-- Example 8 - More efficient Channel Communications

-- Author: Steven Yi <stevenyi@gmail.com>

-- 2013.10.28

--

-- This example builds on Example 7 by replacing the calls to SetChannel

-- with using GetChannelPtr. In the Csound API, using SetChannel and GetChannel

-- is great for quick work, but ultimately it is slower than pre-fetching the

-- actual channel pointer. This is because Set/GetChannel operates by doing a

-- lookup of the Channel Pointer, then setting or getting the value. This

-- happens on each call. The alternative is to use GetChannelPtr, which fetches

-- the Channel Pointer and lets you directly set and get the value on the pointer.

--

-- In C/C++/Objective-C, one can directly use MYFLT* to get/set values. However,

-- for wrapped languages such as Python, Java, and Lua, it is generally not possible

-- to get/set the value on the pointer itself. The Csound API for host languages

-- uses a special wrapper object called CsoundMYFLTArray, which will hold a reference

-- to a MYFLT*. The CsoundMYFLTArray in turn has convenience methods for setting

-- and getting values.

--

-- The code below shows how to use the CsoundMYFLTArray in conjunction with GetChannelPtr

-- to have a more optimized channel setting system.

require "luaCsnd6"

local RandomLine = {}

function RandomLine:new(base, range)

local o = {}

setmetatable(o, self)

self.__index = self

o.curVal = 0.0

o:reset()

o.base = base

o.range = range

return o

end

function RandomLine:reset()

self.dur = math.random(256,512)

self.End = math.random()

self.increment = (self.End - self.curVal) / self.dur

end

function RandomLine:getValue()

self.dur = self.dur - 1

if(self.dur < 0) then

self:reset()

end

retVal = self.curVal

self.curVal = self.curVal + self.increment

return self.base + (self.range * retVal)

end

-- Our Orchestra for our project

orc = [[

sr=44100

ksmps=32

nchnls=2

0dbfs=1

instr 1

kamp chnget "amp"

kfreq chnget "freq"

printk 0.5, kamp

printk 0.5, kfreq

aout vco2 kamp, kfreq

aout moogladder aout, 2000, 0.25

outs aout, aout

endin

]]

local c = luaCsnd6.Csound() -- create an instance of Csound

c:SetOption("-odac") -- Set option for Csound

c:SetOption("-m7") -- Set option for Csound

c:CompileOrc(orc) -- Compile Orchestra from String

local sco = "i1 0 60\n"

c:ReadScore(sco) -- Read in Score generated from notes

c:Start() -- When compiling from strings, this call is necessary before doing any performing

ampChannel = luaCsnd6.CsoundMYFLTArray(1) -- create a CsoundMYFLTArray of size 1

freqChannel = luaCsnd6.CsoundMYFLTArray(1) -- create a CsoundMYFLTArray of size 1

c:GetChannelPtr(ampChannel:GetPtr(), "amp", luaCsnd6.CSOUND_CONTROL_CHANNEL + luaCsnd6.CSOUND_INPUT_CHANNEL)

c:GetChannelPtr(freqChannel:GetPtr(), "freq", luaCsnd6.CSOUND_CONTROL_CHANNEL + luaCsnd6.CSOUND_INPUT_CHANNEL)

amp = RandomLine:new(.4, .2)

freq = RandomLine:new(400, 80)

ampChannel:SetValue(0, amp:getValue()) -- note we are now setting values on the CsoundMYFLTArray

freqChannel:SetValue(0, freq:getValue())

--print(amp:getValue())

--print(freq:getValue())

while (c:PerformKsmps() == 0) do

ampChannel:SetValue(0, amp:getValue())

freqChannel:SetValue(0, freq:getValue())

end

c:Stop()