Make Reset a trait (#672)

Bool implements Reset. Compatibility package includes an implicit
conversion from Reset to Bool.

7 files changed, 29 insertions, 15 deletions

diff --git a/chiselFrontend/src/main/scala/chisel3/core/Assert.scala b/chiselFrontend/src/main/scala/chisel3/core/Assert.scala
index 8616154b..7f67f244 100644
--- a/chiselFrontend/src/main/scala/chisel3/core/Assert.scala
+++ b/chiselFrontend/src/main/scala/chisel3/core/Assert.scala
@@ -51,7 +51,7 @@ object assert { // scalastyle:ignore object.name
   }
 
   def apply_impl_do(cond: Bool, line: String, message: Option[String], data: Bits*)(implicit sourceInfo: SourceInfo, compileOptions: CompileOptions) {
-    when (!(cond || Builder.forcedReset)) {
+    when (!(cond || Module.reset.toBool)) {
       val fmt = message match {
         case Some(str) => s"Assertion failed: $str\n    at $line\n"
         case None => s"Assertion failed\n    at $line\n"
@@ -77,7 +77,7 @@ object assert { // scalastyle:ignore object.name
 object stop { // scalastyle:ignore object.name
   /** Terminate execution with a failure code. */
   def apply(code: Int)(implicit sourceInfo: SourceInfo, compileOptions: CompileOptions): Unit = {
-    when (!Builder.forcedReset) {
+    when (!Module.reset.toBool) {
       pushCommand(Stop(sourceInfo, Node(Builder.forcedClock), code))
     }
   }
diff --git a/chiselFrontend/src/main/scala/chisel3/core/Bits.scala b/chiselFrontend/src/main/scala/chisel3/core/Bits.scala
index f61ca5a9..090c320b 100644
--- a/chiselFrontend/src/main/scala/chisel3/core/Bits.scala
+++ b/chiselFrontend/src/main/scala/chisel3/core/Bits.scala
@@ -36,12 +36,26 @@ abstract class Element(private[chisel3] val width: Width) extends Data {
     pushCommand(Connect(sourceInfo, this.lref, that.ref))
 }
 
+/** Exists to unify common interfaces of [[Bits]] and [[Reset]]
+  * Workaround because macros cannot override abstract methods
+  */
+private[chisel3] sealed trait ToBoolable extends Element {
+
+  /** Casts this object to a [[Bool]]
+    *
+    * @note Width must be known and equal to 1
+    */
+  final def toBool(): Bool = macro SourceInfoWhiteboxTransform.noArg
+
+  def do_toBool(implicit sourceInfo: SourceInfo, compileOptions: CompileOptions): Bool
+}
+
 /** A data type for values represented by a single bitvector. Provides basic
   * bitwise operations.
   */
 //scalastyle:off number.of.methods
 sealed abstract class Bits(width: Width, override val litArg: Option[LitArg])
-    extends Element(width) {
+    extends Element(width) with ToBoolable {
   // TODO: perhaps make this concrete?
   // Arguments for: self-checking code (can't do arithmetic on bits)
   // Arguments against: generates down to a FIRRTL UInt anyways
@@ -266,9 +280,7 @@ sealed abstract class Bits(width: Width, override val litArg: Option[LitArg])
   @deprecated("Use asUInt, which makes the reinterpret cast more explicit", "chisel3")
   final def toUInt(implicit compileOptions: CompileOptions): UInt = do_asUInt(DeprecatedSourceInfo, compileOptions)
 
-  final def toBool(): Bool = macro SourceInfoTransform.noArg
-
-  def do_toBool(implicit sourceInfo: SourceInfo, compileOptions: CompileOptions): Bool = {
+  final def do_toBool(implicit sourceInfo: SourceInfo, compileOptions: CompileOptions): Bool = {
     width match {
       case KnownWidth(1) => this(0)
       case _ => throwException(s"can't covert UInt<$width> to Bool")
@@ -699,11 +711,13 @@ trait SIntFactory {
 
 object SInt extends SIntFactory
 
+sealed trait Reset extends Element with ToBoolable
+
 // REVIEW TODO: Why does this extend UInt and not Bits? Does defining airth
 // operations on a Bool make sense?
 /** A data type for booleans, defined as a single bit indicating true or false.
   */
-sealed class Bool(lit: Option[ULit] = None) extends UInt(1.W, lit) {
+sealed class Bool(lit: Option[ULit] = None) extends UInt(1.W, lit) with Reset {
   private[core] override def cloneTypeWidth(w: Width): this.type = {
     require(!w.known || w.get == 1)
     new Bool().asInstanceOf[this.type]
diff --git a/chiselFrontend/src/main/scala/chisel3/core/Module.scala b/chiselFrontend/src/main/scala/chisel3/core/Module.scala
index dfb9081c..0e919d3c 100644
--- a/chiselFrontend/src/main/scala/chisel3/core/Module.scala
+++ b/chiselFrontend/src/main/scala/chisel3/core/Module.scala
@@ -70,7 +70,7 @@ object Module {
   /** Returns the implicit Clock */
   def clock: Clock = Builder.forcedClock
   /** Returns the implicit Reset */
-  def reset: Bool = Builder.forcedReset
+  def reset: Reset = Builder.forcedReset
 }
 
