path: root/src/vhdl/ieee-vital_timing.adb

--  Nodes recognizer for ieee.vital_timing.
--  Copyright (C) 2002, 2003, 2004, 2005 Tristan Gingold
--
--  GHDL is free software; you can redistribute it and/or modify it under
--  the terms of the GNU General Public License as published by the Free
--  Software Foundation; either version 2, or (at your option) any later
--  version.
--
--  GHDL is distributed in the hope that it will be useful, but WITHOUT ANY
--  WARRANTY; without even the implied warranty of MERCHANTABILITY or
--  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
--  for more details.
--
--  You should have received a copy of the GNU General Public License
--  along with GHDL; see the file COPYING.  If not, write to the Free
--  Software Foundation, 59 Temple Place - Suite 330, Boston, MA
--  02111-1307, USA.
with Types; use Types;
with Std_Names;
with Errorout; use Errorout;
with Std_Package; use Std_Package;
with Tokens; use Tokens;
with Name_Table;
with Ieee.Std_Logic_1164; use Ieee.Std_Logic_1164;
with Sem_Scopes;
with Evaluation;
with Sem;
with Iirs_Utils;
with Flags;

package body Ieee.Vital_Timing is
   --  This package is based on IEEE 1076.4 1995.

   --  Control generics identifier.
   InstancePath_Id : Name_Id;
   TimingChecksOn_Id : Name_Id;
   XOn_Id : Name_Id;
   MsgOn_Id : Name_Id;

   --  Extract declarations from package IEEE.VITAL_Timing.
   procedure Extract_Declarations (Pkg : Iir_Package_Declaration)
   is
      use Name_Table;

      Ill_Formed : exception;

      Decl : Iir;
      Id : Name_Id;

      VitalDelayType_Id : Name_Id;
      VitalDelayType01_Id   : Name_Id;
      VitalDelayType01Z_Id  : Name_Id;
      VitalDelayType01ZX_Id : Name_Id;

      VitalDelayArrayType_Id     : Name_Id;
      VitalDelayArrayType01_Id   : Name_Id;
      VitalDelayArrayType01Z_Id  : Name_Id;
      VitalDelayArrayType01ZX_Id : Name_Id;
   begin
      --  Get Vital delay type identifiers.
      Name_Buffer (1 .. 18) := "vitaldelaytype01zx";
      Name_Length := 14;
      VitalDelayType_Id := Get_Identifier_No_Create;
      if VitalDelayType_Id = Null_Identifier then
         raise Ill_Formed;
      end if;
      Name_Length := 16;
      VitalDelayType01_Id := Get_Identifier_No_Create;
      if VitalDelayType01_Id = Null_Identifier then
         raise Ill_Formed;
      end if;
      Name_Length := 17;
      VitalDelayType01Z_Id := Get_Identifier_No_Create;
      if VitalDelayType01Z_Id = Null_Identifier then
         raise Ill_Formed;
      end if;
      Name_Length := 18;
      VitalDelayType01ZX_Id := Get_Identifier_No_Create;
      if VitalDelayType01ZX_Id = Null_Identifier then
         raise Ill_Formed;
      end if;

      Name_Buffer (1 .. 23) := "vitaldelayarraytype01zx";
      Name_Length := 19;
      VitalDelayArrayType_Id := Get_Identifier_No_Create;
      if VitalDelayArrayType_Id = Null_Identifier then
         raise Ill_Formed;
      end if;
      Name_Length := 21;
      VitalDelayArrayType01_Id := Get_Identifier_No_Create;
      if VitalDelayArrayType01_Id = Null_Identifier then
         raise Ill_Formed;
      end if;
      Name_Length := 22;
      VitalDelayArrayType01Z_Id := Get_Identifier_No_Create;
      if VitalDelayArrayType01Z_Id = Null_Identifier then
         raise Ill_Formed;
      end if;
      Name_Length := 23;
      VitalDelayArrayType01ZX_Id := Get_Identifier_No_Create;
      if VitalDelayArrayType01ZX_Id = Null_Identifier then
         raise Ill_Formed;
      end if;

      --  Iterate on every declaration.
      --  Do name-matching.
      Decl := Get_Declaration_Chain (Pkg);
      while Decl /= Null_Iir loop
         case Get_Kind (Decl) is
            when Iir_Kind_Attribute_Declaration =>
               Id := Get_Identifier (Decl);
               if Id = Std_Names.Name_VITAL_Level0 then
                  Vital_Level0_Attribute := Decl;
               elsif Id = Std_Names.Name_VITAL_Level1 then
                  Vital_Level1_Attribute := Decl;
               end if;
            when Iir_Kind_Subtype_Declaration =>
               Id := Get_Identifier (Decl);
               if Id = VitalDelayType_Id then
                  VitalDelayType := Get_Type (Decl);
               end if;
            when Iir_Kind_Type_Declaration =>
               Id := Get_Identifier (Decl);
               if Id = VitalDelayArrayType_Id then
                  VitalDelayArrayType := Get_Type_Definition (Decl);
               elsif Id = VitalDelayArrayType01_Id then
                  VitalDelayArrayType01 := Get_Type_Definition (Decl);
               elsif Id = VitalDelayArrayType01Z_Id then
                  VitalDelayArrayType01Z := Get_Type_Definition (Decl);
               elsif Id = VitalDelayArrayType01ZX_Id then
                  VitalDelayArrayType01ZX := Get_Type_Definition (Decl);
               end if;
            when Iir_Kind_Anonymous_Type_Declaration =>
               Id := Get_Identifier (Decl);
               if Id = VitalDelayType01_Id then
                  VitalDelayType01 := Get_Type_Definition (Decl);
               elsif Id = VitalDelayType01Z_Id then
                  VitalDelayType01Z := Get_Type_Definition (Decl);
               elsif Id = VitalDelayType01ZX_Id then
                  VitalDelayType01ZX := Get_Type_Definition (Decl);
               end if;
            when others =>
               null;
         end case;
         Decl := Get_Chain (Decl);
      end loop;

