Different approach to timing

[yosys.git] / techlibs / xilinx / lut_map.v

diff --git a/techlibs/xilinx/lut_map.v b/techlibs/xilinx/lut_map.v
index d07c59dee29c71cea49ce85440021b43bf7a6cda..13d3c32688b37569625c7e9b661168342ea68013 100644 (file)
--- a/techlibs/xilinx/lut_map.v
+++ b/techlibs/xilinx/lut_map.v
@@ -29,61 +29,86 @@ module \$lut (A, Y);
   input [WIDTH-1:0] A;
   output Y;
 
+  // Need to swap input ordering, and fix init accordingly,
+  // to match ABC's expectation of LUT inputs in non-decreasing
+  // delay order
+  function [WIDTH-1:0] permute_index;
+      input [WIDTH-1:0] i;
+      integer j;
+      begin
+          permute_index = 0;
+          for (j = 0; j < WIDTH; j = j + 1)
+              permute_index[WIDTH-1 - j] = i[j];
+      end
+  endfunction
+
+  function [2**WIDTH-1:0] permute_init;
+      input [2**WIDTH-1:0] orig;
+      integer i;
+      begin
+          permute_init = 0;
+          for (i = 0; i < 2**WIDTH; i = i + 1)
+              permute_init[i] = orig[permute_index(i)];
+      end
+  endfunction
+
+  parameter [2**WIDTH-1:0] P_LUT = permute_init(LUT);
+
   generate
     if (WIDTH == 1) begin
-      LUT1 #(.INIT(LUT)) _TECHMAP_REPLACE_ (.O(Y),
+      LUT1 #(.INIT(P_LUT)) _TECHMAP_REPLACE_ (.O(Y),
         .I0(A[0]));
     end else
     if (WIDTH == 2) begin
-      LUT2 #(.INIT(LUT)) _TECHMAP_REPLACE_ (.O(Y),
-        .I0(A[0]), .I1(A[1]));
+      LUT2 #(.INIT(P_LUT)) _TECHMAP_REPLACE_ (.O(Y),
+        .I0(A[1]), .I1(A[0]));
     end else
     if (WIDTH == 3) begin
-      LUT3 #(.INIT(LUT)) _TECHMAP_REPLACE_ (.O(Y),
-        .I0(A[0]), .I1(A[1]), .I2(A[2]));
+      LUT3 #(.INIT(P_LUT)) _TECHMAP_REPLACE_ (.O(Y),
+        .I0(A[2]), .I1(A[1]), .I2(A[0]));
     end else
     if (WIDTH == 4) begin
-      LUT4 #(.INIT(LUT)) _TECHMAP_REPLACE_ (.O(Y),
-        .I0(A[0]), .I1(A[1]), .I2(A[2]),
-        .I3(A[3]));
+      LUT4 #(.INIT(P_LUT)) _TECHMAP_REPLACE_ (.O(Y),
+        .I0(A[3]), .I1(A[2]), .I2(A[1]),
+        .I3(A[0]));
     end else
     if (WIDTH == 5) begin
-      LUT5 #(.INIT(LUT)) _TECHMAP_REPLACE_ (.O(Y),
-        .I0(A[0]), .I1(A[1]), .I2(A[2]),
-        .I3(A[3]), .I4(A[4]));
+      LUT5 #(.INIT(P_LUT)) _TECHMAP_REPLACE_ (.O(Y),
+        .I0(A[4]), .I1(A[3]), .I2(A[2]),
+        .I3(A[1]), .I4(A[0]));
     end else
     if (WIDTH == 6) begin
-      LUT6 #(.INIT(LUT)) _TECHMAP_REPLACE_ (.O(Y),
-        .I0(A[0]), .I1(A[1]), .I2(A[2]),
-        .I3(A[3]), .I4(A[4]), .I5(A[5]));
