bitstream

Overview ¶

Package bitstream is a simple library for sending byte data across the wire.

Bitstream messages are built using the following guidelines for primitive types:

[total message length]  - 4 bytes
  [byte][value]         - 1 byte + 1 byte
  [int32][value]        - 1 byte + 4 bytes
  [float32][value]      - 1 byte + 4 bytes
  [bool (byte)][value]  - 1 byte + 1 byte
  [string][size][value] - 1 byte + 4 bytes + N bytes
  ...

Message reading and writing is completely user driven.

The user defined network loop handles reading the first 4 bytes to determine the message size. The following data should then be passed to the instantiated Read() method.

Example:

// Sender
bs := NewBitStream()
bs.WriteByte(messageType)
bs.WriteInt(objectId)
bs.WriteFloat(position.x)
bs.WriteFloat(position.y)
bs.WriteFloat(position.z)
msg := bs.Write()

// Network loop reads first 4 bytes, passes rest of data to MessageHandler()

// Receiver
func MessageHandler(msg []byte) error {
  bs := NewBitStream()
  if err := bs.Read(msg); err != nil {
    return err
  } else {
    if msgType, err := bs.ReadByte(); err != nil {
      return err
    } else {
      switch msgType {
        case ENTITY_MOVED:
          // read id
          id, err := bs.ReadInt()
          if err != nil {
            return err
          }
          e := entity[id]
          // read position
          x, err := bs.ReadFloat()
          if err != nil {
            return err
          }
          y, err := bs.ReadFloat()
          if err != nil {
            return err
          }
          z, err := bs.ReadFloat()
          if err != nil {
            return err
          }
          e.SetPosition(x, y, z)
          break
      }
    }
  }
}

This library assumes the reciever understands the order the message parts are received in.