Add serialization support for LoadMemoryFileType in LoadMemoryAnnotation (#1056)

* Add serialization support for LoadMemoryFileType in LoadMemoryAnnotation
Add custom LoadMemoryFileTypeSerializer.
Add test to verify LoadMemoryAnnotation can be correctly serialized/deserialized.

* Simplify and focus LoadMemoryAnnotation serialization/deserialization.
Respond to comments on earlier implementations.

* Add type FileType definition for current chisel3 code.

1 files changed, 6 insertions, 2 deletions

diff --git a/src/main/scala/firrtl/annotations/JsonProtocol.scala b/src/main/scala/firrtl/annotations/JsonProtocol.scala
index acb2d957..ea29f090 100644
--- a/src/main/scala/firrtl/annotations/JsonProtocol.scala
+++ b/src/main/scala/firrtl/annotations/JsonProtocol.scala
@@ -45,7 +45,10 @@ object JsonProtocol {
       }},
     { case x: Transform => JString(x.getClass.getName) }
   ))
-
+  class LoadMemoryFileTypeSerializer extends CustomSerializer[MemoryLoadFileType](format => (
+    { case JString(s) => MemoryLoadFileType.deserialize(s) },
+    { case named: MemoryLoadFileType => JString(named.serialize) }
+  ))
 
   class TargetSerializer extends CustomSerializer[Target](format => (
     { case JString(s) => Target.deserialize(s) },
@@ -78,7 +81,8 @@ object JsonProtocol {
       new TransformClassSerializer + new NamedSerializer + new CircuitNameSerializer +
       new ModuleNameSerializer + new ComponentNameSerializer + new TargetSerializer +
       new GenericTargetSerializer + new CircuitTargetSerializer + new ModuleTargetSerializer +
-      new InstanceTargetSerializer + new ReferenceTargetSerializer + new TransformSerializer
+      new InstanceTargetSerializer + new ReferenceTargetSerializer + new TransformSerializer  +
+      new LoadMemoryFileTypeSerializer
   }
 
   /** Serialize annotations to a String for emission */