Refactor $__SHREG__ in cells_map.v

1 files changed, 24 insertions, 32 deletions

diff --git a/techlibs/xilinx/cells_map.v b/techlibs/xilinx/cells_map.v
index d2cc96969..92358620e 100644
--- a/techlibs/xilinx/cells_map.v
+++ b/techlibs/xilinx/cells_map.v
@@ -105,32 +105,17 @@ module \$__SHREG_ (input C, input D, input E, output Q);
       localparam [3:0] A = DEPTH - 1;
       SRL16E #(.INIT(INIT), .IS_CLK_INVERTED(~CLKPOL[0])) _TECHMAP_REPLACE_ (.A0(A[0]), .A1(A[1]), .A2(A[2]), .A3(A[3]), .CE(CE), .CLK(C), .D(D), .Q(Q));
     end else
-    if (DEPTH == 17) begin
-      wire T0;
-      \$__SHREG_ #(.DEPTH(DEPTH-1), .INIT(INIT[DEPTH-2:0]), .CLKPOL(CLKPOL), .ENPOL(ENPOL)) fpga_srl_0 (.C(C), .D(D), .E(E), .Q(T0));
-      \$__SHREG_ #(.DEPTH(1), .INIT(INIT[DEPTH-1]), .CLKPOL(CLKPOL), .ENPOL(ENPOL)) fpga_srl_1 (.C(C), .D(T0), .E(E), .Q(Q));
-    end else
-    if (DEPTH <= 32) begin
+    if (DEPTH > 17 && DEPTH <= 32) begin
       SRLC32E #(.INIT(INIT), .IS_CLK_INVERTED(~CLKPOL[0])) _TECHMAP_REPLACE_ (.A(DEPTH-1), .CE(CE), .CLK(C), .D(D), .Q(Q));
     end else
-    if (DEPTH == 33 || DEPTH == 49) begin
-      wire T0;
-      \$__SHREG_ #(.DEPTH(DEPTH-1), .INIT(INIT[DEPTH-2:0]), .CLKPOL(CLKPOL), .ENPOL(ENPOL)) fpga_srl_0 (.C(C), .D(D), .E(E), .Q(T0));
-      \$__SHREG_ #(.DEPTH(1), .INIT(INIT[DEPTH-1]), .CLKPOL(CLKPOL), .ENPOL(ENPOL)) fpga_srl_1 (.C(C), .D(T0), .E(E), .Q(Q));
-    end else
-    if (DEPTH <= 64) begin
+    if (DEPTH > 33 && DEPTH <= 64) begin
       wire T0, T1, T2;
       localparam [5:0] A = DEPTH-1;
       SRLC32E #(.INIT(INIT[32-1:0]), .IS_CLK_INVERTED(~CLKPOL[0])) fpga_srl_0 (.A(A[4:0]), .CE(CE), .CLK(C), .D(D), .Q(T0), .Q31(T1));
       \$__SHREG_ #(.DEPTH(DEPTH-32), .INIT(INIT[DEPTH-1:32]), .CLKPOL(CLKPOL), .ENPOL(ENPOL)) fpga_srl_1 (.C(C), .D(T1), .E(E), .Q(T2));
       MUXF7 fpga_mux_0 (.O(Q), .I0(T0), .I1(T2), .S(A[5]));
     end else
-    if (DEPTH == 65 || DEPTH == 81) begin
-      wire T0;
-      \$__SHREG_ #(.DEPTH(DEPTH-1), .INIT(INIT[DEPTH-2:0]), .CLKPOL(CLKPOL), .ENPOL(ENPOL)) fpga_srl_0 (.C(C), .D(D), .E(E), .Q(T0));
-      \$__SHREG_ #(.DEPTH(1), .INIT(INIT[DEPTH-1]), .CLKPOL(CLKPOL), .ENPOL(ENPOL)) fpga_srl_1 (.C(C), .D(T0), .E(E), .Q(Q));
-    end else
-    if (DEPTH <= 96) begin
+    if (DEPTH > 65 && DEPTH <= 96) begin
       localparam [6:0] A = DEPTH-1;
       wire T0, T1, T2, T3, T4, T5, T6;
       SRLC32E #(.INIT(INIT[32-1:0]), .IS_CLK_INVERTED(~CLKPOL[0])) fpga_srl_0 (.A(A[4:0]), .CE(CE), .CLK(C), .D(D), .Q(T0), .Q31(T1));
@@ -140,23 +125,30 @@ module \$__SHREG_ (input C, input D, input E, output Q);
       MUXF7 fpga_mux_1 (.O(T6), .I0(T4), .I1(1'b0 /* unused */), .S(A[5]));
       MUXF8 fpga_mux_2 (.O(Q), .I0(T5), .I1(T6), .S(A[6]));
     end else
-    if (DEPTH == 97 || DEPTH == 113) begin
-      wire T0;
