low-level aout functionality in module AudioPanning (with no integrat…

…ion into worklet compilation)

src/AudioPanning.purs

@@ -1,31 +1,43 @@
 module AudioPanning where
 
 import Prelude ((>),($),pure,otherwise,(*),(<>),(/),(>>=),bind,(-),(+),(<=),map,(==),(<$>))
+import Data.Maybe (Maybe(..))
 import Data.Int (toNumber)
 import Data.Number (pi,cos)
 import Data.Ord (abs)
 import Data.Either (Either(..))
-import Data.List.NonEmpty (head, length, zipWith)
+import Data.List (take)
+import Data.List.NonEmpty (head, length, zipWith, NonEmptyList, fromList, toList)
 import Data.Unfoldable1 (iterateN)
+import Data.Unfoldable (replicate)
 import Data.Traversable (traverse,sequence)
 import Data.Tuple (Tuple(..))
 
-import W (W,Sample,Frame,assign,product,sumChannels)
+import W (W,Sample,Frame,assign,product,sumChannels,zero)
 import W as W
 import Matrix (fromNonEmptyList,flatten)
 
-splay :: Int -> Frame -> W Frame
+splay :: Int -> Frame -> W (NonEmptyList Sample)
 splay nOutputChnls xs
   | nOutputChnls <= 1 = pure <$> W.sum xs
-  | length (flatten xs) == 1 = pan nOutputChnls (Left 0.5) (head $ flatten xs)
+  | length (flatten xs) == 1 = flatten <$> pan nOutputChnls (Left 0.5) (head $ flatten xs)
   | otherwise = do
       let xs' = flatten xs
       let nInputChnls = length xs'
       let stepSize = 1.0 / toNumber (nInputChnls - 1)
       let inputPositions = map Left $ iterateN nInputChnls (_ + stepSize) 0.0
       xss <- sequence $ zipWith (pan nOutputChnls) inputPositions xs' -- :: NonEmptyList Frame -- one Frame per input, each Frame has nOutputChnls Samples
-      sumChannels xss
-
+      flatten <$> sumChannels xss
+
+aout :: Int -> Int -> Int -> Frame -> W (NonEmptyList Sample)
+aout totalOutputChnls nOutputChnls channelOffset xs = do
+  let a = replicate channelOffset zero -- :: List Sample
+  b <- toList <$> splay nOutputChnls xs -- :: List Sample
+  let c = replicate (totalOutputChnls - channelOffset - nOutputChnls) zero -- :: List Sample
+  case fromList (take totalOutputChnls $ a <> b <> c) of
+    Just x -> pure x
+    Nothing -> pure $ pure zero -- only possible with meaningless input (totalOutputChnls or nOutputChnls < 1)
+
 pan :: Int -> Sample -> Sample -> W Frame
 pan nOutputChnls pos i 
   | nOutputChnls <= 1 = pure $ pure i

src/AudioWorklet.purs

@@ -14,7 +14,6 @@ import Signal (Signal)
 import WebAudio (WebAudioContext,WebAudioNode)
 import W
 import AudioPanning (splay)
-import Matrix (flatten)
 
 type AudioWorklet = {
   name :: String,
@@ -51,8 +50,7 @@ foreign import setWorkletParamValue :: WebAudioNode -> String -> Number -> Effec
 generateWorkletCode :: Signal -> String -> Number -> Number -> String
 generateWorkletCode s name fInStart fInDur = prefix <> classHeader <> getParameterDescriptors <> constructor <> innerLoopPrefix <> fadeCalculations <> wState.code <> outputs <> restOfClass <> registerProcessor
   where
-    Tuple frameMulti wState = runW $ signalToFrame s >>= splay 2
-    frame = flatten frameMulti
+    Tuple frame wState = runW $ signalToFrame s >>= splay 2
     prefix = """'use strict';
 
 function clamp(min,max,x) { return Math.max(Math.min(max,x),min); }

src/W.purs

@@ -44,6 +44,9 @@ showSample :: Sample -> String
 showSample (Left x) = Number.showNumber x
 showSample (Right x) = x
 
+zero :: Sample
+zero = Left 0.0
+
 assign :: String -> W Sample
 assign x = do
   f <- allocateFloat