iverilog/netmisc.h

#ifndef IVL_netmisc_H
#define IVL_netmisc_H
/*
 * Copyright (c) 1999-2026 Stephen Williams ([email protected])
 *
 *    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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

# include  "netlist.h"

class netsarray_t;

/*
 * Search for a hierarchical name. The input path is one or more name
 * components (name_component_t) which describe a path to the object. The
 * simplest case is the path is a single name_component_t. This is the most
 * usual case. More complex cases might include a string of name components
 * that end in an item or scope, like this:
 *
 *   a.b[1].c
 *
 * In this case, the "path input would include a.b.c, with index expressions
 * on name_component_t for "b". In this case, usually "c" is the found item
 * and "a" and "b" are scopes that lead up to the item.
 *
 * The search will stop when it finds a component in the path that is an
 * object of some sort (other then a scope. So for example, if a.b is an
 * array, then the search for a.b[1].c will stop at a.b, leave a.b[1] in
 * path_head, and "c" in path_tail. It is up to the caller to then note that
 * "c" must be a method of some sort.
 */
struct symbol_search_results {
      inline symbol_search_results() {
	    scope = 0;
	    net = 0;
	    par_val = 0;
	    type = 0;
	    eve = 0;
	    decl_after_use = 0;
	    interface_alias_scope = 0;
	    interface_alias_target = 0;
	    interface_alias_modport = 0;
      }

      inline bool is_scope() const {
	    if (net) return false;
	    if (eve) return false;
	    if (par_val) return false;
	    if (scope) return true;
	    return false;
      }

      inline bool is_found() const {
	    if (net) return true;
	    if (eve) return true;
	    if (par_val) return true;
	    if (scope) return true;
	    return false;
      }

      inline const char *result_type() const {
	    if (net)     return "net";
	    if (eve)     return "named event";
	    if (par_val) return "parameter";
	    if (scope)   return "scope";
	    return "nothing found";
      }

      inline bool through_interface_alias() const {
	    return interface_alias_target != 0;
      }

	// Scope where symbol was located. This is set in all cases,
	// assuming the search succeeded.
      NetScope*scope;
	// If this was a net, the signal itself.
      NetNet*net;
	// If this was a parameter, the value expression and the
	// optional value dimensions.
      const NetExpr*par_val;
      ivl_type_t type;
	// If this is a named event, ...
      NetEvent*eve;
	// If a symbol was located but skipped because its lexical position
	// is after the lexical position of the name being searched, it is
	// stored here. If more than one such symbol is found, the first
	// one is retained.
      const LineInfo*decl_after_use;

	// If lookup traversed an interface-typed formal port alias, these
	// fields describe the alias edge. The resolved object remains in the
	// normal scope/net/parameter/event fields.
      NetScope*interface_alias_scope;
      perm_string interface_alias_name;
      NetScope*interface_alias_target;
      const PModport*interface_alias_modport;

        // Store bread crumbs of the search here. The path_tail is the parts
        // of the original path that were not found, or are after an object
        // (and so are probably members or methods).
      pform_name_t path_tail;
        // The path_head is the parts of the original path that were found.
        // The last item in path_head is the final name (possibly before the
        // path_tail items) that identifies the object. This name may contain
        // index expressions. If the search result is a scope, then this name
        // is also the name of the scope identified.
      pform_name_t path_head;
};

/*
 * Test the search results and return true if this represents a function
 * return value. That will be the case if the object is a net, the scope
 * containing the object is a FUNCtion, and the containing scope and the
 * object have the same name.
 */
static inline bool test_function_return_value(const symbol_search_results&search_results)
{
      if (!search_results.net) return false;
      if (search_results.scope->type()!=NetScope::FUNC) return false;
      if (search_results.net->name() != search_results.scope->basename()) return false;
      return true;
}

extern bool symbol_search(const LineInfo *li, Design *des, NetScope *scope,
			  pform_name_t path, unsigned int lexical_pos,
			  struct symbol_search_results *res);

/* The forward-reference flag applies only to the terminal name. Prefix
   components still use lexical_pos. */
extern bool symbol_search(const LineInfo *li, Design *des, NetScope *scope,
			  const pform_scoped_name_t &path,
			  unsigned int lexical_pos,
			  struct symbol_search_results *res,
			  bool allow_terminal_forward_reference = false);

extern bool check_interface_modport_access(const LineInfo *li, Design *des,
					   const symbol_search_results &res,
					   bool is_write);

