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gap_darwin.go
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gap_darwin.go
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package bluetooth
import (
"errors"
"fmt"
"time"
"github.com/tinygo-org/cbgo"
)
// default connection timeout
const defaultConnectionTimeout time.Duration = 10 * time.Second
// Address contains a Bluetooth address which on macOS is a UUID.
type Address struct {
// UUID since this is macOS.
UUID
}
// IsRandom ignored on macOS.
func (ad Address) IsRandom() bool {
return false
}
// SetRandom ignored on macOS.
func (ad *Address) SetRandom(val bool) {
}
// Set the address
func (ad *Address) Set(val string) {
uuid, err := ParseUUID(val)
if err != nil {
return
}
ad.UUID = uuid
}
// Scan starts a BLE scan. It is stopped by a call to StopScan. A common pattern
// is to cancel the scan when a particular device has been found.
func (a *Adapter) Scan(callback func(*Adapter, ScanResult)) (err error) {
if callback == nil {
return errors.New("must provide callback to Scan function")
}
if a.scanChan != nil {
return errors.New("already calling Scan function")
}
a.peripheralFoundHandler = callback
// Channel that will be closed when the scan is stopped.
// Detecting whether the scan is stopped can be done by doing a non-blocking
// read from it. If it succeeds, the scan is stopped.
a.scanChan = make(chan error)
a.cm.Scan(nil, &cbgo.CentralManagerScanOpts{
AllowDuplicates: false,
})
// Check whether the scan is stopped. This is necessary to avoid a race
// condition between the signal channel and the cancelScan channel when
// the callback calls StopScan() (no new callbacks may be called after
// StopScan is called).
select {
case <-a.scanChan:
close(a.scanChan)
a.scanChan = nil
return nil
}
}
// StopScan stops any in-progress scan. It can be called from within a Scan
// callback to stop the current scan. If no scan is in progress, an error will
// be returned.
func (a *Adapter) StopScan() error {
if a.scanChan == nil {
return errors.New("not calling Scan function")
}
a.scanChan <- nil
a.cm.StopScan()
return nil
}
// Device is a connection to a remote peripheral.
type Device struct {
Address Address
*deviceInternal
}
type deviceInternal struct {
delegate *peripheralDelegate
cm cbgo.CentralManager
prph cbgo.Peripheral
servicesChan chan error
charsChan chan error
services map[UUID]DeviceService
}
// Connect starts a connection attempt to the given peripheral device address.
func (a *Adapter) Connect(address Address, params ConnectionParams) (Device, error) {
uuid, err := cbgo.ParseUUID(address.UUID.String())
if err != nil {
return Device{}, err
}
prphs := a.cm.RetrievePeripheralsWithIdentifiers([]cbgo.UUID{uuid})
if len(prphs) == 0 {
return Device{}, fmt.Errorf("Connect failed: no peer with address: %s", address.UUID.String())
}
timeout := defaultConnectionTimeout
if params.ConnectionTimeout != 0 {
timeout = time.Duration(int64(params.ConnectionTimeout)*625) * time.Microsecond
}
id := prphs[0].Identifier().String()
prphCh := make(chan cbgo.Peripheral)
a.connectMap.Store(id, prphCh)
defer a.connectMap.Delete(id)
a.cm.Connect(prphs[0], nil)
timeoutTimer := time.NewTimer(timeout)
var connectionError error
for {
// wait on channel for connect
select {
case p := <-prphCh:
// check if we have received a disconnected peripheral
if p.State() == cbgo.PeripheralStateDisconnected {
return Device{}, connectionError
}
d := Device{
Address: address,
deviceInternal: &deviceInternal{
cm: a.cm,
prph: p,
servicesChan: make(chan error),
charsChan: make(chan error),
},
}
d.delegate = &peripheralDelegate{d: d}
p.SetDelegate(d.delegate)
a.connectHandler(d, true)
return d, nil
case <-timeoutTimer.C:
// we need to cancel the connection if we have timed out ourselves
a.cm.CancelConnect(prphs[0])
// record an error to use when the disconnect comes through later.
connectionError = errors.New("timeout on Connect")
// we are not ready to return yet, we need to wait for the disconnect event to come through
// so continue on from this case and wait for something to show up on prphCh
continue
}
}
}
// Disconnect from the BLE device. This method is non-blocking and does not
// wait until the connection is fully gone.
func (d Device) Disconnect() error {
d.cm.CancelConnect(d.prph)
return nil
}
// RequestConnectionParams requests a different connection latency and timeout
// of the given device connection. Fields that are unset will be left alone.
// Whether or not the device will actually honor this, depends on the device and
// on the specific parameters.
//
// This call has not yet been implemented on macOS.
func (d Device) RequestConnectionParams(params ConnectionParams) error {
// TODO: implement this using setDesiredConnectionLatency, see:
// https://developer.apple.com/documentation/corebluetooth/cbperipheralmanager/1393277-setdesiredconnectionlatency
return nil
}
// Peripheral delegate functions
type peripheralDelegate struct {
cbgo.PeripheralDelegateBase
d Device
}
// DidDiscoverServices is called when the services for a Peripheral
// have been discovered.
func (pd *peripheralDelegate) DidDiscoverServices(prph cbgo.Peripheral, err error) {
pd.d.servicesChan <- nil
}
// DidDiscoverCharacteristics is called when the characteristics for a Service
// for a Peripheral have been discovered.
func (pd *peripheralDelegate) DidDiscoverCharacteristics(prph cbgo.Peripheral, svc cbgo.Service, err error) {
pd.d.charsChan <- nil
}
// DidUpdateValueForCharacteristic is called when the characteristic for a Service
// for a Peripheral receives a notification with a new value,
// or receives a value for a read request.
func (pd *peripheralDelegate) DidUpdateValueForCharacteristic(prph cbgo.Peripheral, chr cbgo.Characteristic, err error) {
uuid, _ := ParseUUID(chr.UUID().String())
svcuuid, _ := ParseUUID(chr.Service().UUID().String())
if svc, ok := pd.d.services[svcuuid]; ok {
for _, char := range svc.characteristics {
if char.characteristic == chr && uuid == char.UUID() { // compare pointers
if err == nil && char.callback != nil {
go char.callback(chr.Value())
}
if char.readChan != nil {
char.readChan <- err
}
}
}
}
}
// DidWriteValueForCharacteristic is called after the characteristic for a Service
// for a Peripheral trigger a write with response. It contains the returned error or nil.
func (pd *peripheralDelegate) DidWriteValueForCharacteristic(_ cbgo.Peripheral, chr cbgo.Characteristic, err error) {
uuid, _ := ParseUUID(chr.UUID().String())
svcuuid, _ := ParseUUID(chr.Service().UUID().String())
if svc, ok := pd.d.services[svcuuid]; ok {
for _, char := range svc.characteristics {
if char.characteristic == chr && uuid == char.UUID() { // compare pointers
if char.writeChan != nil {
char.writeChan <- err
}
}
}
}
}