ams-vhdl: handle zoh, ltf and ztf attributes.

12 files changed, 352 insertions, 65 deletions

diff --git a/src/vhdl/vhdl-elocations.adb b/src/vhdl/vhdl-elocations.adb
index f74fd6037..f6e1ac80e 100644
--- a/src/vhdl/vhdl-elocations.adb
+++ b/src/vhdl/vhdl-elocations.adb
@@ -412,6 +412,9 @@ package body Vhdl.Elocations is
            | Iir_Kind_Signal_Slew_Attribute
            | Iir_Kind_Quantity_Slew_Attribute
            | Iir_Kind_Ramp_Attribute
+           | Iir_Kind_Zoh_Attribute
+           | Iir_Kind_Ltf_Attribute
+           | Iir_Kind_Ztf_Attribute
            | Iir_Kind_Dot_Attribute
            | Iir_Kind_Integ_Attribute
            | Iir_Kind_Above_Attribute
diff --git a/src/vhdl/vhdl-elocations.ads b/src/vhdl/vhdl-elocations.ads
index 2a185341c..daeda35ae 100644
--- a/src/vhdl/vhdl-elocations.ads
+++ b/src/vhdl/vhdl-elocations.ads
@@ -644,6 +644,9 @@ package Vhdl.Elocations is
 
    -- Iir_Kind_Signal_Slew_Attribute (None)
    -- Iir_Kind_Quantity_Slew_Attribute (None)
+   -- Iir_Kind_Zoh_Attribute (None)
+   -- Iir_Kind_Ltf_Attribute (None)
+   -- Iir_Kind_Ztf_Attribute (None)
    -- Iir_Kind_Dot_Attribute (None)
    -- Iir_Kind_Integ_Attribute (None)
 
diff --git a/src/vhdl/vhdl-errors.adb b/src/vhdl/vhdl-errors.adb
index 02dc0df5d..63e3bb02b 100644
--- a/src/vhdl/vhdl-errors.adb
+++ b/src/vhdl/vhdl-errors.adb
@@ -688,6 +688,12 @@ package body Vhdl.Errors is
          when Iir_Kind_Signal_Slew_Attribute
            | Iir_Kind_Quantity_Slew_Attribute =>
             return "'slew attribute";
+         when Iir_Kind_Zoh_Attribute =>
+            return "'zoh attribute";
+         when Iir_Kind_Ltf_Attribute =>
+            return "'ltf attribute";
+         when Iir_Kind_Ztf_Attribute =>
+            return "'ztf attribute";
          when Iir_Kind_Ramp_Attribute =>
             return "'ramp attribute";
          when Iir_Kind_Dot_Attribute =>
diff --git a/src/vhdl/vhdl-nodes.adb b/src/vhdl/vhdl-nodes.adb
index 84b94196d..50d7fe2cf 100644
--- a/src/vhdl/vhdl-nodes.adb
+++ b/src/vhdl/vhdl-nodes.adb
@@ -1274,7 +1274,10 @@ package body Vhdl.Nodes is
            | Iir_Kind_Wait_Statement
            | Iir_Kind_Signal_Slew_Attribute
            | Iir_Kind_Quantity_Slew_Attribute
-           | Iir_Kind_Ramp_Attribute =>
+           | Iir_Kind_Ramp_Attribute
+           | Iir_Kind_Zoh_Attribute
+           | Iir_Kind_Ltf_Attribute
+           | Iir_Kind_Ztf_Attribute =>
             return Format_Medium;
       end case;
    end Get_Format;
@@ -5960,6 +5963,38 @@ package body Vhdl.Nodes is
       Set_Field6 (Target, Param);
    end Set_Parameter_2;
 
