songplayer.lua

local _conf = {
    pal = true,
    rate = 1,
}

local args = {...}
if #args ~= 1 then
    print("Usage: songplayer.lua filename")
    return
end

local datfile, err = io.open(args[1],"rb")
if not datfile then
    print("Failed to open file: " .. err)
    return
end

local framems, freqdiv
if _conf.pal then
    framems = 1000/50
    freqdiv = 17734475/(18*2^24)
else
    framems = 1000/60
    freqdiv = 14318182/(14*2^24)
end

local attackrates = {[0]=2,8,16,24,38,56,68,80,100,250,500,800,1000,3000,5000,8000}
local decayrates = {[0]=6,24,48,72,114,168,204,240,300,750,1500,2400,3000,9000,15000,24000}

local bit = require("bit32")
local component = require("component")
local sound = component.sound

sound.clear()
sound.setTotalVolume(1)
for i = 1,8 do
    sound.resetEnvelope(i)
    sound.resetAM(i)
    sound.resetFM(i)
    sound.setVolume(i,1)
    sound.close(i)
end
sound.process()

os.sleep(0.05)

local sid = {
    c1 = {
        freq=0,
        waveform=0,
        attack=0,
        decay=0,
        sustain=0,
        release=0,
        pulse=0,
        stat = {
            mode=0,
            pos=0,
        },
    },
    c2 = {
        freq=0,
        waveform=0,
        attack=0,
        decay=0,
        sustain=0,
        release=0,
        pulse=0,
        stat = {
            mode=0,
            pos=0,
        },
    },
    c3 = {
        freq=0,
        waveform=0,
        attack=0,
        decay=0,
        sustain=0,
        release=0,
        pulse=0,
        stat = {
            mode=0,
            pos=0,
        },
    },
    cutoff=0,
    kind=0,
    volume=0,
}

local function getFreq(x)
    return x*freqdiv
end

local function moveTowards(cur,targ,amt)
    if cur == targ then
        return targ, true
    elseif cur < targ then
        cur = cur + amt
        if cur >= targ then
            return targ, true
        end
    elseif cur > targ then
        cur = cur - amt
        if cur <= targ then
            return targ, true
        end
    end
    return cur, false
end

local lastchannel=0
local chadata={}
local function emulateADSR(chan)
    local key = "c" .. chan

    local freq = getFreq(sid[key].freq)

    local mvol = (sid.volume/15)

    local tenab = math.floor(sid[key].waveform/2^0)%2 == 1
    local senab = math.floor(sid[key].waveform/2^1)%2 == 1
    local penab = math.floor(sid[key].waveform/2^2)%2 == 1
    local nenab = math.floor(sid[key].waveform/2^3)%2 == 1

    local sus = sid[key].sustain/15

    for i = 1,framems/_conf.rate do
        local tv,ep
        if sid[key].stat.mode == 0 then
            tv,ep = 1,attackrates[sid[key].attack]
        elseif sid[key].stat.mode == 1 then
            tv,ep = sus,decayrates[sid[key].decay]
        elseif sid[key].stat.mode == 2 then
            tv,ep = sus,math.huge
        elseif sid[key].stat.mode == 3 then
            tv,ep = 0,decayrates[sid[key].release]
        else
            tv,ep = 0,math.huge
        end
        local nextv
        sid[key].stat.pos, nextv = moveTowards(sid[key].stat.pos, tv, 1/ep)
        if nextv and sid[key].stat.mode < 2 then
            sid[key].stat.mode = sid[key].stat.mode + 1
        end
    end