+      LUT6 #(.INIT(P_LUT)) _TECHMAP_REPLACE_ (.O(Y),
+        .I0(A[5]), .I1(A[4]), .I2(A[3]),
+        .I3(A[2]), .I4(A[1]), .I5(A[0]));
     end else
     if (WIDTH == 7) begin
       wire T0, T1;
-      LUT6 #(.INIT(LUT[63:0])) fpga_lut_0 (.O(T0),
-        .I0(A[0]), .I1(A[1]), .I2(A[2]),
-        .I3(A[3]), .I4(A[4]), .I5(A[5]));
-      LUT6 #(.INIT(LUT[127:64])) fpga_lut_1 (.O(T1),
-        .I0(A[0]), .I1(A[1]), .I2(A[2]),
-        .I3(A[3]), .I4(A[4]), .I5(A[5]));
-      MUXF7 fpga_mux_0 (.O(Y), .I0(T0), .I1(T1), .S(A[6]));
+      LUT6 #(.INIT(P_LUT[63:0])) fpga_lut_0 (.O(T0),
+        .I0(A[6]), .I1(A[5]), .I2(A[4]),
+        .I3(A[3]), .I4(A[2]), .I5(A[1]));
+      LUT6 #(.INIT(P_LUT[127:64])) fpga_lut_1 (.O(T1),
+        .I0(A[6]), .I1(A[5]), .I2(A[4]),
+        .I3(A[3]), .I4(A[2]), .I5(A[1]));
+      MUXF7 fpga_mux_0 (.O(Y), .I0(T0), .I1(T1), .S(A[0]));
     end else
     if (WIDTH == 8) begin
       wire T0, T1, T2, T3, T4, T5;
-      LUT6 #(.INIT(LUT[63:0])) fpga_lut_0 (.O(T0),
-        .I0(A[0]), .I1(A[1]), .I2(A[2]),
-        .I3(A[3]), .I4(A[4]), .I5(A[5]));
-      LUT6 #(.INIT(LUT[127:64])) fpga_lut_1 (.O(T1),
-        .I0(A[0]), .I1(A[1]), .I2(A[2]),
-        .I3(A[3]), .I4(A[4]), .I5(A[5]));
-      LUT6 #(.INIT(LUT[191:128])) fpga_lut_2 (.O(T2),
-        .I0(A[0]), .I1(A[1]), .I2(A[2]),
-        .I3(A[3]), .I4(A[4]), .I5(A[5]));
-      LUT6 #(.INIT(LUT[255:192])) fpga_lut_3 (.O(T3),
-        .I0(A[0]), .I1(A[1]), .I2(A[2]),
-        .I3(A[3]), .I4(A[4]), .I5(A[5]));
-      MUXF7 fpga_mux_0 (.O(T4), .I0(T0), .I1(T1), .S(A[6]));
-      MUXF7 fpga_mux_1 (.O(T5), .I0(T2), .I1(T3), .S(A[6]));
-      MUXF8 fpga_mux_2 (.O(Y), .I0(T4), .I1(T5), .S(A[7]));
+      LUT6 #(.INIT(P_LUT[63:0])) fpga_lut_0 (.O(T0),
+        .I0(A[7]), .I1(A[6]), .I2(A[5]),
+        .I3(A[4]), .I4(A[3]), .I5(A[2]));
+      LUT6 #(.INIT(P_LUT[127:64])) fpga_lut_1 (.O(T1),
+        .I0(A[7]), .I1(A[6]), .I2(A[5]),
+        .I3(A[4]), .I4(A[3]), .I5(A[2]));
+      LUT6 #(.INIT(P_LUT[191:128])) fpga_lut_2 (.O(T2),
+        .I0(A[7]), .I1(A[6]), .I2(A[5]),
+        .I3(A[4]), .I4(A[3]), .I5(A[2]));
+      LUT6 #(.INIT(P_LUT[255:192])) fpga_lut_3 (.O(T3),
+        .I0(A[7]), .I1(A[6]), .I2(A[5]),
+        .I3(A[4]), .I4(A[3]), .I5(A[2]));
+      MUXF7 fpga_mux_0 (.O(T4), .I0(T0), .I1(T1), .S(A[1]));
+      MUXF7 fpga_mux_1 (.O(T5), .I0(T2), .I1(T3), .S(A[1]));
+      MUXF8 fpga_mux_2 (.O(Y), .I0(T4), .I1(T5), .S(A[0]));
     end else begin
       wire _TECHMAP_FAIL_ = 1;
     end