Allow counters to be reset manually (#1527)

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

1 files changed, 15 insertions, 3 deletions

diff --git a/src/main/scala/chisel3/util/Counter.scala b/src/main/scala/chisel3/util/Counter.scala
index fa1bb80c..603ebeb6 100644
--- a/src/main/scala/chisel3/util/Counter.scala
+++ b/src/main/scala/chisel3/util/Counter.scala
@@ -57,7 +57,7 @@ class Counter private (r: Range, oldN: Option[Int] = None) {
   def this(n: Int) { this(0 until math.max(1, n), Some(n)) }
 
   /** The current value of the counter. */
-  val value = if (r.length > 1) RegInit(r.head.U(width.W)) else r.head.U
+  val value = if (r.length > 1) RegInit(r.head.U(width.W)) else WireInit(r.head.U)
 
   /** The range of the counter values. */
   def range: Range = r
@@ -91,6 +91,11 @@ class Counter private (r: Range, oldN: Option[Int] = None) {
       true.B
     }
   }
+
+  /** Resets the counter to its initial value */
+  def reset(): Unit = {
+    value := r.head.U
+  }
 }
 
 object Counter
@@ -118,14 +123,21 @@ object Counter
     *
     * @param r the range of counter values
     * @param enable controls whether the counter increments this cycle
+    * @param reset resets the counter to its initial value during this cycle
     * @return tuple of the counter value and whether the counter will wrap (the value is at
     * maximum and the condition is true).
     */
   @chiselName
-  def apply(r: Range, enable: Bool = true.B): (UInt, Bool) = {
+  def apply(r: Range, enable: Bool = true.B, reset: Bool = false.B): (UInt, Bool) = {
     val c = new Counter(r)
     val wrap = WireInit(false.B)
-    when (enable) { wrap := c.inc() }
+
+    when(reset) {
+      c.reset()
+    }.elsewhen(enable) {
+      wrap := c.inc()
+    }
+
     (c.value, wrap)
   }
 }