add decoder test

1 files changed, 41 insertions, 0 deletions

diff --git a/src/test/scala/chiselTests/Decoder.scala b/src/test/scala/chiselTests/Decoder.scala
new file mode 100644
index 00000000..cc463600
--- /dev/null
+++ b/src/test/scala/chiselTests/Decoder.scala
@@ -0,0 +1,41 @@
+package chiselTests
+import Chisel._
+import org.scalatest._
+import org.scalatest.prop._
+import org.scalacheck._
+import Chisel.testers.BasicTester
+
+class Decoder(bitpats: List[String]) extends Module {
+  val io = new Bundle {
+    val inst  = UInt(INPUT, 32)
+    val match_idx = UInt(OUTPUT, 5)
+  }
+  io.match_idx := Vec(bitpats.map(BitPat(_) === io.inst)).indexWhere{i: Bool => i}
+}
+
+class DecoderSpec extends ChiselPropSpec {
+
+  class DecoderTester(pairs: List[(String, String)]) extends BasicTester {
+    val (insts, bitpats) = pairs.unzip
+    val (cnt, wrap) = Counter(Bool(true), pairs.size)
+    val dut = Module(new Decoder(bitpats))
+    dut.io.inst := Vec(insts.map(UInt(_)))(cnt)
+    when(dut.io.match_idx != cnt) { io.done := Bool(true); io.error := cnt }
+    when(wrap) { io.done := Bool(true) }
+  }
+
+  // Use a single Int to make both a specific instruction and a BitPat that will match it
+  val bitpatPair = for(seed <- Arbitrary.arbitrary[Int]) yield {
+    val rnd = new scala.util.Random(seed)
+    val bs = seed.toBinaryString
+    val bp = bs.map(if(rnd.nextBoolean) _ else "?").mkString
+    ("b"+bs, "b"+bp)
+  } 
+  def nPairs(n: Int) = Gen.containerOfN[List, (String,String)](n,bitpatPair)
+
+  property("BitPat wildcards should be usable in decoding") {
+    forAll(nPairs(16)){ (pairs: List[(String, String)]) =>
+      assert(execute{ new DecoderTester(pairs) })
+    }
+  }
+}