      --  If a declaration was not found, then the package is not the expected
      --  one.
      if Vital_Level0_Attribute = Null_Iir
        or Vital_Level1_Attribute = Null_Iir
        or VitalDelayType = Null_Iir
        or VitalDelayType01 = Null_Iir
        or VitalDelayType01Z = Null_Iir
        or VitalDelayType01ZX = Null_Iir
        or VitalDelayArrayType = Null_Iir
        or VitalDelayArrayType01 = Null_Iir
        or VitalDelayArrayType01Z = Null_Iir
        or VitalDelayArrayType01ZX = Null_Iir
      then
         raise Ill_Formed;
      end if;

      --  Create identifier for control generics.
      InstancePath_Id := Get_Identifier ("instancepath");
      TimingChecksOn_Id := Get_Identifier ("timingcheckson");
      XOn_Id := Get_Identifier ("xon");
      MsgOn_Id := Get_Identifier ("msgon");

      exception
         when Ill_Formed =>
            Error_Msg_Sem ("package ieee.vital_timing is ill-formed", Pkg);

            Vital_Level0_Attribute := Null_Iir;
            Vital_Level1_Attribute := Null_Iir;

            VitalDelayType := Null_Iir;
            VitalDelayType01 := Null_Iir;
            VitalDelayType01Z := Null_Iir;
            VitalDelayType01ZX := Null_Iir;

            VitalDelayArrayType := Null_Iir;
            VitalDelayArrayType01 := Null_Iir;
            VitalDelayArrayType01Z := Null_Iir;
            VitalDelayArrayType01ZX := Null_Iir;
   end Extract_Declarations;

   procedure Error_Vital (Msg : String; Loc : Iir) renames Error_Msg_Sem;
   procedure Error_Vital (Msg : String; Loc : Location_Type)
     renames Error_Msg_Sem;
   procedure Warning_Vital (Msg : String; Loc : Iir) renames Warning_Msg_Sem;

   --  Check DECL is the VITAL level 0 attribute specification.
   procedure Check_Level0_Attribute_Specification (Decl : Iir)
   is
      Expr : Iir;
   begin
      if Get_Kind (Decl) /= Iir_Kind_Attribute_Specification
        or else (Get_Named_Entity (Get_Attribute_Designator (Decl))
                   /= Vital_Level0_Attribute)
      then
         Error_Vital
           ("first declaration must be the VITAL attribute specification",
            Decl);
         return;
      end if;

      --  IEEE 1076.4 4.1
      --  The expression in the VITAL_Level0 attribute specification shall be
      --  the Boolean literal TRUE.
      Expr := Get_Expression (Decl);
      if Get_Kind (Expr) not in Iir_Kinds_Denoting_Name
        or else Get_Named_Entity (Expr) /= Boolean_True
      then
         Error_Vital
           ("the expression in the VITAL_Level0 attribute specification shall "
            & "be the Boolean literal TRUE", Decl);
      end if;

      --  IEEE 1076.4 4.1
      --  The entity specification of the decorating attribute specification
      --  shall be such that the enclosing entity or architecture inherits the
      --  VITAL_Level0 attribute.
      case Get_Entity_Class (Decl) is
         when Tok_Entity
           | Tok_Architecture =>
            null;
         when others =>
            Error_Vital ("VITAL attribute specification does not decorate the "
                         & "enclosing entity or architecture", Decl);
      end case;
   end Check_Level0_Attribute_Specification;

   procedure Check_Entity_Port_Declaration
     (Decl : Iir_Interface_Signal_Declaration)
   is
      use Name_Table;

      Atype : Iir;
      Base_Type : Iir;
      Type_Decl : Iir;
   begin
      --  IEEE 1076.4 4.3.1
      --  The identifiers in an entity port declaration shall not contain
      --  underscore characters.
      Image (Get_Identifier (Decl));
      if Name_Buffer (1) = '/' then
         Error_Vital ("VITAL entity port shall not be an extended identifier",
                      Decl);
      end if;
      for I in 1 .. Name_Length loop
         if Name_Buffer (I) = '_' then
            Error_Vital
              ("VITAL entity port shall not contain underscore", Decl);
            exit;
         end if;
      end loop;

      --  IEEE 1076.4 4.3.1
      --  A port that is declared in an entity port declaration shall not be
      --  of mode LINKAGE.
      if Get_Mode (Decl) = Iir_Linkage_Mode then
         Error_Vital ("VITAL entity port shall not be of mode LINKAGE", Decl);
      end if;

      --  IEEE 1076.4 4.3.1
      --  The type mark in an entity port declaration shall denote a type or
      --  a subtype that is declared in package Std_Logic_1164.  The type
      --  mark in the declaration of a scalar port shall denote the subtype
      --  Std_Ulogic or a subtype of Std_Ulogic.  The type mark in the
      --  declaration of an array port shall denote the type Std_Logic_Vector.
      Atype := Get_Type (Decl);
      Base_Type := Get_Base_Type (Atype);
      Type_Decl := Get_Type_Declarator (Atype);
      if Base_Type = Std_Logic_Vector_Type then
         if Get_Resolution_Indication (Atype) /= Null_Iir then
            Error_Vital
              ("VITAL array port type cannot override resolution function",
               Decl);
         end if;
         --  FIXME: is an unconstrained array port allowed ?
         --  FIXME: what about staticness of the index_constraint ?
      elsif Base_Type = Std_Ulogic_Type then
         if Type_Decl = Null_Iir
           or else Get_Parent (Type_Decl) /= Std_Logic_1164_Pkg
         then
            Error_Vital
              ("VITAL entity port type mark shall be one of Std_Logic_1164",
               Decl);
         end if;
      else
         Error_Vital ("VITAL port type must be Std_Logic_Vector or Std_Ulogic",
                      Decl);
      end if;

      if Get_Signal_Kind (Decl) /= Iir_No_Signal_Kind then
         Error_Vital ("VITAL entity port cannot be guarded", Decl);
      end if;
   end Check_Entity_Port_Declaration;

   --  Current position in the generic name, stored into
   --  name_table.name_buffer.
   Gen_Name_Pos : Natural;

   --  Length of the generic name.
   Gen_Name_Length : Natural;