    local vol = sid[key].stat.pos*mvol

    if not (nenab and (tenab or senab or penab)) then
        if tenab then
            lastchannel = lastchannel + 1
            sound.setWave(lastchannel,sound.modes.triangle,freq)
            sound.setVolume(lastchannel,vol)
            chadata[lastchannel] = true
        end
        if senab then
            lastchannel = lastchannel + 1
            sound.setWave(lastchannel,sound.modes.sawtooth,freq)
            sound.setVolume(lastchannel,vol)
            chadata[lastchannel] = true
        end
        if penab then
            lastchannel = lastchannel + 1
            sound.setWave(lastchannel,sound.modes.square,freq)
            sound.setVolume(lastchannel,vol)
            chadata[lastchannel] = true
        end
        if nenab then
            lastchannel = lastchannel + 1
            sound.setWave(lastchannel,sound.modes.noise,freq*8)
            sound.setVolume(lastchannel,vol)
            chadata[lastchannel] = true
        end
    end
end

local stat = 0
while true do
    local line = datfile:read("*l")
    if not line then
        break
    end
    if #line ~= 47 then
        _conf.rate = line/(_conf.pal and 50 or 60)
        goto continue
    end
    local c = {{},{},{}}
    c[1].freq = line:sub(1,4)
    c[1].wf = line:sub(5,6)
    c[1].adsr = line:sub(7,10)
    c[1].pulse = line:sub(11,13)

    c[2].freq = line:sub(14,17)
    c[2].wf = line:sub(18,19)
    c[2].adsr = line:sub(20,23)
    c[2].pulse = line:sub(24,26)

    c[3].freq = line:sub(27,30)
    c[3].wf = line:sub(31,32)
    c[3].adsr = line:sub(33,36)
    c[3].pulse = line:sub(37,39)

    local cut = line:sub(40,43)
    local ft = line:sub(44,46)
    local volume = line:sub(47,47)

    for i = 1,3 do
        local key = "c" .. i
        if c[i].freq ~= "...." then sid[key].freq = tonumber(c[i].freq,16) end
        if c[i].wf ~= ".." then
            sid[key].waveform = math.floor(tonumber(c[i].wf,16)/16)
            local gate = math.floor(tonumber(c[i].wf,16)/2^0)%2 == 1
            sid[key].sync = math.floor(tonumber(c[i].wf,16)/2^1)%2 == 1
            sid[key].ring = math.floor(tonumber(c[i].wf,16)/2^2)%2 == 1
            sid[key].test = math.floor(tonumber(c[i].wf,16)/2^3)%2 == 1
            if gate and sid[key].stat.mode >= 3 then
                sid[key].stat.mode = 0
            elseif not gate and sid[key].stat.mode < 3 then
                sid[key].stat.mode = 3
            end
        end
        if c[i].pulse ~= "..." then sid[key].pulse = tonumber(c[i].pulse,16) end
        if c[i].adsr ~= "...." then
            sid[key].attack  = math.floor(tonumber(c[i].adsr,16)/2^12)%16
            sid[key].decay   = math.floor(tonumber(c[i].adsr,16)/2^8)%16
            sid[key].sustain = math.floor(tonumber(c[i].adsr,16)/2^4)%16
            sid[key].release = math.floor(tonumber(c[i].adsr,16)/2^0)%16
        end
    end

    if volume ~= "." then sid.volume = tonumber(volume,16) end

    lastchannel = 0
    local lcs = #chadata
    for i = 1,3 do
        local key = "c" .. i
        if not sid[key].test then
            emulateADSR(i)
        end
    end

    if lcs < lastchannel then
        for i = lcs + 1,lastchannel do
            sound.open(i)
        end
    elseif lcs > lastchannel then
        for i = lastchannel + 1,lcs do
            sound.close(i)
            chadata[i]=nil
        end
    end

    sound.delay(framems/_conf.rate)
    stat = stat + 1
    if stat >= 50/2*_conf.rate then
        stat = 0
        while not sound.process() do
            os.sleep(0.05)
        end
        os.sleep(0.05)
    end
    ::continue::
end

for i = 1,8 do
    sound.resetEnvelope(i)
    sound.resetAM(i)
    sound.resetFM(i)
    sound.setVolume(i, 1)
    sound.close(i)
end

sound.delay(1000)

while not sound.process() do
    os.sleep(0.05)
end