8bitworkshop/presets/vcs/ecs/sound.ecs

//#resource "vcs-ca65.h"

import "vcslib.ecs"

component SoundEffect
  duration: 0..255
  sounddata: array of 0..255
end

component SoundChannel
  sfx: [SoundEffect]
  timer: 0..255
end

// TODO
component SoundPriority
  priority: 0..15
end

system SoundEngine
  locals 3
  on preframe do 
  join [SoundChannel]
  with [SoundEffect]
  ---
  lda {{base timer}},y
  jeq @nosound
  sec
  sbc #1
  sta {{base timer}},y
  pha
  lda {{<sounddata}}
  sta {{$0}}
  lda {{>sounddata}}
  sta {{$1}}		; save pointer to sound data
  sty {{$2}}		; save Y (sound channel #)
  pla
  tay
  lda ({{$0}}),y	; get sound data
  bpl @setfreq		; hi bit clear = just freq
  ldy {{$2}}
  lsr			; right shift (/ 2)
  bcs @setvol		; lo bit set = volume
  sta AUDC0,y		; lo bit clear = control
  lsr			; also set freq (/ 2)
@setfreq:
  ldy {{$2}}
  sta AUDF0,y		; set frequency
  jmp @done
@nosound:
  lda #0
@setvol:
  sta AUDV0,y		; set volume
@done:
  ---
  // TODO: need to pass sound entity as arg
  on playsound do select [SoundChannel]
  ---
; arg 0 = sound channel
  ldy #{{arg 0}}
; arg 1 = sound effect #
  lda #{{arg 1}}
  sta {{base sfx}},y
  tax
  ---
  // TODO: shouldn't need to split up like this...
  on playsound do select [SoundEffect]
  ---
  lda {{base duration}},x
  ---
  on playsound do select [SoundChannel]
  ---
  sta {{base timer}},y
; arg 2 = base volume
  lda #{{arg 2}}
  sta AUDV0,y
  ---
end

// TODO: default entities?


demo SoundDemo
  using FrameLoop, SoundEngine
  
  entity SFXScore [SoundEffect]
    const duration = 11
    const sounddata = [
    $02,$03,$04,$08,$10,$20,$10,$20,$10,$08,
    $a8]
  end

  // TODO: make sfx have priority?
  entity SFX1 [SoundChannel] end
  entity SFX2 [SoundChannel] end
  
  system Test
    on preframeloop do once
    ---
    {{!playsound 0 0 15}}
    ---
  end
end demo