+   function Get_Parameter_3 (Target : Iir) return Iir is
+   begin
+      pragma Assert (Target /= Null_Iir);
+      pragma Assert (Has_Parameter_3 (Get_Kind (Target)),
+                     "no field Parameter_3");
+      return Get_Field7 (Target);
+   end Get_Parameter_3;
+
+   procedure Set_Parameter_3 (Target : Iir; Param : Iir) is
+   begin
+      pragma Assert (Target /= Null_Iir);
+      pragma Assert (Has_Parameter_3 (Get_Kind (Target)),
+                     "no field Parameter_3");
+      Set_Field7 (Target, Param);
+   end Set_Parameter_3;
+
+   function Get_Parameter_4 (Target : Iir) return Iir is
+   begin
+      pragma Assert (Target /= Null_Iir);
+      pragma Assert (Has_Parameter_4 (Get_Kind (Target)),
+                     "no field Parameter_4");
+      return Get_Field8 (Target);
+   end Get_Parameter_4;
+
+   procedure Set_Parameter_4 (Target : Iir; Param : Iir) is
+   begin
+      pragma Assert (Target /= Null_Iir);
+      pragma Assert (Has_Parameter_4 (Get_Kind (Target)),
+                     "no field Parameter_4");
+      Set_Field8 (Target, Param);
+   end Set_Parameter_4;
+
    function Get_Attr_Chain (Attr : Iir) return Iir is
    begin
       pragma Assert (Attr /= Null_Iir);
diff --git a/src/vhdl/vhdl-nodes.ads b/src/vhdl/vhdl-nodes.ads
index cb51e8920..217f6a562 100644
--- a/src/vhdl/vhdl-nodes.ads
+++ b/src/vhdl/vhdl-nodes.ads
@@ -4475,6 +4475,9 @@ package Vhdl.Nodes is
    -- Iir_Kind_Ramp_Attribute (Medium)
    -- Iir_Kind_Signal_Slew_Attribute (Medium)
    -- Iir_Kind_Quantity_Slew_Attribute (Medium)
+   -- Iir_Kind_Zoh_Attribute (Medium)
+   -- Iir_Kind_Ltf_Attribute (Medium)
+   -- Iir_Kind_Ztf_Attribute (Medium)
    --
    --   Get/Set_Prefix (Field0)
    --
@@ -4486,6 +4489,12 @@ package Vhdl.Nodes is
    --
    --   Get/Set_Parameter_2 (Field6)
    --
+   -- Only for Iir_Kind_Ztf_Attribute:
+   --   Get/Set_Parameter_3 (Field7)
+   --
+   -- Only for Iir_Kind_Ztf_Attribute:
+   --   Get/Set_Parameter_4 (Field8)
+   --
    --   Get/Set_Base_Name (Field5)
    --
    --   Get/Set_Name_Staticness (State2)
@@ -4991,6 +5000,9 @@ package Vhdl.Nodes is
       Iir_Kind_Signal_Slew_Attribute,
       Iir_Kind_Quantity_Slew_Attribute,
       Iir_Kind_Ramp_Attribute,
+      Iir_Kind_Zoh_Attribute,
+      Iir_Kind_Ltf_Attribute,
+      Iir_Kind_Ztf_Attribute,
       Iir_Kind_Dot_Attribute,
       Iir_Kind_Integ_Attribute,
       Iir_Kind_Above_Attribute,
@@ -6205,6 +6217,9 @@ package Vhdl.Nodes is
    --Iir_Kind_Signal_Slew_Attribute
    --Iir_Kind_Quantity_Slew_Attribute
    --Iir_Kind_Ramp_Attribute
+   --Iir_Kind_Zoh_Attribute
+   --Iir_Kind_Ltf_Attribute
+   --Iir_Kind_Ztf_Attribute
    --Iir_Kind_Dot_Attribute
    --Iir_Kind_Integ_Attribute
    --Iir_Kind_Above_Attribute
@@ -8265,6 +8280,16 @@ package Vhdl.Nodes is
    function Get_Parameter_2 (Target : Iir) return Iir;
    procedure Set_Parameter_2 (Target : Iir; Param : Iir);
 
