--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/semiconginev2/audio/mixer.nim	Wed Jul 17 22:02:11 2024 +0700
@@ -0,0 +1,310 @@
+
+const NBUFFERS = 32
+const BUFFERSAMPLECOUNT = 256
+const AUDIO_SAMPLE_RATE* = 44100
+
+type
+  Level* = 0'f .. 1'f
+  Sample* = array[2, int16]
+  SoundData* = seq[Sample]
+
+  Playback = object
+    sound: SoundData
+    position: int
+    loop: bool
+    levelLeft: Level
+    levelRight: Level
+    paused: bool
+  Track = object
+    playing: Table[uint64, Playback]
+    level: Level
+    targetLevel: Level
+    fadeTime: float
+    fadeStep: float
+
+when defined(windows):
+  include ./platform/windows
+when defined(linux):
+  include ./platform/linux
+
+type
+  Mixer* = object
+    playbackCounter: uint64
+    tracks: Table[string, Track]
+    sounds*: Table[string, SoundData]
+    level: Level
+    device: NativeSoundDevice
+    lock: Lock
+    buffers: seq[SoundData]
+    currentBuffer: int
+    lastUpdate: MonoTime
+
+proc initMixer(): Mixer =
+  result = Mixer(
+    tracks: {"": Track(level: 1'f)}.toTable,
+    level: 1'f,
+  )
+  result.lock.initLock()
+
+proc setupDevice(mixer: var Mixer) =
+  # call this inside audio thread
+  var bufferaddresses: seq[ptr SoundData]
+  for i in 0 ..< NBUFFERS:
+    mixer.buffers.add newSeq[Sample](BUFFERSAMPLECOUNT)
+  for i in 0 ..< mixer.buffers.len:
+    bufferaddresses.add (addr mixer.buffers[i])
+  mixer.device = OpenSoundDevice(AUDIO_SAMPLE_RATE, bufferaddresses)
+
+# TODO: this should probably be in the load-code-stuff
+# proc LoadSound*(mixer: var Mixer, name: string, resource: string) =
+  # assert not (name in mixer.sounds)
+  # mixer.sounds[name] = LoadAudio(resource)
+
+proc AddSound*(mixer: var Mixer, name: string, sound: SoundData) =
+  assert not (name in mixer.sounds)
+  mixer.sounds[name] = sound
+
+proc ReplaceSound*(mixer: var Mixer, name: string, sound: SoundData) =
+  assert (name in mixer.sounds)
+  mixer.sounds[name] = sound
+
+proc AddTrack*(mixer: var Mixer, name: string, level: Level = 1'f) =
+  assert not (name in mixer.tracks)
+  mixer.lock.withLock():
+    mixer.tracks[name] = Track(level: level)
+
+proc Play*(mixer: var Mixer, soundName: string, track = "", stopOtherSounds = false, loop = false, levelLeft, levelRight: Level): uint64 =
+  assert track in mixer.tracks, &"Track '{track}' does not exists"
+  assert soundName in mixer.sounds, soundName & " not loaded"
+  mixer.lock.withLock():
+    if stopOtherSounds:
+      mixer.tracks[track].playing.clear()
+    mixer.tracks[track].playing[mixer.playbackCounter] = Playback(
+      sound: mixer.sounds[soundName],
+      position: 0,
+      loop: loop,
+      levelLeft: levelLeft,
+      levelRight: levelRight,
+      paused: false,
+    )
+  result = mixer.playbackCounter
+  inc mixer.playbackCounter
+
+proc Play*(mixer: var Mixer, soundName: string, track = "", stopOtherSounds = false, loop = false, level: Level = 1'f): uint64 =
+  Play(
+    mixer = mixer,
+    soundName = soundName,
+    track = track,
+    stopOtherSounds = stopOtherSounds,
+    loop = loop,
+    levelLeft = level,
+    levelRight = level
+  )
+
+proc Stop*(mixer: var Mixer) =
+  mixer.lock.withLock():
+    for track in mixer.tracks.mvalues:
+      track.playing.clear()
+
+proc GetLevel*(mixer: var Mixer): Level = mixer.level
+proc GetLevel*(mixer: var Mixer, track: string): Level = mixer.tracks[track].level
