PExpr.h

#ifndef __PExpr_H
#define __PExpr_H
/*
 * Copyright (c) 1998-2000 Stephen Williams <steve@icarus.com>
 *
 *    This source code is free software; you can redistribute it
 *    and/or modify it in source code form under the terms of the GNU
 *    General Public License as published by the Free Software
 *    Foundation; either version 2 of the License, or (at your option)
 *    any later version.
 *
 *    This program 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 this program; if not, write to the Free Software
 *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
 */
#ifdef HAVE_CVS_IDENT
#ident "$Id: PExpr.h,v 1.90 2007/06/04 19:14:06 steve Exp $"
#endif

# include  <string>
# include  <vector>
# include  "netlist.h"
# include  "verinum.h"
# include  "LineInfo.h"
# include  "pform_types.h"

class Design;
class Module;
class NetNet;
class NetExpr;
class NetScope;

/*
 * The PExpr class hierarchy supports the description of
 * expressions. The parser can generate expression objects from the
 * source, possibly reducing things that it knows how to reduce.
 *
 * The elaborate_net method is used by structural elaboration to build
 * up a netlist interpretation of the expression.
 */

class PExpr : public LineInfo {

    public:
      PExpr();
      virtual ~PExpr();

      virtual void dump(ostream&) const;

	// This method tests the width that the expression wants to
	// be. It is used by elaboration of assignments to figure out
	// the width of the expression.
	//
	// The "min" is the width of the local context, so it the
	// minimum width that this function should return. Initially
	// this is the same as the lval width.
	//
	// The "lval" is the width of the destination where this
	// result is going to go. This can be used to constrain the
	// amount that an expression can reasonably expand. For
	// example, there is no point expanding an addition to beyond
	// the lval. This extra bit of information allows the
	// expression to optimize itself a bit. If the lval==0, then
	// the subexpression should not make l-value related
	// optimizations.
	//
	// The unsigned_flag is set to true if the expression is
	// unsized and therefore expandable. This happens if a
	// sub-expression is an unsized literal. Some expressions make
	// special use of that.
      virtual unsigned test_width(Design*des, NetScope*scope,
				  unsigned min, unsigned lval,
				  bool&unsized_flag) const;

	// Procedural elaboration of the expression. The expr_width is
	// the width of the context of the expression (i.e. the
	// l-value width of an assignment) or -1 if the expression is
	// self-determinted. The sys_task_arg flag is true if
	// expressions are allowed to be incomplete.
      virtual NetExpr*elaborate_expr(Design*des, NetScope*scope,
				     int expr_width, bool sys_task_arg) const;

	// Elaborate expressions that are the r-value of parameter
	// assignments. This elaboration follows the restrictions of
	// constant expressions and supports later overriding and
	// evaluation of parameters.
      virtual NetExpr*elaborate_pexpr(Design*des, NetScope*sc) const;

	// This method elaborate the expression as gates, for use in a
	// continuous assign or other wholly structural context.
      virtual NetNet* elaborate_net(Design*des, NetScope*scope,
				    unsigned lwidth,
				    const NetExpr* rise,
				    const NetExpr* fall,
				    const NetExpr* decay,
				    Link::strength_t drive0 =Link::STRONG,
				    Link::strength_t drive1 =Link::STRONG)
	    const;

	// This method elaborates the expression as gates, but
	// restricted for use as l-values of continuous assignments.
      virtual NetNet* elaborate_lnet(Design*des, NetScope*scope,
				     bool implicit_net_ok =false) const;

	// This is similar to elaborate_lnet, except that the
	// expression is evaluated to be bi-directional. This is
	// useful for arguments to inout ports of module instances and
	// ports of tran primitives.
      virtual NetNet* elaborate_bi_net(Design*des, NetScope*scope) const;

	// Expressions that can be in the l-value of procedural
	// assignments can be elaborated with this method. If the
	// is_force flag is true, then the set of valid l-value types
	// is slightly modified to accomodate the Verilog force
	// statement
      virtual NetAssign_* elaborate_lval(Design*des,
					 NetScope*scope,
					 bool is_force) const;