/*
 * This function transforms an expression by either zero or sign extending
 * the high bits until the expression has the desired width. This may mean
 * not transforming the expression at all, if it is already wide enough.
 * The extension method and the returned expression type is determined by
 * signed_flag.
 */
extern NetExpr*pad_to_width(NetExpr*expr, unsigned wid, bool signed_flag,
			    const LineInfo&info, ivl_type_t use_type = 0);
/*
 * This version determines the extension method from the base expression type.
 */
inline NetExpr*pad_to_width(NetExpr*expr, unsigned wid, const LineInfo&info, ivl_type_t use_type = 0)
{
      return pad_to_width(expr, wid, expr->has_sign(), info, use_type);
}

/*
 * This function transforms an expression by either zero or sign extending
 * or discarding the high bits until the expression has the desired width.
 * This may mean not transforming the expression at all, if it is already
 * the correct width. The extension method (if needed) and the returned
 * expression type is determined by signed_flag.
 */
extern NetExpr*cast_to_width(NetExpr*expr, unsigned wid, bool signed_flag,
			     const LineInfo&info);

extern NetNet*pad_to_width(Design*des, NetNet*n, unsigned w,
                           const LineInfo&info);

extern NetNet*pad_to_width_signed(Design*des, NetNet*n, unsigned w,
                                  const LineInfo&info);

/*
 * Generate the nodes necessary to cast an expression (a net) to a
 * real value.
 */
extern NetNet*cast_to_int4(Design*des, NetScope*scope, NetNet*src, unsigned wid);
extern NetNet*cast_to_int2(Design*des, NetScope*scope, NetNet*src, unsigned wid);
extern NetNet*cast_to_real(Design*des, NetScope*scope, NetNet*src);

extern NetExpr*cast_to_int4(NetExpr*expr, unsigned width);
extern NetExpr*cast_to_int2(NetExpr*expr, unsigned width);
extern NetExpr*cast_to_real(NetExpr*expr);

/*
 * Take the input expression and return a variation that assures that
 * the expression is 1-bit wide and logical. This reflects the needs
 * of conditions i.e. for "if" statements or logical operators.
 */
extern NetExpr*condition_reduce(NetExpr*expr);

/*
 * This function transforms an expression by cropping the high bits
 * off with a part select. The result has the width w passed in. This
 * function does not pad, use pad_to_width if padding is desired.
 */
extern NetNet*crop_to_width(Design*des, NetNet*n, unsigned w);

extern bool calculate_part(const LineInfo*li, Design*des, NetScope*scope,
			   const index_component_t&index,
			   long&off, unsigned long&wid);

/*
 * These functions generate an equation to normalize an expression using
 * the provided vector/array information.
 */
extern NetExpr*normalize_variable_base(NetExpr *base, long msb, long lsb,
                                       unsigned long wid, bool is_up,
				       long slice_off =0);

/*
 * Calculate a canonicalizing expression for a bit select, when the
 * base expression is the last index of an otherwise complete bit
 * select. For example:
 *   reg [3:0][7:0] foo;
 *   ... foo[1][x] ...
 * base is (x) and the generated expression will be (x+8).
 */
extern NetExpr*normalize_variable_bit_base(const std::list<long>&indices, NetExpr *base,
					   const NetNet*reg);

/*
 * This is similar to normalize_variable_bit_base, but the tail index
 * it a base and width, instead of a bit. This is used for handling
 * indexed part selects:
 *   reg [3:0][7:0] foo;
 *   ... foo[1][x +: 2]
 * base is (x), wid input is (2), and is_up is (true). The output
 * expression is (x+8).
 */
extern NetExpr *normalize_variable_part_base(const std::list<long>&indices, NetExpr*base,
					     const NetNet*reg,
					     unsigned long wid, bool is_up);
/*
 * Calculate a canonicalizing expression for a slice select. The
 * indices array is less than needed to fully address a bit, so the
 * result is a slice of the packed array. The return value is an
 * expression that gets to the base of the slice, and (lwid) becomes
 * the width of the slice, in bits. For example:
 *   reg [4:1][7:0] foo
 *   ...foo[x]...
 * base is (x) and the generated expression will be (x*8 - 8), with
 * lwid set to (8).
 */
extern NetExpr*normalize_variable_slice_base(const std::list<long>&indices, NetExpr *base,
					     const NetNet*reg, unsigned long&lwid);

/*
 * The as_indices() manipulator is a convenient way to emit a list of
 * index values in the form [<>][<>]....
 */
template <class TYPE> struct __IndicesManip {
      explicit inline __IndicesManip(const std::list<TYPE>&v) : val(v) { }
      const std::list<TYPE>&val;
};
template <class TYPE> inline __IndicesManip<TYPE> as_indices(const std::list<TYPE>&indices)
{ return __IndicesManip<TYPE>(indices); }

extern std::ostream& operator << (std::ostream&o, __IndicesManip<long>);
extern std::ostream& operator << (std::ostream&o, __IndicesManip<NetExpr*>);

