synth: add const_z gate.

4 files changed, 33 insertions, 3 deletions

diff --git a/src/synth/netlists-builders.adb b/src/synth/netlists-builders.adb
index 78ed38a41..9cb357b34 100644
--- a/src/synth/netlists-builders.adb
+++ b/src/synth/netlists-builders.adb
@@ -142,6 +142,13 @@ package body Netlists.Builders is
                      Typ => Param_Uns32),
                1 => (New_Sname_Artificial (Get_Identifier ("xz")),
                      Typ => Param_Uns32)));
+
+      Res := New_User_Module
+        (Ctxt.Design, New_Sname_Artificial (Get_Identifier ("const_Z")),
+         Id_Const_Z, 0, 1, 0);
+      Ctxt.M_Const_Z := Res;
+      Outputs := (0 => Create_Output ("o"));
+      Set_Port_Desc (Res, Port_Desc_Array'(1 .. 0 => <>), Outputs);
    end Create_Const_Modules;
 
    procedure Create_Extract_Module (Ctxt : Context_Acc)
@@ -529,11 +536,23 @@ package body Netlists.Builders is
       return O;
    end Build_Compare;
 
+   function Build_Const_Z (Ctxt : Context_Acc; W : Width) return Net
+   is
+      pragma Assert (W > 0);
+      Inst : Instance;
+      O : Net;
+   begin
+      Inst := New_Internal_Instance (Ctxt, Ctxt.M_Const_Z);
+      O := Get_Output (Inst, 0);
+      Set_Width (O, W);
+      return O;
+   end Build_Const_Z;
+
    function Build_Const_UB32 (Ctxt : Context_Acc;
                               Val : Uns32;
                               W : Width) return Net
    is
-      pragma Assert (W <= 32);
+      pragma Assert (W > 0 and W <= 32);
       Inst : Instance;
       O : Net;
    begin
@@ -549,7 +568,7 @@ package body Netlists.Builders is
                               Xz : Uns32;
                               W : Width) return Net
    is
-      pragma Assert (W <= 32);
+      pragma Assert (W > 0 and W <= 32);
       Inst : Instance;
       O : Net;
    begin
diff --git a/src/synth/netlists-builders.ads b/src/synth/netlists-builders.ads
index 7c016dedc..654fc6e9a 100644
--- a/src/synth/netlists-builders.ads
+++ b/src/synth/netlists-builders.ads
@@ -48,6 +48,9 @@ package Netlists.Builders is
                           Id : Reduce_Module_Id;
                           Op : Net) return Net;
 
+   function Build_Const_Z (Ctxt : Context_Acc;
+                           W : Width) return Net;
+
    function Build_Const_UB32 (Ctxt : Context_Acc;
                               Val : Uns32;
                               W : Width) return Net;
@@ -65,6 +68,7 @@ package Netlists.Builders is
                         Sel : Net;
                         I0, I1, I2, I3 : Net) return Net;
 
+   --  Build: I0 & I1 [ & I2 [ & I3 ]]
    function Build_Concat2 (Ctxt : Context_Acc; I0, I1 : Net) return Net;
    function Build_Concat3 (Ctxt : Context_Acc; I0, I1, I2 : Net) return Net;
    function Build_Concat4 (Ctxt : Context_Acc; I0, I1, I2, I3 : Net)
@@ -129,6 +133,7 @@ private
       M_Concat : Module_Arr (Concat_Module_Id);
       M_Const_UB32 : Module;
       M_Const_UL32 : Module;
+      M_Const_Z : Module;
       M_Edge : Module;
       M_Mux2 : Module;
       M_Mux4 : Module;
diff --git a/src/synth/netlists-disp_vhdl.adb b/src/synth/netlists-disp_vhdl.adb
index 139b2c0d0..5525d54ee 100644
--- a/src/synth/netlists-disp_vhdl.adb
+++ b/src/synth/netlists-disp_vhdl.adb
@@ -480,6 +480,9 @@ package body Netlists.Disp_Vhdl is
             Disp_Binary_Lit (Get_Param_Uns32 (Inst, 0),
                              Get_Param_Uns32 (Inst, 1),
                              Get_Width (O));
+         when Id_Const_Z =>
+            Disp_Template ("(\n0 downto 0 => 'Z')",
+                           Inst, (0 => Get_Width (O) - 1));
          when others =>
             raise Internal_Error;
       end case;
@@ -550,7 +553,8 @@ package body Netlists.Disp_Vhdl is
                   Inst, (0 => Iw - 1));
             end;
          when Id_Const_UB32
-           | Id_Const_UL32 =>
+           | Id_Const_UL32
+           | Id_Const_Z =>
             Disp_Template ("  \o0 <= ", Inst);
             Disp_Constant_Inline (Inst);
             Put_Line (";");
diff --git a/src/synth/netlists-gates.ads b/src/synth/netlists-gates.ads
index 44b5486bf..61d5ab8d4 100644
--- a/src/synth/netlists-gates.ads
+++ b/src/synth/netlists-gates.ads
@@ -154,4 +154,6 @@ package Netlists.Gates is
    Id_Const_SB128 : constant Module_Id := 69;
    Id_Const_UL32 : constant Module_Id := 70;
    Id_Const_SL32 : constant Module_Id := 71;
+   Id_Const_Z : constant Module_Id := 72;
+   Id_Const_0 : constant Module_Id := 73;
 end Netlists.Gates;