-      \$__SHREG_ #(.DEPTH(DEPTH-1), .INIT(INIT[DEPTH-2:0]), .CLKPOL(CLKPOL), .ENPOL(ENPOL)) fpga_srl_0 (.C(C), .D(D), .E(E), .Q(T0));
-      \$__SHREG_ #(.DEPTH(1), .INIT(INIT[DEPTH-1]), .CLKPOL(CLKPOL), .ENPOL(ENPOL)) fpga_srl_1 (.C(C), .D(T0), .E(E), .Q(Q));
-    end else
     if (DEPTH <= 128) begin
-      localparam [6:0] A = DEPTH-1;
-      wire T0, T1, T2, T3, T4, T5, T6, T7, T8;
-      SRLC32E #(.INIT(INIT[32-1:0]), .IS_CLK_INVERTED(~CLKPOL[0])) fpga_srl_0 (.A(A[4:0]), .CE(CE), .CLK(C), .D(D), .Q(T0), .Q31(T1));
-      SRLC32E #(.INIT(INIT[64-1:32]), .IS_CLK_INVERTED(~CLKPOL[0])) fpga_srl_1 (.A(A[4:0]), .CE(CE), .CLK(C), .D(T1), .Q(T2), .Q31(T3));
-      SRLC32E #(.INIT(INIT[96-1:64]), .IS_CLK_INVERTED(~CLKPOL[0])) fpga_srl_2 (.A(A[4:0]), .CE(CE), .CLK(C), .D(T3), .Q(T4), .Q31(T5));
-      \$__SHREG_ #(.DEPTH(DEPTH-96), .INIT(INIT[DEPTH-1:96]), .CLKPOL(CLKPOL), .ENPOL(ENPOL)) fpga_srl_3 (.C(C), .D(T5), .E(E), .Q(T6));
-      MUXF7 fpga_mux_0 (.O(T7), .I0(T0), .I1(T2), .S(A[5]));
-      MUXF7 fpga_mux_1 (.O(T8), .I0(T4), .I1(T6), .S(A[5]));
-      MUXF8 fpga_mux_2 (.O(Q), .I0(T7), .I1(T8), .S(A[6]));
+      if (DEPTH > 97) begin
+        localparam [6:0] A = DEPTH-1;
+        wire T0, T1, T2, T3, T4, T5, T6, T7, T8;
+        SRLC32E #(.INIT(INIT[32-1:0]), .IS_CLK_INVERTED(~CLKPOL[0])) fpga_srl_0 (.A(A[4:0]), .CE(CE), .CLK(C), .D(D), .Q(T0), .Q31(T1));
+        SRLC32E #(.INIT(INIT[64-1:32]), .IS_CLK_INVERTED(~CLKPOL[0])) fpga_srl_1 (.A(A[4:0]), .CE(CE), .CLK(C), .D(T1), .Q(T2), .Q31(T3));
+        SRLC32E #(.INIT(INIT[96-1:64]), .IS_CLK_INVERTED(~CLKPOL[0])) fpga_srl_2 (.A(A[4:0]), .CE(CE), .CLK(C), .D(T3), .Q(T4), .Q31(T5));
+        \$__SHREG_ #(.DEPTH(DEPTH-96), .INIT(INIT[DEPTH-1:96]), .CLKPOL(CLKPOL), .ENPOL(ENPOL)) fpga_srl_3 (.C(C), .D(T5), .E(E), .Q(T6));
+        MUXF7 fpga_mux_0 (.O(T7), .I0(T0), .I1(T2), .S(A[5]));
+        MUXF7 fpga_mux_1 (.O(T8), .I0(T4), .I1(T6), .S(A[5]));
+        MUXF8 fpga_mux_2 (.O(Q), .I0(T7), .I1(T8), .S(A[6]));
+      end
+      // Handle case where depth is just 1 over a convenient value,
+      // in which case use the flop
+      else begin
+        wire T0;
+        \$__SHREG_ #(.DEPTH(DEPTH-1), .INIT(INIT[DEPTH-2:0]), .CLKPOL(CLKPOL), .ENPOL(ENPOL)) fpga_srl_0 (.C(C), .D(D), .E(E), .Q(T0));
+        \$__SHREG_ #(.DEPTH(1), .INIT(INIT[DEPTH-1]), .CLKPOL(CLKPOL), .ENPOL(ENPOL)) fpga_srl_1 (.C(C), .D(T0), .E(E), .Q(Q));
+      end
     end else
     begin
+      // UG474 (v1.8, p34) states that:
+      //   "There are no direct connections between slices to form longer shift
+      //    registers, nor is the MC31 output at LUT B/C/D available."
       wire T0, T1;
       \$__SHREG_ #(.DEPTH(128), .INIT(INIT[128-1:0]), .CLKPOL(CLKPOL), .ENPOL(ENPOL)) fpga_srl_0 (.C(C), .D(D), .E(E), .Q(T0));
       \$__SHREG_ #(.DEPTH(DEPTH-128), .INIT(INIT[DEPTH-1:128]), .CLKPOL(CLKPOL), .ENPOL(ENPOL)) fpga_srl_1 (.C(C), .D(T0), .E(E), .Q(Q));