xilinx: Improve flip-flop handling.

This adds support for infering more kinds of flip-flops:

- FFs with async set/reset and clock enable
- FFs with sync set/reset
- FFs with sync set/reset and clock enable

Some passes have been moved (and some added) in order for dff2dffs to
work correctly.

This gives us complete coverage of Virtex 6+ and Spartan 6 flip-flop
capabilities (though not latch capabilities).  Older FPGAs also support
having both a set and a reset input, which will be handled at a later
data.

1 files changed, 112 insertions, 18 deletions

diff --git a/techlibs/xilinx/xc6s_ff_map.v b/techlibs/xilinx/xc6s_ff_map.v
index bf35b09e5..c40f446e0 100644
--- a/techlibs/xilinx/xc6s_ff_map.v
+++ b/techlibs/xilinx/xc6s_ff_map.v
@@ -27,6 +27,8 @@
 
 `ifndef _NO_FFS
 
+// No reset.
+
 module  \$_DFF_N_   (input D, C, output Q);
   parameter [0:0] _TECHMAP_WIREINIT_Q_ = 1'bx;
   generate if (_TECHMAP_WIREINIT_Q_ === 1'b1)
@@ -46,6 +48,8 @@ module  \$_DFF_P_   (input D, C, output Q);
   wire _TECHMAP_REMOVEINIT_Q_ = 1;
 endmodule
 
+// No reset, enable.
+
 module  \$_DFFE_NP_ (input D, C, E, output Q);
   parameter [0:0] _TECHMAP_WIREINIT_Q_ = 1'bx;
   generate if (_TECHMAP_WIREINIT_Q_ === 1'b1)
@@ -65,80 +69,168 @@ module  \$_DFFE_PP_ (input D, C, E, output Q);
   wire _TECHMAP_REMOVEINIT_Q_ = 1;
 endmodule
 
-module  \$_DFF_NN0_ (input D, C, R, output Q);
+// Async reset.
+
+module  \$_DFF_NP0_ (input D, C, R, output Q);
   parameter [0:0] _TECHMAP_WIREINIT_Q_ = 1'bx;
   generate if (_TECHMAP_WIREINIT_Q_ === 1'b1)
     $error("Spartan 6 doesn't support FFs with asynchronous reset initialized to 1");
   else
-    FDCE_1 #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .CLR(!R));
+    FDCE_1 #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .CLR( R));
   endgenerate
   wire _TECHMAP_REMOVEINIT_Q_ = 1;
 endmodule
-module  \$_DFF_NP0_ (input D, C, R, output Q);
+module  \$_DFF_PP0_ (input D, C, R, output Q);
   parameter [0:0] _TECHMAP_WIREINIT_Q_ = 1'bx;
   generate if (_TECHMAP_WIREINIT_Q_ === 1'b1)
     $error("Spartan 6 doesn't support FFs with asynchronous reset initialized to 1");
   else
-    FDCE_1 #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .CLR( R));
+    FDCE   #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .CLR( R));
   endgenerate
   wire _TECHMAP_REMOVEINIT_Q_ = 1;
 endmodule
-module  \$_DFF_PN0_ (input D, C, R, output Q);
+
+module  \$_DFF_NP1_ (input D, C, R, output Q);
+  parameter [0:0] _TECHMAP_WIREINIT_Q_ = 1'bx;
+  generate if (_TECHMAP_WIREINIT_Q_ === 1'b0)
+    $error("Spartan 6 doesn't support FFs with asynchronous set initialized to 0");
+  else
+    FDPE_1 #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .PRE( R));
+  endgenerate
+  wire _TECHMAP_REMOVEINIT_Q_ = 1;
+endmodule
+module  \$_DFF_PP1_ (input D, C, R, output Q);
+  parameter [0:0] _TECHMAP_WIREINIT_Q_ = 1'bx;
+  generate if (_TECHMAP_WIREINIT_Q_ === 1'b0)
+    $error("Spartan 6 doesn't support FFs with asynchronous set initialized to 0");
+  else
+    FDPE   #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .PRE( R));
+  endgenerate
+  wire _TECHMAP_REMOVEINIT_Q_ = 1;
+endmodule
+
+// Async reset, enable.
+
+module  \$__DFFE_NP0 (input D, C, E, R, output Q);
   parameter [0:0] _TECHMAP_WIREINIT_Q_ = 1'bx;
   generate if (_TECHMAP_WIREINIT_Q_ === 1'b1)
     $error("Spartan 6 doesn't support FFs with asynchronous reset initialized to 1");
   else
-    FDCE   #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .CLR(!R));
+    FDCE_1 #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(E), .CLR( R));
   endgenerate
   wire _TECHMAP_REMOVEINIT_Q_ = 1;
 endmodule
-module  \$_DFF_PP0_ (input D, C, R, output Q);
+module  \$__DFFE_PP0 (input D, C, E, R, output Q);
   parameter [0:0] _TECHMAP_WIREINIT_Q_ = 1'bx;
   generate if (_TECHMAP_WIREINIT_Q_ === 1'b1)
     $error("Spartan 6 doesn't support FFs with asynchronous reset initialized to 1");
   else
-    FDCE   #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .CLR( R));
+    FDCE   #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(E), .CLR( R));
   endgenerate
   wire _TECHMAP_REMOVEINIT_Q_ = 1;
 endmodule
 
