/
decoder.go
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/
decoder.go
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// Copyright 2019 The go-daq 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 tdaq // import "github.com/go-daq/tdaq"
import (
"encoding/binary"
"fmt"
"io"
"math"
)
// Decoder decodes values from the underlying io.Reader, according to the TDAQ wire protocol.
type Decoder struct {
r io.Reader
err error
buf []byte
}
// NewDecoder creates a new decoder connected to the provided io.Reader.
func NewDecoder(r io.Reader) *Decoder {
return &Decoder{r: r, buf: make([]byte, 8)}
}
// Decode decodes a value from the underlying io.Reader into the provided pointer.
func (dec *Decoder) Decode(ptr interface{}) error {
if dec.err != nil {
return dec.err
}
if v, ok := ptr.(Unmarshaler); ok {
n := dec.ReadU64()
if dec.err != nil {
return dec.err
}
if sz := uint64(len(dec.buf)); sz < n {
dec.buf = append(dec.buf, make([]byte, n-sz)...)
}
dec.load(int(n))
if dec.err != nil {
return dec.err
}
dec.err = v.UnmarshalTDAQ(dec.buf)
return dec.err
}
switch v := ptr.(type) {
case *bool:
*v = dec.ReadBool()
case *uint8:
*v = dec.ReadU8()
case *uint16:
*v = dec.ReadU16()
case *uint32:
*v = dec.ReadU32()
case *uint64:
*v = dec.ReadU64()
case *int8:
*v = dec.ReadI8()
case *int16:
*v = dec.ReadI16()
case *int32:
*v = dec.ReadI32()
case *int64:
*v = dec.ReadI64()
case *float32:
*v = dec.ReadF32()
case *float64:
*v = dec.ReadF64()
case *string:
*v = dec.ReadStr()
default:
return fmt.Errorf("invalid value-type=%T", v)
}
return dec.err
}
func (dec *Decoder) Err() error { return dec.err }
func (dec *Decoder) load(n int) {
if dec.err != nil {
copy(dec.buf, []byte{0, 0, 0, 0, 0, 0, 0, 0})
return
}
_, dec.err = io.ReadFull(dec.r, dec.buf[:n])
}
func (dec *Decoder) ReadBool() bool {
v := dec.ReadU8()
return v != 0
}
func (dec *Decoder) ReadI8() int8 {
dec.load(1)
return int8(dec.buf[0])
}
func (dec *Decoder) ReadI16() int16 {
dec.load(2)
return int16(binary.LittleEndian.Uint16(dec.buf[:2]))
}
func (dec *Decoder) ReadI32() int32 {
dec.load(4)
return int32(binary.LittleEndian.Uint32(dec.buf[:4]))
}
func (dec *Decoder) ReadI64() int64 {
dec.load(8)
return int64(binary.LittleEndian.Uint64(dec.buf[:8]))
}
func (dec *Decoder) ReadU8() uint8 {
dec.load(1)
return dec.buf[0]
}
func (dec *Decoder) ReadU16() uint16 {
dec.load(2)
return binary.LittleEndian.Uint16(dec.buf[:2])
}
func (dec *Decoder) ReadU32() uint32 {
dec.load(4)
return binary.LittleEndian.Uint32(dec.buf[:4])
}
func (dec *Decoder) ReadU64() uint64 {
dec.load(8)
return binary.LittleEndian.Uint64(dec.buf[:8])
}
func (dec *Decoder) ReadF32() float32 {
dec.load(4)
return math.Float32frombits(binary.LittleEndian.Uint32(dec.buf[:4]))
}
func (dec *Decoder) ReadF64() float64 {
dec.load(8)
return math.Float64frombits(binary.LittleEndian.Uint64(dec.buf[:8]))
}
func (dec *Decoder) ReadStr() string {
n := dec.ReadI32()
if n <= 0 || dec.err != nil || uint32(n) >= math.MaxInt32 {
return ""
}
str := make([]byte, n)
_, dec.err = io.ReadFull(dec.r, str)
return string(str)
}