   --  The generic being analyzed.
   Gen_Decl : Iir;
   Gen_Chain : Iir;

   procedure Error_Vital_Name (Str : String)
   is
      Loc : Location_Type;
   begin
      Loc := Get_Location (Gen_Decl);
      Error_Vital (Str, Loc + Location_Type (Gen_Name_Pos - 1));
   end Error_Vital_Name;

   --  Check the next sub-string in the generic name is a port.
   --  Returns the port.
   function Check_Port return Iir
   is
      use Sem_Scopes;
      use Name_Table;

      C : Character;
      Res : Iir;
      Id : Name_Id;
      Inter : Name_Interpretation_Type;
   begin
      Name_Length := 0;
      while Gen_Name_Pos <= Gen_Name_Length loop
         C := Name_Buffer (Gen_Name_Pos);
         Gen_Name_Pos := Gen_Name_Pos + 1;
         exit when C = '_';
         Name_Length := Name_Length + 1;
         Name_Buffer (Name_Length) := C;
      end loop;

      if Name_Length = 0 then
         Error_Vital_Name ("port expected in VITAL generic name");
         return Null_Iir;
      end if;

      Id := Get_Identifier_No_Create;
      Res := Null_Iir;
      if Id /= Null_Identifier then
         Inter := Get_Interpretation (Id);
         if Valid_Interpretation (Inter) then
            Res := Get_Declaration (Inter);
         end if;
      end if;
      if Res = Null_Iir then
         Warning_Vital ("'" & Name_Buffer (1 .. Name_Length)
                        & "' is not a port name (in VITAL generic name)",
                        Gen_Decl);
      end if;
      return Res;
   end Check_Port;

   --  Checks the port is an input port.
   function Check_Input_Port return Iir
   is
      use Name_Table;

      Res : Iir;
   begin
      Res := Check_Port;
      if Res /= Null_Iir then
         --  IEEE 1076.4 4.3.2.1.3
         --  an input port is a VHDL port of mode IN or INOUT.
         case Get_Mode (Res) is
            when Iir_In_Mode
              | Iir_Inout_Mode =>
               null;
            when others =>
               Error_Vital ("'" & Name_Buffer (1 .. Name_Length)
                            & "' must be an input port", Gen_Decl);
         end case;
      end if;
      return Res;
   end Check_Input_Port;

   --  Checks the port is an output port.
   function Check_Output_Port return Iir
   is
      use Name_Table;

      Res : Iir;
   begin
      Res := Check_Port;
      if Res /= Null_Iir then
         --  IEEE 1076.4 4.3.2.1.3
         --  An output port is a VHDL port of mode OUT, INOUT or BUFFER.
         case Get_Mode (Res) is
            when Iir_Out_Mode
              | Iir_Inout_Mode
              | Iir_Buffer_Mode =>
               null;
            when others =>
               Error_Vital ("'" & Name_Buffer (1 .. Name_Length)
                            & "' must be an output port", Gen_Decl);
         end case;
      end if;
      return Res;
   end Check_Output_Port;

   --  Extract a suffix from the generic name.
   type Suffixes_Kind is
     (
      Suffix_Name,     --  [a-z]*
      Suffix_Num_Name,  --  [0-9]*
      Suffix_Edge,     --  posedge, negedge, 01, 10, 0z, z1, 1z, z0
      Suffix_Noedge,   --  noedge
      Suffix_Eon       --  End of name
     );

   function Get_Next_Suffix_Kind return Suffixes_Kind
   is
      use Name_Table;

      Len : Natural;
      P : constant Natural := Gen_Name_Pos;
      C : Character;
   begin
      Len := 0;
      while Gen_Name_Pos <= Gen_Name_Length loop
         C := Name_Buffer (Gen_Name_Pos);
         Gen_Name_Pos := Gen_Name_Pos + 1;
         exit when C = '_';
         Len := Len + 1;
      end loop;
      if Len = 0 then
         return Suffix_Eon;
      end if;

      case Name_Buffer (P) is
         when '0' =>
            if Len = 2 and then (Name_Buffer (P + 1) = '1'
                                 or Name_Buffer (P + 1) = 'z')
            then
               return Suffix_Edge;
            else
               return Suffix_Num_Name;
            end if;
         when '1' =>
            if Len = 2 and then (Name_Buffer (P + 1) = '0'
                                 or Name_Buffer (P + 1) = 'z')
            then
               return Suffix_Edge;
            else
               return Suffix_Num_Name;
            end if;
         when '2' .. '9' =>
            return Suffix_Num_Name;
         when 'z' =>
            if Len = 2 and then (Name_Buffer (P + 1) = '0'
                                 or Name_Buffer (P + 1) = '1')
            then
               return Suffix_Edge;
            else
               return Suffix_Name;
            end if;
         when 'p' =>
            if Len = 7 and then Name_Buffer (P .. P + 6) = "posedge" then
               return Suffix_Edge;
            else
               return Suffix_Name;
            end if;
         when 'n' =>
            if Len = 7 and then Name_Buffer (P .. P + 6) = "negedge" then
               return Suffix_Edge;
            elsif Len = 6 and then Name_Buffer (P .. P + 5) = "noedge" then
               return Suffix_Edge;
            else
               return Suffix_Name;
            end if;
         when 'a' .. 'm'
           | 'o'
           | 'q' .. 'y' =>
            return Suffix_Name;
         when others =>
            raise Internal_Error;
      end case;
   end Get_Next_Suffix_Kind;

   --  <SDFSimpleConditionAndOrEdge> ::=
   --     <ConditionName>
   --   | <Edge>
   --   | <ConditionName>_<Edge>
   procedure Check_Simple_Condition_And_Or_Edge
   is
      First : Boolean := True;
   begin
      loop
         case Get_Next_Suffix_Kind is
            when Suffix_Eon =>
               --  Simple condition is optional.
               return;
            when Suffix_Edge =>
               if Get_Next_Suffix_Kind /= Suffix_Eon then
                  Error_Vital_Name ("garbage after edge");
               end if;
               return;
            when Suffix_Num_Name =>
               if First then
                  Error_Vital_Name ("condition is a simple name");
               end if;
            when Suffix_Noedge =>
               Error_Vital_Name ("'noedge' not allowed in simple condition");
            when Suffix_Name =>
               null;
         end case;
         First := False;
      end loop;
   end Check_Simple_Condition_And_Or_Edge;

