From: Eddie Hung <eddie@fpgeh.com>
Date: Wed, 17 Apr 2019 20:01:17 +0000 (-0700)
Subject: Map to SB_LUT4 from fastest input first
X-Git-Tag: working-ls180~1237^2~207
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=437fec0d88b4a2ad172edf0d1a861a38845f3b1d;p=yosys.git

Map to SB_LUT4 from fastest input first
---

diff --git a/techlibs/ice40/cells_map.v b/techlibs/ice40/cells_map.v
index d0ddfd02e..287c48b11 100644
--- a/techlibs/ice40/cells_map.v
+++ b/techlibs/ice40/cells_map.v
@@ -37,20 +37,24 @@ module \$lut (A, Y);
 
   generate
     if (WIDTH == 1) begin
-      SB_LUT4 #(.LUT_INIT(LUT)) _TECHMAP_REPLACE_ (.O(Y),
-        .I0(A[0]), .I1(1'b0), .I2(1'b0), .I3(1'b0));
+      localparam [15:0] INIT = {{8{LUT[1]}}, {8{LUT[0]}}};
+      SB_LUT4 #(.LUT_INIT(INIT)) _TECHMAP_REPLACE_ (.O(Y),
+        .I0(1'b0), .I1(1'b0), .I2(1'b0), .I3(A[0]));
     end else
     if (WIDTH == 2) begin
-      SB_LUT4 #(.LUT_INIT(LUT)) _TECHMAP_REPLACE_ (.O(Y),
-        .I0(A[0]), .I1(A[1]), .I2(1'b0), .I3(1'b0));
+      localparam [15:0] INIT = {{4{LUT[3]}}, {4{LUT[1]}}, {4{LUT[2]}}, {4{LUT[0]}}};
+      SB_LUT4 #(.LUT_INIT(INIT)) _TECHMAP_REPLACE_ (.O(Y),
+        .I0(1'b0), .I1(1'b0), .I2(A[1]), .I3(A[0]));
     end else
     if (WIDTH == 3) begin
-      SB_LUT4 #(.LUT_INIT(LUT)) _TECHMAP_REPLACE_ (.O(Y),
-        .I0(A[0]), .I1(A[1]), .I2(A[2]), .I3(1'b0));
+      localparam [15:0] INIT = {{2{LUT[7]}}, {2{LUT[3]}}, {2{LUT[5]}}, {2{LUT[1]}}, {2{LUT[6]}}, {2{LUT[2]}}, {2{LUT[4]}}, {2{LUT[0]}}};
+      SB_LUT4 #(.LUT_INIT(INIT)) _TECHMAP_REPLACE_ (.O(Y),
+        .I0(1'b0), .I1(A[2]), .I2(A[1]), .I3(A[0]));
     end else
     if (WIDTH == 4) begin
+      localparam [15:0] INIT = {LUT[15], LUT[7], LUT[11], LUT[3], LUT[13], LUT[5], LUT[9], LUT[1], LUT[14], LUT[6], LUT[10], LUT[2], LUT[12], LUT[4], LUT[8], LUT[0]};
       SB_LUT4 #(.LUT_INIT(LUT)) _TECHMAP_REPLACE_ (.O(Y),
-        .I0(A[0]), .I1(A[1]), .I2(A[2]), .I3(A[3]));
+        .I0(A[3]), .I1(A[2]), .I2(A[1]), .I3(A[0]));
     end else begin
       wire _TECHMAP_FAIL_ = 1;
     end