better names in TagEngine

bs/TagEngine.bs

@@ -23,10 +23,10 @@ mkTagEngine =
     do
         let reifiedNumTags = fromInteger |> valueOf numTags
 
-        -- we really only use inUseVec after emptying out our `resetTagCounter` buffer
-        -- perhaps rename this variable to better communicate that
-        inUseVec :: Vector numTags (Reg Bool)
-        inUseVec <- replicateM |> mkReg False
+        -- we really only use tagUsageTracker after emptying out our 
+        -- `initialTagDistributor` buffer
+        tagUsageTracker :: Vector numTags (Reg Bool)
+        tagUsageTracker <- replicateM |> mkReg False
 
         -- Since Bluespec doesn't allow us to initialize FIFOs with values at
         -- reset, we can pretend as if the buffer within our tagFIFO is populated
@@ -34,15 +34,14 @@ mkTagEngine =
         -- by having our tag engine effectively return the value of a decrementing
         -- counter initialized to (numTags - 1) for the first n tag requests made 
         -- to TagEngine where `n := numTags`.
-        -- Maybe resetTagCounter isn't the greatest name?
-        resetTagCounter :: (Reg (Maybe UIntLog2N(numTags)))
-        resetTagCounter <- mkReg |> Just |> reifiedNumTags - 1
+        initialTagDistributor :: (Reg (Maybe UIntLog2N(numTags)))
+        initialTagDistributor <- mkReg |> Just |> reifiedNumTags - 1
 
         retireTag ::  Wire UIntLog2N(numTags)
         retireTag <- mkWire
 
-        freeQueue ::  FIFOF UIntLog2N(numTags)
-        freeQueue <- mkSizedFIFOF reifiedNumTags
+        tagFIFO ::  FIFOF UIntLog2N(numTags)
+        tagFIFO <- mkSizedFIFOF reifiedNumTags
 
         debugOnce <- mkReg True
 
@@ -50,18 +49,14 @@ mkTagEngine =
             rules
                 "display": when (debugOnce == True) ==>
                     do
-                        $display "inUseVec : " (fshow |> readVReg inUseVec)
+                        $display "tagUsageTracker : " (fshow |> readVReg tagUsageTracker)
                         debugOnce := False
             
-                -- The "retire_tags" rule can't fire when the `requestTag` method is called.
-                -- In practice, this is Ok since:
-                --    1. the `requestTag` method should take priority over the "retire_tags" rule
-                --    2. the `requestTag` method handles the case where there are some tags to retire.
                 "retire_tags": when True ==>
                     do
                         $display "firing retire_tags" (fshow retireTag)
-                        freeQueue.enq retireTag
-                        (select inUseVec retireTag) := False
+                        tagFIFO.enq retireTag
+                        (select tagUsageTracker retireTag) := False
 
         return $
           interface TagEngine
@@ -69,18 +64,18 @@ mkTagEngine =
             requestTag :: ActionValue UIntLog2N(numTags)
             requestTag =
                 do
-                    case resetTagCounter of
+                    case initialTagDistributor of
                         Just 0 -> do
-                            resetTagCounter := Nothing
-                            (select inUseVec 0) := True
+                            initialTagDistributor := Nothing
+                            (select tagUsageTracker 0) := True
                             return 0
                         Just tag -> do
-                            resetTagCounter := Just |> tag - 1
-                            (select inUseVec tag) := True
+                            initialTagDistributor := Just |> tag - 1
+                            (select tagUsageTracker tag) := True
                             return tag
                         Nothing -> do
-                            let tag = freeQueue.first
-                            freeQueue.deq
+                            let tag = tagFIFO.first
+                            tagFIFO.deq
                             return tag
 
             -- `retireTag` isn't guarded on tag validity(this would break Bluespec's safety model) 
@@ -92,7 +87,7 @@ mkTagEngine =
                 do
                     let
                         tagValid = tag < reifiedNumTags
-                        tagInUse = readReg (select inUseVec tag)
+                        tagInUse = readReg (select tagUsageTracker tag)
                     if (tagValid && tagInUse)
                         then do
                             retireTag := tag