# SBT-MAVLink Plugin

This plugin provides generation of Scala sources from MAVLink message definition files.
It translates a MAVLink dialect defined in XML to useable scala objects and provides utilities for parsing
and creating MAVLink packets.

## Generated Code

### General
The generated code is in general used as the following examples illustrates.

```scala
import org.mavlink._

//parser to transform an incoming byte stream into packets
val parser = new Parser(
  (pckt: Packet) => {
    val msg: Message = Message.unpack(pckt.messageId, pckt.payload)
  	println("received message: " + msg)
  },
  (err: Parser.Errors.Error) => {
    sys.error("parse error: " + err)
  }
)

//assembles messages into packets from a specific sender
val assembler = new Assembler(SenderSystemId, SenderComponentId)

//create an explicit message
val message = Heartbeat(0)

//pack the message into a payload
val (id: Byte, payload: Array[Byte]) = Message.pack(message)

//assemble into packet
val packet = assembler.assemble(id, payload)

//simulate wire transfer
val data = packet.toArray
parser.push(data)
```

The concrete message implementations are generated according to the selected dialect (see section Keys).

### Types
Every message is mapped to a Scala case class, its name converted to CamelCase. The fields of
the case class correspond to the fields defined in the dialect definition (names are converted to camelCase).

Field types are mapped according to the following table

| Definition Type			| Scala Type            |
| ------------------------- | --------------------- |
| int8_t / uint8_t / char	| Byte                  |
| in16_t / uint16_t			| Short                 |
| int32_t / uint32_t		| Int                   |
| int64_t / uint64_t		| Long                  |
| float						| Float                 |
| double					| Double                |
| char[]					| String                |
| <type>[]			| Array[<type>]   |

*Note that since Scala only supports unsigned integer types, it is up to the client to
interpret the values of fields correctly.*

## Usage
Add the following to your plugins:

 ```scala
 addSbtPlugin("com.github.jodersky" % "sbt-mavlink" % "0.2")`
 ```

Set a MAVLink dialect
 ```scala
 mavlinkDialect := (baseDirectory in ThisBuild).value / "mavlink" / "dialect.xml"
 ```

Compile your project.

## Keys
All keys are defined in ```com.github.jodersky.mavlink.sbt.MavlinkKeys```

 -  ```mavlinkDialect``` - [Setting] - Specifies the location of the MAVLink dialect definition for which to generate Scala code.
 -  ```mavlinkGenerate``` - [Task] - Generates Scala code to interoperate with MAVLink. In a standard project using this plugin this
    task is added to ```sourceGenerators```, i.e. it is automatically called before compiling.

 - ```mavlinkTarget``` - [Setting] - Output directory of generated Scala sources. This should be within ```sourceManaged```.

## Limitations
  - Enums are not used, instead their corresponding integer value is substituted

## Credits
Copyright (c) 2015 Jakob Odersky

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.