Fix/workaround symptom unveiled by #1023

diff --git a/techlibs/xilinx/cells_map.v b/techlibs/xilinx/cells_map.v
index f566a8584729ad9452e26763a0e19b6289865a8f..af6414667b931e6d1ec6a132f6018690d6fc8d6f 100644 (file)
--- a/techlibs/xilinx/cells_map.v
+++ b/techlibs/xilinx/cells_map.v
@@ -220,7 +220,10 @@ module \$shiftx (A, B, Y);
       localparam a_widthN = A_WIDTH - a_width0;
       wire T0, T1;
       \$shiftx  #(.A_SIGNED(A_SIGNED), .B_SIGNED(B_SIGNED), .A_WIDTH(a_width0), .B_WIDTH(2),                .Y_WIDTH(Y_WIDTH)) fpga_shiftx      (.A(A[a_width0-1:0]),       .B(B[2-1:0]),                .Y(T0));
-      \$shiftx  #(.A_SIGNED(A_SIGNED), .B_SIGNED(B_SIGNED), .A_WIDTH(a_widthN), .B_WIDTH($clog2(a_widthN)), .Y_WIDTH(Y_WIDTH)) fpga_shiftx_last (.A(A[A_WIDTH-1:a_width0]), .B(B[$clog2(a_widthN)-1:0]), .Y(T1));
+      if (a_widthN > 1)
+        \$shiftx  #(.A_SIGNED(A_SIGNED), .B_SIGNED(B_SIGNED), .A_WIDTH(a_widthN), .B_WIDTH($clog2(a_widthN)), .Y_WIDTH(Y_WIDTH)) fpga_shiftx_last (.A(A[A_WIDTH-1:a_width0]), .B(B[$clog2(a_widthN)-1:0]), .Y(T1));
+      else
+        assign T1 = A[A_WIDTH-1];
       MUXF7 fpga_mux (.I0(T0), .I1(T1), .S(B[B_WIDTH-1]), .O(Y));
     end
     else if (B_WIDTH == 4) begin
@@ -232,8 +235,12 @@ module \$shiftx (A, B, Y);
       for (i = 0; i < 4; i++)
         if (i < num_mux8)
           \$shiftx  #(.A_SIGNED(A_SIGNED), .B_SIGNED(B_SIGNED), .A_WIDTH(a_width0), .B_WIDTH(2),                .Y_WIDTH(Y_WIDTH)) fpga_shiftx      (.A(A[i*a_width0+:a_width0]), .B(B[2-1:0]),                .Y(T[i]));
-        else if (i == num_mux8 && a_widthN > 0)
-          \$shiftx  #(.A_SIGNED(A_SIGNED), .B_SIGNED(B_SIGNED), .A_WIDTH(a_widthN), .B_WIDTH($clog2(a_widthN)), .Y_WIDTH(Y_WIDTH)) fpga_shiftx_last (.A(A[A_WIDTH-1:i*a_width0]), .B(B[$clog2(a_widthN)-1:0]), .Y(T[i]));
+        else if (i == num_mux8 && a_widthN > 0) begin
+          if (a_widthN > 1)
+            \$shiftx  #(.A_SIGNED(A_SIGNED), .B_SIGNED(B_SIGNED), .A_WIDTH(a_widthN), .B_WIDTH($clog2(a_widthN)), .Y_WIDTH(Y_WIDTH)) fpga_shiftx_last (.A(A[A_WIDTH-1:i*a_width0]), .B(B[$clog2(a_widthN)-1:0]), .Y(T[i]));
+          else
+            assign T[i] = A[A_WIDTH-1];
+        end
         else
           assign T[i] = 1'bx;
       MUXF7 fpga_mux_0 (.I0(T[0]), .I1(T[1]), .S(B[2]), .O(T0));
@@ -249,7 +256,10 @@ module \$shiftx (A, B, Y);
         if (i < num_mux16)
           \$shiftx  #(.A_SIGNED(A_SIGNED), .B_SIGNED(B_SIGNED), .A_WIDTH(a_width0), .B_WIDTH(4),                .Y_WIDTH(Y_WIDTH)) fpga_shiftx      (.A(A[i*a_width0+:a_width0]), .B(B[4-1:0]),                .Y(T[i]));
         else if (i == num_mux16 && a_widthN > 0) begin
-          \$shiftx  #(.A_SIGNED(A_SIGNED), .B_SIGNED(B_SIGNED), .A_WIDTH(a_widthN), .B_WIDTH($clog2(a_widthN)), .Y_WIDTH(Y_WIDTH)) fpga_shiftx_last (.A(A[A_WIDTH-1:i*a_width0]), .B(B[$clog2(a_widthN)-1:0]), .Y(T[i]));
+          if (a_widthN > 1)
+            \$shiftx  #(.A_SIGNED(A_SIGNED), .B_SIGNED(B_SIGNED), .A_WIDTH(a_widthN), .B_WIDTH($clog2(a_widthN)), .Y_WIDTH(Y_WIDTH)) fpga_shiftx_last (.A(A[A_WIDTH-1:i*a_width0]), .B(B[$clog2(a_widthN)-1:0]), .Y(T[i]));
+          else
+            assign T[i] = A[A_WIDTH-1];
         end
         else
           assign T[i] = 1'bx;