Rename variables to be more clear, document

1 files changed, 15 insertions, 11 deletions

diff --git a/nandgame/arith_unit.sv b/nandgame/arith_unit.sv
index e0254aa..53ea17e 100644
--- a/nandgame/arith_unit.sv
+++ b/nandgame/arith_unit.sv
@@ -10,20 +10,24 @@
 module  arith_unit #(
   parameter DATA_WIDTH = 16
 ) (
-  input [(DATA_WIDTH-1):0] X,
-  input [(DATA_WIDTH-1):0] Y,
-  input ArithCode operation,
-
-  output logic [(DATA_WIDTH-1):0] RES
+  // first operand
+  input [(DATA_WIDTH-1):0] X_in,
+  // second operand
+  input [(DATA_WIDTH-1):0] Y_in,
+  // opcode, see ArithCode
+  input ArithCode arith_operation_in,
+
+  // result of operation
+  output logic [(DATA_WIDTH-1):0] result_out
 );
 
 always_comb begin
-    case (operation)
-        ARITH_PLUS: RES = X + Y;
-        ARITH_MINUS:  RES = X - Y;
-        ARITH_INC: RES = X + 1;
-        ARITH_DEC: RES = X - 1;
-        default: RES = 0;
+    case (arith_operation_in)
+        ARITH_PLUS: result_out = X_in + Y_in;
+        ARITH_MINUS:  result_out = X_in - Y_in;
+        ARITH_INC: result_out = X_in + 1;
+        ARITH_DEC: result_out = X_in - 1;
+        default: result_out = 0;
     endcase
 end