Fixed bug with unary minus on FixedPoint and Interval (#2154)

In `Bits.scala`, `FixedPoint` and `Interval` did not defeine the `do_unary_-` methods (the `do_`) was missing
The recent PR #2124 combined with the above fact made DspTools break. This fix is necessary to get
that repo to build.

1 files changed, 7 insertions, 0 deletions

diff --git a/src/test/scala/chiselTests/IntervalSpec.scala b/src/test/scala/chiselTests/IntervalSpec.scala
index abc619e5..a33cedc1 100644
--- a/src/test/scala/chiselTests/IntervalSpec.scala
+++ b/src/test/scala/chiselTests/IntervalSpec.scala
@@ -406,6 +406,13 @@ class IntervalChainedSubTester extends BasicTester {
   assert(intervalResult1 === 5.I)
   assert(intervalResult2 === 5.I)
 
+  val negativeInterval = (-3.5).I(4.BP)
+  val positiveInterval = 3.5.I(4.BP)
+
+  assert(negativeInterval =/= positiveInterval)
+  assert(-negativeInterval === positiveInterval)
+  assert(negativeInterval === -positiveInterval)
+
   stop()
 }