	// This attempts to evaluate a constant expression, and return
	// a verinum as a result. If the expression cannot be
	// evaluated, return 0.
      virtual verinum* eval_const(Design*des, NetScope*sc) const;

	// This method returns true if that expression is the same as
	// this expression. This method is used for comparing
	// expressions that must be structurally "identical".
      virtual bool is_the_same(const PExpr*that) const;

	// Return true if this expression is a valid constant
	// expression. the Module pointer is needed to find parameter
	// identifiers and any other module specific interpretations
	// of expressions.
      virtual bool is_constant(Module*) const;

    private: // not implemented
      PExpr(const PExpr&);
      PExpr& operator= (const PExpr&);
};

ostream& operator << (ostream&, const PExpr&);

class PEConcat : public PExpr {

    public:
      PEConcat(const svector<PExpr*>&p, PExpr*r =0);
      ~PEConcat();

      virtual verinum* eval_const(Design*des, NetScope*sc) const;
      virtual void dump(ostream&) const;

      virtual NetNet* elaborate_lnet(Design*des, NetScope*scope,
				     bool implicit_net_ok =false) const;
      virtual NetNet* elaborate_bi_net(Design*des, NetScope*scope) const;
      virtual NetNet* elaborate_net(Design*des, NetScope*scope,
				    unsigned width,
				    const NetExpr* rise,
				    const NetExpr* fall,
				    const NetExpr* decay,
				    Link::strength_t drive0,
				    Link::strength_t drive1) const;
      virtual NetExpr*elaborate_expr(Design*des, NetScope*,
				     int expr_width, bool sys_task_arg) const;
      virtual NetEConcat*elaborate_pexpr(Design*des, NetScope*) const;
      virtual NetAssign_* elaborate_lval(Design*des,
					 NetScope*scope,
					 bool is_force) const;
      virtual bool is_constant(Module*) const;

    private:
      NetNet* elaborate_lnet_common_(Design*des, NetScope*scope,
				     bool implicit_net_ok,
				     bool bidirectional_flag) const;
    private:
      svector<PExpr*>parms_;
      PExpr*repeat_;
};

/*
 * Event expressions are expressions that can be combined with the
 * event "or" operator. These include "posedge foo" and similar, and
 * also include named events. "edge" events are associated with an
 * expression, whereas named events simply have a name, which
 * represents an event variable.
 */
class PEEvent : public PExpr {

    public:
      enum edge_t {ANYEDGE, POSEDGE, NEGEDGE, POSITIVE};

	// Use this constructor to create events based on edges or levels.
      PEEvent(edge_t t, PExpr*e);

      ~PEEvent();

      edge_t type() const;
      PExpr* expr() const;

      virtual void dump(ostream&) const;

    private:
      edge_t type_;
      PExpr *expr_;
};

/*
 * This holds a floating point constant in the source.
 */
class PEFNumber : public PExpr {

    public:
      explicit PEFNumber(verireal*vp);
      ~PEFNumber();

      const verireal& value() const;

	/* The eval_const method as applied to a floating point number
	   gets the *integer* value of the number. This accounts for
	   any rounding that is needed to get the value. */
      virtual verinum* eval_const(Design*des, NetScope*sc) const;

	/* A PEFNumber is a constant, so this returns true. */
      virtual bool is_constant(Module*) const;

      virtual NetExpr*elaborate_expr(Design*des, NetScope*,
				     int expr_width, bool sys_task_arg) const;
      virtual NetExpr*elaborate_pexpr(Design*des, NetScope*sc) const;

      virtual NetNet* elaborate_net(Design*des, NetScope*scope,
				    unsigned lwidth,
				    const NetExpr* rise,
				    const NetExpr* fall,
				    const NetExpr* decay,
				    Link::strength_t drive0,
				    Link::strength_t drive1) const;

      virtual void dump(ostream&) const;

    private:
      verireal*value_;
};

class PEIdent : public PExpr {

    public:
      explicit PEIdent(perm_string);
      explicit PEIdent(const pform_name_t&);
      ~PEIdent();