   --  <SDFFullConditionAndOrEdge> ::=
   --    <ConditionNameEdge>[_<SDFSimpleConditionAndOrEdge>]
   --
   --  <ConditionNameEdge> ::=
   --      [<ConditionName>_]<Edge>
   --    | [<ConditionName>_]noedge
   procedure Check_Full_Condition_And_Or_Edge
   is
   begin
      case Get_Next_Suffix_Kind is
         when Suffix_Eon =>
            --  FullCondition is always optional.
            return;
         when Suffix_Edge
           | Suffix_Noedge =>
            Check_Simple_Condition_And_Or_Edge;
            return;
         when Suffix_Num_Name =>
            Error_Vital_Name ("condition is a simple name");
         when Suffix_Name =>
            null;
      end case;

      loop
         case Get_Next_Suffix_Kind is
            when Suffix_Eon =>
               Error_Vital_Name ("missing edge or noedge");
               return;
            when Suffix_Edge
              | Suffix_Noedge =>
               Check_Simple_Condition_And_Or_Edge;
               return;
            when Suffix_Num_Name
              | Suffix_Name =>
               null;
         end case;
      end loop;
   end Check_Full_Condition_And_Or_Edge;

   procedure Check_End is
   begin
      if Get_Next_Suffix_Kind /= Suffix_Eon then
         Error_Vital_Name ("garbage at end of name");
      end if;
   end Check_End;

   --  Return the length of a port P.
   --  If P is a scalar port, return PORT_LENGTH_SCALAR
   --  If P is a vector, return the length of the vector (>= 0)
   --  Otherwise, return PORT_LENGTH_ERROR.
   Port_Length_Unknown : constant Iir_Int64 := -1;
   Port_Length_Scalar  : constant Iir_Int64 := -2;
   Port_Length_Error   : constant Iir_Int64 := -3;
   function Get_Port_Length (P : Iir) return Iir_Int64
   is
      Ptype : Iir;
      Itype : Iir;
   begin
      Ptype := Get_Type (P);
      if Get_Base_Type (Ptype) = Std_Ulogic_Type then
         return Port_Length_Scalar;
      elsif Get_Kind (Ptype) = Iir_Kind_Array_Subtype_Definition
        and then Get_Base_Type (Ptype) = Std_Logic_Vector_Type
      then
         Itype := Get_First_Element (Get_Index_Subtype_List (Ptype));
         if Get_Type_Staticness (Itype) /= Locally then
            return Port_Length_Unknown;
         end if;
         return Evaluation.Eval_Discrete_Type_Length (Itype);
      else
         return Port_Length_Error;
      end if;
   end Get_Port_Length;

   --  IEEE 1076.4  9.1  VITAL delay types and subtypes.
   --  The transition dependent delay types are
   --  VitalDelayType01, VitalDelayType01Z, VitalDelayType01ZX,
   --  VitalDelayArrayType01, VitalDelayArrayType01Z, VitalDelayArrayType01ZX.
   --  The first three are scalar forms, the last three are vector forms.
   --
   --  The simple delay types and subtypes include
   --  Time, VitalDelayType, and VitalDelayArrayType.
   --  The first two are scalar forms, and the latter is the vector form.
   type Timing_Generic_Type_Kind is
     (
      Timing_Type_Simple_Scalar,
      Timing_Type_Simple_Vector,
      Timing_Type_Trans_Scalar,
      Timing_Type_Trans_Vector,
      Timing_Type_Bad
     );

   function Get_Timing_Generic_Type_Kind return Timing_Generic_Type_Kind
   is
      Gtype : Iir;
      Btype : Iir;
   begin
      Gtype := Get_Type (Gen_Decl);
      Btype := Get_Base_Type (Gtype);
      case Get_Kind (Gtype) is
         when Iir_Kind_Array_Subtype_Definition =>
            if Btype = VitalDelayArrayType then
               return Timing_Type_Simple_Vector;
            end if;
            if Btype = VitalDelayType01
              or Btype = VitalDelayType01Z
              or Btype = VitalDelayType01ZX
            then
               return Timing_Type_Trans_Scalar;
            end if;
            if Btype = VitalDelayArrayType01
              or Btype = VitalDelayArrayType01Z
              or Btype = VitalDelayArrayType01ZX
            then
               return Timing_Type_Trans_Vector;
            end if;
         when Iir_Kind_Physical_Subtype_Definition =>
            if Gtype = Time_Subtype_Definition
              or else Gtype = VitalDelayType
            then
               return Timing_Type_Simple_Scalar;
            end if;
         when others =>
            null;
      end case;
      Error_Vital ("type of timing generic is not a VITAL delay type",
                   Gen_Decl);
      return Timing_Type_Bad;
   end Get_Timing_Generic_Type_Kind;

   function Get_Timing_Generic_Type_Length return Iir_Int64
   is
      Itype : Iir;
   begin
      Itype := Get_First_Element
        (Get_Index_Subtype_List (Get_Type (Gen_Decl)));
      if Get_Type_Staticness (Itype) /= Locally then
         return Port_Length_Unknown;
      else
         return Evaluation.Eval_Discrete_Type_Length (Itype);
      end if;
   end Get_Timing_Generic_Type_Length;

   --  IEEE 1076.4  4.3.2.1.2  Timing generic subtypes
   --  *  If the timing generic is associated with a single port and that port
   --     is a scalar, then the type of the timing generic shall be a scalar
   --     form of delay type.
   --  *  If such a timing generic is associated with a single port and that
   --     port is a vector, then the type of the timing generic shall be a
   --     vector form of delay type, and the constraint on the generic shall
   --     match that on the associated port.
   procedure Check_Vital_Delay_Type (P : Iir;
                                     Is_Simple : Boolean := False;
                                     Is_Scalar : Boolean := False)
   is
      Kind : Timing_Generic_Type_Kind;
      Len : Iir_Int64;
      Len1 : Iir_Int64;
   begin
      Kind := Get_Timing_Generic_Type_Kind;
      if P = Null_Iir or Kind = Timing_Type_Bad then
         return;
      end if;
      Len := Get_Port_Length (P);
      if Len = Port_Length_Scalar then
         case Kind is
            when Timing_Type_Simple_Scalar =>
               null;
            when Timing_Type_Trans_Scalar =>
               if Is_Simple then
                  Error_Vital
                    ("VITAL simple scalar timing type expected", Gen_Decl);
                  return;
               end if;
            when others =>
               Error_Vital ("VITAL scalar timing type expected", Gen_Decl);
               return;
         end case;
      elsif Len >= Port_Length_Unknown then
         if Is_Scalar then
            Error_Vital ("VITAL scalar timing type expected", Gen_Decl);
            return;
         end if;

