Rename AutoPipeLoopBack to Cycle.

src/main/scala/examples/Cluster.scala

@@ -296,17 +296,16 @@ object Cluster {
 
         }
 
-        val Loop = new AutoPipeLoopBack(ClusterType)
-
         val Cluster = new Application {
-            val csrc = ClusterSource(Loop.output())
+            val loop = Cycle(ClusterType)
+            val csrc = ClusterSource(loop)
             val bmp = BMPReader('file -> "in.bmp")
             val vsrc = ValueSource(bmp(0), bmp(1), bmp(2))
             val assignments = Assign(vsrc(0), vsrc(1), vsrc(2), csrc(0))
             val updated = UpdateClusters(assignments(0), assignments(1),
                                          assignments(2), assignments(3))
             val out = Output(updated(0), assignments(4), updated(1), updated(2))
-            Loop.input(out(0))
+            loop(out(0))
             BMPWriter(out(1), out(2), out(3), 'file -> "out.bmp")
         }
         Cluster.emit("cluster")

src/main/scala/examples/NBody.scala

@@ -224,7 +224,6 @@ object NBody {
 
         }
 
-        val Loop = new AutoPipeLoopBack(PARTICLE)
 
         val Buffer = new Kernel("Buffer") {
 
@@ -457,8 +456,9 @@ object NBody {
 
         val app = new Application {
 
+            val cycle = Cycle(PARTICLE)
             val source = Source()
-            val buffer = Buffer(source(0), Loop.output())
+            val buffer = Buffer(source(0), cycle)
             val stream = Streamer(buffer(0))
 
             val oldParticle = Dup(stream(0))
@@ -467,7 +467,7 @@ object NBody {
             val updated = Dup(newParticle)
 
             Print(updated(0))
-            Loop.input(updated(1))
+            cycle(updated(1))
 
             if (hw) {
                 map(ANY_KERNEL -> Force, CPU2FPGA());

src/main/scala/examples/Simplex.scala

@@ -286,9 +286,6 @@ object Simplex extends App {
 
     }
 
-    // Loop-back kernel.
-    val Loop = AutoPipeLoopBack(VALUE_TYPE)
-
     // Output the result.
     // This will terminate the program when a solution is found.
     val Output = new Kernel("Output") {
@@ -334,7 +331,8 @@ object Simplex extends App {
         map(Parser -> ANY_KERNEL, CPU2FPGA())
         map(ANY_KERNEL -> Output, FPGA2CPU())
 
-        val stream = Streamer(Parser(), Loop.output())
+        val cycle = Cycle(VALUE_TYPE)
+        val stream = Streamer(Parser(), cycle)
         val split = ArraySplitter(stream(0))
         val pivot = PivotSelect(stream(1))
         val prow = DupValues(pivot(0))
@@ -346,7 +344,7 @@ object Simplex extends App {
                                           pindex(i), column(i), 'index -> i)
             RowBuffer(row)
         }
-        Loop.input(ArrayBuilder(rows))
+        cycle(ArrayBuilder(rows))
         Output(stream(2))
     }
     app.emit("simplex")

src/main/scala/scalapipe/KernelType.scala

@@ -6,8 +6,7 @@ private[scalapipe] abstract class KernelType(
         val sp: ScalaPipe,
         val name: String,
         val symbols: SymbolTable,
-        val platform: Platforms.Value,
-        val loopBack: Boolean
+        val platform: Platforms.Value
     ) {
 
     private[scalapipe] val configs = symbols.configs
@@ -20,7 +19,7 @@ private[scalapipe] abstract class KernelType(
     private[scalapipe] val outputs = symbols.outputs
 
     def this(sp: ScalaPipe, kernel: Kernel, p: Platforms.Value) = {
-        this(sp, kernel.name, new SymbolTable(kernel), p, kernel.loopBack)
+        this(sp, kernel.name, new SymbolTable(kernel), p)
         kernel.inputs.foreach { i =>
             symbols.addInput(i.name, i.valueType)
         }

src/main/scala/scalapipe/dsl/Application.scala

@@ -49,6 +49,8 @@ class Application {
 
     implicit def streamList2Stream(sl: StreamList) = sl.apply()
 
+    implicit def cycle2Arg(cycle: Cycle) = (null, cycle.output(sp))
+
     implicit def objToEdge[T <: Edge](e: EdgeObject[T]): T = e.apply()
 
     def measure(streamList: StreamList, stat: Symbol, metric: Symbol) {

src/main/scala/scalapipe/dsl/Cycle.scala

@@ -0,0 +1,34 @@
+package scalapipe.dsl
+
+import scalapipe._
+
+object Cycle {
+    def apply(t: Type) = new Cycle(t)
+}
+
+class Cycle(val t: Type) {
+
+    private var stream: Stream = null
+
+    private val kernel = new Kernel {
+        val in = input(t)
+        val out = output(t)
+        out = in
+    }
+
+    private var instance: KernelInstance = null
+
+    private[dsl] def output(sp: ScalaPipe): Stream = {
+        instance = sp.createInstance(kernel)
+        instance.apply()()
+    }
+
+    def apply(s: Stream) {
+        if (instance == null) {
+            Error.raise("unconnected cycle")
+        } else {
+            instance.setInput(null, s)
+        }
+    }
+
+}

src/main/scala/scalapipe/dsl/Kernel.scala

@@ -15,7 +15,6 @@ class Kernel(val name: String) extends EmbeddedControls {
     private[scalapipe] val externals = new ListBuffer[Platforms.Value]
     private[scalapipe] val dependencies = new DependencySet
     private[scalapipe] val scopeStack = new ListBuffer[scalapipe.Scope]
-    private[scalapipe] var loopBack = false
 
     def this() = this(LabelMaker.getKernelLabel)
 
@@ -34,10 +33,6 @@ class Kernel(val name: String) extends EmbeddedControls {
         !externals.contains(p)
     }
 
-    private[scalapipe] def setLoopBack {
-        super.__assign(loopBack, true)
-    }
-
     private def getLabel: String = labelCounter.next()
 
     def inputType(i: Int): Type = inputs(i).t