/*
 * Given a list of index expressions, generate elaborated expressions
 * and constant values, if possible.
 */
struct indices_flags {
      bool invalid;    // at least one index failed elaboration
      bool variable;   // at least one index is a dynamic value
      bool undefined;  // at least one index is an undefined value
};
extern void indices_to_expressions(Design*des, NetScope*scope,
				     // loc is for error messages.
				   const LineInfo*loc,
				     // src is the index list, and count is
				     // the number of items in the list to use.
				   const std::list<index_component_t>&src, unsigned count,
				     // True if the expression MUST be constant.
				   bool need_const,
				     // These are the outputs.
				   indices_flags&flags,
				   std::list<NetExpr*>&indices,std::list<long>&indices_const);

extern NetExpr*normalize_variable_unpacked(const NetNet*net, const std::list<long>&indices);
extern NetExpr*normalize_variable_unpacked(const netsarray_t*net, const std::list<long>&indices);

extern NetExpr*normalize_variable_unpacked(const NetNet*net, const std::list<NetExpr*>&indices);
extern NetExpr*normalize_variable_unpacked(const LineInfo&loc, const netsarray_t*net, const std::list<NetExpr*>&indices);

extern NetExpr*make_canonical_index(Design*des, NetScope*scope,
				      // loc for error messages
				    const LineInfo*loc,
				      // src is the index list
				    const std::list<index_component_t>&src,
				      // This is the reference type
				    const netsarray_t*stype,
				      // True if the expression MUST be constant.
				    bool need_const);

/*
 * This function takes as input a NetNet signal and adds a constant
 * value to it. If the val is 0, then simply return sig. Otherwise,
 * return a new NetNet value that is the output of an addition.
 *
 * Not currently used.
 */
#if 0
extern NetNet*add_to_net(Design*des, NetNet*sig, long val);
#endif
extern NetNet*sub_net_from(Design*des, NetScope*scope, long val, NetNet*sig);

/*
 * Make a NetEConst object that contains only X bits.
 */
extern NetEConst*make_const_x(unsigned long wid);
extern NetEConst*make_const_0(unsigned long wid);
extern NetEConst*make_const_val(unsigned long val);
extern NetEConst*make_const_val_s(long val);

/*
 * Make a const net.
 */
extern NetNet* make_const_0(Design*des, NetScope*scope, unsigned long wid);
extern NetNet* make_const_x(Design*des, NetScope*scope, unsigned long wid);
extern NetNet* make_const_z(Design*des, NetScope*scope, unsigned long wid);

/*
 * In some cases the lval is accessible as a pointer to the head of
 * a list of NetAssign_ objects. This function returns the width of
 * the l-value represented by this list.
 */
extern unsigned count_lval_width(const class NetAssign_*first);

/*
 * This function elaborates an expression, and tries to evaluate it
 * right away. If the expression can be evaluated, this returns a
 * constant expression. If it cannot be evaluated, it returns whatever
 * it can. If the expression cannot be elaborated, return 0.
 *
 * The context_width is the width of the context where the expression is
 * being elaborated, or -1 if the expression is self-determined, or -2
 * if the expression is lossless self-determined (this last option is
 * treated as standard self-determined if the gn_strict_expr_width flag
 * is set).
 *
 * cast_type allows the expression to be cast to a different type
 * (before it is evaluated). If cast to a vector type, the vector
 * width will be set to the context_width. The default value of
 * IVL_VT_NO_TYPE causes the expression to retain its self-determined
 * type.
 */
class PExpr;

extern NetExpr* elab_and_eval(Design*des, NetScope*scope,
			      PExpr*pe, int context_width,
                              bool need_const =false,
                              bool annotatable =false,
			      ivl_variable_type_t cast_type =IVL_VT_NO_TYPE,
			      bool force_unsigned =false);

/*
 * This form of elab_and_eval uses the ivl_type_t to carry type
 * information instead of the piecemeal form. We should transition to
 * this form as we reasonably can.
 */
extern NetExpr* elab_and_eval(Design*des, NetScope*scope,
			      PExpr*expr, ivl_type_t lv_net_type,
			      bool need_const);