	// Add another name to the string of heirarchy that is the
	// current identifier.
      void append_name(perm_string);

      virtual void dump(ostream&) const;
      virtual unsigned test_width(Design*des, NetScope*scope,
				  unsigned min, unsigned lval,
				  bool&unsized_flag) const;

	// Identifiers are allowed (with restrictions) is assign l-values.
      virtual NetNet* elaborate_lnet(Design*des, NetScope*scope,
				     bool implicit_net_ok =false) const;

      virtual NetNet* elaborate_bi_net(Design*des, NetScope*scope) const;

	// Identifiers are also allowed as procedural assignment l-values.
      virtual NetAssign_* elaborate_lval(Design*des,
					 NetScope*scope,
					 bool is_force) const;

	// Structural r-values are OK.
      virtual NetNet* elaborate_net(Design*des, NetScope*scope,
				    unsigned lwidth,
				    const NetExpr* rise,
				    const NetExpr* fall,
				    const NetExpr* decay,
				    Link::strength_t drive0,
				    Link::strength_t drive1) const;

      virtual NetExpr*elaborate_expr(Design*des, NetScope*,
				     int expr_width, bool sys_task_arg) const;
      virtual NetExpr*elaborate_pexpr(Design*des, NetScope*sc) const;

	// Elaborate the PEIdent as a port to a module. This method
	// only applies to Ident expressions.
      NetNet* elaborate_port(Design*des, NetScope*sc) const;

      virtual bool is_constant(Module*) const;
      verinum* eval_const(Design*des, NetScope*sc) const;

      const pform_name_t& path() const { return path_; }

    private:
      pform_name_t path_;

    private:
	// Common functions to calculate parts of part/bit selects.
      bool calculate_parts_(Design*, NetScope*, long&msb, long&lsb) const;
      bool calculate_up_do_width_(Design*, NetScope*, unsigned long&wid) const;

    private:
      NetAssign_*elaborate_lval_net_word_(Design*, NetScope*, NetNet*) const;
      bool elaborate_lval_net_part_(Design*, NetScope*, NetAssign_*) const;
      bool elaborate_lval_net_idx_up_(Design*, NetScope*, NetAssign_*) const;
      bool elaborate_lval_net_idx_do_(Design*, NetScope*, NetAssign_*) const;

    private:
      NetExpr*elaborate_expr_param(Design*des,
				   NetScope*scope,
				   const NetExpr*par,
				   NetScope*found,
				   const NetExpr*par_msb,
				   const NetExpr*par_lsb) const;
      NetExpr*elaborate_expr_net(Design*des,
				 NetScope*scope,
				 NetNet*net,
				 NetScope*found,
				 bool sys_task_arg) const;
      NetExpr*elaborate_expr_net_word_(Design*des,
				       NetScope*scope,
				       NetNet*net,
				       NetScope*found,
				       bool sys_task_arg) const;
      NetExpr*elaborate_expr_net_part_(Design*des,
				   NetScope*scope,
				   NetESignal*net,
				   NetScope*found) const;
      NetExpr*elaborate_expr_net_idx_up_(Design*des,
				   NetScope*scope,
				   NetESignal*net,
				   NetScope*found) const;
      NetExpr*elaborate_expr_net_idx_do_(Design*des,
				   NetScope*scope,
				   NetESignal*net,
				   NetScope*found) const;
      NetExpr*elaborate_expr_net_bit_(Design*des,
				   NetScope*scope,
				   NetESignal*net,
				   NetScope*found) const;

    public:

      NetNet* elaborate_net_array_(Design*des, NetScope*scope,
				   NetNet*sig, unsigned lwidth,
				   const NetExpr* rise,
				   const NetExpr* fall,
				   const NetExpr* decay,
				   Link::strength_t drive0,
				   Link::strength_t drive1) const;

      NetNet* elaborate_net_bitmux_(Design*des, NetScope*scope,
				    NetNet*sig,
				    const NetExpr* rise,
				    const NetExpr* fall,
				    const NetExpr* decay,
				    Link::strength_t drive0,
				    Link::strength_t drive1) const;

    private:
      NetNet* elaborate_lnet_common_(Design*des, NetScope*scope,
				     bool implicit_net_ok,
				     bool bidirectional_flag) const;

