209 lines
5.3 KiB
Go
209 lines
5.3 KiB
Go
package bluetooth
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import (
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"errors"
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"fmt"
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"time"
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"github.com/tinygo-org/cbgo"
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)
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// default connection timeout
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const defaultConnectionTimeout time.Duration = 10 * time.Second
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// Address contains a Bluetooth address which on macOS is a UUID.
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type Address struct {
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// UUID since this is macOS.
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UUID
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}
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// IsRandom ignored on macOS.
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func (ad Address) IsRandom() bool {
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return false
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}
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// SetRandom ignored on macOS.
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func (ad *Address) SetRandom(val bool) {
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}
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// Set the address
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func (ad *Address) Set(val string) {
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uuid, err := ParseUUID(val)
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if err != nil {
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return
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}
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ad.UUID = uuid
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}
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// Scan starts a BLE scan. It is stopped by a call to StopScan. A common pattern
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// is to cancel the scan when a particular device has been found.
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func (a *Adapter) Scan(callback func(*Adapter, ScanResult)) (err error) {
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if callback == nil {
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return errors.New("must provide callback to Scan function")
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}
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if a.scanChan != nil {
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return errors.New("already calling Scan function")
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}
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a.peripheralFoundHandler = callback
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// Channel that will be closed when the scan is stopped.
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// Detecting whether the scan is stopped can be done by doing a non-blocking
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// read from it. If it succeeds, the scan is stopped.
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a.scanChan = make(chan error)
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a.cm.Scan(nil, &cbgo.CentralManagerScanOpts{
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AllowDuplicates: false,
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})
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// Check whether the scan is stopped. This is necessary to avoid a race
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// condition between the signal channel and the cancelScan channel when
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// the callback calls StopScan() (no new callbacks may be called after
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// StopScan is called).
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select {
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case <-a.scanChan:
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close(a.scanChan)
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a.scanChan = nil
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return nil
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}
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}
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// StopScan stops any in-progress scan. It can be called from within a Scan
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// callback to stop the current scan. If no scan is in progress, an error will
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// be returned.
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func (a *Adapter) StopScan() error {
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if a.scanChan == nil {
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return errors.New("not calling Scan function")
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}
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a.scanChan <- nil
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a.cm.StopScan()
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return nil
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}
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// Device is a connection to a remote peripheral.
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type Device struct {
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delegate *peripheralDelegate
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cm cbgo.CentralManager
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prph cbgo.Peripheral
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servicesChan chan error
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charsChan chan error
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services map[UUID]DeviceService
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}
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// Connect starts a connection attempt to the given peripheral device address.
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func (a *Adapter) Connect(address Address, params ConnectionParams) (*Device, error) {
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uuid, err := cbgo.ParseUUID(address.UUID.String())
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if err != nil {
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return nil, err
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}
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prphs := a.cm.RetrievePeripheralsWithIdentifiers([]cbgo.UUID{uuid})
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if len(prphs) == 0 {
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return nil, fmt.Errorf("Connect failed: no peer with address: %s", address.UUID.String())
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}
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timeout := defaultConnectionTimeout
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if params.ConnectionTimeout != 0 {
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timeout = time.Duration(int64(params.ConnectionTimeout)*625) * time.Microsecond
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}
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id := prphs[0].Identifier().String()
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prphCh := make(chan cbgo.Peripheral)
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a.connectMap.Store(id, prphCh)
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defer a.connectMap.Delete(id)
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a.cm.Connect(prphs[0], nil)
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timeoutTimer := time.NewTimer(timeout)
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var connectionError error
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for {
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// wait on channel for connect
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select {
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case p := <-prphCh:
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// check if we have received a disconnected peripheral
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if p.State() == cbgo.PeripheralStateDisconnected {
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return nil, connectionError
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}
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d := &Device{
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cm: a.cm,
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prph: p,
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servicesChan: make(chan error),
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charsChan: make(chan error),
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}
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d.delegate = &peripheralDelegate{d: d}
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p.SetDelegate(d.delegate)
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a.connectHandler(address, true)
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return d, nil
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case <-timeoutTimer.C:
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// we need to cancel the connection if we have timed out ourselves
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a.cm.CancelConnect(prphs[0])
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// record an error to use when the disconnect comes through later.
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connectionError = errors.New("timeout on Connect")
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// we are not ready to return yet, we need to wait for the disconnect event to come through
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// so continue on from this case and wait for something to show up on prphCh
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continue
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}
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}
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}
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// Disconnect from the BLE device. This method is non-blocking and does not
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// wait until the connection is fully gone.
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func (d *Device) Disconnect() error {
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d.cm.CancelConnect(d.prph)
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return nil
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}
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// Peripheral delegate functions
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type peripheralDelegate struct {
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cbgo.PeripheralDelegateBase
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d *Device
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}
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// DidDiscoverServices is called when the services for a Peripheral
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// have been discovered.
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func (pd *peripheralDelegate) DidDiscoverServices(prph cbgo.Peripheral, err error) {
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pd.d.servicesChan <- nil
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}
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// DidDiscoverCharacteristics is called when the characteristics for a Service
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// for a Peripheral have been discovered.
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func (pd *peripheralDelegate) DidDiscoverCharacteristics(prph cbgo.Peripheral, svc cbgo.Service, err error) {
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pd.d.charsChan <- nil
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}
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// DidUpdateValueForCharacteristic is called when the characteristic for a Service
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// for a Peripheral receives a notification with a new value,
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// or receives a value for a read request.
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func (pd *peripheralDelegate) DidUpdateValueForCharacteristic(prph cbgo.Peripheral, chr cbgo.Characteristic, err error) {
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uuid, _ := ParseUUID(chr.UUID().String())
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svcuuid, _ := ParseUUID(chr.Service().UUID().String())
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if svc, ok := pd.d.services[svcuuid]; ok {
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if char, ok := svc.characteristics[uuid]; ok {
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if err == nil && char.callback != nil {
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go char.callback(chr.Value())
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}
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if char.readChan != nil {
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char.readChan <- err
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}
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}
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}
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}
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