sfxcache.lua

local sfxcache = {
 channel=1,   -- the channel to check (1-4)
 beats=8,     -- fire on every nth beat (0, 4, 8, or 16)
 sfx={},
 valid=true,
 play=function(self,...)
  add(self.sfx,{...})
 end,
 check=function(self)
  if stat(19+self.channel)%self.beats==0 then
    if #self.sfx>0 and self.valid then
     for s in all(self.sfx) do
      sfx(s[1],s[2] or -1,s[3] or 0,s[4] or 0)
     end
     self.sfx={}
     self.valid=false
     return true
    end
  else
   self.valid=true
  end
  return false
 end
}

function _init()
 music(29)
end

function _update60()
 if btnp(4) then
  sfxcache:play(1)
 end
 if btnp(5) then
  sfxcache:play(2)
 end
 sfxcache:check()
end