      NetNet*make_implicit_net_(Design*des, NetScope*scope) const;

      bool eval_part_select_(Design*des, NetScope*scope, NetNet*sig,
			     unsigned&midx, unsigned&lidx) const;
      NetNet*process_select_(Design*des, NetScope*scope, NetNet*sig) const;

};

class PENumber : public PExpr {

    public:
      explicit PENumber(verinum*vp);
      ~PENumber();

      const verinum& value() const;

      virtual void dump(ostream&) const;
      virtual unsigned test_width(Design*des, NetScope*scope,
				  unsigned min, unsigned lval,
				  bool&unsized_flag) const;

      virtual NetNet* elaborate_net(Design*des, NetScope*scope,
				    unsigned lwidth,
				    const NetExpr* rise,
				    const NetExpr* fall,
				    const NetExpr* decay,
				    Link::strength_t drive0,
				    Link::strength_t drive1) const;
      virtual NetEConst*elaborate_expr(Design*des, NetScope*,
				       int expr_width, bool) const;
      virtual NetExpr*elaborate_pexpr(Design*des, NetScope*sc) const;
      virtual NetAssign_* elaborate_lval(Design*des,
					 NetScope*scope,
					 bool is_force) const;

      virtual verinum* eval_const(Design*des, NetScope*sc) const;

      virtual bool is_the_same(const PExpr*that) const;
      virtual bool is_constant(Module*) const;

    private:
      verinum*const value_;
};

/*
 * This represents a string constant in an expression.
 *
 * The s parameter to the PEString constructor is a C string that this
 * class instance will take for its own. The caller should not delete
 * the string, the destructor will do it.
 */
class PEString : public PExpr {

    public:
      explicit PEString(char*s);
      ~PEString();

      string value() const;
      virtual void dump(ostream&) const;

      virtual unsigned test_width(Design*des, NetScope*scope,
				  unsigned min, unsigned lval,
				  bool&unsized_flag) const;

      virtual NetNet* elaborate_net(Design*des, NetScope*scope,
				    unsigned width,
				    const NetExpr* rise,
				    const NetExpr* fall,
				    const NetExpr* decay,
				    Link::strength_t drive0,
				    Link::strength_t drive1) const;
      virtual NetEConst*elaborate_expr(Design*des, NetScope*,
				       int expr_width, bool) const;
      virtual NetEConst*elaborate_pexpr(Design*des, NetScope*sc) const;
      verinum* eval_const(Design*, NetScope*) const;

      virtual bool is_constant(Module*) const;

    private:
      char*text_;
};

class PEUnary : public PExpr {

    public:
      explicit PEUnary(char op, PExpr*ex);
      ~PEUnary();

      virtual void dump(ostream&out) const;

      virtual NetNet* elaborate_net(Design*des, NetScope*scope,
				    unsigned width,
				    const NetExpr* rise,
				    const NetExpr* fall,
				    const NetExpr* decay,
				    Link::strength_t drive0,
				    Link::strength_t drive1) const;
      virtual NetExpr*elaborate_expr(Design*des, NetScope*,
				     int expr_width, bool sys_task_arg) const;
      virtual NetExpr*elaborate_pexpr(Design*des, NetScope*sc) const;
      virtual verinum* eval_const(Design*des, NetScope*sc) const;

      virtual bool is_constant(Module*) const;

    private:
      char op_;
      PExpr*expr_;
};

class PEBinary : public PExpr {

    public:
      explicit PEBinary(char op, PExpr*l, PExpr*r);
      ~PEBinary();

      virtual bool is_constant(Module*) const;

      virtual void dump(ostream&out) const;

      virtual unsigned test_width(Design*des, NetScope*scope,
				  unsigned min, unsigned lval,
				  bool&unsized_flag) const;

      virtual NetNet* elaborate_net(Design*des, NetScope*scope,
				    unsigned width,
				    const NetExpr* rise,
				    const NetExpr* fall,
				    const NetExpr* decay,
				    Link::strength_t drive0,
				    Link::strength_t drive1) const;
      virtual NetEBinary*elaborate_expr(Design*des, NetScope*,
					int expr_width, bool sys_task_arg) const;
      virtual NetExpr*elaborate_pexpr(Design*des, NetScope*sc) const;
      virtual verinum* eval_const(Design*des, NetScope*sc) const;

    protected:
      char op_;
      PExpr*left_;
      PExpr*right_;

