Put off evaluation of concatenation repeat expresions

 until after parameters are defined. This allows parms
 to be used in repeat expresions.

 Add the builtin $signed system function.

README.txt

@@ -405,6 +405,35 @@ constructs.
   - force to nets are not supported. Force to variables, and
     assign/deassign, are supported.
 
+5.0 Nonstandard Constructs
+
+Icarus Verilog includes some features that are not part of the
+IEEE1364 standard, but have well defined meaning. These are extensions
+to the language.
+
+    $sizeof(<expr>)
+	This system function returns the size in bits of the
+	expression that is its argument. The result of this
+	function is undefined if the argument doesn't have a
+	self-determined size.
+
+    Builtin system functions
+
+	Certain of the system functions have well defined meanings, so
+	can theoretically be evaluated at compile time, instead of
+	using runtime VPI code. Doing so means that VPI cannot
+	override the definitions of functions handled in this
+	manner. On the other hand, this makes them synthesizeable, and
+	also allows for more agressive constant propagation. The
+	functions handled in this manner are:
+
+		$signed
+		$sizeof
+		$unsigned
+
+	Implementations of these system functions in VPI modules will
+	be ignored.
+
 6.0 CREDITS
 
 Except where otherwise noted, Icarus Verilog, ivl and ivlpp are

design_dump.cc

@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #if !defined(WINNT) && !defined(macintosh)
-#ident "$Id: design_dump.cc,v 1.122 2002/03/09 02:10:22 steve Exp $"
+#ident "$Id: design_dump.cc,v 1.123 2002/05/05 21:11:49 steve Exp $"
 #endif
 
 # include "config.h"
@@ -850,8 +850,8 @@ void NetEBinary::dump(ostream&o) const
 
 void NetEConcat::dump(ostream&o) const
 {
-      if (repeat_ != 1)
-	    o << repeat_;
+      if (repeat_)
+	    o << *repeat_;
 
       if (parms_[0])
 	    o << "{" << *parms_[0];
@@ -980,6 +980,13 @@ void Design::dump(ostream&o) const
 
 /*
  * $Log: design_dump.cc,v $
+ * Revision 1.123  2002/05/05 21:11:49  steve
+ *  Put off evaluation of concatenation repeat expresions
+ *  until after parameters are defined. This allows parms
+ *  to be used in repeat expresions.
+ *
+ *  Add the builtin $signed system function.
+ *
  * Revision 1.122  2002/03/09 02:10:22  steve
  *  Add the NetUserFunc netlist node.
  *

elab_expr.cc

@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #if !defined(WINNT) && !defined(macintosh)
-#ident "$Id: elab_expr.cc,v 1.57 2002/04/27 05:03:46 steve Exp $"
+#ident "$Id: elab_expr.cc,v 1.58 2002/05/05 21:11:49 steve Exp $"
 #endif
 
 # include "config.h"
@@ -182,6 +182,29 @@ NetExpr* PECallFunction::elaborate_sfunc_(Design*des, NetScope*scope) const
 	    return sub;
       }
 
+	/* Interpret the internal $sizeof system function to return
+	   the bit width of the sub-expression. The value of the
+	   sub-expression is not used, so the expression itself can be
+	   deleted. */
+      if (strcmp(path_.peek_name(0), "$sizeof") == 0) {
+	    if ((parms_.count() != 1) || (parms_[0] == 0)) {
+		  cerr << get_line() << ": error: The $sizeof() function "
+		       << "takes exactly one(1) argument." << endl;
+		  des->errors += 1;
+		  return 0;
+	    }
+
+	    PExpr*expr = parms_[0];
+	    NetExpr*sub = expr->elaborate_expr(des, scope, true);
+	    verinum val (sub->expr_width(), sizeof(unsigned));
+	    delete sub;
+
+	    sub = new NetEConst(val);
+	    sub->set_line(*this);
+
+	    return sub;
+      }
+
       unsigned wid = 32;
 
       if (strcmp(path_.peek_name(0), "$time") == 0)
@@ -322,7 +345,7 @@ NetExpr* PECallFunction::elaborate_expr(Design*des, NetScope*scope, bool) const
 
 NetExpr* PEConcat::elaborate_expr(Design*des, NetScope*scope, bool) const
 {
-      unsigned repeat = 1;
+      NetExpr* repeat = 0;
 
 	/* If there is a repeat expression, then evaluate the constant
 	   value and set the repeat count. */
@@ -338,10 +361,9 @@ NetExpr* PEConcat::elaborate_expr(Design*des, NetScope*scope, bool) const
 		  cerr << get_line() << ":      : The expression is: "
 		       << *tmp << endl;
 		  des->errors += 1;
-		  return 0;
 	    }
 
-	    repeat = rep->value().as_ulong();
+	    repeat = rep;
       }
 
 	/* Make the empty concat expression. */
@@ -842,6 +864,13 @@ NetExpr* PEUnary::elaborate_expr(Design*des, NetScope*scope, bool) const
 
 /*
  * $Log: elab_expr.cc,v $
+ * Revision 1.58  2002/05/05 21:11:49  steve
+ *  Put off evaluation of concatenation repeat expresions
+ *  until after parameters are defined. This allows parms
+ *  to be used in repeat expresions.
+ *
+ *  Add the builtin $signed system function.
+ *
  * Revision 1.57  2002/04/27 05:03:46  steve
  *  Preserve stringiness string part select and concatenation.
  *

elab_pexpr.cc

@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #if !defined(WINNT) && !defined(macintosh)
-#ident "$Id: elab_pexpr.cc,v 1.13 2002/01/28 00:52:41 steve Exp $"
+#ident "$Id: elab_pexpr.cc,v 1.14 2002/05/05 21:11:50 steve Exp $"
 #endif
 
