Merge branch 'master' into tobits-deprecation

1 files changed, 65 insertions, 0 deletions

diff --git a/src/main/scala/chisel3/util/Mux.scala b/src/main/scala/chisel3/util/Mux.scala
new file mode 100644
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+++ b/src/main/scala/chisel3/util/Mux.scala
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+// See LICENSE for license details.
+
+/** Mux circuit generators.
+  */
+
+package chisel3.util
+
+import chisel3._
+import chisel3.core.SeqUtils
+
+/** Builds a Mux tree out of the input signal vector using a one hot encoded
+  * select signal. Returns the output of the Mux tree.
+  *
+  * @note results undefined if multiple select signals are simultaneously high
+  */
+object Mux1H {
+  def apply[T <: Data](sel: Seq[Bool], in: Seq[T]): T =
+    apply(sel zip in)
+  def apply[T <: Data](in: Iterable[(Bool, T)]): T = SeqUtils.oneHotMux(in)
+  def apply[T <: Data](sel: UInt, in: Seq[T]): T =
+    apply((0 until in.size).map(sel(_)), in)
+  def apply(sel: UInt, in: UInt): Bool = (sel & in).orR
+}
+
+/** Builds a Mux tree under the assumption that multiple select signals
+  * can be enabled. Priority is given to the first select signal.
+  *
+  * Returns the output of the Mux tree.
+  */
+object PriorityMux {
+  def apply[T <: Data](in: Seq[(Bool, T)]): T = SeqUtils.priorityMux(in)
+  def apply[T <: Data](sel: Seq[Bool], in: Seq[T]): T = apply(sel zip in)
+  def apply[T <: Data](sel: Bits, in: Seq[T]): T = apply((0 until in.size).map(sel(_)), in)
+}
+
+/** Creates a cascade of n Muxs to search for a key value. */
+object MuxLookup {
+  /** @param key a key to search for
+    * @param default a default value if nothing is found
+    * @param mapping a sequence to search of keys and values
+    * @return the value found or the default if not
+    */
+  def apply[S <: UInt, T <: Data] (key: S, default: T, mapping: Seq[(S, T)]): T = {
+    var res = default
+    for ((k, v) <- mapping.reverse)
+      res = Mux(k === key, v, res)
+    res
+  }
+}
+
+/** Given an association of values to enable signals, returns the first value with an associated
+  * high enable signal.
+  */
+object MuxCase {
+  /** @param default the default value if none are enabled
+    * @param mapping a set of data values with associated enables
+    * @return the first value in mapping that is enabled */
+  def apply[T <: Data] (default: T, mapping: Seq[(Bool, T)]): T = {
+    var res = default
+    for ((t, v) <- mapping.reverse){
+      res = Mux(t, v, res)
+    }
+    res
+  }
+}