synth_xilinx: Support latches, remove used-up FF init values.

Fixes #1387.

1 files changed, 39 insertions, 1 deletions

diff --git a/techlibs/xilinx/xc7_ff_map.v b/techlibs/xilinx/xc7_ff_map.v
index f6197b78b..32ca9f560 100644
--- a/techlibs/xilinx/xc7_ff_map.v
+++ b/techlibs/xilinx/xc7_ff_map.v
@@ -18,60 +18,98 @@
  */
 
 // ============================================================================
-// FF mapping
+// FF mapping for Virtex 6, Series 7 and Ultrascale.  These families support
+// the following features:
+//
+// - a CLB flip-flop can be used as a latch or as a flip-flop
+// - a CLB flip-flop has the following pins:
+//
+//   - data input
+//   - clock (or gate for latches) (with optional inversion)
+//   - clock enable (or gate enable, which is just ANDed with gate — unused by
+//     synthesis)
+//   - either a set or a reset input, which (for FFs) can be either
+//     synchronous or asynchronous (with optional inversion)
+//   - data output
+//
+// - a flip-flop also has an initial value, which is set at device
+//   initialization (or whenever GSR is asserted)
 
 `ifndef _NO_FFS
 
 module  \$_DFF_N_   (input D, C, output Q);
   parameter _TECHMAP_WIREINIT_Q_ = 1'bx;
   FDRE_1 #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .R(1'b0));
+  wire _TECHMAP_REMOVEINIT_Q_ = 1;
 endmodule
 module  \$_DFF_P_   (input D, C, output Q);
   parameter _TECHMAP_WIREINIT_Q_ = 1'bx;
   FDRE   #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .R(1'b0));
+  wire _TECHMAP_REMOVEINIT_Q_ = 1;
 endmodule
 
 module  \$_DFFE_NP_ (input D, C, E, output Q);
   parameter _TECHMAP_WIREINIT_Q_ = 1'bx;
   FDRE_1 #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(E),    .R(1'b0));
+  wire _TECHMAP_REMOVEINIT_Q_ = 1;
 endmodule
 module  \$_DFFE_PP_ (input D, C, E, output Q);
   parameter _TECHMAP_WIREINIT_Q_ = 1'bx;
   FDRE   #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(E),    .R(1'b0));
+  wire _TECHMAP_REMOVEINIT_Q_ = 1;
 endmodule
 
 module  \$_DFF_NN0_ (input D, C, R, output Q);
   parameter _TECHMAP_WIREINIT_Q_ = 1'bx;
   FDCE_1 #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .CLR(!R));
+  wire _TECHMAP_REMOVEINIT_Q_ = 1;
 endmodule
 module  \$_DFF_NP0_ (input D, C, R, output Q);
   parameter _TECHMAP_WIREINIT_Q_ = 1'bx;
   FDCE_1 #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .CLR( R));
+  wire _TECHMAP_REMOVEINIT_Q_ = 1;
 endmodule
 module  \$_DFF_PN0_ (input D, C, R, output Q);
   parameter _TECHMAP_WIREINIT_Q_ = 1'bx;
   FDCE   #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .CLR(!R));
+  wire _TECHMAP_REMOVEINIT_Q_ = 1;
 endmodule
 module  \$_DFF_PP0_ (input D, C, R, output Q);
   parameter _TECHMAP_WIREINIT_Q_ = 1'bx;
   FDCE   #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .CLR( R));
+  wire _TECHMAP_REMOVEINIT_Q_ = 1;
 endmodule
 
 module  \$_DFF_NN1_ (input D, C, R, output Q);
   parameter _TECHMAP_WIREINIT_Q_ = 1'bx;
   FDPE_1 #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .PRE(!R));
+  wire _TECHMAP_REMOVEINIT_Q_ = 1;
 endmodule
 module  \$_DFF_NP1_ (input D, C, R, output Q);
   parameter _TECHMAP_WIREINIT_Q_ = 1'bx;
   FDPE_1 #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .PRE( R));
+  wire _TECHMAP_REMOVEINIT_Q_ = 1;
 endmodule
 module  \$_DFF_PN1_ (input D, C, R, output Q);
   parameter _TECHMAP_WIREINIT_Q_ = 1'bx;
   FDPE   #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .PRE(!R));
+  wire _TECHMAP_REMOVEINIT_Q_ = 1;
 endmodule
 module  \$_DFF_PP1_ (input D, C, R, output Q);
   parameter _TECHMAP_WIREINIT_Q_ = 1'bx;
   FDPE   #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .PRE( R));
+  wire _TECHMAP_REMOVEINIT_Q_ = 1;
+endmodule
+
+module  \$_DLATCH_N_ (input E, D, output Q);
+  parameter _TECHMAP_WIREINIT_Q_ = 1'bx;
+  LDCE #(.INIT(_TECHMAP_WIREINIT_Q_), .IS_G_INVERTED(1'b1)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .G(E), .GE(1'b1), .CLR(1'b0));
+  wire _TECHMAP_REMOVEINIT_Q_ = 1;
+endmodule
+module  \$_DLATCH_P_ (input E, D, output Q);
+  parameter _TECHMAP_WIREINIT_Q_ = 1'bx;
+  LDCE   #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .G(E), .GE(1'b1), .CLR(1'b0));
+  wire _TECHMAP_REMOVEINIT_Q_ = 1;
 endmodule
 
 `endif