Break Core.scala into bite-sized pieces

1 files changed, 52 insertions, 0 deletions

diff --git a/src/main/scala/Chisel/When.scala b/src/main/scala/Chisel/When.scala
new file mode 100644
index 00000000..a051e52c
--- /dev/null
+++ b/src/main/scala/Chisel/When.scala
@@ -0,0 +1,52 @@
+// See LICENSE for license details.
+
+package Chisel
+import Builder.pushCommand
+
+object when {  // scalastyle:ignore object.name
+  /** Create a `when` condition block, where whether a block of logic is
+    * executed or not depends on the conditional.
+    *
+    * @param cond condition to execute upon
+    * @param block logic that runs only if `cond` is true
+    *
+    * @example
+    * {{{
+    * when ( myData === UInt(3) ) {
+    *   // Some logic to run when myData equals 3.
+    * } .elsewhen ( myData === UInt(1) ) {
+    *   // Some logic to run when myData equals 1.
+    * } .otherwise {
+    *   // Some logic to run when myData is neither 3 nor 1.
+    * }
+    * }}}
+    */
+  def apply(cond: => Bool)(block: => Unit): WhenContext = {
+    new WhenContext(cond)(block)
+  }
+}
+
+class WhenContext(cond: => Bool)(block: => Unit) {
+  /** This block of logic gets executed if above conditions have been false
+    * and this condition is true.
+    */
+  def elsewhen (cond: => Bool)(block: => Unit): WhenContext =
+    doOtherwise(when(cond)(block))
+
+  /** This block of logic gets executed only if the above conditions were all
+    * false. No additional logic blocks may be appended past the `otherwise`.
+    */
+  def otherwise(block: => Unit): Unit =
+    doOtherwise(block)
+
+  pushCommand(WhenBegin(cond.ref))
+  block
+  pushCommand(WhenEnd())
+
+  private def doOtherwise[T](block: => T): T = {
+    pushCommand(WhenElse())
+    val res = block
+    pushCommand(WhenEnd())
+    res
+  }
+}