mieki256's diary

-- title:  wavetest
-- author: mieki256
-- desc:   short description
-- script: lua

waveid=4

WAVADR=0x0ffe4

function makeWave()
 dt={}
 for i=0,31 do
  local v=0
  -- multiplier, speed, shift
  v=v+getSin(i, 1.0, 1.0, 0)
  v=v+getSin(i, 1.5, 0.5, 0)
  v=v+getSin(i, 1.5, 2.0, 0)
  v=v+getSin(i, 0.5, 3.0, 90)
  --[[
  v=v+getSin(i, 0.5, 3.0, 0)
  v=v+getSin(i, 0.25, 4.0, 0)
  --]]
  table.insert(dt,v)
 end
 return dt
end

function getSin(i,m,spd,sft)
 return m*math.sin(math.rad(spd*i*360/32+sft))
end

function writeWave(id,dt)
 -- adjust
 if id<0 or id>15 then return end
 if #dt>32 then return end
 local vmax,vmin
 vmax=0
 vmin=0
 for i=1,#dt do
  if dt[i]>vmax then vmax=dt[i] end
  if dt[i]<vmin then vmin=dt[i] end
 end
 local range=vmax-vmin
 for i=1,#dt do
  dt[i]=math.floor(15*(dt[i]-vmin)/range)
 end

 -- write wave 
 local addr=WAVADR+id*16
 for i=1,#dt,2 do
  local v=0
  v = v | ((dt[i+1] & 0x0f)<<4)
  v = v | (dt[i] & 0x0f)
  poke(addr+((i-1)//2),v)
 end
end

function drawGuide(bx,by,w,h)
 local x0,y0,x1,y1
 local c=3
 x0,x1=bx,bx+w*32-2
 y0=by+h*8-1
 line(x0,y0,x1,y0,c)
 y0=by+h*4-1
 line(x0,y0,x1,y0,c)
 y0=by+h*12-1
 line(x0,y0,x1,y0,c)
 x0=bx+w*16-1
 y0,y1=by,by+h*16-2
 line(x0,y0,x0,y1,c)
 x0=bx+w*8-1
 line(x0,y0,x0,y1,c)
 x0=bx+w*24-1
 line(x0,y0,x0,y1,c)
end

function drawWave(id)
 -- read wave
 local addr=WAVADR+id*16
 local dt={}
 for i=0,15 do
  local v=peek(addr+i)
  local v1=v&0x0f
  local v2=(v>>4)&0x0f
  table.insert(dt,v1)
  table.insert(dt,v2)
 end

 -- draw wave
 local bx,by=24,12
 local w,h=6,6
 local x,y
 for ix=0,31 do
  x = ix * w + bx
  for iy=0,15 do
   y = iy * h + by
   rect(x,y,w,h,0)
   rect(x,y,w-1,h-1,1)
  end
  y=(15-dt[ix+1])*h+by
  rect(x,y,w-1,h-1,6)
 end
 drawGuide(bx,by,w,h)
end

dt=makeWave()
writeWave(waveid,dt)
t=0

function TIC()

 if keyp(14) then sfx(0,"A-4",30,0) end
 if keyp(25) then sfx(1,"A-4",30,0) end
 if btnp(5) then
  -- write to cart
  sync(1<<3,0,true)
 end

 cls(0)
 drawWave(waveid)
 print("WAVE ID: "..waveid, 2,120)
 print("Play: N or Y / Write: X", 2,128)
 t=t+1
end

| 0FFE4 | WAVEFORMS | 256 | 16 waveforms, each 32 x 4bit values

• 0x0FFE4番地から、256byteほど確保してあって、16種類の波形が記録されてる。
• 1つの波形につき、4bitの音量が32個並んでる。つまり、16byteで一つの波形になる。

bytes : 0x10, 0x32, 0x54, 0x76, 0x98, 0xBA, 0xDC, 0xFE, ...

wave memory : 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F, ...