+   --  Third parameter of an attribute (for AMS VHDL).
+   --  Field: Field7
+   function Get_Parameter_3 (Target : Iir) return Iir;
+   procedure Set_Parameter_3 (Target : Iir; Param : Iir);
+
+   --  Fourth parameter of an attribute (for AMS VHDL).
+   --  Field: Field8
+   function Get_Parameter_4 (Target : Iir) return Iir;
+   procedure Set_Parameter_4 (Target : Iir; Param : Iir);
+
    --  Field: Field2 Forward_Ref
    function Get_Attr_Chain (Attr : Iir) return Iir;
    procedure Set_Attr_Chain (Attr : Iir; Chain : Iir);
diff --git a/src/vhdl/vhdl-nodes_meta.adb b/src/vhdl/vhdl-nodes_meta.adb
index ed955d05c..48029e8c9 100644
--- a/src/vhdl/vhdl-nodes_meta.adb
+++ b/src/vhdl/vhdl-nodes_meta.adb
@@ -305,6 +305,8 @@ package body Vhdl.Nodes_Meta is
       Field_Index_Subtype => Type_Iir,
       Field_Parameter => Type_Iir,
       Field_Parameter_2 => Type_Iir,
+      Field_Parameter_3 => Type_Iir,
+      Field_Parameter_4 => Type_Iir,
       Field_Attr_Chain => Type_Iir,
       Field_Signal_Attribute_Declaration => Type_Iir,
       Field_Actual_Type => Type_Iir,
@@ -957,6 +959,10 @@ package body Vhdl.Nodes_Meta is
             return "parameter";
          when Field_Parameter_2 =>
             return "parameter_2";
+         when Field_Parameter_3 =>
+            return "parameter_3";
+         when Field_Parameter_4 =>
+            return "parameter_4";
          when Field_Attr_Chain =>
             return "attr_chain";
          when Field_Signal_Attribute_Declaration =>
@@ -1653,6 +1659,12 @@ package body Vhdl.Nodes_Meta is
             return "quantity_slew_attribute";
          when Iir_Kind_Ramp_Attribute =>
             return "ramp_attribute";
+         when Iir_Kind_Zoh_Attribute =>
+            return "zoh_attribute";
+         when Iir_Kind_Ltf_Attribute =>
+            return "ltf_attribute";
+         when Iir_Kind_Ztf_Attribute =>
+            return "ztf_attribute";
          when Iir_Kind_Dot_Attribute =>
             return "dot_attribute";
          when Iir_Kind_Integ_Attribute =>
@@ -2287,6 +2299,10 @@ package body Vhdl.Nodes_Meta is
             return Attr_None;
          when Field_Parameter_2 =>
             return Attr_None;
+         when Field_Parameter_3 =>
+            return Attr_None;
+         when Field_Parameter_4 =>
+            return Attr_None;
          when Field_Attr_Chain =>
             return Attr_Forward_Ref;
          when Field_Signal_Attribute_Declaration =>
@@ -4798,6 +4814,35 @@ package body Vhdl.Nodes_Meta is
       Field_Parameter,
       Field_Parameter_2,
       Field_Base_Name,
+      --  Iir_Kind_Zoh_Attribute
+      Field_Expr_Staticness,
+      Field_Name_Staticness,
+      Field_Prefix,
+      Field_Type,
+      Field_Attr_Chain,
+      Field_Parameter,
+      Field_Parameter_2,
+      Field_Base_Name,
+      --  Iir_Kind_Ltf_Attribute
+      Field_Expr_Staticness,
+      Field_Name_Staticness,
+      Field_Prefix,
+      Field_Type,
+      Field_Attr_Chain,
+      Field_Parameter,
+      Field_Parameter_2,
+      Field_Base_Name,
+      --  Iir_Kind_Ztf_Attribute
+      Field_Expr_Staticness,
+      Field_Name_Staticness,
+      Field_Prefix,
+      Field_Type,
+      Field_Attr_Chain,
+      Field_Parameter,
+      Field_Parameter_2,
+      Field_Parameter_3,
+      Field_Parameter_4,
+      Field_Base_Name,
       --  Iir_Kind_Dot_Attribute
       Field_Expr_Staticness,
       Field_Name_Staticness,
@@ -5273,34 +5318,37 @@ package body Vhdl.Nodes_Meta is
       Iir_Kind_Signal_Slew_Attribute => 2074,
       Iir_Kind_Quantity_Slew_Attribute => 2082,
       Iir_Kind_Ramp_Attribute => 2090,
-      Iir_Kind_Dot_Attribute => 2097,
-      Iir_Kind_Integ_Attribute => 2104,
-      Iir_Kind_Above_Attribute => 2112,
-      Iir_Kind_Delayed_Attribute => 2121,
-      Iir_Kind_Stable_Attribute => 2130,
-      Iir_Kind_Quiet_Attribute => 2139,
-      Iir_Kind_Transaction_Attribute => 2148,
-      Iir_Kind_Event_Attribute => 2152,
-      Iir_Kind_Active_Attribute => 2156,
-      Iir_Kind_Last_Event_Attribute => 2160,
-      Iir_Kind_Last_Active_Attribute => 2164,
-      Iir_Kind_Last_Value_Attribute => 2168,
-      Iir_Kind_Driving_Attribute => 2172,
-      Iir_Kind_Driving_Value_Attribute => 2176,
-      Iir_Kind_Behavior_Attribute => 2176,
-      Iir_Kind_Structure_Attribute => 2176,
-      Iir_Kind_Simple_Name_Attribute => 2183,
-      Iir_Kind_Instance_Name_Attribute => 2188,
-      Iir_Kind_Path_Name_Attribute => 2193,
-      Iir_Kind_Left_Array_Attribute => 2200,
-      Iir_Kind_Right_Array_Attribute => 2207,
-      Iir_Kind_High_Array_Attribute => 2214,
-      Iir_Kind_Low_Array_Attribute => 2221,
-      Iir_Kind_Length_Array_Attribute => 2228,
-      Iir_Kind_Ascending_Array_Attribute => 2235,
-      Iir_Kind_Range_Array_Attribute => 2242,
-      Iir_Kind_Reverse_Range_Array_Attribute => 2249,
-      Iir_Kind_Attribute_Name => 2258
+      Iir_Kind_Zoh_Attribute => 2098,
+      Iir_Kind_Ltf_Attribute => 2106,
+      Iir_Kind_Ztf_Attribute => 2116,
+      Iir_Kind_Dot_Attribute => 2123,
+      Iir_Kind_Integ_Attribute => 2130,
+      Iir_Kind_Above_Attribute => 2138,
+      Iir_Kind_Delayed_Attribute => 2147,
+      Iir_Kind_Stable_Attribute => 2156,
+      Iir_Kind_Quiet_Attribute => 2165,
+      Iir_Kind_Transaction_Attribute => 2174,
+      Iir_Kind_Event_Attribute => 2178,
+      Iir_Kind_Active_Attribute => 2182,
+      Iir_Kind_Last_Event_Attribute => 2186,
+      Iir_Kind_Last_Active_Attribute => 2190,
+      Iir_Kind_Last_Value_Attribute => 2194,
+      Iir_Kind_Driving_Attribute => 2198,
+      Iir_Kind_Driving_Value_Attribute => 2202,
+      Iir_Kind_Behavior_Attribute => 2202,
+      Iir_Kind_Structure_Attribute => 2202,
+      Iir_Kind_Simple_Name_Attribute => 2209,
+      Iir_Kind_Instance_Name_Attribute => 2214,
+      Iir_Kind_Path_Name_Attribute => 2219,
+      Iir_Kind_Left_Array_Attribute => 2226,
+      Iir_Kind_Right_Array_Attribute => 2233,
+      Iir_Kind_High_Array_Attribute => 2240,
+      Iir_Kind_Low_Array_Attribute => 2247,
+      Iir_Kind_Length_Array_Attribute => 2254,
+      Iir_Kind_Ascending_Array_Attribute => 2261,
+      Iir_Kind_Range_Array_Attribute => 2268,
+      Iir_Kind_Reverse_Range_Array_Attribute => 2275,
+      Iir_Kind_Attribute_Name => 2284
      );
 