 /** Abstract base class for Modules, an instantiable organizational unit for RTL.
diff --git a/chiselFrontend/src/main/scala/chisel3/core/MultiClock.scala b/chiselFrontend/src/main/scala/chisel3/core/MultiClock.scala
index 62163318..6af4da41 100644
--- a/chiselFrontend/src/main/scala/chisel3/core/MultiClock.scala
+++ b/chiselFrontend/src/main/scala/chisel3/core/MultiClock.scala
@@ -9,7 +9,7 @@ import chisel3.internal.Builder.pushCommand
 import chisel3.internal.firrtl._
 import chisel3.internal.sourceinfo.{SourceInfo}
 
-private[chisel3] final case class ClockAndReset(clock: Clock, reset: Bool)
+private[chisel3] final case class ClockAndReset(clock: Clock, reset: Reset)
 
 object withClockAndReset {  // scalastyle:ignore object.name
   /** Creates a new Clock and Reset scope
@@ -19,7 +19,7 @@ object withClockAndReset {  // scalastyle:ignore object.name
     * @param block the block of code to run with new implicit Clock and Reset
     * @return the result of the block
     */
-  def apply[T](clock: Clock, reset: Bool)(block: => T): T = {
+  def apply[T](clock: Clock, reset: Reset)(block: => T): T = {
     // Save parentScope
     val parentScope = Builder.currentClockAndReset
     Builder.currentClockAndReset = Some(ClockAndReset(clock, reset))
@@ -48,7 +48,7 @@ object withReset {  // scalastyle:ignore object.name
     * @param block the block of code to run with new implicit Reset
     * @return the result of the block
     */
-  def apply[T](reset: Bool)(block: => T): T =
+  def apply[T](reset: Reset)(block: => T): T =
     withClockAndReset(Module.clock, reset)(block)
 }
 
diff --git a/chiselFrontend/src/main/scala/chisel3/core/Printf.scala b/chiselFrontend/src/main/scala/chisel3/core/Printf.scala
index d6e2c8de..87134eda 100644
--- a/chiselFrontend/src/main/scala/chisel3/core/Printf.scala
+++ b/chiselFrontend/src/main/scala/chisel3/core/Printf.scala
@@ -55,7 +55,7 @@ object printf { // scalastyle:ignore object.name
     * @param pable [[Printable]] to print
     */
   def apply(pable: Printable)(implicit sourceInfo: SourceInfo, compileOptions: CompileOptions): Unit = {
-    when (!Builder.forcedReset) {
+    when (!Module.reset.toBool) {
       printfWithoutReset(pable)
     }
   }
diff --git a/chiselFrontend/src/main/scala/chisel3/core/UserModule.scala b/chiselFrontend/src/main/scala/chisel3/core/UserModule.scala
index 8b176c3b..218b27c6 100644
--- a/chiselFrontend/src/main/scala/chisel3/core/UserModule.scala
+++ b/chiselFrontend/src/main/scala/chisel3/core/UserModule.scala
@@ -88,8 +88,8 @@ abstract class UserModule(implicit moduleCompileOptions: CompileOptions)
 abstract class ImplicitModule(implicit moduleCompileOptions: CompileOptions)
     extends UserModule {
   // Implicit clock and reset pins
-  val clock = IO(Input(Clock()))
-  val reset = IO(Input(Bool()))
+  val clock: Clock = IO(Input(Clock()))
+  val reset: Reset = IO(Input(Bool()))
 
   // Setup ClockAndReset
   Builder.currentClockAndReset = Some(ClockAndReset(clock, reset))
diff --git a/chiselFrontend/src/main/scala/chisel3/internal/Builder.scala b/chiselFrontend/src/main/scala/chisel3/internal/Builder.scala
index 1d7a45e0..8af1835d 100644
--- a/chiselFrontend/src/main/scala/chisel3/internal/Builder.scala
+++ b/chiselFrontend/src/main/scala/chisel3/internal/Builder.scala
@@ -205,7 +205,7 @@ private[chisel3] object Builder {
     case None => throwException("Error: No implicit clock and reset.")
   }
   def forcedClock: Clock = forcedClockAndReset.clock
-  def forcedReset: Bool = forcedClockAndReset.reset
+  def forcedReset: Reset = forcedClockAndReset.reset
 
   // TODO(twigg): Ideally, binding checks and new bindings would all occur here
   // However, rest of frontend can't support this yet.