From e939181aebb5a0131562609a5782e1f1df88699d Mon Sep 17 00:00:00 2001
From: Jack Koenig
Date: Mon, 16 Sep 2019 15:54:31 -0700
Subject: Da steve101 tree reduce (#485)

* Add a tree reduce function to Vec

* Change function names of reduce operation function in Vec

* Change reference to single layer operation in Vec.reduce

* Commint name change for pair macro

* Remove pair, call not necessary and can just be used from grouped(2) and map

* Changed to reduceTree, added default identity function for single reduce.

* Change style of Vec.reduceTree and tests to chisel3 and canonical Scala style

* Cleanup Vec initialization, implicitCompileOptions
---
 src/test/scala/chiselTests/AdderTree.scala | 33 ++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)
 create mode 100644 src/test/scala/chiselTests/AdderTree.scala

(limited to 'src')

diff --git a/src/test/scala/chiselTests/AdderTree.scala b/src/test/scala/chiselTests/AdderTree.scala
new file mode 100644
index 00000000..4e7ad1a6
--- /dev/null
+++ b/src/test/scala/chiselTests/AdderTree.scala
@@ -0,0 +1,33 @@
+package chiselTests
+
+import chisel3._
+import chisel3.testers.BasicTester
+
+class AdderTree[T <: Bits with Num[T]](genType: T, vecSize: Int) extends Module {
+  val io = IO(new Bundle {
+    val numIn = Input(Vec(vecSize, genType))
+    val numOut = Output(genType)
+  })
+  io.numOut := io.numIn.reduceTree((a : T, b : T) => (a + b))
+}
+
+class AdderTreeTester(bitWidth: Int, numsToAdd: List[Int]) extends BasicTester {
+  val genType = UInt(bitWidth.W)
+  val dut = Module(new AdderTree(genType, numsToAdd.size))
+  dut.io.numIn := VecInit(numsToAdd.map(x => x.asUInt(bitWidth.W)))
+  val sumCorrect = dut.io.numOut === (numsToAdd.reduce(_+_) % (1 << bitWidth)).asUInt(bitWidth.W)
+  assert(sumCorrect)
+  stop()
+}
+
+class AdderTreeSpec extends ChiselPropSpec {
+  property("All numbers should be added correctly by an Adder Tree") {
+    forAll(safeUIntN(20)) {
+      case (w: Int, v: List[Int]) => {
+        whenever(v.size > 0 && w > 0) {
+          assertTesterPasses { new AdderTreeTester(w, v.map(x => math.abs(x) % ( 1 << w )).toList) }
+        }
+      }
+    }
+  }
+}
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