AVR optimisations

adapter.go

@@ -135,19 +135,6 @@ func (a *Adapter) Receive() (*Message, error) {
  }
 }
 
-// Wait for a message with the given command and direction.
-func (a *Adapter) Wait(command Command, direction Direction, timeout time.Duration) (*Message, error) {
- start := time.Now()
- for time.Since(start) < timeout {
- message, _ := a.Receive()
- // wait for correct message
- if message != nil && message.Command == command && message.Direction == direction {
- return message, nil
- }
- }
- return nil, ErrTimeout
-}
-
 // Reset the state machine and clear the message buffer.
 func (a *Adapter) Reset() {
  a.state = stateIdle
@@ -160,39 +147,3 @@ func (a *Adapter) Reset() {
  }
  }
 }
-
-// BeaconTime returns the next time when a beacon with the given ID should be broadcasted.
-func (a *Adapter) BeaconTime(id byte) time.Time {
- if a.beaconReferenceTime == 0 {
- return time.Time{}
- }
- offset := beaconOffset(id)
- t := a.beaconReferenceTime + offset.Milliseconds()
- now := time.Now().UnixMilli()
- for t < now {
- t += BeaconInterval.Milliseconds()
- }
- return time.UnixMilli(t)
-}
-
-func (a *Adapter) handleBeaconMaybe(message *Message) {
- if message.Command != CmdBeacon {
- return
- }
- id := message.Payload[0]
- if a.lowestID == 0 || a.lowestID > id {
- a.lowestID = id
- }
- if id != a.lowestID {
- return
- }
- // The beacon with the lowest ID is the reference beacon.
- offset := beaconOffset(a.lowestID)
- a.beaconReferenceTime = time.Now().UnixMilli() - offset.Milliseconds()
-}
-
-func beaconOffset(id byte) time.Duration {
- team := (id << 4) - 0x0A
- player := (id & 0x0F) - 1
- return time.Duration(team)*time.Second + time.Duration(player)*100*time.Millisecond
-}

adapter_avr.go

@@ -0,0 +1,52 @@
+//go:build avr
+
+package csp
+
+// Wait for a message with the given command and direction.
+func (a *Adapter) Wait(command Command, direction Direction, timeout int64) (*Message, error) {
+ start := runtime_nanotime()
+ for runtime_nanotime()-start < timeout {
+ message, _ := a.Receive()
+ // wait for correct message
+ if message != nil && message.Command == command && message.Direction == direction {
+ return message, nil
+ }
+ }
+ return nil, ErrTimeout
+}
+
+// BeaconTime returns the next time when a beacon with the given ID should be broadcasted.
+func (a *Adapter) BeaconTime(id byte) int64 {
+ if a.beaconReferenceTime == 0 {
+ return 0
+ }
+ offset := beaconOffset(id)
+ t := a.beaconReferenceTime + offset
+ now := runtime_nanotime()
+ for t < now {
+ t += int64(BeaconInterval)
+ }
+ return t
+}
+
+func (a *Adapter) handleBeaconMaybe(message *Message) {
+ if message.Command != CmdBeacon {
+ return
+ }
+ id := message.Payload[0]
+ if a.lowestID == 0 || a.lowestID > id {
+ a.lowestID = id
+ }
+ if id != a.lowestID {
+ return
+ }
+ // The beacon with the lowest ID is the reference beacon.
+ offset := beaconOffset(a.lowestID)
+ a.beaconReferenceTime = runtime_nanotime() - offset
+}
+
+func beaconOffset(id byte) int64 {
+ team := (id << 4) - 0x0A
+ player := (id & 0x0F) - 1
+ return int64(team)*1_000_000_000 + int64(player)*100_000_000
+}

adapter_common.go

@@ -0,0 +1,54 @@
+//go:build !avr
+
+package csp
+
+import "time"
+
+// Wait for a message with the given command and direction.
+func (a *Adapter) Wait(command Command, direction Direction, timeout time.Duration) (*Message, error) {
+ start := time.Now()
+ for time.Since(start) < timeout {
+ message, _ := a.Receive()
+ // wait for correct message
+ if message != nil && message.Command == command && message.Direction == direction {
+ return message, nil
+ }
+ }
+ return nil, ErrTimeout
+}
+
+// BeaconTime returns the next time when a beacon with the given ID should be broadcasted.
+func (a *Adapter) BeaconTime(id byte) time.Time {
+ if a.beaconReferenceTime == 0 {
+ return time.Time{}
+ }
+ offset := beaconOffset(id)
+ t := a.beaconReferenceTime + offset.Milliseconds()
+ now := time.Now().UnixMilli()
+ for t < now {
+ t += BeaconInterval.Milliseconds()
+ }
+ return time.UnixMilli(t)
+}
+
+func (a *Adapter) handleBeaconMaybe(message *Message) {
+ if message.Command != CmdBeacon {
+ return
+ }
+ id := message.Payload[0]
+ if a.lowestID == 0 || a.lowestID > id {
+ a.lowestID = id
+ }
+ if id != a.lowestID {
+ return
+ }
+ // The beacon with the lowest ID is the reference beacon.
+ offset := beaconOffset(a.lowestID)
+ a.beaconReferenceTime = time.Now().UnixMilli() - offset.Milliseconds()
+}
+
+func beaconOffset(id byte) time.Duration {
+ team := (id << 4) - 0x0A
+ player := (id & 0x0F) - 1
+ return time.Duration(team)*time.Second + time.Duration(player)*100*time.Millisecond
+}

runtime.go

@@ -0,0 +1,8 @@
+//go:build avr
+
+package csp
+
+import _ "unsafe" // for go:linkname to work
+
+//go:linkname runtime_nanotime runtime.nanotime
+func runtime_nanotime() int64