      NetEBinary*elaborate_expr_base_(Design*, NetExpr*lp, NetExpr*rp, int use_wid) const;
      NetEBinary*elaborate_eval_expr_base_(Design*, NetExpr*lp, NetExpr*rp, int use_wid) const;

    private:
      NetNet* elaborate_net_add_(Design*des, NetScope*scope,
				 unsigned lwidth,
				 const NetExpr* rise,
				 const NetExpr* fall,
				 const NetExpr* decay) const;
      NetNet* elaborate_net_bit_(Design*des, NetScope*scope,
				 unsigned lwidth,
				 const NetExpr* rise,
				 const NetExpr* fall,
				 const NetExpr* decay) const;
      NetNet* elaborate_net_cmp_(Design*des, NetScope*scope,
				 unsigned lwidth,
				 const NetExpr* rise,
				 const NetExpr* fall,
				 const NetExpr* decay) const;
      NetNet* elaborate_net_div_(Design*des, NetScope*scope,
				 unsigned lwidth,
				 const NetExpr* rise,
				 const NetExpr* fall,
				 const NetExpr* decay) const;
      NetNet* elaborate_net_mod_(Design*des, NetScope*scope,
				 unsigned lwidth,
				 const NetExpr* rise,
				 const NetExpr* fall,
				 const NetExpr* decay) const;
      NetNet* elaborate_net_log_(Design*des, NetScope*scope,
				 unsigned lwidth,
				 const NetExpr* rise,
				 const NetExpr* fall,
				 const NetExpr* decay) const;
      NetNet* elaborate_net_mul_(Design*des, NetScope*scope,
				 unsigned lwidth,
				 const NetExpr* rise,
				 const NetExpr* fall,
				 const NetExpr* decay) const;
      NetNet* elaborate_net_shift_(Design*des, NetScope*scope,
				   unsigned lwidth,
				   const NetExpr* rise,
				   const NetExpr* fall,
				   const NetExpr* decay) const;
};

/*
 * Here are a few specilized classes for handling specific binary
 * operators.
 */
class PEBComp  : public PEBinary {

    public:
      explicit PEBComp(char op, PExpr*l, PExpr*r);
      ~PEBComp();

      virtual unsigned test_width(Design*des, NetScope*scope,
				  unsigned min, unsigned lval,
				  bool&flag) const;

      NetEBinary* elaborate_expr(Design*des, NetScope*scope,
				 int expr_width, bool sys_task_arg) const;
};

class PEBShift  : public PEBinary {

    public:
      explicit PEBShift(char op, PExpr*l, PExpr*r);
      ~PEBShift();

      virtual unsigned test_width(Design*des, NetScope*scope,
				  unsigned min, unsigned lval, bool&flag) const;
};

/*
 * This class supports the ternary (?:) operator. The operator takes
 * three expressions, the test, the true result and the false result.
 */
class PETernary : public PExpr {

    public:
      explicit PETernary(PExpr*e, PExpr*t, PExpr*f);
      ~PETernary();

      virtual bool is_constant(Module*) const;

      virtual void dump(ostream&out) const;
      virtual unsigned test_width(Design*des, NetScope*scope,
				  unsigned min, unsigned lval,
				  bool&unsized_flag) const;

      virtual NetNet* elaborate_net(Design*des, NetScope*scope,
				    unsigned width,
				    const NetExpr* rise,
				    const NetExpr* fall,
				    const NetExpr* decay,
				    Link::strength_t drive0,
				    Link::strength_t drive1) const;
      virtual NetETernary*elaborate_expr(Design*des, NetScope*,
					 int expr_width, bool sys_task_arg) const;
      virtual NetETernary*elaborate_pexpr(Design*des, NetScope*sc) const;
      virtual verinum* eval_const(Design*des, NetScope*sc) const;

    private:
      PExpr*expr_;
      PExpr*tru_;
      PExpr*fal_;
};