/*
 * This function is a variant of elab_and_eval that elaborates and
 * evaluates the arguments of a system task.
 */
extern NetExpr* elab_sys_task_arg(Design*des, NetScope*scope,
                                  perm_string name, unsigned arg_idx,
                                  PExpr*pe, bool need_const =false);
/*
 * This function elaborates an expression as if it is for the r-value
 * of an assignment, The lv_type and lv_width are the type and width
 * of the l-value, and the expr is the expression to elaborate. The
 * result is the NetExpr elaborated and evaluated. (See elab_expr.cc)
 *
 * I would rather that all calls to elaborate_rval_expr use the
 * lv_net_type argument to express the l-value type, but, for now,
 * that it not possible. Those cases will be indicated by the
 * lv_net_type being set to nil.
 */
extern NetExpr* elaborate_rval_expr(Design*des, NetScope*scope,
				    ivl_type_t lv_net_type,
				    ivl_variable_type_t lv_type,
				    unsigned lv_width, PExpr*expr,
				    bool need_const =false,
				    bool force_unsigned =false);
/*
 * Same as above, but lv_width and lv_type are derived from the lv_net_type.
 */
extern NetExpr* elaborate_rval_expr(Design *des, NetScope *scope,
				    ivl_type_t lv_net_type, PExpr *expr,
				    bool need_const = false,
				    bool force_unsigned = false);

extern bool evaluate_range(Design*des, NetScope*scope, const LineInfo*li,
                           const pform_range_t&range,
                           long&index_l, long&index_r);

extern bool evaluate_ranges(Design*des, NetScope*scope, const LineInfo*li,
			    netranges_t&llist,
			    const std::list<pform_range_t>&rlist);
/*
 * This procedure evaluates an expression and if the evaluation is
 * successful the original expression is replaced with the new one.
 */
void eval_expr(NetExpr*&expr, int context_width =-1);

/*
 * Get the long integer value for the passed in expression, if
 * possible. If it is not possible (the expression is not evaluated
 * down to a constant) then return false and leave value unchanged.
 */
bool eval_as_long(long&value, const NetExpr*expr);
bool eval_as_double(double&value, NetExpr*expr);

/*
 * Evaluate an entire scope path in the context of the given scope.
 */
extern std::list<hname_t> eval_scope_path(Design*des, NetScope*scope,
					  const pform_name_t&path);
extern hname_t eval_path_component(Design*des, NetScope*scope,
				   const name_component_t&comp,
				   bool&error_flag);

/*
 * If this scope is contained within a class scope (i.e. a method of a
 * class) then return the class definition that contains it.
 */
extern const netclass_t*find_class_containing_scope(const LineInfo&loc,const NetScope*scope);
extern NetScope* find_method_containing_scope(const LineInfo&log, NetScope*scope);

/*
 * Return true if the data type is a type that is normally available
 * in vector for. IVL_VT_BOOL and IVL_VT_LOGIC are vectorable,
 * IVL_VT_REAL is not.
 */
extern bool type_is_vectorable(ivl_variable_type_t type);

/*
 * Return a human readable version of the operator.
 */
const char *human_readable_op(const char op, bool unary = false);

/*
 * Is the expression a constant value and if so what is its logical
 * value.
 *
 * C_NON - the expression is not a constant value.
 * C_0   - the expression is constant and it has a false value.
 * C_1   - the expression is constant and it has a true value.
 * C_X   - the expression is constant and it has an 'bX value.
 */
enum const_bool { C_NON, C_0, C_1, C_X };
const_bool const_logical(const NetExpr*expr);

/*
 * When scaling a real value to a time we need to do some standard
 * processing.
 */
extern uint64_t get_scaled_time_from_real(const Design*des,
                                          NetScope*scope,
                                          const NetECReal*val);

extern void collapse_partselect_pv_to_concat(Design*des, NetNet*sig);

extern bool evaluate_index_prefix(Design*des, NetScope*scope,
				  std::list<long>&prefix_indices,
				  const std::list<index_component_t>&indices);

extern NetExpr*collapse_array_indices(Design*des, NetScope*scope, const NetNet*net,
				      const std::list<index_component_t>&indices);

extern NetExpr*collapse_array_exprs(Design*des, NetScope*scope,
				    const LineInfo*loc, const NetNet*net,
				    const std::list<index_component_t>&indices);

extern void assign_unpacked_with_bufz(Design*des, NetScope*scope,
				      const LineInfo*loc,
				      NetNet*lval, NetNet*rval,
				      const drive_strength_t &drive =
					    drive_strength_t(),
				      const delay_exprs_t &delays =
					    delay_exprs_t());

extern NetPartSelect* detect_partselect_lval(Link&pin);

/*
 * Print a warning if we find a mixture of default and explicit timescale
 * based delays in the design, since this is likely an error.
 */
extern void check_for_inconsistent_delays(const NetScope*scope);

#endif /* IVL_netmisc_H */