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xplane.go
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xplane.go
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// Copyright 2016 Ornen. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package xplane
import (
"bytes"
"encoding/binary"
"errors"
"log"
"net"
"time"
"github.com/ornen/go-xplane/messages"
)
const (
datagramPrefixLength = 5
messageLength = 36
)
type XPlane struct {
RemoteAddress string
LocalAddress string
Messages chan Message
connection *net.UDPConn
receivePeriod *time.Duration
}
type Opt func(*XPlane)
func New(remoteAddress, localAddress string, opts ...Opt) XPlane {
x := XPlane{
RemoteAddress: remoteAddress,
LocalAddress: localAddress,
Messages: make(chan Message),
}
for _, o := range opts {
o(&x)
}
return x
}
func ReceiveEvery(t time.Duration) Opt {
return func(x *XPlane) {
x.receivePeriod = &t
}
}
func (x *XPlane) Receive() error {
serverAddr, err := net.ResolveUDPAddr("udp", x.LocalAddress)
serverConn, err := net.ListenUDP("udp", serverAddr)
if err != nil {
return err
}
defer serverConn.Close()
buf := make([]byte, 1024)
if x.receivePeriod != nil {
t := time.NewTicker(*x.receivePeriod)
for {
select {
case <-t.C:
x.readBuf(serverConn, buf)
}
}
} else {
for {
x.readBuf(serverConn, buf)
}
}
return nil
}
func (x *XPlane) readBuf(c *net.UDPConn, b []byte) {
n, _, _ := c.ReadFromUDP(b)
m := (n - datagramPrefixLength) / messageLength
for i := 0; i < m; i++ {
sentence := b[datagramPrefixLength+i*messageLength : datagramPrefixLength+(i+1)*messageLength]
x.parse(sentence)
}
}
func (x *XPlane) parse(sentence []byte) {
messageType := sentence[0]
messageBuffer := bytes.NewBuffer(sentence[4:])
messageData := make([]float32, 8)
binary.Read(messageBuffer, binary.LittleEndian, &messageData)
switch messageType {
case messages.SpeedMessageType:
x.Messages <- messages.NewSpeedMessage(messageData)
case messages.GLoadMessageType:
x.Messages <- messages.NewGLoadMessage(messageData)
case messages.AngularVelocitiesMessageType:
x.Messages <- messages.NewAngularVelocitiesMessage(messageData)
case messages.PitchRollHeadingMessageType:
x.Messages <- messages.NewPitchRollHeadingMessage(messageData)
case messages.FlightControlMessageType:
x.Messages <- messages.NewFlightControlMessage(messageData)
case messages.GearsBrakesMessageType:
x.Messages <- messages.NewGearsBrakesMessage(messageData)
case messages.WeatherMessageType:
x.Messages <- messages.NewWeatherMessage(messageData)
case messages.LatLonAltMessageType:
x.Messages <- messages.NewLatLonAltMessage(messageData)
case messages.LocVelDistTraveledMessageType:
x.Messages <- messages.NewLocVelDistTraveledMessage(messageData)
case messages.BatteryAmperageMessageType:
x.Messages <- messages.NewBatteryAmperageMessage(messageData)
case messages.BatteryVoltageMessageType:
x.Messages <- messages.NewBatteryVoltageMessage(messageData)
case messages.EngineRPMMessageType:
x.Messages <- messages.NewEngineRPMMessage(messageData)
case messages.PropRPMMessageType:
x.Messages <- messages.NewPropRPMMessage(messageData)
case messages.PropPitchMessageType:
x.Messages <- messages.NewPropPitchMessage(messageData)
case messages.AngleOfAttackSideslipMessageType:
x.Messages <- messages.NewAngleOfAttackSideslipMessage(messageData)
default:
log.Println("Unknown message type: ", messageType)
}
}
func (x *XPlane) Connect() error {
udpAddr, err := net.ResolveUDPAddr("udp", x.RemoteAddress)
if err != nil {
return errors.New("wrong address!")
}
x.connection, err = net.DialUDP("udp", nil, udpAddr)
return err
}
func (x *XPlane) Send(command Command) error {
commandData := command.Data()
buf := new(bytes.Buffer)
buf.Write([]byte{'D', 'A', 'T', 'A', 0})
buf.Write([]byte{byte(command.Type()), 0, 0, 0})
if err := binary.Write(buf, binary.LittleEndian, &commandData); err != nil {
return err
}
_, err := x.connection.Write(buf.Bytes())
return err
}