         case Kind is
            when Timing_Type_Simple_Vector =>
               null;
            when Timing_Type_Trans_Vector =>
               if Is_Simple then
                  Error_Vital
                    ("VITAL simple vector timing type expected", Gen_Decl);
                  return;
               end if;
            when others =>
               Error_Vital ("VITAL vector timing type expected", Gen_Decl);
               return;
         end case;
         Len1 := Get_Timing_Generic_Type_Length;
         if Len1 /= Len then
            Error_Vital ("length of port and VITAL vector timing subtype "
                         & "does not match", Gen_Decl);
         end if;
      end if;
   end Check_Vital_Delay_Type;

   --  IEEE 1076.4  4.3.2.1.2  Timing generic subtypes
   --  * If the timing generic is associated with two scalar ports, then the
   --    type of the timing generic shall be a scalar form of delay type.
   --  * If the timing generic is associated with two ports, one or more of
   --    which is a vector, then the type of the timing generic shall be a
   --    vector form of delay type, and the length of the index range of the
   --    generic shall be equal to the product of the number of scalar
   --    subelements in the first port and the number of scalar subelements
   --    in the second port.
   procedure Check_Vital_Delay_Type
     (P1, P2 : Iir;
      Is_Simple : Boolean := False;
      Is_Scalar : Boolean := False)
   is
      Kind : Timing_Generic_Type_Kind;
      Len1 : Iir_Int64;
      Len2 : Iir_Int64;
      Lenp : Iir_Int64;
   begin
      Kind := Get_Timing_Generic_Type_Kind;
      if P1 = Null_Iir or P2 = Null_Iir or Kind = Timing_Type_Bad then
         return;
      end if;
      Len1 := Get_Port_Length (P1);
      Len2 := Get_Port_Length (P2);
      if Len1 = Port_Length_Scalar and Len2 = Port_Length_Scalar then
         case Kind is
            when Timing_Type_Simple_Scalar =>
               null;
            when Timing_Type_Trans_Scalar =>
               if Is_Simple then
                  Error_Vital
                    ("VITAL simple scalar timing type expected", Gen_Decl);
                  return;
               end if;
            when others =>
               Error_Vital ("VITAL scalar timing type expected", Gen_Decl);
               return;
         end case;
      elsif Len1 >= Port_Length_Unknown or Len2 >= Port_Length_Unknown then
         if Is_Scalar then
            Error_Vital ("VITAL scalar timing type expected", Gen_Decl);
            return;
         end if;
         case Kind is
            when Timing_Type_Simple_Vector =>
               null;
            when Timing_Type_Trans_Vector =>
               if Is_Simple then
                  Error_Vital
                    ("VITAL simple vector timing type expected", Gen_Decl);
                  return;
               end if;
            when others =>
               Error_Vital ("VITAL vector timing type expected", Gen_Decl);
               return;
         end case;
         if Len1 = Port_Length_Scalar then
            Len1 := 1;
         elsif Len1 = Port_Length_Error then
            return;
         end if;
         if Len2 = Port_Length_Scalar then
            Len2 := 1;
         elsif Len2 = Port_Length_Error then
            return;
         end if;
         Lenp := Get_Timing_Generic_Type_Length;
         if Lenp /= Len1 * Len2 then
            Error_Vital ("length of port and VITAL vector timing subtype "
                         & "does not match", Gen_Decl);
         end if;
      end if;
   end Check_Vital_Delay_Type;

   function Check_Timing_Generic_Prefix
     (Decl : Iir_Interface_Constant_Declaration; Length : Natural)
     return Boolean
   is
      use Name_Table;
   begin
      --  IEEE 1076.4 4.3.1
      --  It is an error for a model to use a timing generic prefix to begin
      --  the simple name of an entity generic that is not a timing generic.
      if Name_Length < Length or Name_Buffer (Length) /= '_' then
         Error_Vital ("invalid use of a VITAL timing generic prefix", Decl);
         return False;
      end if;
      Gen_Name_Pos := Length + 1;
      Gen_Name_Length := Name_Length;
      Gen_Decl := Decl;
      return True;
   end Check_Timing_Generic_Prefix;

   --  IEEE 1076.4 4.3.2.1.3.1 Propagation Delay
   --  <VITALPropagationDelayName> ::=
   --     TPD_<InputPort>_<OutputPort>[_<SDFSimpleConditionAndOrEdge>]
   procedure Check_Propagation_Delay_Name
     (Decl : Iir_Interface_Constant_Declaration)
   is
      Iport : Iir;
      Oport : Iir;
   begin
      if not Check_Timing_Generic_Prefix (Decl, 4) then
         return;
      end if;
      Iport := Check_Input_Port;
      Oport := Check_Output_Port;
      Check_Simple_Condition_And_Or_Edge;
      Check_Vital_Delay_Type (Iport, Oport);
   end Check_Propagation_Delay_Name;

   procedure Check_Test_Reference
   is
      Tport : Iir;
      Rport : Iir;
   begin
      Tport := Check_Input_Port;
      Rport := Check_Input_Port;
      Check_Full_Condition_And_Or_Edge;
      Check_Vital_Delay_Type (Tport, Rport, Is_Simple => True);
   end Check_Test_Reference;

   --  tsetup
   procedure Check_Input_Setup_Time_Name
     (Decl : Iir_Interface_Constant_Declaration)
   is
   begin
      if not Check_Timing_Generic_Prefix (Decl, 7) then
         return;
      end if;
      Check_Test_Reference;
   end Check_Input_Setup_Time_Name;

