mirror of git://gcc.gnu.org/git/gcc.git
510 lines
12 KiB
Go
510 lines
12 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package binary implements translation between numbers and byte sequences
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// and encoding and decoding of varints.
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//
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// Numbers are translated by reading and writing fixed-size values.
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// A fixed-size value is either a fixed-size arithmetic
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// type (int8, uint8, int16, float32, complex64, ...)
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// or an array or struct containing only fixed-size values.
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//
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// Varints are a method of encoding integers using one or more bytes;
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// numbers with smaller absolute value take a smaller number of bytes.
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// For a specification, see http://code.google.com/apis/protocolbuffers/docs/encoding.html.
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package binary
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import (
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"errors"
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"io"
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"math"
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"reflect"
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)
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// A ByteOrder specifies how to convert byte sequences into
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// 16-, 32-, or 64-bit unsigned integers.
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type ByteOrder interface {
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Uint16([]byte) uint16
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Uint32([]byte) uint32
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Uint64([]byte) uint64
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PutUint16([]byte, uint16)
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PutUint32([]byte, uint32)
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PutUint64([]byte, uint64)
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String() string
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}
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// LittleEndian is the little-endian implementation of ByteOrder.
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var LittleEndian littleEndian
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// BigEndian is the big-endian implementation of ByteOrder.
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var BigEndian bigEndian
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type littleEndian struct{}
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func (littleEndian) Uint16(b []byte) uint16 { return uint16(b[0]) | uint16(b[1])<<8 }
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func (littleEndian) PutUint16(b []byte, v uint16) {
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b[0] = byte(v)
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b[1] = byte(v >> 8)
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}
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func (littleEndian) Uint32(b []byte) uint32 {
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return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24
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}
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func (littleEndian) PutUint32(b []byte, v uint32) {
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b[0] = byte(v)
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b[1] = byte(v >> 8)
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b[2] = byte(v >> 16)
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b[3] = byte(v >> 24)
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}
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func (littleEndian) Uint64(b []byte) uint64 {
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return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
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uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
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}
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func (littleEndian) PutUint64(b []byte, v uint64) {
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b[0] = byte(v)
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b[1] = byte(v >> 8)
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b[2] = byte(v >> 16)
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b[3] = byte(v >> 24)
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b[4] = byte(v >> 32)
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b[5] = byte(v >> 40)
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b[6] = byte(v >> 48)
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b[7] = byte(v >> 56)
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}
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func (littleEndian) String() string { return "LittleEndian" }
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func (littleEndian) GoString() string { return "binary.LittleEndian" }
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type bigEndian struct{}
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func (bigEndian) Uint16(b []byte) uint16 { return uint16(b[1]) | uint16(b[0])<<8 }
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func (bigEndian) PutUint16(b []byte, v uint16) {
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b[0] = byte(v >> 8)
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b[1] = byte(v)
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}
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func (bigEndian) Uint32(b []byte) uint32 {
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return uint32(b[3]) | uint32(b[2])<<8 | uint32(b[1])<<16 | uint32(b[0])<<24
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}
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func (bigEndian) PutUint32(b []byte, v uint32) {
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b[0] = byte(v >> 24)
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b[1] = byte(v >> 16)
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b[2] = byte(v >> 8)
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b[3] = byte(v)
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}
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func (bigEndian) Uint64(b []byte) uint64 {
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return uint64(b[7]) | uint64(b[6])<<8 | uint64(b[5])<<16 | uint64(b[4])<<24 |
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uint64(b[3])<<32 | uint64(b[2])<<40 | uint64(b[1])<<48 | uint64(b[0])<<56
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}
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func (bigEndian) PutUint64(b []byte, v uint64) {
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b[0] = byte(v >> 56)
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b[1] = byte(v >> 48)
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b[2] = byte(v >> 40)
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b[3] = byte(v >> 32)
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b[4] = byte(v >> 24)
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b[5] = byte(v >> 16)
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b[6] = byte(v >> 8)
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b[7] = byte(v)
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}
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func (bigEndian) String() string { return "BigEndian" }
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func (bigEndian) GoString() string { return "binary.BigEndian" }
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// Read reads structured binary data from r into data.
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// Data must be a pointer to a fixed-size value or a slice
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// of fixed-size values.
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// Bytes read from r are decoded using the specified byte order
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// and written to successive fields of the data.
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func Read(r io.Reader, order ByteOrder, data interface{}) error {
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// Fast path for basic types.
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if n := intDestSize(data); n != 0 {
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var b [8]byte
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bs := b[:n]
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if _, err := io.ReadFull(r, bs); err != nil {
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return err
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}
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switch v := data.(type) {
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case *int8:
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*v = int8(b[0])
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case *uint8:
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*v = b[0]
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case *int16:
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*v = int16(order.Uint16(bs))
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case *uint16:
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*v = order.Uint16(bs)
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case *int32:
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*v = int32(order.Uint32(bs))
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case *uint32:
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*v = order.Uint32(bs)
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case *int64:
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*v = int64(order.Uint64(bs))
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case *uint64:
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*v = order.Uint64(bs)
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}
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return nil
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}
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// Fallback to reflect-based.