+proc GetLevel*(mixer: var Mixer, playbackId: uint64): (Level, Level) =
+  for track in mixer.tracks.mvalues:
+    if playbackId in track.playing:
+      return (track.playing[playbackId].levelLeft, track.playing[playbackId].levelRight)
+
+proc SetLevel*(mixer: var Mixer, level: Level) = mixer.level = level
+proc SetLevel*(mixer: var Mixer, track: string, level: Level) =
+  mixer.lock.withLock():
+    mixer.tracks[track].level = level
+proc SetLevel*(mixer: var Mixer, playbackId: uint64, levelLeft, levelRight: Level) =
+  mixer.lock.withLock():
+    for track in mixer.tracks.mvalues:
+      if playbackId in track.playing:
+        track.playing[playbackId].levelLeft = levelLeft
+        track.playing[playbackId].levelRight = levelRight
+proc SetLevel*(mixer: var Mixer, playbackId: uint64, level: Level) =
+  SetLevel(mixer, playbackId, level, level)
+
+proc Stop*(mixer: var Mixer, track: string) =
+  assert track in mixer.tracks
+  mixer.lock.withLock():
+    mixer.tracks[track].playing.clear()
+
+proc Stop*(mixer: var Mixer, playbackId: uint64) =
+  mixer.lock.withLock():
+    for track in mixer.tracks.mvalues:
+      if playbackId in track.playing:
+        track.playing.del(playbackId)
+        break
+
+proc Pause*(mixer: var Mixer, value: bool) =
+  mixer.lock.withLock():
+    for track in mixer.tracks.mvalues:
+      for playback in track.playing.mvalues:
+        playback.paused = value
+
+proc Pause*(mixer: var Mixer, track: string, value: bool) =
+  mixer.lock.withLock():
+    for playback in mixer.tracks[track].playing.mvalues:
+      playback.paused = value
+
+proc Pause*(mixer: var Mixer, playbackId: uint64, value: bool) =
+  mixer.lock.withLock():
+    for track in mixer.tracks.mvalues:
+      if playbackId in track.playing:
+        track.playing[playbackId].paused = value
+
+proc Pause*(mixer: var Mixer) = mixer.Pause(true)
+proc Pause*(mixer: var Mixer, track: string) = mixer.Pause(track, true)
+proc Pause*(mixer: var Mixer, playbackId: uint64) = mixer.Pause(playbackId, true)
+proc Unpause*(mixer: var Mixer) = mixer.Pause(false)
+proc Unpause*(mixer: var Mixer, track: string) = mixer.Pause(track, false)
+proc Unpause*(mixer: var Mixer, playbackId: uint64) = mixer.Pause(playbackId, false)
+
+proc FadeTo*(mixer: var Mixer, track: string, level: Level, time: float) =
+  mixer.tracks[track].targetLevel = level
+  mixer.tracks[track].fadeTime = time
+  mixer.tracks[track].fadeStep = level.float - mixer.tracks[track].level.float / time
+
+proc IsPlaying*(mixer: var Mixer): bool =
+  mixer.lock.withLock():
+    for track in mixer.tracks.mvalues:
+      for playback in track.playing.values:
+        if not playback.paused:
+          return true
+  return false
+
+proc IsPlaying*(mixer: var Mixer, track: string): bool =
+  mixer.lock.withLock():
+    if mixer.tracks.contains(track):
+      for playback in mixer.tracks[track].playing.values:
+        if not playback.paused:
+          return true
+    return false
+
+func applyLevel(sample: Sample, levelLeft, levelRight: Level): Sample =
+  [int16(float(sample[0]) * levelLeft), int16(float(sample[1]) * levelRight)]
+
+func clip(value: int32): int16 =
+  int16(max(min(int32(high(int16)), value), int32(low(int16))))
+
+# used for combining sounds
+func mix(a, b: Sample): Sample =
+  [
+    clip(int32(a[0]) + int32(b[0])),
+    clip(int32(a[1]) + int32(b[1])),
+  ]
+
+proc updateSoundBuffer(mixer: var Mixer) =