/*
 * This class represents a parsed call to a function, including calls
 * to system functions. The parameters in the parms list are the
 * expressions that are passed as input to the ports of the function.
 */
class PECallFunction : public PExpr {
    public:
      explicit PECallFunction(const pform_name_t&n, const svector<PExpr *> &parms);
	// Call of system function (name is not heirarchical)
      explicit PECallFunction(perm_string n, const svector<PExpr *> &parms);
      explicit PECallFunction(perm_string n);
      ~PECallFunction();

      virtual void dump(ostream &) const;

      virtual NetNet* elaborate_net(Design*des, NetScope*scope,
				    unsigned width,
				    const NetExpr* rise,
				    const NetExpr* fall,
				    const NetExpr* decay,
				    Link::strength_t drive0,
				    Link::strength_t drive1) const;
      virtual NetExpr*elaborate_expr(Design*des, NetScope*scope,
				     int expr_wid, bool sys_task_arg) const;

    private:
      pform_name_t path_;
      svector<PExpr *> parms_;

      bool check_call_matches_definition_(Design*des, NetScope*dscope) const;

      NetExpr* elaborate_sfunc_(Design*des, NetScope*scope) const;
      NetNet* elaborate_net_sfunc_(Design*des, NetScope*scope,
				   unsigned width,
				   const NetExpr* rise,
				   const NetExpr* fall,
				   const NetExpr* decay,
				   Link::strength_t drive0,
				   Link::strength_t drive1) const;
};