   --  thold
   procedure Check_Input_Hold_Time_Name
     (Decl : Iir_Interface_Constant_Declaration)
   is
   begin
      if not Check_Timing_Generic_Prefix (Decl, 6) then
         return;
      end if;
      Check_Test_Reference;
   end Check_Input_Hold_Time_Name;

   --  trecovery
   procedure Check_Input_Recovery_Time_Name
     (Decl : Iir_Interface_Constant_Declaration)
   is
   begin
      if not Check_Timing_Generic_Prefix (Decl, 10) then
         return;
      end if;
      Check_Test_Reference;
   end Check_Input_Recovery_Time_Name;

   --  tremoval
   procedure Check_Input_Removal_Time_Name
     (Decl : Iir_Interface_Constant_Declaration)
   is
   begin
      if not Check_Timing_Generic_Prefix (Decl, 9) then
         return;
      end if;
      Check_Test_Reference;
   end Check_Input_Removal_Time_Name;

   --  tperiod
   procedure Check_Input_Period_Name
     (Decl : Iir_Interface_Constant_Declaration)
   is
      Iport : Iir;
   begin
      if not Check_Timing_Generic_Prefix (Decl, 8) then
         return;
      end if;
      Iport := Check_Input_Port;
      Check_Simple_Condition_And_Or_Edge;
      Check_Vital_Delay_Type (Iport, Is_Simple => True);
   end Check_Input_Period_Name;

   --  tpw
   procedure Check_Pulse_Width_Name
     (Decl : Iir_Interface_Constant_Declaration)
   is
      Iport : Iir;
   begin
      if not Check_Timing_Generic_Prefix (Decl, 4) then
         return;
      end if;
      Iport := Check_Input_Port;
      Check_Simple_Condition_And_Or_Edge;
      Check_Vital_Delay_Type (Iport, Is_Simple => True);
   end Check_Pulse_Width_Name;

   --  tskew
   procedure Check_Input_Skew_Time_Name
     (Decl : Iir_Interface_Constant_Declaration)
   is
      Fport : Iir;
      Sport : Iir;
   begin
      if not Check_Timing_Generic_Prefix (Decl, 6) then
         return;
      end if;
      Fport := Check_Port;
      Sport := Check_Port;
      Check_Full_Condition_And_Or_Edge;
      Check_Vital_Delay_Type (Fport, Sport, Is_Simple => True);
   end Check_Input_Skew_Time_Name;

   --  tncsetup
   procedure Check_No_Change_Setup_Time_Name
     (Decl : Iir_Interface_Constant_Declaration)
   is
   begin
      if not Check_Timing_Generic_Prefix (Decl, 9) then
         return;
      end if;
      Check_Test_Reference;
   end Check_No_Change_Setup_Time_Name;

   --  tnchold
   procedure Check_No_Change_Hold_Time_Name
     (Decl : Iir_Interface_Constant_Declaration)
   is
   begin
      if not Check_Timing_Generic_Prefix (Decl, 8) then
         return;
      end if;
      Check_Test_Reference;
   end Check_No_Change_Hold_Time_Name;

   --  tipd
   procedure Check_Interconnect_Path_Delay_Name
     (Decl : Iir_Interface_Constant_Declaration)
   is
      Iport : Iir;
   begin
      if not Check_Timing_Generic_Prefix (Decl, 5) then
         return;
      end if;
      Iport := Check_Input_Port;
      Check_End;
      Check_Vital_Delay_Type (Iport);
   end Check_Interconnect_Path_Delay_Name;

   --  tdevice
   procedure Check_Device_Delay_Name
     (Decl : Iir_Interface_Constant_Declaration)
   is
      Oport : Iir;
      pragma Unreferenced (Oport);
      Pos : Natural;
      Kind : Timing_Generic_Type_Kind;
      pragma Unreferenced (Kind);
   begin
      if not Check_Timing_Generic_Prefix (Decl, 8) then
         return;
      end if;
      if Get_Next_Suffix_Kind /= Suffix_Name then
         Error_Vital_Name ("instance_name expected in VITAL generic name");
         return;
      end if;
      Pos := Gen_Name_Pos;
      if Get_Next_Suffix_Kind /= Suffix_Eon then
         Gen_Name_Pos := Pos;
         Oport := Check_Output_Port;
         Check_End;
      end if;
      Kind := Get_Timing_Generic_Type_Kind;
   end Check_Device_Delay_Name;

   --  tisd
   procedure Check_Internal_Signal_Delay_Name
     (Decl : Iir_Interface_Constant_Declaration)
   is
      Iport : Iir;
      Cport : Iir;
   begin
      if not Check_Timing_Generic_Prefix (Decl, 5) then
         return;
      end if;
      Iport := Check_Input_Port;
      Cport := Check_Input_Port;
      Check_End;
      Check_Vital_Delay_Type (Iport, Cport,
                              Is_Simple => True, Is_Scalar => True);
   end Check_Internal_Signal_Delay_Name;

   --  tbpd
   procedure Check_Biased_Propagation_Delay_Name
     (Decl : Iir_Interface_Constant_Declaration)
   is
      Iport : Iir;
      Oport : Iir;
      Cport : Iir;
      pragma Unreferenced (Cport);
      Clock_Start : Natural;
      Clock_End : Natural;
   begin
      if not Check_Timing_Generic_Prefix (Decl, 5) then
         return;
      end if;
      Iport := Check_Input_Port;
      Oport := Check_Output_Port;
      Clock_Start := Gen_Name_Pos - 1; -- At the '_'.
      Cport := Check_Input_Port;
      Clock_End := Gen_Name_Pos;
      Check_Simple_Condition_And_Or_Edge;
      Check_Vital_Delay_Type (Iport, Oport);

      --  IEEE 1076.4  4.3.2.1.3.14  Biased propagation delay
      --  There shall exist, in the same entity generic clause, a corresponding
      --  propagation delay generic denoting the same ports, condition name,
      --  and edge.
      declare
         use Name_Table;

         --  '-1' is for the missing 'b' in 'tpd'.
         Tpd_Name : String
           (1 .. Gen_Name_Length - 1 - (Clock_End - Clock_Start));
         Tpd_Decl : Iir;
      begin
         Image (Get_Identifier (Decl));
         Tpd_Name (1) := 't';
         --  The part before '_<ClockPort>'.
         Tpd_Name (2 .. Clock_Start - 2) := Name_Buffer (3 .. Clock_Start - 1);
         Tpd_Name (Clock_Start - 1 .. Tpd_Name'Last) :=
           Name_Buffer (Clock_End .. Name_Length);