+  let t = getMonoTime()
+
+  let tDebug = getTime()
+  # echo ""
+  # echo tDebug
+
+  let dt = (t - mixer.lastUpdate).inNanoseconds.float64 / 1_000_000_000'f64
+  mixer.lastUpdate = t
+
+  # update fadings
+  for track in mixer.tracks.mvalues:
+    if track.fadeTime > 0:
+      track.fadeTime -= dt
+      track.level = (track.level.float64 + track.fadeStep.float64 * dt).clamp(Level.low, Level.high)
+      if track.fadeTime <= 0:
+        track.level = track.targetLevel
+  # mix
+  for i in 0 ..< mixer.buffers[mixer.currentBuffer].len:
+    var mixedSample = [0'i16, 0'i16]
+    mixer.lock.withLock():
+      for track in mixer.tracks.mvalues:
+        var stoppedSounds: seq[uint64]
+        for (id, playback) in track.playing.mpairs:
+          if playback.paused:
+            continue
+          let sample = applyLevel(
+            playback.sound[playback.position],
+            mixer.level * track.level * playback.levelLeft,
+            mixer.level * track.level * playback.levelRight,
+          )
+          mixedSample = mix(mixedSample, sample)
+          inc playback.position
+          if playback.position >= playback.sound.len:
+            if playback.loop:
+              playback.position = 0
+            else:
+              stoppedSounds.add id
+        for id in stoppedSounds:
+          track.playing.del(id)
+      mixer.buffers[mixer.currentBuffer][i] = mixedSample
+  # send data to sound device
+  # echo getTime() - tDebug
+  mixer.device.WriteSoundData(mixer.currentBuffer)
+  # echo getTime() - tDebug
+  mixer.currentBuffer = (mixer.currentBuffer + 1) mod mixer.buffers.len
+
+# DSP functions
+# TODO: finish implementation, one day
+
+#[
+#
+proc lowPassFilter(data: var SoundData, cutoff: int) =
+  let alpha = float(cutoff) / AUDIO_SAMPLE_RATE
+  var value = data[0]
+  for i in 0 ..< data.len:
+    value[0] += int16(alpha * float(data[i][0] - value[0]))
+    value[1] += int16(alpha * float(data[i][1] - value[1]))
+    data[i] = value
+
+  proc downsample(data: var SoundData, n: int) =
+    let newLen = (data.len - 1) div n + 1
+    for i in 0 ..< newLen:
+      data[i] = data[i * n]
+    data.setLen(newLen)
+
+  proc upsample(data: var SoundData, m: int) =
+    data.setLen(data.len * m)
+    var i = data.len - 1
+    while i < 0:
+      if i mod m == 0:
+        data[i] = data[i div m]
+      else:
+        data[i] = [0, 0]
+      i.dec
+
+    proc slowdown(data: var SoundData, m, n: int) =
+      data.upsample(m)
+      # TODO
+      # data.lowPassFilter(m)
+      data.downsample(n)
+
+    ]#
+
+proc destroy(mixer: var Mixer) =
+  mixer.lock.deinitLock()
+  mixer.device.CloseSoundDevice()
+
+var
+  mixer* = createShared(Mixer)
+  audiothread: Thread[void]
+
+proc audioWorker() {.thread.} =
+  mixer[].setupDevice()
+  onThreadDestruction(proc() = mixer[].lock.withLock(mixer[].destroy()); freeShared(mixer))
+  while true:
+    mixer[].updateSoundBuffer()
+
+# for thread priority (really necessary?)
+when defined(windows):
+  import ./thirdparty/winim/winim/inc/winbase
+when defined(linux):
+  import std/posix
+
+proc StartMixerThread() =
+  mixer[] = initMixer()
+  audiothread.createThread(audioWorker)
+  debug "Created audio thread"
+  when defined(windows):
+    SetThreadPriority(audiothread.handle(), THREAD_PRIORITY_TIME_CRITICAL)
+  when defined(linux):
+    discard pthread_setschedprio(Pthread(audiothread.handle()), cint(-20))