Add OHToUInt, PriorityEncoder

2 files changed, 35 insertions, 10 deletions

diff --git a/src/main/scala/Log2.scala b/src/main/scala/Log2.scala
new file mode 100644
index 00000000..fe1c1372
--- /dev/null
+++ b/src/main/scala/Log2.scala
@@ -0,0 +1,35 @@
+package Chisel
+
+// TODO: these operators should be backend nodes so their width can be
+// inferred, rather than using getWidth.  also, C++ perf would improve.
+
+object Log2 {
+  def apply(x: Bits, width: Int): UInt = {
+    if (width < 2) UInt(0)
+    else if (width == 2) x(1)
+    else Mux(x(width-1), UInt(width-1), apply(x, width-1))
+  }
+
+  def apply(x: Bits): UInt = apply(x, x.getWidth)
+}
+
+object OHToUInt {
+  def apply(in: Seq[Bool]): UInt = apply(Vec(in))
+  def apply(in: Vec[Bool]): UInt = apply(in.toBits, in.size)
+  def apply(in: Bits): UInt = apply(in, in.getWidth)
+
+  def apply(in: Bits, width: Int): UInt = {
+    if (width <= 2) Log2(in, width)
+    else {
+      val mid = 1 << (log2Up(width)-1)
+      val hi = in(width-1, mid)
+      val lo = in(mid-1, 0)
+      Cat(hi.orR, apply(hi | lo, mid))
+    }
+  }
+}
+
+object PriorityEncoder {
+  def apply(in: Iterable[Bool]): UInt = PriorityMux(in, (0 until in.size).map(UInt(_)))
+  def apply(in: Bits): UInt = apply(in.toBools)
+}
diff --git a/src/main/scala/utils.scala b/src/main/scala/utils.scala
index 804ed12e..0fb275d6 100644
--- a/src/main/scala/utils.scala
+++ b/src/main/scala/utils.scala
@@ -29,16 +29,6 @@ object isPow2
   def apply(in: Int): Boolean = in > 0 && ((in & (in-1)) == 0)
 }
 
-object Log2 {
-  def apply(x: UInt, width: Int): UInt = {
-    if (width < 2) UInt(0)
-    else Mux(x(width-1), UInt(width-1), apply(x, width-1))
-  }
-
-  // TODO: infer the width in the backend
-  def apply(x: UInt): UInt = apply(x, x.getWidth)
-}
-
 object FillInterleaved
 {
   def apply(n: Int, in: Bits): Bits = apply(n, in.toBools)