         Tpd_Decl := Gen_Chain;
         loop
            exit when Tpd_Decl = Null_Iir;
            Image (Get_Identifier (Tpd_Decl));
            exit when Name_Length = Tpd_Name'Length
              and then Name_Buffer (1 .. Name_Length) = Tpd_Name;
            Tpd_Decl := Get_Chain (Tpd_Decl);
         end loop;

         if Tpd_Decl = Null_Iir then
            Error_Vital
              ("no matching 'tpd' generic for VITAL 'tbpd' timing generic",
               Decl);
         else
            --  IEEE 1076.4  4.3.2.1.3.14  Biased propagation delay
            --  Furthermore, the type of the biased propagation generic shall
            --  be the same as the type of the corresponding delay generic.
            if not Sem.Are_Trees_Equal (Get_Type (Decl), Get_Type (Tpd_Decl))
            then
               Error_Vital
                 ("type of VITAL 'tbpd' generic mismatch type of "
                  & "'tpd' generic", Decl);
               Error_Vital
                 ("(corresponding 'tpd' timing generic)", Tpd_Decl);
            end if;
         end if;
      end;
   end Check_Biased_Propagation_Delay_Name;

   --  ticd
   procedure Check_Internal_Clock_Delay_Generic_Name
     (Decl : Iir_Interface_Constant_Declaration)
   is
      Cport : Iir;
      P_Start : Natural;
      P_End : Natural;
   begin
      if not Check_Timing_Generic_Prefix (Decl, 5) then
         return;
      end if;
      P_Start := Gen_Name_Pos;
      Cport := Check_Input_Port;
      P_End := Gen_Name_Pos;
      Check_End;
      Check_Vital_Delay_Type (Cport, Is_Simple => True, Is_Scalar => True);

      --  IEEE 1076.4  4.3.2.1.3.15  Internal clock delay
      --  It is an error for a clocks signal name to appear as one of the
      --  following elements in the name of a timing generic:
      --  * As either the input port in the name of a biased propagation
      --    delay generic.
      --  * As the input signal name in an internal delay timing generic.
      --  * As the test port in a timing check or recovery removal timing
      --    generic.
      --  FIXME: recovery OR removal ?

      if P_End - 1 /= Gen_Name_Length then
         --  Do not check in case of error.
         return;
      end if;
      declare
         use Name_Table;
         Port : String (1 .. Name_Length);
         El : Iir;
         Offset : Natural;

         procedure Check_Not_Clock
         is
            S : Natural;
         begin
            S := Offset;
            loop
               Offset := Offset + 1;
               exit when Offset > Name_Length
                 or else Name_Buffer (Offset) = '_';
            end loop;
            if Offset - S = Port'Length
              and then Name_Buffer (S .. Offset - 1) = Port
            then
               Error_Vital ("clock port name of 'ticd' VITAL generic must not"
                            & " appear here", El);
            end if;
         end Check_Not_Clock;
      begin
         Port := Name_Buffer (P_Start .. Gen_Name_Length);

         El := Gen_Chain;
         while El /= Null_Iir loop
            Image (Get_Identifier (El));
            if Name_Length > 5
              and then Name_Buffer (1) = 't'
            then
               if Name_Buffer (2 .. 5) = "bpd_" then
                  Offset := 6;
                  Check_Not_Clock; -- input
                  Check_Not_Clock; -- output
               elsif Name_Buffer (2 .. 5) = "isd_" then
                  Offset := 6;
                  Check_Not_Clock; -- input
               elsif Name_Length > 10
                 and then Name_Buffer (2 .. 10) = "recovery_"
               then
                  Offset := 11;
                  Check_Not_Clock; -- test port
               elsif Name_Length > 9
                 and then Name_Buffer (2 .. 9) = "removal_"
               then
                  Offset := 10;
                  Check_Not_Clock;
               end if;
            end if;
            El := Get_Chain (El);
         end loop;
      end;
   end Check_Internal_Clock_Delay_Generic_Name;

   procedure Check_Entity_Generic_Declaration
     (Decl : Iir_Interface_Constant_Declaration)
   is
      use Name_Table;
      Id : Name_Id;
   begin
      Id := Get_Identifier (Decl);
      Image (Id);

      --  Extract prefix.
      if Name_Buffer (1) = 't' and Name_Length >= 3 then
         --  Timing generic names.
         if Name_Buffer (2) = 'p' then
            if Name_Buffer (3) = 'd' then
               Check_Propagation_Delay_Name (Decl); --  tpd
               return;
            elsif Name_Buffer (3) = 'w' then
               Check_Pulse_Width_Name (Decl); -- tpw
               return;
            elsif Name_Length >= 7
              and then Name_Buffer (3 .. 7) = "eriod"
            then
               Check_Input_Period_Name (Decl); --  tperiod
               return;
            end if;
         elsif Name_Buffer (2) = 'i'
           and then Name_Length >= 4
           and then Name_Buffer (4) = 'd'
         then
            if Name_Buffer (3) = 'p' then
               Check_Interconnect_Path_Delay_Name (Decl); --  tipd
               return;
            elsif Name_Buffer (3) = 's' then
               Check_Internal_Signal_Delay_Name (Decl); --  tisd
               return;
            elsif Name_Buffer (3) = 'c' then
               Check_Internal_Clock_Delay_Generic_Name (Decl); --  ticd
               return;
            end if;
         elsif Name_Length >= 6 and then Name_Buffer (2 .. 6) = "setup" then
            Check_Input_Setup_Time_Name (Decl); --  tsetup
            return;
         elsif Name_Length >= 5 and then Name_Buffer (2 .. 5) = "hold" then
            Check_Input_Hold_Time_Name (Decl); -- thold
            return;
         elsif Name_Length >= 9 and then Name_Buffer (2 .. 9) = "recovery" then
            Check_Input_Recovery_Time_Name (Decl); -- trecovery
            return;
         elsif Name_Length >= 8 and then Name_Buffer (2 .. 8) = "removal" then
            Check_Input_Removal_Time_Name (Decl); -- tremoval
            return;
         elsif Name_Length >= 5 and then Name_Buffer (2 .. 5) = "skew" then
            Check_Input_Skew_Time_Name (Decl); -- tskew
            return;
         elsif Name_Length >= 8 and then Name_Buffer (2 .. 8) = "ncsetup" then
            Check_No_Change_Setup_Time_Name (Decl); -- tncsetup
            return;
         elsif Name_Length >= 7 and then Name_Buffer (2 .. 7) = "nchold" then
            Check_No_Change_Hold_Time_Name (Decl); -- tnchold
            return;
         elsif Name_Length >= 7 and then Name_Buffer (2 .. 7) = "device" then
            Check_Device_Delay_Name (Decl); -- tdevice
            return;
         elsif Name_Length >= 4 and then Name_Buffer (2 .. 4) = "bpd" then
            Check_Biased_Propagation_Delay_Name (Decl); -- tbpd
            return;
         end if;
      end if;

