Add fixed point type (#322)

* WIP: Adding FixedType to Firrtl proper

Got simple example running through width inference
Checks should be ok
Need to look into FixedLiteral more

* Added simple test for fixed types

* Added asFixedPoint to primops

* Added tail case for FixedType

* Added ConvertFixedToSInt.scala

Added pass to MiddleToLowerFirrtl transform

* Replace AsFixedType with AsSInt in fixed removal

* Bugfix: constant from asFixed not deleted

* Added unit test for bulk connect

* Fixed partial connect bug #241

* Fixed missing case for FixedPoint in legalizeConnect

* Add FixedMathSpec that demonstrates some problems with FixedPointMath

* Fixed test and ConvertToSInt to pass.

Negative binary points not easily supported, needs much more time to
implement.

* Refactored checking neg widths

Make checking for negative binary points easier

* Added tests for inferring many FixedType ops

shl, shr, cat, bits, head, tail, setbp, shiftbp

* Handle bpshl, bpshr, bpset in ConvertFixedToSInt

Changed name from shiftbp -> bpshl, bpshr
Change name from setbp -> bpset
Added more tests

* Added set binary point test that fails

* Added simple test for zero binary point

* gitignore fixes for antlr intermediate dir and intellij dir

* removed unused imports
retool the fixed point with zero binary point test

* simplified example of inability to set binary point to zero

* Temporary fix for zero-width binary point

This fix allows for all widths to be zero, but since this is a feature I
am working on next, I'm not going to bother with a more stringent check.

* change version for dsp tools

* Removed extra temporary file

* Fixed merge bug

* Fixed another merge bug

* Removed commented out/unrelated files

* Removed snake case

1 files changed, 17 insertions, 0 deletions

diff --git a/src/main/scala/firrtl/ir/IR.scala b/src/main/scala/firrtl/ir/IR.scala
index 3d65e3b1..f5b80ac6 100644
--- a/src/main/scala/firrtl/ir/IR.scala
+++ b/src/main/scala/firrtl/ir/IR.scala
@@ -127,6 +127,16 @@ case class SIntLiteral(value: BigInt, width: Width) extends Literal {
   def mapType(f: Type => Type): Expression = this
   def mapWidth(f: Width => Width): Expression = SIntLiteral(value, f(width))
 }
+case class FixedLiteral(value: BigInt, width: Width, point: Width) extends Literal {
+  def tpe = FixedType(width, point)
+  def serialize = {
+    val pstring = if(point == UnknownWidth) "" else s"<${point.serialize}>"
+    s"Fixed${width.serialize}$pstring(" + Utils.serialize(value) + ")"
+  }
+  def mapExpr(f: Expression => Expression): Expression = this
+  def mapType(f: Type => Type): Expression = this
+  def mapWidth(f: Width => Width): Expression = FixedLiteral(value, f(width), f(point))
+}
 case class DoPrim(op: PrimOp, args: Seq[Expression], consts: Seq[BigInt], tpe: Type) extends Expression {
   def serialize: String = op.serialize + "(" +
     (args.map(_.serialize) ++ consts.map(_.toString)).mkString(", ") + ")"
@@ -381,6 +391,13 @@ case class SIntType(width: Width) extends GroundType {
   def serialize: String = "SInt" + width.serialize
   def mapWidth(f: Width => Width): Type = SIntType(f(width))
 }
+case class FixedType(width: Width, point: Width) extends GroundType {
+  override def serialize: String = {
+    val pstring = if(point == UnknownWidth) "" else s"<${point.serialize}>"
+    s"Fixed${width.serialize}$pstring"
+  }
+  def mapWidth(f: Width => Width): Type = FixedType(f(width), f(point))
+}
 case class BundleType(fields: Seq[Field]) extends AggregateType {
   def serialize: String = "{ " + (fields map (_.serialize) mkString ", ") + "}"
   def mapType(f: Type => Type): Type =