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var v reflect.Value
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switch d := reflect.ValueOf(data); d.Kind() {
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case reflect.Ptr:
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v = d.Elem()
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case reflect.Slice:
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v = d
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default:
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return errors.New("binary.Read: invalid type " + d.Type().String())
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}
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size := dataSize(v)
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if size < 0 {
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return errors.New("binary.Read: invalid type " + v.Type().String())
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}
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d := &decoder{order: order, buf: make([]byte, size)}
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if _, err := io.ReadFull(r, d.buf); err != nil {
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return err
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}
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d.value(v)
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return nil
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}
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// Write writes the binary representation of data into w.
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// Data must be a fixed-size value or a slice of fixed-size
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// values, or a pointer to such data.
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// Bytes written to w are encoded using the specified byte order
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// and read from successive fields of the data.
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func Write(w io.Writer, order ByteOrder, data interface{}) error {
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// Fast path for basic types.
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var b [8]byte
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var bs []byte
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switch v := data.(type) {
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case *int8:
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bs = b[:1]
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b[0] = byte(*v)
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case int8:
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bs = b[:1]
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b[0] = byte(v)
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case *uint8:
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bs = b[:1]
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b[0] = *v
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case uint8:
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bs = b[:1]
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b[0] = byte(v)
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case *int16:
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bs = b[:2]
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order.PutUint16(bs, uint16(*v))
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case int16:
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bs = b[:2]
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order.PutUint16(bs, uint16(v))
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case *uint16:
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bs = b[:2]
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order.PutUint16(bs, *v)
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case uint16:
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bs = b[:2]
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order.PutUint16(bs, v)
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case *int32:
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bs = b[:4]
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order.PutUint32(bs, uint32(*v))
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case int32:
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bs = b[:4]
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order.PutUint32(bs, uint32(v))
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case *uint32:
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bs = b[:4]
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order.PutUint32(bs, *v)
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case uint32:
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bs = b[:4]
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order.PutUint32(bs, v)
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case *int64:
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bs = b[:8]
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order.PutUint64(bs, uint64(*v))
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case int64:
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bs = b[:8]
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order.PutUint64(bs, uint64(v))
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case *uint64:
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bs = b[:8]
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order.PutUint64(bs, *v)
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case uint64:
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bs = b[:8]
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order.PutUint64(bs, v)
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}
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if bs != nil {
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_, err := w.Write(bs)
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return err
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}
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v := reflect.Indirect(reflect.ValueOf(data))
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size := dataSize(v)
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if size < 0 {
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return errors.New("binary.Write: invalid type " + v.Type().String())
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}
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buf := make([]byte, size)
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e := &encoder{order: order, buf: buf}
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e.value(v)
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_, err := w.Write(buf)
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return err
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}
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// Size returns how many bytes Write would generate to encode the value v, which
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// must be a fixed-size value or a slice of fixed-size values, or a pointer to such data.
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func Size(v interface{}) int {
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return dataSize(reflect.Indirect(reflect.ValueOf(v)))
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}
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// dataSize returns the number of bytes the actual data represented by v occupies in memory.
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// For compound structures, it sums the sizes of the elements. Thus, for instance, for a slice
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// it returns the length of the slice times the element size and does not count the memory
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// occupied by the header.
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func dataSize(v reflect.Value) int {
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if v.Kind() == reflect.Slice {
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elem := sizeof(v.Type().Elem())
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if elem < 0 {
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return -1
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}
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return v.Len() * elem
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}
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return sizeof(v.Type())
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}
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func sizeof(t reflect.Type) int {
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switch t.Kind() {
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case reflect.Array:
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n := sizeof(t.Elem())
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if n < 0 {
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return -1
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}
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return t.Len() * n
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case reflect.Struct:
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sum := 0
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for i, n := 0, t.NumField(); i < n; i++ {
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s := sizeof(t.Field(i).Type)
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if s < 0 {
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return -1
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}
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sum += s
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}
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return sum
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case reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64,
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reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
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reflect.Float32, reflect.Float64, reflect.Complex64, reflect.Complex128:
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return int(t.Size())
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}
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return -1
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}
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type decoder struct {
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order ByteOrder
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buf []byte
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}
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type encoder struct {
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order ByteOrder
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buf []byte
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}
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func (d *decoder) uint8() uint8 {
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x := d.buf[0]
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d.buf = d.buf[1:]
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return x
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}
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func (e *encoder) uint8(x uint8) {
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e.buf[0] = x
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e.buf = e.buf[1:]
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}
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func (d *decoder) uint16() uint16 {
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x := d.order.Uint16(d.buf[0:2])
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d.buf = d.buf[2:]