      if Id = InstancePath_Id then
         if Get_Type (Decl) /= String_Type_Definition then
            Error_Vital
              ("InstancePath VITAL generic must be of type String", Decl);
         end if;
         return;
      elsif Id = TimingChecksOn_Id
        or Id = XOn_Id
        or Id = MsgOn_Id
      then
         if Get_Type (Decl) /= Boolean_Type_Definition then
            Error_Vital
              (Image (Id) & " VITAL generic must be of type Boolean", Decl);
         end if;
         return;
      end if;

      if Flags.Warn_Vital_Generic then
         Warning_Vital (Disp_Node (Decl) & " is not a VITAL generic", Decl);
      end if;
   end Check_Entity_Generic_Declaration;

   --  Checks rules for a VITAL level 0 entity.
   procedure Check_Vital_Level0_Entity (Ent : Iir_Entity_Declaration)
   is
      use Sem_Scopes;
      Decl : Iir;
   begin
      --  IEEE 1076.4 4.3.1
      --  The only form of declaration allowed in the entity declarative part
      --  is the specification of the VITAL_Level0 attribute.
      Decl := Get_Declaration_Chain (Ent);
      if Decl = Null_Iir then
         --  Cannot happen, since there is at least the attribute spec.
         raise Internal_Error;
      end if;
      Check_Level0_Attribute_Specification (Decl);
      Decl := Get_Chain (Decl);
      if Decl /= Null_Iir then
         Error_Vital ("VITAL entity declarative part must only contain the "
                      & "attribute specification", Decl);
      end if;

      --  IEEE 1076.4 4.3.1
      --  No statements are allowed in the entity statement part.
      Decl := Get_Concurrent_Statement_Chain (Ent);
      if Decl /= Null_Iir then
         Error_Vital ("VITAL entity must not have concurrent statement", Decl);
      end if;

      --  Check ports.
      Name_Table.Assert_No_Infos;
      Open_Declarative_Region;
      Decl := Get_Port_Chain (Ent);
      while Decl /= Null_Iir loop
         Check_Entity_Port_Declaration (Decl);
         Add_Name (Decl);
         Decl := Get_Chain (Decl);
      end loop;

      --  Check generics.
      Gen_Chain := Get_Generic_Chain (Ent);
      Decl := Gen_Chain;
      while Decl /= Null_Iir loop
         Check_Entity_Generic_Declaration (Decl);
         Decl := Get_Chain (Decl);
      end loop;
      Close_Declarative_Region;
   end Check_Vital_Level0_Entity;

   --  Return TRUE if UNIT was decorated with attribute VITAL_Level0.
   function Is_Vital_Level0 (Unit : Iir_Entity_Declaration) return Boolean
   is
      Value : Iir_Attribute_Value;
      Spec : Iir_Attribute_Specification;
   begin
      Value := Get_Attribute_Value_Chain (Unit);
      while Value /= Null_Iir loop
         Spec := Get_Attribute_Specification (Value);
         if Get_Named_Entity (Get_Attribute_Designator (Spec))
           = Vital_Level0_Attribute
         then
            return True;
         end if;
         Value := Get_Chain (Value);
      end loop;

      return False;
   end Is_Vital_Level0;

   procedure Check_Vital_Level0_Architecture (Arch : Iir_Architecture_Body)
   is
      Decl : Iir;
   begin
      --  IEEE 1076.4 4.1
      --  The entity associated with a Level 0 architecture shall be a VITAL
      --  Level 0 entity.
      if not Is_Vital_Level0 (Iirs_Utils.Get_Entity (Arch)) then
         Error_Vital ("entity associated with a VITAL level 0 architecture "
                      & "shall be a VITAL level 0 entity", Arch);
      end if;

      --  VITAL_Level_0_architecture_declarative_part ::=
      --    VITAL_Level0_attribute_specification { block_declarative_item }
      Decl := Get_Declaration_Chain (Arch);
      Check_Level0_Attribute_Specification (Decl);
   end Check_Vital_Level0_Architecture;

   --  Check a VITAL level 0 decorated design unit.
   procedure Check_Vital_Level0 (Unit : Iir_Design_Unit)
   is
      Lib_Unit : Iir;
   begin
      Lib_Unit := Get_Library_Unit (Unit);
      case Get_Kind (Lib_Unit) is
         when Iir_Kind_Entity_Declaration =>
            Check_Vital_Level0_Entity (Lib_Unit);
         when Iir_Kind_Architecture_Body =>
            Check_Vital_Level0_Architecture (Lib_Unit);
         when others =>
            Error_Vital
              ("only entity or architecture can be VITAL_Level0", Lib_Unit);
      end case;
   end Check_Vital_Level0;

   procedure Check_Vital_Level1 (Unit : Iir_Design_Unit)
   is
      Arch : Iir;
   begin
      Arch := Get_Library_Unit (Unit);
      if Get_Kind (Arch) /= Iir_Kind_Architecture_Body then
         Error_Vital ("only architecture can be VITAL_Level1", Arch);
         return;
      end if;
      --  FIXME: todo
   end Check_Vital_Level1;

end Ieee.Vital_Timing;