From 29aee0989fb3a73388d4567409ad6998373edc99 Mon Sep 17 00:00:00 2001
From: Eddie Hung <eddie@fpgeh.com>
Date: Fri, 21 Jun 2019 16:55:59 -0700
Subject: [PATCH] mux_map to no longer copy last value into 1'bx

---
 techlibs/xilinx/mux_map.v | 21 ++-------------------
 1 file changed, 2 insertions(+), 19 deletions(-)

diff --git a/techlibs/xilinx/mux_map.v b/techlibs/xilinx/mux_map.v
index 441c02ac2..0c6b2b78c 100644
--- a/techlibs/xilinx/mux_map.v
+++ b/techlibs/xilinx/mux_map.v
@@ -35,23 +35,6 @@ module \$shiftx (A, B, Y);
   parameter [B_WIDTH-1:0] _TECHMAP_CONSTVAL_B_ = 0;
 
   generate
-    genvar i;
-    wire [A_WIDTH-1:0] A_forward;
-    assign A_backward[A_WIDTH-1] = A[A_WIDTH-1];
-    for (i = A_WIDTH-2; i >= 0; i = i - 1)
-      if (_TECHMAP_CONSTMSK_A_[i] && _TECHMAP_CONSTVAL_A_[i] === 1'bx)
-        assign A_backward[i] = A_backward[i+1];
-      else
-        assign A_backward[i] = A[i];
-
-    wire [A_WIDTH-1:0] A_without_x;
-    assign A_without_x[0] = A_backward[0];
-    for (i = 1; i < A_WIDTH; i = i + 1)
-      if (_TECHMAP_CONSTMSK_A_[i] && _TECHMAP_CONSTVAL_A_[i] === 1'bx)
-        assign A_without_x[i] = A_without_x[i-1];
-      else
-        assign A_without_x[i] = A[i];
-
     if (B_SIGNED) begin
       if (B_WIDTH < 4 || A_WIDTH <= 4)
         wire _TECHMAP_FAIL_ = 1;
@@ -64,7 +47,7 @@ module \$shiftx (A, B, Y);
           .B_WIDTH(B_WIDTH-1'd1),
           .Y_WIDTH(Y_WIDTH)
         ) _TECHMAP_REPLACE_ (
-          .A(A_without_x), .B(B[B_WIDTH-2:0]), .Y(Y)
+          .A(A), .B(B[B_WIDTH-2:0]), .Y(Y)
         );
       else
         wire _TECHMAP_FAIL_ = 1;
@@ -80,7 +63,7 @@ module \$shiftx (A, B, Y);
           .B_WIDTH(B_WIDTH),
           .Y_WIDTH(Y_WIDTH)
         ) _TECHMAP_REPLACE_ (
-          .A(A_without_x), .B(B), .Y(Y)
+          .A(A), .B(B), .Y(Y)
         );
     end
   endgenerate
-- 
2.30.2