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return x
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}
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func (e *encoder) uint16(x uint16) {
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e.order.PutUint16(e.buf[0:2], x)
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e.buf = e.buf[2:]
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}
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func (d *decoder) uint32() uint32 {
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x := d.order.Uint32(d.buf[0:4])
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d.buf = d.buf[4:]
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return x
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}
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func (e *encoder) uint32(x uint32) {
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e.order.PutUint32(e.buf[0:4], x)
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e.buf = e.buf[4:]
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}
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func (d *decoder) uint64() uint64 {
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x := d.order.Uint64(d.buf[0:8])
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d.buf = d.buf[8:]
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return x
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}
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func (e *encoder) uint64(x uint64) {
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e.order.PutUint64(e.buf[0:8], x)
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e.buf = e.buf[8:]
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}
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func (d *decoder) int8() int8 { return int8(d.uint8()) }
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func (e *encoder) int8(x int8) { e.uint8(uint8(x)) }
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func (d *decoder) int16() int16 { return int16(d.uint16()) }
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func (e *encoder) int16(x int16) { e.uint16(uint16(x)) }
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func (d *decoder) int32() int32 { return int32(d.uint32()) }
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func (e *encoder) int32(x int32) { e.uint32(uint32(x)) }
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func (d *decoder) int64() int64 { return int64(d.uint64()) }
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func (e *encoder) int64(x int64) { e.uint64(uint64(x)) }
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func (d *decoder) value(v reflect.Value) {
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switch v.Kind() {
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case reflect.Array:
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l := v.Len()
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for i := 0; i < l; i++ {
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d.value(v.Index(i))
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}
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case reflect.Struct:
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l := v.NumField()
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for i := 0; i < l; i++ {
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d.value(v.Field(i))
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}
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case reflect.Slice:
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l := v.Len()
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for i := 0; i < l; i++ {
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d.value(v.Index(i))
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}
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case reflect.Int8:
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v.SetInt(int64(d.int8()))
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case reflect.Int16:
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v.SetInt(int64(d.int16()))
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case reflect.Int32:
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v.SetInt(int64(d.int32()))
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case reflect.Int64:
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v.SetInt(d.int64())
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case reflect.Uint8:
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v.SetUint(uint64(d.uint8()))
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case reflect.Uint16:
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v.SetUint(uint64(d.uint16()))
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case reflect.Uint32:
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v.SetUint(uint64(d.uint32()))
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case reflect.Uint64:
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v.SetUint(d.uint64())
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case reflect.Float32:
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v.SetFloat(float64(math.Float32frombits(d.uint32())))
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case reflect.Float64:
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v.SetFloat(math.Float64frombits(d.uint64()))
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case reflect.Complex64:
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v.SetComplex(complex(
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float64(math.Float32frombits(d.uint32())),
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float64(math.Float32frombits(d.uint32())),
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))
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case reflect.Complex128:
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v.SetComplex(complex(
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math.Float64frombits(d.uint64()),
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math.Float64frombits(d.uint64()),
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))
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}
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}
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func (e *encoder) value(v reflect.Value) {
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switch v.Kind() {
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case reflect.Array:
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l := v.Len()
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for i := 0; i < l; i++ {
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e.value(v.Index(i))
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}
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case reflect.Struct:
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l := v.NumField()
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for i := 0; i < l; i++ {
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e.value(v.Field(i))
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}
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case reflect.Slice:
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l := v.Len()
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for i := 0; i < l; i++ {
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e.value(v.Index(i))
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}
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case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
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switch v.Type().Kind() {
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case reflect.Int8:
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e.int8(int8(v.Int()))
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case reflect.Int16:
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e.int16(int16(v.Int()))
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case reflect.Int32:
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e.int32(int32(v.Int()))
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case reflect.Int64:
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e.int64(v.Int())
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}
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case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
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switch v.Type().Kind() {
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case reflect.Uint8:
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e.uint8(uint8(v.Uint()))
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case reflect.Uint16:
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e.uint16(uint16(v.Uint()))
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case reflect.Uint32:
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e.uint32(uint32(v.Uint()))
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case reflect.Uint64:
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e.uint64(v.Uint())
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}
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case reflect.Float32, reflect.Float64:
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switch v.Type().Kind() {
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case reflect.Float32:
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e.uint32(math.Float32bits(float32(v.Float())))
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case reflect.Float64:
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e.uint64(math.Float64bits(v.Float()))
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}
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case reflect.Complex64, reflect.Complex128:
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switch v.Type().Kind() {
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case reflect.Complex64:
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x := v.Complex()
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e.uint32(math.Float32bits(float32(real(x))))
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e.uint32(math.Float32bits(float32(imag(x))))
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case reflect.Complex128:
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x := v.Complex()
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e.uint64(math.Float64bits(real(x)))
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e.uint64(math.Float64bits(imag(x)))
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}
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}
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}
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// intDestSize returns the size of the integer that ptrType points to,
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// or 0 if the type is not supported.
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func intDestSize(ptrType interface{}) int {
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switch ptrType.(type) {
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case *int8, *uint8:
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return 1
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case *int16, *uint16:
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return 2
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case *int32, *uint32:
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return 4
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case *int64, *uint64:
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return 8
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}
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return 0
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}
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