ 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 {
+ 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[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 { return uint16(b[1]) | uint16(b[0])<<8 }
+
+func (bigEndian) PutUint16(b []byte, v uint16) {
+ b[0] = byte(v >> 8)
+ b[1] = byte(v)
+}
+
+func (bigEndian) Uint32(b []byte) uint32 {
+ return uint32(b[3]) | uint32(b[2])<<8 | uint32(b[1])<<16 | uint32(b[0])<<24
+}
+
+func (bigEndian) PutUint32(b []byte, v uint32) {
+ 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 {
+ 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[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 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.
+func Read(r io.Reader, order ByteOrder, data interface{}) error {
+ // Fast path for basic types and slices.
+ if n := intDataSize(data); n != 0 {
+ var b [8]byte
+ var bs []byte
+ if n > len(b) {
+ bs = make([]byte, n)
+ } else {
+ bs = b[:n]
+ }
+ if _, err := io.ReadFull(r, bs); err != nil {
+ return err
+ }
+ switch data := data.(type) {
+ case *int8:
+ *data = int8(b[0])
+ case *uint8:
+ *data = b[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 []int8:
+ for i, x := range bs { // Easier to loop over the input for 8-bit values.
+ 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.
+// 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 {
+ var b [8]byte
+ var bs []byte
+ if n > len(b) {
+ bs = make([]byte, n)
+ } else {
+ bs = b[:n]
+ }
+ switch v := data.(type) {
+ case *int8:
+ bs = b[:1]
+ b[0] = byte(*v)
+ case int8:
+ bs = b[:1]
+ b[0] = byte(v)
+ case []int8:
+ for i, x := range v {
+ bs[i] = byte(x)
+ }
+ case *uint8:
+ bs = b[:1]
+ b[0] = *v
+ case uint8:
+ bs = b[:1]
+ b[0] = byte(v)
+ case []uint8:
+ bs = v
+ case *int16:
+ bs = b[:2]
+ order.PutUint16(bs, uint16(*v))
+ case int16:
+ bs = b[:2]
+ order.PutUint16(bs, uint16(v))
+ case []int16:
+ for i, x := range v {
+ order.PutUint16(bs[2*i:], uint16(x))
+ }
+ case *uint16:
+ bs = b[:2]
+ order.PutUint16(bs, *v)
+ case uint16:
+ bs = b[:2]
+ order.PutUint16(bs, v)
+ case []uint16:
+ for i, x := range v {
+ order.PutUint16(bs[2*i:], x)
+ }
+ case *int32:
+ bs = b[:4]
+ order.PutUint32(bs, uint32(*v))
+ case int32:
+ bs = b[:4]
+ order.PutUint32(bs, uint32(v))
+ case []int32:
+ for i, x := range v {
+ order.PutUint32(bs[4*i:], uint32(x))
+ }
+ case *uint32:
+ bs = b[:4]
+ order.PutUint32(bs, *v)
+ case uint32:
+ bs = b[:4]
+ order.PutUint32(bs, v)
+ case []uint32:
+ for i, x := range v {
+ order.PutUint32(bs[4*i:], x)
+ }
+ case *int64:
+ bs = b[:8]
+ order.PutUint64(bs, uint64(*v))
+ case int64:
+ bs = b[:8]
+ order.PutUint64(bs, uint64(v))
+ case []int64:
+ for i, x := range v {
+ order.PutUint64(bs[8*i:], uint64(x))
+ }
+ case *uint64:
+ bs = b[:8]
+ order.PutUint64(bs, *v)
+ case uint64:
+ bs = b[:8]
+ 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)))
+}
+
+// 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 {
+ if v.Kind() == reflect.Slice {
+ if s := sizeof(v.Type().Elem()); s >= 0 {
+ return s * v.Len()
+ }
+ return -1
+ }
+ 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.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
+}
+
+type decoder coder
+type encoder coder
+
+func (d *decoder) uint8() uint8 {
+ x := d.buf[0]
+ d.buf = d.buf[1:]
+ return x
+}
+
+func (e *encoder) uint8(x uint8) {
+ e.buf[0] = x
+ e.buf = e.buf[1:]
+}
+
+func (d *decoder) uint16() uint16 {
+ x := d.order.Uint16(d.buf[0:2])
+ d.buf = d.buf[2:]
+ return x
+}
+
+func (e *encoder) uint16(x uint16) {
+ e.order.PutUint16(e.buf[0:2], x)
+ e.buf = e.buf[2:]
+}
+
+func (d *decoder) uint32() uint32 {
+ x := d.order.Uint32(d.buf[0:4])
+ d.buf = d.buf[4:]
+ return x
+}
+
+func (e *encoder) uint32(x uint32) {
+ e.order.PutUint32(e.buf[0:4], x)
+ e.buf = e.buf[4:]
+}
+
+func (d *decoder) uint64() uint64 {
+ x := d.order.Uint64(d.buf[0:8])
+ d.buf = d.buf[8:]
+ return x
+}
+
+func (e *encoder) uint64(x uint64) {
+ e.order.PutUint64(e.buf[0:8], x)
+ e.buf = e.buf[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.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.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.buf = d.buf[dataSize(v):]
+}
+
+func (e *encoder) skip(v reflect.Value) {
+ n := dataSize(v)
+ for i := range e.buf[0:n] {
+ e.buf[i] = 0
+ }
+ e.buf = e.buf[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 int8, *int8, *uint8:
+ return 1
+ case []int8:
+ return len(data)
+ case []uint8:
+ return len(data)
+ case int16, *int16, *uint16:
+ return 2
+ case []int16:
+ return 2 * len(data)
+ case []uint16:
+ return 2 * len(data)
+ case int32, *int32, *uint32:
+ return 4
+ case []int32:
+ return 4 * len(data)
+ case []uint32:
+ return 4 * len(data)
+ case int64, *int64, *uint64:
+ return 8
+ case []int64:
+ return 8 * len(data)
+ case []uint64:
+ return 8 * len(data)
+ }
+ return 0
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-06-13 15:21:20 +0000