    function Get_Fields_First (K : Iir_Kind) return Fields_Index is
@@ -6089,6 +6137,10 @@ package body Vhdl.Nodes_Meta is
             return Get_Parameter (N);
          when Field_Parameter_2 =>
             return Get_Parameter_2 (N);
+         when Field_Parameter_3 =>
+            return Get_Parameter_3 (N);
+         when Field_Parameter_4 =>
+            return Get_Parameter_4 (N);
          when Field_Attr_Chain =>
             return Get_Attr_Chain (N);
          when Field_Signal_Attribute_Declaration =>
@@ -6533,6 +6585,10 @@ package body Vhdl.Nodes_Meta is
             Set_Parameter (N, V);
          when Field_Parameter_2 =>
             Set_Parameter_2 (N, V);
+         when Field_Parameter_3 =>
+            Set_Parameter_3 (N, V);
+         when Field_Parameter_4 =>
+            Set_Parameter_4 (N, V);
          when Field_Attr_Chain =>
             Set_Attr_Chain (N, V);
          when Field_Signal_Attribute_Declaration =>
@@ -8351,6 +8407,9 @@ package body Vhdl.Nodes_Meta is
            | Iir_Kind_Signal_Slew_Attribute
            | Iir_Kind_Quantity_Slew_Attribute
            | Iir_Kind_Ramp_Attribute
+           | Iir_Kind_Zoh_Attribute
+           | Iir_Kind_Ltf_Attribute
+           | Iir_Kind_Ztf_Attribute
            | Iir_Kind_Dot_Attribute
            | Iir_Kind_Integ_Attribute
            | Iir_Kind_Above_Attribute
@@ -8558,6 +8617,9 @@ package body Vhdl.Nodes_Meta is
            | Iir_Kind_Signal_Slew_Attribute
            | Iir_Kind_Quantity_Slew_Attribute
            | Iir_Kind_Ramp_Attribute
+           | Iir_Kind_Zoh_Attribute
+           | Iir_Kind_Ltf_Attribute
+           | Iir_Kind_Ztf_Attribute
            | Iir_Kind_Dot_Attribute
            | Iir_Kind_Integ_Attribute
            | Iir_Kind_Above_Attribute
@@ -10751,6 +10813,9 @@ package body Vhdl.Nodes_Meta is
            | Iir_Kind_Signal_Slew_Attribute
            | Iir_Kind_Quantity_Slew_Attribute
            | Iir_Kind_Ramp_Attribute
+           | Iir_Kind_Zoh_Attribute
+           | Iir_Kind_Ltf_Attribute
+           | Iir_Kind_Ztf_Attribute
            | Iir_Kind_Dot_Attribute
            | Iir_Kind_Integ_Attribute
            | Iir_Kind_Above_Attribute
@@ -10990,6 +11055,9 @@ package body Vhdl.Nodes_Meta is
            | Iir_Kind_Signal_Slew_Attribute
            | Iir_Kind_Quantity_Slew_Attribute
            | Iir_Kind_Ramp_Attribute
+           | Iir_Kind_Zoh_Attribute
+           | Iir_Kind_Ltf_Attribute
+           | Iir_Kind_Ztf_Attribute
            | Iir_Kind_Dot_Attribute
            | Iir_Kind_Integ_Attribute
            | Iir_Kind_Above_Attribute
@@ -11057,6 +11125,9 @@ package body Vhdl.Nodes_Meta is
            | Iir_Kind_Signal_Slew_Attribute
            | Iir_Kind_Quantity_Slew_Attribute
            | Iir_Kind_Ramp_Attribute
+           | Iir_Kind_Zoh_Attribute
+           | Iir_Kind_Ltf_Attribute
+           | Iir_Kind_Ztf_Attribute
            | Iir_Kind_Dot_Attribute
            | Iir_Kind_Integ_Attribute
            | Iir_Kind_Above_Attribute
@@ -11181,6 +11252,9 @@ package body Vhdl.Nodes_Meta is
            | Iir_Kind_Signal_Slew_Attribute
            | Iir_Kind_Quantity_Slew_Attribute
            | Iir_Kind_Ramp_Attribute
+           | Iir_Kind_Zoh_Attribute
+           | Iir_Kind_Ltf_Attribute
+           | Iir_Kind_Ztf_Attribute
            | Iir_Kind_Above_Attribute
            | Iir_Kind_Delayed_Attribute
            | Iir_Kind_Stable_Attribute
@@ -11205,19 +11279,35 @@ package body Vhdl.Nodes_Meta is
       case K is
          when Iir_Kind_Signal_Slew_Attribute
            | Iir_Kind_Quantity_Slew_Attribute
-           | Iir_Kind_Ramp_Attribute =>
+           | Iir_Kind_Ramp_Attribute
+           | Iir_Kind_Zoh_Attribute
+           | Iir_Kind_Ltf_Attribute
+           | Iir_Kind_Ztf_Attribute =>
             return True;
          when others =>
             return False;
       end case;
    end Has_Parameter_2;
 
