Add chisel3.stage.phases.Emitter Phase

This adds an Emitter Phase that writes a ChiselCircuitAnnotation to
a file if a ChiselOutputFileAnnotation is present.

Signed-off-by: Schuyler Eldridge <schuyler.eldridge@ibm.com>

1 files changed, 44 insertions, 0 deletions

diff --git a/src/main/scala/chisel3/stage/phases/Emitter.scala b/src/main/scala/chisel3/stage/phases/Emitter.scala
new file mode 100644
index 00000000..1bdb9f8d
--- /dev/null
+++ b/src/main/scala/chisel3/stage/phases/Emitter.scala
@@ -0,0 +1,44 @@
+// See LICENSE for license details.
+
+package chisel3.stage.phases
+
+import firrtl.{AnnotationSeq, EmittedFirrtlCircuit, EmittedFirrtlCircuitAnnotation}
+import firrtl.annotations.DeletedAnnotation
+import firrtl.options.{Phase, StageOptions}
+import firrtl.options.Viewer.view
+
+import chisel3.internal.firrtl.{Emitter => OldEmitter}
+import chisel3.stage.{ChiselCircuitAnnotation, ChiselOptions}
+
+import java.io.{File, FileWriter}
+
+/** Emit a [[chisel3.stage.ChiselCircuitAnnotation]] to a file if a [[chisel3.stage.ChiselOutputFileAnnotation]] is
+  * present. A deleted [[firrtl.EmittedFirrtlCircuitAnnotation]] is added.
+  *
+  * @todo This should be switched to support correct emission of multiple circuits to multiple files. The API should
+  * likely mirror how the [[firrtl.stage.phases.Compiler]] parses annotations into "global" annotations and
+  * left-associative per-circuit annotations.
+  * @todo The use of the deleted [[firrtl.EmittedFirrtlCircuitAnnotation]] is a kludge to provide some breadcrumbs such
+  * that the emitted CHIRRTL can be provided back to the old Driver. This should be removed or a better solution
+  * developed.
+  */
+class Emitter extends Phase {
+
+  def transform(annotations: AnnotationSeq): AnnotationSeq = {
+    val copts = view[ChiselOptions](annotations)
+    val sopts = view[StageOptions](annotations)
+
+    annotations.flatMap {
+      case a: ChiselCircuitAnnotation if copts.outputFile.isDefined =>
+        val file = new File(sopts.getBuildFileName(copts.outputFile.get, Some(".fir")))
+        val emitted = OldEmitter.emit(a.circuit)
+        val w = new FileWriter(file)
+        w.write(emitted)
+        w.close()
+        val anno = EmittedFirrtlCircuitAnnotation(EmittedFirrtlCircuit(a.circuit.name, emitted, ".fir"))
+        Seq(DeletedAnnotation(name, anno), a)
+      case a => Some(a)
+    }
+  }
+
+}