Add Linux support

Very much experimental, no BLE service support yet and BLE LocalName in
advertisement packet doesn't seem to work. So rather useless at the
moment.

adapter_linux.go

@@ -0,0 +1,39 @@
+// +build !baremetal
+
+package bluetooth
+
+import (
+	"github.com/muka/go-bluetooth/api"
+	"github.com/muka/go-bluetooth/bluez/profile/adapter"
+)
+
+type Adapter struct {
+	adapter *adapter.Adapter1
+	id      string
+	handler func(Event)
+}
+
+// DefaultAdapter returns the default adapter on the current system. On Linux,
+// it will return the first adapter available.
+func DefaultAdapter() (*Adapter, error) {
+	adapter, err := api.GetDefaultAdapter()
+	if err != nil {
+		return nil, err
+	}
+	adapterID, err := adapter.GetAdapterID()
+	if err != nil {
+		return nil, err
+	}
+	return &Adapter{
+		adapter: adapter,
+		id:      adapterID,
+	}, nil
+}
+
+// Enable configures the BLE stack. It must be called before any
+// Bluetooth-related calls (unless otherwise indicated).
+//
+// The Linux implementation is a no-op.
+func (a *Adapter) Enable() error {
+	return nil
+}

adapter_sd.go

@@ -62,9 +62,15 @@ type Adapter struct {
 	charWriteHandlers []charWriteHandler
 }
 
-// DefaultAdapter is an adapter to the default Bluetooth stack on a given
+// defaultAdapter is an adapter to the default Bluetooth stack on a given
 // target.
-var DefaultAdapter = &Adapter{isDefault: true}
+var defaultAdapter = Adapter{isDefault: true}
+
+// DefaultAdapter returns the default adapter on the current system. On Nordic
+// chips, it will return the SoftDevice interface.
+func DefaultAdapter() (*Adapter, error) {
+	return &defaultAdapter, nil
+}
 
 // Enable configures the BLE stack. It must be called before any
 // Bluetooth-related calls (unless otherwise indicated).
@@ -108,7 +114,7 @@ func (a *Adapter) Enable() error {
 }
 
 func handleEvent() {
-	handler := DefaultAdapter.handler
+	handler := defaultAdapter.handler
 	if handler == nil {
 		return
 	}
@@ -131,7 +137,7 @@ func handleEvent() {
 			writeEvent := gattsEvent.params.unionfield_write()
 			len := writeEvent.len - writeEvent.offset
 			data := (*[255]byte)(unsafe.Pointer(&writeEvent.data[0]))[:len:len]
-			handler := DefaultAdapter.getCharWriteHandler(writeEvent.handle)
+			handler := defaultAdapter.getCharWriteHandler(writeEvent.handle)
 			if handler != nil {
 				handler.callback(Connection(gattsEvent.conn_handle), int(writeEvent.offset), data)
 			}

examples/advertisement/main.go

@@ -10,7 +10,8 @@ import (
 var advPayload = []byte("\x02\x01\x06" + "\x07\x09TinyGo")
 
 func main() {
-	adapter := bluetooth.DefaultAdapter
+	adapter, err := bluetooth.DefaultAdapter()
+	must("get default adapter", err)
 	must("enable SD", adapter.Enable())
 	adv := adapter.NewAdvertisement()
 	options := &bluetooth.AdvertiseOptions{

examples/heartrate/main.go

@@ -11,7 +11,8 @@ var advPayload = []byte("\x02\x01\x06" + "\x07\x09TinyGo")
 
 func main() {
 	println("starting")
-	adapter := bluetooth.DefaultAdapter
+	adapter, err := bluetooth.DefaultAdapter()
+	must("get default adapter", err)
 	adapter.SetEventHandler(handleBluetoothEvents)
 	must("enable SD", adapter.Enable())
 	adv := adapter.NewAdvertisement()

gap.go

@@ -1,10 +1,5 @@
 package bluetooth
 
-// Advertisement encapsulates a single advertisement instance.
-type Advertisement struct {
-	handle uint8
-}
-
 // AdvertiseOptions configures everything related to BLE advertisements.
 type AdvertiseOptions struct {
 	Interval AdvertiseInterval

gap_linux.go

@@ -0,0 +1,80 @@
+// +build !baremetal
+
+package bluetooth
+
+import (
+	"errors"
+
+	"github.com/muka/go-bluetooth/api"
+	"github.com/muka/go-bluetooth/bluez/profile/advertising"
+)
+
+var (
+	ErrMalformedAdvertisement = errors.New("bluetooth: malformed advertisement packet")
+)
+
+// Advertisement encapsulates a single advertisement instance.
+type Advertisement struct {
+	adapter       *Adapter
+	advertisement *api.Advertisement
+	properties    *advertising.LEAdvertisement1Properties
+}
+
+// NewAdvertisement creates a new advertisement instance but does not configure
+// it.
+func (a *Adapter) NewAdvertisement() *Advertisement {
+	return &Advertisement{
+		adapter: a,
+	}
+}
+
+// Configure this advertisement.
+func (a *Advertisement) Configure(broadcastData, scanResponseData []byte, options *AdvertiseOptions) error {
+	if a.advertisement != nil {
+		panic("todo: configure advertisement a second time")
+	}
+	if scanResponseData != nil {
+		panic("todo: scan response data")
+	}
+
+	// Quick-and-dirty advertisement packet parser.
+	a.properties = &advertising.LEAdvertisement1Properties{
+		Type:    advertising.AdvertisementTypeBroadcast,
+		Timeout: 1<<16 - 1,
+	}
+	for len(broadcastData) != 0 {
+		if len(broadcastData) < 2 {
+			return ErrMalformedAdvertisement
+		}
+		fieldLength := broadcastData[0]
+		fieldType := broadcastData[1]
+		fieldValue := broadcastData[2 : fieldLength+1]
+		if int(fieldLength) > len(broadcastData) {
+			return ErrMalformedAdvertisement
+		}
+		switch fieldType {
+		case 1:
+			// BLE advertisement flags. Ignore.
+		case 9:
+			// Complete Local Name.
+			a.properties.LocalName = string(fieldValue)
+		default:
+			return ErrMalformedAdvertisement
+		}
+		broadcastData = broadcastData[fieldLength+1:]
+	}
+
+	return nil
+}
+
+// Start advertisement. May only be called after it has been configured.
+func (a *Advertisement) Start() error {
+	if a.advertisement != nil {
+		panic("todo: start advertisement a second time")
+	}
+	_, err := api.ExposeAdvertisement(a.adapter.id, a.properties, uint32(a.properties.Timeout))
+	if err != nil {
+		return err
+	}
+	return nil
+}

gap_sd.go

@@ -11,6 +11,11 @@ package bluetooth
 */
 import "C"
 
+// Advertisement encapsulates a single advertisement instance.
+type Advertisement struct {
+	handle uint8
+}
+
 // NewAdvertisement creates a new advertisement instance but does not configure
 // it. It can be called before the SoftDevice has been initialized.
 func (a *Adapter) NewAdvertisement() *Advertisement {