+   function Has_Parameter_3 (K : Iir_Kind) return Boolean is
+   begin
+      return K = Iir_Kind_Ztf_Attribute;
+   end Has_Parameter_3;
+
+   function Has_Parameter_4 (K : Iir_Kind) return Boolean is
+   begin
+      return K = Iir_Kind_Ztf_Attribute;
+   end Has_Parameter_4;
+
    function Has_Attr_Chain (K : Iir_Kind) return Boolean is
    begin
       case K is
          when Iir_Kind_Signal_Slew_Attribute
            | Iir_Kind_Quantity_Slew_Attribute
            | Iir_Kind_Ramp_Attribute
+           | Iir_Kind_Zoh_Attribute
+           | Iir_Kind_Ltf_Attribute
+           | Iir_Kind_Ztf_Attribute
            | Iir_Kind_Dot_Attribute
            | Iir_Kind_Integ_Attribute
            | Iir_Kind_Above_Attribute
diff --git a/src/vhdl/vhdl-nodes_meta.ads b/src/vhdl/vhdl-nodes_meta.ads
index a3a9c66c6..7da2ac823 100644
--- a/src/vhdl/vhdl-nodes_meta.ads
+++ b/src/vhdl/vhdl-nodes_meta.ads
@@ -347,6 +347,8 @@ package Vhdl.Nodes_Meta is
       Field_Index_Subtype,
       Field_Parameter,
       Field_Parameter_2,
+      Field_Parameter_3,
+      Field_Parameter_4,
       Field_Attr_Chain,
       Field_Signal_Attribute_Declaration,
       Field_Actual_Type,
@@ -909,6 +911,8 @@ package Vhdl.Nodes_Meta is
    function Has_Index_Subtype (K : Iir_Kind) return Boolean;
    function Has_Parameter (K : Iir_Kind) return Boolean;
    function Has_Parameter_2 (K : Iir_Kind) return Boolean;
+   function Has_Parameter_3 (K : Iir_Kind) return Boolean;
+   function Has_Parameter_4 (K : Iir_Kind) return Boolean;
    function Has_Attr_Chain (K : Iir_Kind) return Boolean;
    function Has_Signal_Attribute_Declaration (K : Iir_Kind) return Boolean;
    function Has_Actual_Type (K : Iir_Kind) return Boolean;
diff --git a/src/vhdl/vhdl-prints.adb b/src/vhdl/vhdl-prints.adb
index af230fe83..5b466857b 100644
--- a/src/vhdl/vhdl-prints.adb
+++ b/src/vhdl/vhdl-prints.adb
@@ -3479,14 +3479,7 @@ package body Vhdl.Prints is
       Disp_Ident (Ctxt, Name);
       Has_Params := False;
       for I in 1 .. Num loop
-         case I is
-            when 1 =>
-               Param := Get_Parameter (Expr);
-            when 2 =>
-               Param := Get_Parameter_2 (Expr);
-            when others =>
-               raise Internal_Error;
-         end case;
+         Param := Get_Attribute_Parameter (Expr, I);
          exit when Param = Null_Iir;
          if not Has_Params then
             Disp_Token (Ctxt, Tok_Left_Paren);
@@ -4643,6 +4636,12 @@ package body Vhdl.Prints is
             Disp_Name_Attribute (Ctxt, Expr, Name_Dot);
          when Iir_Kind_Integ_Attribute =>
             Disp_Name_Attribute (Ctxt, Expr, Name_Integ);
+         when Iir_Kind_Zoh_Attribute =>
+            Disp_Parametered_Attribute (Ctxt, Name_Zoh, Expr, 2);
+         when Iir_Kind_Ltf_Attribute =>
+            Disp_Parametered_Attribute (Ctxt, Name_Ltf, Expr, 2);
+         when Iir_Kind_Ztf_Attribute =>
+            Disp_Parametered_Attribute (Ctxt, Name_Ztf, Expr, 4);
 
