ardour {
    ["type"]    = "dsp",
    name        = "SinGen",
    category    = "Instrument",
    license     = "MIT",
    author      = "Nik",
    description = [[Sine Wave Generator (v-1.2)]]
}

function dsp_params ()
    return
    {
        { ["type"] = "input", name = "Frequency", min = 20, max = 20000, default = 1000, unit="Hz", logarithmic = true },
        { ["type"] = "input", name = "Gain", min = -90, max = 0, default = -18, unit="dB" },
    }
end

function dsp_ioconfig ()
    return { [1] = { audio_in = -1, audio_out = -1}, }
end

function dsp_init (rate)
    r = rate
    lpf  = 2048 / rate
end

function low_pass_filter_param(old, new, limit)
    if math.abs (old - new) < limit  then
        return new
    else
        return old + lpf * (new - old)
    end
end

local p  = 0
local fo = 0
local ao = 0

function dsp_run (ins, outs, n_samples)
    local ctrl = CtrlPorts:array() --call parameters

    local a = {} --init array
    local f = ctrl[1] or 1000
    local amp =  low_pass_filter_param(ao, ARDOUR.DSP.dB_to_coefficient(ctrl[2]), 0.02)
    local inc = f / r

    for s = 1, n_samples do --fill table with fragments of a sine wave
        p = p + inc
        a[s] = amp * math.sin(p * (2 * math.pi))
    end

    for c = 1,#outs do
        outs[c]:set_table(a, n_samples) --passes array into buffer
    end

    if f ~= fo then
        self:queue_draw()
    end
    fo = f
    ao = amp
end

function render_inline (ctx, w, max_h) --inline display
    local ctrl = CtrlPorts:array()
    h = 30
    p = 0
    inc = 1/w
    f = ctrl[1] / 1000

    if f < 0.5 then f = 0.5 end
    if f > 8 then f  = 8 end

    --draw rectangle
    ctx:rectangle(0, 0, w, h)
    ctx:set_source_rgba(0, 0, 0, 1.0)
    ctx:fill()
    ctx:set_line_width(1.5)
    ctx:set_source_rgba(0.8, 0.8, 0.8, 1.0)

    l_x = 0
    l_y = 0
    for x = 0,w do
        y = math.sin(f * (2 * math.pi * (p)))
        yc = 0.5 * h + ((-0.5 * h) * y)
        ctx:move_to (x, yc + 3)
        ctx:line_to (l_x, l_y + 3)
        l_x = x
        l_y = yc
        ctx:stroke()
        p = p + inc
    end
    return {w, h + 6}
end