 # include "config.h"
@@ -66,28 +66,21 @@ NetExpr*PEBinary::elaborate_pexpr (Design*des, NetScope*scope) const
  */
 NetEConcat* PEConcat::elaborate_pexpr(Design*des, NetScope*scope) const
 {
-      unsigned repeat = 1;
+      NetExpr* repeat = 0;
 
 	/* If there is a repeat expression, then evaluate the constant
-	   value and set the repeat count.
-
-	   XXXX Potential bug XXX In principle, the repeat expression
-	   can have a parameter name in it. Since where are in the
-	   working of parameters now, we will not be able to
-	   accurately evaluate such expressions. So eventually, I will
-	   need to be able to defer the evaluation of the expression. */
+	   value and set the repeat count.  */
       if (repeat_) {
-	    verinum*vrep = repeat_->eval_const(des, scope);
-	    if (vrep == 0) {
+	    repeat = repeat_->elaborate_pexpr(des, scope);
+	    if (repeat == 0) {
 		  cerr << get_line() << ": error: "
 			"concatenation repeat expression cannot be evaluated."
 		       << endl;
 		  des->errors += 1;
-		  return 0;
 	    }
 
-	    repeat = vrep->as_ulong();
-	    delete vrep;
+	      /* continue on even if the repeat expression doesn't
+		 work, as we can find more errors. */
       }
 
 	/* Make the empty concat expression. */
@@ -224,6 +217,13 @@ NetExpr*PEUnary::elaborate_pexpr (Design*des, NetScope*scope) const
 
 /*
  * $Log: elab_pexpr.cc,v $
+ * Revision 1.14  2002/05/05 21:11:50  steve
+ *  Put off evaluation of concatenation repeat expresions
+ *  until after parameters are defined. This allows parms
+ *  to be used in repeat expresions.
+ *
+ *  Add the builtin $signed system function.
+ *
  * Revision 1.13  2002/01/28 00:52:41  steve
  *  Add support for bit select of parameters.
  *  This leads to a NetESelect node and the

eval_tree.cc

@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #if !defined(WINNT) && !defined(macintosh)
-#ident "$Id: eval_tree.cc,v 1.37 2002/04/27 05:03:46 steve Exp $"
+#ident "$Id: eval_tree.cc,v 1.38 2002/05/05 21:11:50 steve Exp $"
 #endif
 
 # include "config.h"
@@ -705,17 +705,23 @@ NetEConst* NetEBShift::eval_tree()
 
 NetEConst* NetEConcat::eval_tree()
 {
+      unsigned repeat_val = repeat();
+
+      unsigned gap = 0;
       for (unsigned idx = 0 ;  idx < parms_.count() ;  idx += 1) {
 
 	      // Parameter not here? This is an error, but presumably
 	      // already caught and we are here just to catch more.
 	    if (parms_[idx] == 0)
 		  continue;
 
+
 	      // If this parameter is already a constant, all is well
 	      // so go on.
-	    if (dynamic_cast<NetEConst*>(parms_[idx]))
+	    if (dynamic_cast<NetEConst*>(parms_[idx])) {
+		  gap += parms_[idx]->expr_width();
 		  continue;
+	    }
 
 	      // Finally, try to evaluate the parameter expression
 	      // that is here. If I succeed, reset the parameter to
@@ -725,23 +731,24 @@ NetEConst* NetEConcat::eval_tree()
 	    if (expr) {
 		  delete parms_[idx];
 		  parms_[idx] = expr;
+		  gap += expr->expr_width();
 	    }
       }
 
 	// Handle the special case that the repeat expression is
 	// zero. In this case, just return a 0 value with the expected
 	// width.
-      if (repeat_ == 0) {
+      if (repeat_val == 0) {
 	    verinum val (verinum::V0, expr_width());
 	    NetEConst*res = new NetEConst(val);
 	    res->set_width(val.len());
 	    return res;
       }
 
-	// Figure out the width of the repeated expression, and make a
-	// verinum to hold the result.
-      unsigned gap = expr_width() / repeat_;
-      verinum val (verinum::Vx, repeat_ * gap);
+	// At this point, the "gap" is the width of a single repeat of
+	// the concatenation. The total width of the result is the gap
+	// times the repeat count.
+      verinum val (verinum::Vx, repeat_val * gap);
 
 	// build up the result from least significant to most.
 
@@ -754,7 +761,7 @@ NetEConst* NetEConcat::eval_tree()
 
 	    verinum tmp = expr->value();
 	    for (unsigned bit = 0;  bit < tmp.len(); bit += 1, cur += 1)
-		  for (unsigned rep = 0 ;  rep < repeat_ ;  rep += 1)
+		  for (unsigned rep = 0 ;  rep < repeat_val ;  rep += 1)
 			val.set(rep*gap+cur, tmp[bit]);
 
 	    is_string_flag = is_string_flag && tmp.is_string();
@@ -1079,6 +1086,13 @@ NetEConst* NetEUReduce::eval_tree()
 
 /*
  * $Log: eval_tree.cc,v $
+ * Revision 1.38  2002/05/05 21:11:50  steve
+ *  Put off evaluation of concatenation repeat expresions
+ *  until after parameters are defined. This allows parms
+ *  to be used in repeat expresions.
+ *
+ *  Add the builtin $signed system function.
+ *
  * Revision 1.37  2002/04/27 05:03:46  steve
  *  Preserve stringiness string part select and concatenation.
  *