          when Iir_Kind_Signal_Slew_Attribute
            | Iir_Kind_Quantity_Slew_Attribute =>
diff --git a/src/vhdl/vhdl-sem_expr.adb b/src/vhdl/vhdl-sem_expr.adb
index 8a3ea8d15..fc7e59a7c 100644
--- a/src/vhdl/vhdl-sem_expr.adb
+++ b/src/vhdl/vhdl-sem_expr.adb
@@ -4371,6 +4371,9 @@ package body Vhdl.Sem_Expr is
               | Iir_Kinds_Signal_Attribute
               | Iir_Kinds_Signal_Value_Attribute
               | Iir_Kind_Above_Attribute
+              | Iir_Kind_Zoh_Attribute
+              | Iir_Kind_Ltf_Attribute
+              | Iir_Kind_Ztf_Attribute
               | Iir_Kind_Dot_Attribute
               | Iir_Kind_Integ_Attribute
               | Iir_Kind_Ramp_Attribute =>
diff --git a/src/vhdl/vhdl-sem_names.adb b/src/vhdl/vhdl-sem_names.adb
index 10636bcb3..2830e6e77 100644
--- a/src/vhdl/vhdl-sem_names.adb
+++ b/src/vhdl/vhdl-sem_names.adb
@@ -1241,6 +1241,39 @@ package body Vhdl.Sem_Names is
       end if;
    end Finish_Sem_Signal_Attribute;
 