/*
 * $Log: PExpr.h,v $
 * Revision 1.90  2007/06/04 19:14:06  steve
 *  Build errors in picky GCC compilers.
 *
 * Revision 1.89  2007/06/04 02:19:07  steve
 *  Handle bit/part select of array words in nets.
 *
 * Revision 1.88  2007/05/24 04:07:11  steve
 *  Rework the heirarchical identifier parse syntax and pform
 *  to handle more general combinations of heirarch and bit selects.
 *
 * Revision 1.87  2007/01/16 05:44:14  steve
 *  Major rework of array handling. Memories are replaced with the
 *  more general concept of arrays. The NetMemory and NetEMemory
 *  classes are removed from the ivl core program, and the IVL_LPM_RAM
 *  lpm type is removed from the ivl_target API.
 *
 * Revision 1.86  2006/11/10 04:54:26  steve
 *  Add test_width methods for PETernary and PEString.
 *
 * Revision 1.85  2006/11/04 06:19:24  steve
 *  Remove last bits of relax_width methods, and use test_width
 *  to calculate the width of an r-value expression that may
 *  contain unsized numbers.
 *
 * Revision 1.84  2006/10/30 05:44:49  steve
 *  Expression widths with unsized literals are pseudo-infinite width.
 *
 * Revision 1.83  2006/06/18 04:15:50  steve
 *  Add support for system functions in continuous assignments.
 *
 * Revision 1.82  2006/06/02 04:48:49  steve
 *  Make elaborate_expr methods aware of the width that the context
 *  requires of it. In the process, fix sizing of the width of unary
 *  minus is context determined sizes.
 *
 * Revision 1.81  2006/04/28 04:28:35  steve
 *  Allow concatenations as arguments to inout ports.
 *
 * Revision 1.80  2006/04/16 00:54:04  steve
 *  Cleanup lval part select handling.
 *
 * Revision 1.79  2006/04/16 00:15:43  steve
 *  Fix part selects in l-values.
 *
 * Revision 1.78  2006/03/25 02:36:26  steve
 *  Get rid of excess PESTring:: prefix within class declaration.
 *
 * Revision 1.77  2006/02/02 02:43:57  steve
 *  Allow part selects of memory words in l-values.
 *
 * Revision 1.76  2006/01/02 05:33:19  steve
 *  Node delays can be more general expressions in structural contexts.
 *
 * Revision 1.75  2005/12/07 04:04:23  steve
 *  Allow constant concat expressions.
 *
 * Revision 1.74  2005/11/27 17:01:56  steve
 *  Fix for stubborn compiler.
 *
 * Revision 1.73  2005/11/27 05:56:20  steve
 *  Handle bit select of parameter with ranges.
 *
 * Revision 1.72  2005/11/10 13:28:11  steve
 *  Reorganize signal part select handling, and add support for
 *  indexed part selects.
 *
 *  Expand expression constant propagation to eliminate extra
 *  sums in certain cases.
 *
 * Revision 1.71  2005/10/04 04:09:25  steve
 *  Add support for indexed select attached to parameters.
 *
 * Revision 1.70  2005/08/06 17:58:16  steve
 *  Implement bi-directional part selects.
 *
 * Revision 1.69  2005/07/07 16:22:49  steve
 *  Generalize signals to carry types.
 *
 * Revision 1.68  2005/01/09 20:16:00  steve
 *  Use PartSelect/PV and VP to handle part selects through ports.
 *
 * Revision 1.67  2004/12/29 23:55:43  steve
 *  Unify elaboration of l-values for all proceedural assignments,
 *  including assing, cassign and force.
 *
 *  Generate NetConcat devices for gate outputs that feed into a
 *  vector results. Use this to hande gate arrays. Also let gate
 *  arrays handle vectors of gates when the outputs allow for it.
 *
 * Revision 1.66  2004/10/04 01:10:51  steve
 *  Clean up spurious trailing white space.
 *
 * Revision 1.65  2003/02/08 19:49:21  steve
 *  Calculate delay statement delays using elaborated
 *  expressions instead of pre-elaborated expression
 *  trees.
 *
 *  Remove the eval_pexpr methods from PExpr.
 *
 * Revision 1.64  2003/01/30 16:23:07  steve
 *  Spelling fixes.
 *
 * Revision 1.63  2002/11/09 19:20:48  steve
 *  Port expressions for output ports are lnets, not nets.
 *
 * Revision 1.62  2002/08/12 01:34:58  steve
 *  conditional ident string using autoconfig.
 *
 * Revision 1.61  2002/06/04 05:38:43  steve
 *  Add support for memory words in l-value of
 *  blocking assignments, and remove the special
 *  NetAssignMem class.
 *
 * Revision 1.60  2002/05/23 03:08:51  steve
 *  Add language support for Verilog-2001 attribute
 *  syntax. Hook this support into existing $attribute
 *  handling, and add number and void value types.
 *
 *  Add to the ivl_target API new functions for access
 *  of complex attributes attached to gates.
 *
 * Revision 1.59  2002/04/23 03:53:59  steve
 *  Add support for non-constant bit select.
 *
 * Revision 1.58  2002/04/14 03:55:25  steve
 *  Precalculate unary - if possible.
 *
 * Revision 1.57  2002/04/13 02:33:17  steve
 *  Detect missing indices to memories (PR#421)
 *
 * Revision 1.56  2002/03/09 04:02:26  steve
 *  Constant expressions are not l-values for task ports.
 *
 * Revision 1.55  2002/03/09 02:10:22  steve
 *  Add the NetUserFunc netlist node.
 *
 * Revision 1.54  2001/12/30 21:32:03  steve
 *  Support elaborate_net for PEString objects.
 *
 * Revision 1.53  2001/12/03 04:47:14  steve
 *  Parser and pform use hierarchical names as hname_t
 *  objects instead of encoded strings.
 *
 * Revision 1.52  2001/11/08 05:15:50  steve
 *  Remove string paths from PExpr elaboration.
 *
 * Revision 1.51  2001/11/07 04:26:46  steve
 *  elaborate_lnet uses scope instead of string path.
 *
 * Revision 1.50  2001/11/07 04:01:59  steve
 *  eval_const uses scope instead of a string path.
 */
#endif