Add some Synth wrappers (#84)

README.md

@@ -33,6 +33,7 @@ Currently, the following sections of the API are implemented:
 - [ ] Sound
   - [x] FilePlayer
   - [x] SamplePlayer
+  - [x] Synth (partial)
 - [x] Sprite
 - [x] System
 

Sources/PlaydateKit/Core/Display.swift

@@ -19,7 +19,7 @@ public enum Display {
     /// The nominal refresh rate in frames per second. The default is 30 fps, which is a recommended
     /// figure that balances animation smoothness with performance and power considerations. Maximum is 50 fps.
     ///
-    /// If rate is 0, the game’s update callback (the function specified by `Playdate.updateCallback`) is called as soon as possible.
+    /// If rate is 0, the game’s update callback (the function specified by ``PlaydateGame/update()``) is called as soon as possible.
     /// Since the display refreshes line-by-line, and unchanged lines aren’t sent to the display,
     /// the update cycle will be faster than 30 times a second but at an indeterminate rate.
     public static var refreshRate: Float {

Sources/PlaydateKit/Core/Sound.swift

@@ -306,10 +306,76 @@ public enum Sound {
         private var samplePointer: OpaquePointer?
     }
 
+    public class Synth {
+        // MARK: Lifecycle
+
+        /// Creates a new synth object to play a waveform or wavetable. See ``Sound/Synth/setWaveform(_:)`` for waveform values.
+        public init() {
+            pointer = synth.newSynth.unsafelyUnwrapped().unsafelyUnwrapped
+        }
+
+        deinit {
+            synth.freeSynth.unsafelyUnwrapped(pointer)
+        }
+
+        // MARK: Public
+
+        public func setWaveform(_ waveform: SoundWaveform) {
+            synth.setWaveform.unsafelyUnwrapped(pointer, waveform)
+        }
+
+        /// Sets the attack time, in seconds.
+        public func setAttackTime(_ attackTime: Float) {
+            synth.setAttackTime.unsafelyUnwrapped(pointer, attackTime)
+        }
+
+        /// Sets the decay time, in seconds.
+        public func setDecayTime(_ decayTime: Float) {
+            synth.setDecayTime.unsafelyUnwrapped(pointer, decayTime)
+        }
+
+        /// Sets the sustain level, as a proportion of the total level (0.0 to 1.0).
+        public func setSustainLevel(_ sustainLevel: Float) {
+            synth.setSustainLevel.unsafelyUnwrapped(pointer, sustainLevel)
+        }
+
+        /// Sets the release time, in seconds.
+        public func setReleaseTime(_ releaseTime: Float) {
+            synth.setReleaseTime.unsafelyUnwrapped(pointer, releaseTime)
+        }
+
+        /// Plays a note with the current waveform or sample.
+        /// - Parameters:
+        ///   - frequency: The frequency of the note to play.
+        ///   - volume: 0 to 1, defaults to 1
+        ///   - length: In seconds. If omitted, note will play until you call noteOff()
+        ///   - when: Seconds since the sound engine started (see ``Sound/currentTime``). Defaults to the current time.
+        public func playNote(frequency: Float, volume: Float = 1, length: Float = -1, when: CUnsignedInt = 0) {
+            synth.playNote.unsafelyUnwrapped(pointer, frequency, volume, length, when)
+        }
+
+        /// Sends a note off event to the synth.
+        /// - Parameter when: The scheduled time to send a note off event. Defaults to immediately.
+        public func noteOff(when: CUnsignedInt = 0) {
+            synth.noteOff.unsafelyUnwrapped(pointer, when)
+        }
+
+        // MARK: Private
+
+        private let pointer: OpaquePointer
+    }
+
+    /// Returns the current time, in seconds, as measured by the audio device.
+    /// The audio device uses its own time base in order to provide accurate timing.
+    public static var currentTime: CUnsignedInt {
+        sound.getCurrentTime.unsafelyUnwrapped()
+    }
+
     // MARK: Private
 
     private static var sound: playdate_sound { Playdate.playdateAPI.sound.pointee }
     private static var sample: playdate_sound_sample { sound.sample.pointee }
+    private static var synth: playdate_sound_synth { sound.synth.pointee }
 
     private static var fileplayer: playdate_sound_fileplayer { sound.fileplayer.pointee }
     private static var sampleplayer: playdate_sound_sampleplayer { sound.sampleplayer.pointee }