+   procedure Sem_Quantity_Attribute_Parameters
+     (Attr : Iir; Params : Iir_Array; Params_Type : Iir_Array; Min : Positive)
+   is
+      Param : Iir;
+   begin
+      pragma Assert (Params'First = 1);
+      pragma Assert (Params_Type'First = 1);
+      pragma Assert (Params_Type'Last = Params'Last);
+      for I in Params'Range loop
+         Param := Params (I);
+         if Param = Null_Iir then
+            if I <= Min then
+               Error_Msg_Sem
+                 (+Attr, "not enough parameters for the attribute");
+            end if;
+            return;
+         end if;
+         if Params_Type (I) = Null_Iir then
+            Error_Msg_Sem (+Attr, "too many parameters for the attribute");
+            return;
+         end if;
+
+         Param := Sem_Expression (Param, Params_Type (I));
+         if Param /= Null_Iir then
+            if Get_Expr_Staticness (Param) < Globally then
+               Error_Msg_Sem
+                 (+Param, "parameter must be a static expression");
+            end if;
+            Set_Attribute_Parameter (Attr, I, Param);
+         end if;
+      end loop;
+   end Sem_Quantity_Attribute_Parameters;
+
    procedure Finish_Sem_Quantity_Attribute
      (Attr_Name : Iir; Attr : Iir; Params : Iir_Array)
    is
@@ -1268,7 +1301,7 @@ package body Vhdl.Sem_Names is
          when Iir_Kind_Ramp_Attribute
            | Iir_Kind_Signal_Slew_Attribute
            | Iir_Kind_Quantity_Slew_Attribute =>
-            pragma Assert (Params'First = 1 and Params'Last = 2);
+            pragma Assert (Params'First = 1 and Params'Last = 4);
             --  AMS-LRM17 16.2.6
             --  S'RAMP [(TRISE [, TFALL])]
             --  Parameters:
@@ -1298,25 +1331,54 @@ package body Vhdl.Sem_Names is
             --     evaluates to a negative value.  If omitted, it defaults
             --     to the negative of MAX_RISING_SLOPE.  The value REAL'LOW
             --     is interpreted as a negative infinite slope.
-            for I in 1 .. 2 loop
-               Param := Params (I);
-               exit when Param = Null_Iir;
-               --  FIXME: type.
-               Param := Sem_Expression (Param, Real_Type_Definition);
-               if Param /= Null_Iir then
-                  if Get_Expr_Staticness (Param) < Globally then
-                     Error_Msg_Sem
-                       (+Param,
-                        "parameters of 'ramp must be static expressions");
-                  end if;
-                  case I is
-                     when 1 =>
-                        Set_Parameter (Attr, Param);
-                     when 2 =>
-                        Set_Parameter_2 (Attr, Param);
-                  end case;
-               end if;
-            end loop;
+            Sem_Quantity_Attribute_Parameters
+              (Attr, Params, (1 => Real_Type_Definition,
+                              2 => Real_Type_Definition,
+                              3 | 4 => Null_Iir), 1);
+         when Iir_Kind_Zoh_Attribute =>
+            --  AMS-LRM17 16.2.6
+            --  Q'LTF(T [, INITIAL_DELAY)
+            --  Parameters:
+            --    T: A static expression of type REAL that evaluates to a
+            --     positive value.  This is the sampling period.
+            --    INITIAL_DELAY: A static expression of type REAL that
+            --     evaluates to a non-negative value.  The first sampling will
+            --     occur after INITIAL_DELAY seconds.  If omitted, it defaults
+            --     to 0.0.
+            Sem_Quantity_Attribute_Parameters
+              (Attr, Params, (1 => Real_Type_Definition,
+                              2 => Real_Type_Definition,
+                              3 | 4 => Null_Iir), 1);
+         when Iir_Kind_Ltf_Attribute =>
+            --  AMS-LRM17 16.2.6
+            --  Q'LTF(NUM, DEN)
+            --  Parameters:
+            --    NUM: a static expression of type REAL_VECTOR that contains
+            --     the numerator coefficients.
+            --    DEN: a static expression of type REAL_VECTOR that contains
+            --     the denominator coefficients.
+            Sem_Quantity_Attribute_Parameters
+              (Attr, Params, (1 => Real_Vector_Type_Definition,
+                              2 => Real_Vector_Type_Definition,
+                              3 | 4 => Null_Iir), 2);
+         when Iir_Kind_Ztf_Attribute =>
+            --  AMS-LRM17 16.2.6
+            --  Q'ZTF(NUM, DEN, T, [, INITIAL_DELAY])
+            --  Parameters:
+            --    NUM: A static expression of type REAL_VECTOR with the
+            --     numerator coefficients.
+            --    DEN: A static expression of type REAL_VECTOR with the
+            --     denominator coefficients.
+            --    T: A static expression of type REAL that evaluates to a
+            --     positive value, which is the sampling period.
+            --    INITIAL_DELAY: A static expression of type REAL that
+            --     evaluates to a non-negative value, which is the time of the
+            --     first sampling.  If omitted, it defaults to 0.0
+            Sem_Quantity_Attribute_Parameters
+              (Attr, Params, (1 => Real_Vector_Type_Definition,
+                              2 => Real_Vector_Type_Definition,
+                              3 => Real_Type_Definition,
+                              4 => Real_Type_Definition), 3);
          when others =>
             Error_Kind ("finish_sem_quantity_attribute", Attr);
       end case;
@@ -1852,7 +1914,10 @@ package body Vhdl.Sem_Names is
          when Iir_Kind_Above_Attribute
            | Iir_Kind_Ramp_Attribute
            | Iir_Kind_Quantity_Slew_Attribute
-           | Iir_Kind_Signal_Slew_Attribute =>
+           | Iir_Kind_Signal_Slew_Attribute
+           | Iir_Kind_Zoh_Attribute
+           | Iir_Kind_Ltf_Attribute
+           | Iir_Kind_Ztf_Attribute =>
             if Get_Parameter (Res) = Null_Iir then
                --  Not finished.  Need to emit an error message.
                Finish_Sem_Quantity_Attribute (Name, Res, (1 => Null_Iir));
@@ -2939,9 +3004,12 @@ package body Vhdl.Sem_Names is
 
          when Iir_Kind_Ramp_Attribute
            | Iir_Kind_Quantity_Slew_Attribute
-           | Iir_Kind_Signal_Slew_Attribute =>
+           | Iir_Kind_Signal_Slew_Attribute
+           | Iir_Kind_Zoh_Attribute
+           | Iir_Kind_Ltf_Attribute
+           | Iir_Kind_Ztf_Attribute =>
             declare
-               Params : Iir_Array (1 .. 2);
+               Params : Iir_Array (1 .. 4);
             begin
                --  Try to extract 2 actuals from the name association list.
                --  Emit a message in case of error.
@@ -3962,6 +4030,7 @@ package body Vhdl.Sem_Names is
       Name_Prefix : constant Iir := Get_Prefix (Attr);
       Prefix: Iir;
       Res : Iir;
+      Res_Type : Iir;
    begin
       Prefix := Get_Named_Entity (Name_Prefix);
       Prefix := Finish_Sem_Name_1 (Name_Prefix, Prefix);
@@ -3970,16 +4039,21 @@ package body Vhdl.Sem_Names is
            (+Attr, "prefix of %i attribute must denote a quantity", +Attr);
       end if;
 