-module  \$_DFF_NN1_ (input D, C, R, output Q);
+module  \$__DFFE_NP1 (input D, C, E, R, output Q);
   parameter [0:0] _TECHMAP_WIREINIT_Q_ = 1'bx;
   generate if (_TECHMAP_WIREINIT_Q_ === 1'b0)
     $error("Spartan 6 doesn't support FFs with asynchronous set initialized to 0");
   else
-    FDPE_1 #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .PRE(!R));
+    FDPE_1 #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(E), .PRE( R));
   endgenerate
   wire _TECHMAP_REMOVEINIT_Q_ = 1;
 endmodule
-module  \$_DFF_NP1_ (input D, C, R, output Q);
+module  \$__DFFE_PP1 (input D, C, E, R, output Q);
   parameter [0:0] _TECHMAP_WIREINIT_Q_ = 1'bx;
   generate if (_TECHMAP_WIREINIT_Q_ === 1'b0)
     $error("Spartan 6 doesn't support FFs with asynchronous set initialized to 0");
   else
-    FDPE_1 #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .PRE( R));
+    FDPE   #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(E), .PRE( R));
+  endgenerate
+  wire _TECHMAP_REMOVEINIT_Q_ = 1;
+endmodule
+
+// Sync reset.
+
+module  \$__DFFS_NP0_ (input D, C, R, output Q);
+  parameter [0:0] _TECHMAP_WIREINIT_Q_ = 1'bx;
+  generate if (_TECHMAP_WIREINIT_Q_ === 1'b1)
+    $error("Spartan 6 doesn't support FFs with reset initialized to 1");
+  else
+    FDRE_1 #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .R( R));
   endgenerate
   wire _TECHMAP_REMOVEINIT_Q_ = 1;
 endmodule
-module  \$_DFF_PN1_ (input D, C, R, output Q);
+module  \$__DFFS_PP0_ (input D, C, R, output Q);
+  parameter [0:0] _TECHMAP_WIREINIT_Q_ = 1'bx;
+  generate if (_TECHMAP_WIREINIT_Q_ === 1'b1)
+    $error("Spartan 6 doesn't support FFs with reset initialized to 1");
+  else
+    FDRE   #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .R( R));
+  endgenerate
+  wire _TECHMAP_REMOVEINIT_Q_ = 1;
+endmodule
+
+module  \$__DFFS_NP1_ (input D, C, R, output Q);
   parameter [0:0] _TECHMAP_WIREINIT_Q_ = 1'bx;
   generate if (_TECHMAP_WIREINIT_Q_ === 1'b0)
-    $error("Spartan 6 doesn't support FFs with asynchronous set initialized to 0");
+    $error("Spartan 6 doesn't support FFs with set initialized to 0");
   else
-    FDPE   #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .PRE(!R));
+    FDSE_1 #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .S( R));
   endgenerate
   wire _TECHMAP_REMOVEINIT_Q_ = 1;
 endmodule
-module  \$_DFF_PP1_ (input D, C, R, output Q);
+module  \$__DFFS_PP1_ (input D, C, R, output Q);
   parameter [0:0] _TECHMAP_WIREINIT_Q_ = 1'bx;
   generate if (_TECHMAP_WIREINIT_Q_ === 1'b0)
-    $error("Spartan 6 doesn't support FFs with asynchronous set initialized to 0");
+    $error("Spartan 6 doesn't support FFs with set initialized to 0");
   else
-    FDPE   #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .PRE( R));
+    FDSE   #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .S( R));
   endgenerate
   wire _TECHMAP_REMOVEINIT_Q_ = 1;
 endmodule
 
+// Sync reset, enable.
+
+module  \$__DFFSE_NP0 (input D, C, E, R, output Q);
+  parameter [0:0] _TECHMAP_WIREINIT_Q_ = 1'bx;
+  generate if (_TECHMAP_WIREINIT_Q_ === 1'b1)
+    $error("Spartan 6 doesn't support FFs with reset initialized to 1");
+  else
+    FDRE_1 #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(E), .R( R));
+  endgenerate
+  wire _TECHMAP_REMOVEINIT_Q_ = 1;
+endmodule
+module  \$__DFFSE_PP0 (input D, C, E, R, output Q);
+  parameter [0:0] _TECHMAP_WIREINIT_Q_ = 1'bx;
+  generate if (_TECHMAP_WIREINIT_Q_ === 1'b1)
+    $error("Spartan 6 doesn't support FFs with reset initialized to 1");
+  else
+    FDRE   #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(E), .R( R));
+  endgenerate
+  wire _TECHMAP_REMOVEINIT_Q_ = 1;
+endmodule
+
+module  \$__DFFSE_NP1 (input D, C, E, R, output Q);
+  parameter [0:0] _TECHMAP_WIREINIT_Q_ = 1'bx;
+  generate if (_TECHMAP_WIREINIT_Q_ === 1'b0)
+    $error("Spartan 6 doesn't support FFs with set initialized to 0");
+  else
+    FDSE_1 #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(E), .S( R));
+  endgenerate
+  wire _TECHMAP_REMOVEINIT_Q_ = 1;
+endmodule
+module  \$__DFFSE_PP1 (input D, C, E, R, output Q);
+  parameter [0:0] _TECHMAP_WIREINIT_Q_ = 1'bx;
+  generate if (_TECHMAP_WIREINIT_Q_ === 1'b0)
+    $error("Spartan 6 doesn't support FFs with set initialized to 0");
+  else
+    FDSE   #(.INIT(_TECHMAP_WIREINIT_Q_)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(E), .S( R));
+  endgenerate
+  wire _TECHMAP_REMOVEINIT_Q_ = 1;
+endmodule
+
+// Latches (no reset).
+
 module  \$_DLATCH_N_ (input E, D, output Q);
   parameter _TECHMAP_WIREINIT_Q_ = 1'bx;
   generate if (_TECHMAP_WIREINIT_Q_ === 1'b1)
@@ -158,5 +250,7 @@ module  \$_DLATCH_P_ (input E, D, output Q);
   wire _TECHMAP_REMOVEINIT_Q_ = 1;
 endmodule
 
+// Latches with reset (TODO).
+
 `endif