TIC80 music

tic80.lua

pos=0

local abs  = math.abs
local exp2 = function(x) return 2.0 ^ x end
local sin  = math.sin
local mod  = function(a, b) return a - math.floor(a / b) * b end  -- GLSL mod (always positive)

local function music(t1)
 local a3 = 0.0
 for i1 = 1, 4 do
  for j1 = 1, 4 do
    local fi = i1 * 1.0
    local fj = j1 * 1.0
    local r1 = math.min(t1 * fj / 32.0 + fi / 3.0, 9.0)
    local s1 = mod(r1, 1.0)
    local inner =
        sin(t1 * fj * fi * exp2(mod(r1 - s1, 3.0) / 6.0 + 8.0)) * 4.0
        + sin(t1 * 3.0)
        + sin(t1 * 11.0)
    a3 = a3 + sin(sin(t1 / fj / 48.0) * inner)
        * exp2(5.0 - 13.0 * s1 - 1.0 / s1)
  end
 end
 if a3>1 then
   return 1
 elseif a3<-1 then
   return -1
 end
 return a3
end


function TIC()
 cls()
 print("Music by PESTIS",0,0,pos/615)
 local tf=1/60/128
 for i=0,127 do
  local t=(pos+i)*tf
  poke(0x14e24+i,127+127*music(t))
 end
 pos=pos+128
end