Add support for clock and reset scoping (#509)

withClockAndReset, withReset, and withClock allow changing the implicit clock and reset.
Module.clock and Module.reset provide access to the current implicit clock and reset.

1 files changed, 54 insertions, 0 deletions

diff --git a/chiselFrontend/src/main/scala/chisel3/core/MultiClock.scala b/chiselFrontend/src/main/scala/chisel3/core/MultiClock.scala
new file mode 100644
index 00000000..62163318
--- /dev/null
+++ b/chiselFrontend/src/main/scala/chisel3/core/MultiClock.scala
@@ -0,0 +1,54 @@
+// See LICENSE for license details.
+
+package chisel3.core
+
+import scala.language.experimental.macros
+
+import chisel3.internal._
+import chisel3.internal.Builder.pushCommand
+import chisel3.internal.firrtl._
+import chisel3.internal.sourceinfo.{SourceInfo}
+
+private[chisel3] final case class ClockAndReset(clock: Clock, reset: Bool)
+
+object withClockAndReset {  // scalastyle:ignore object.name
+  /** Creates a new Clock and Reset scope
+    *
+    * @param clock the new implicit Clock
+    * @param reset the new implicit Reset
+    * @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 = {
+    // Save parentScope
+    val parentScope = Builder.currentClockAndReset
+    Builder.currentClockAndReset = Some(ClockAndReset(clock, reset))
+    val res = block // execute block
+    // Return to old scope
+    Builder.currentClockAndReset = parentScope
+    res
+  }
+}
+
+object withClock {  // scalastyle:ignore object.name
+  /** Creates a new Clock scope
+    *
+    * @param clock the new implicit Clock
+    * @param block the block of code to run with new implicit Clock
+    * @return the result of the block
+    */
+  def apply[T](clock: Clock)(block: => T): T =
+    withClockAndReset(clock, Module.reset)(block)
+}
+
+object withReset {  // scalastyle:ignore object.name
+  /** Creates a new Reset scope
+    *
+    * @param reset the new implicit Reset
+    * @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 =
+    withClockAndReset(Module.clock, reset)(block)
+}
+