+      Res_Type := Get_Type (Prefix);
       case Get_Identifier (Attr) is
          when Name_Above =>
             Res := Create_Iir (Iir_Kind_Above_Attribute);
-            Set_Type (Res, Boolean_Type_Definition);
+            Res_Type := Boolean_Type_Definition;
          when Name_Dot =>
             Res := Create_Iir (Iir_Kind_Dot_Attribute);
-            Set_Type (Res, Get_Type (Prefix));
          when Name_Integ =>
             Res := Create_Iir (Iir_Kind_Integ_Attribute);
-            Set_Type (Res, Get_Type (Prefix));
+         when Name_Zoh =>
+            Res := Create_Iir (Iir_Kind_Zoh_Attribute);
+         when Name_Ltf =>
+            Res := Create_Iir (Iir_Kind_Ltf_Attribute);
+         when Name_Ztf =>
+            Res := Create_Iir (Iir_Kind_Ztf_Attribute);
          when others =>
             --  Not yet implemented attribute, or really an internal error.
             raise Internal_Error;
@@ -3987,6 +4061,7 @@ package body Vhdl.Sem_Names is
 
       Location_Copy (Res, Attr);
       Set_Prefix (Res, Prefix);
+      Set_Type (Res, Res_Type);
 
       --  AMS-LRM17 16.2.6 Predefined analog an mixed-signal attributes
       --  Prefix: Any quantity denoted by the static name Q.
@@ -4210,7 +4285,10 @@ package body Vhdl.Sem_Names is
 
          when Name_Above
            | Name_Dot
-           | Name_Integ =>
+           | Name_Integ
+           | Name_Zoh
+           | Name_Ltf
+           | Name_Ztf =>
             if Flags.AMS_Vhdl then
                Res := Sem_Quantity_Attribute (Attr);
             else
@@ -4600,6 +4678,9 @@ package body Vhdl.Sem_Names is
            | Iir_Kind_Dot_Attribute
            | Iir_Kind_Integ_Attribute
            | Iir_Kind_Ramp_Attribute
+           | Iir_Kind_Zoh_Attribute
+           | Iir_Kind_Ltf_Attribute
+           | Iir_Kind_Ztf_Attribute
            | Iir_Kind_Signal_Slew_Attribute
            | Iir_Kind_Quantity_Slew_Attribute =>
             --  Never static
diff --git a/src/vhdl/vhdl-utils.adb b/src/vhdl/vhdl-utils.adb
index 5a22d3e7a..d11b17a2b 100644
--- a/src/vhdl/vhdl-utils.adb
+++ b/src/vhdl/vhdl-utils.adb
@@ -1693,6 +1693,36 @@ package body Vhdl.Utils is
       return K = K1 or K = K2;
    end Kind_In;
 
+   procedure Set_Attribute_Parameter
+     (Attr : Iir; N : Parameter_Index; Param : Iir) is
+   begin
+      case N is
+         when 1 =>
+            Set_Parameter (Attr, Param);
+         when 2 =>
+            Set_Parameter_2 (Attr, Param);
+         when 3 =>
+            Set_Parameter_3 (Attr, Param);
+         when 4 =>
+            Set_Parameter_4 (Attr, Param);
+      end case;
+   end Set_Attribute_Parameter;
+
+   function Get_Attribute_Parameter
+     (Attr : Iir; N : Parameter_Index) return Iir is
+   begin
+      case N is
+         when 1 =>
+            return Get_Parameter (Attr);
+         when 2 =>
+            return Get_Parameter_2 (Attr);
+         when 3 =>
+            return Get_Parameter_3 (Attr);
+         when 4 =>
+            return Get_Parameter_4 (Attr);
+      end case;
+   end Get_Attribute_Parameter;
+
    function Get_HDL_Node (N : PSL_Node) return Iir is
    begin
       return Iir (PSL.Nodes.Get_HDL_Node (N));
diff --git a/src/vhdl/vhdl-utils.ads b/src/vhdl/vhdl-utils.ads
index c24b3226f..4ca9d83e3 100644
--- a/src/vhdl/vhdl-utils.ads
+++ b/src/vhdl/vhdl-utils.ads
@@ -383,6 +383,14 @@ package Vhdl.Utils is
    function Kind_In (N : Iir; K1, K2 : Iir_Kind) return Boolean;
    pragma Inline (Kind_In);
 
+   subtype Parameter_Index is Natural range 1 .. 4;
+
+   --  Get/Set attribute parameter by index (for AMS attributes).
+   procedure Set_Attribute_Parameter
+     (Attr : Iir; N : Parameter_Index; Param : Iir);
+   function Get_Attribute_Parameter
+     (Attr : Iir; N : Parameter_Index) return Iir;
+
    --  IIR wrapper around Get_HDL_Node/Set_HDL_Node.
    function Get_HDL_Node (N : PSL_Node) return Iir;
    procedure Set_HDL_Node (N : PSL_Node; Expr : Iir);