Calculate expression widths at elaboration time.

netlist.cc

@@ -17,10 +17,11 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #if !defined(WINNT)
-#ident "$Id: netlist.cc,v 1.2 1998/11/07 17:05:05 steve Exp $"
+#ident "$Id: netlist.cc,v 1.3 1998/11/07 19:17:10 steve Exp $"
 #endif
 
 # include  <cassert>
+# include  <typeinfo>
 # include  "netlist.h"
 
 void connect(NetObj::Link&l, NetObj::Link&r)
@@ -98,6 +99,8 @@ NetAssign::NetAssign(NetNet*lv, NetExpr*rv)
       for (unsigned idx = 0 ;  idx < pin_count() ;  idx += 1) {
 	    connect(pin(idx), lv->pin(idx));
       }
+
+      rval_->set_width(lval_->pin_count());
 }
 
 NetAssign::~NetAssign()
@@ -129,28 +132,89 @@ NetExpr::~NetExpr()
 {
 }
 
+void NetExpr::set_width(unsigned w)
+{
+      cerr << typeid(*this).name() << ": set_width(unsigned) "
+	    "not implemented." << endl;
+      expr_width(w);
+}
+
+
 NetEBinary::~NetEBinary()
 {
 }
 
-NetEConst::~NetEConst()
-{
-}
 
 NetEBinary::NetEBinary(char op, NetExpr*l, NetExpr*r)
 : op_(op), left_(l), right_(r)
 {
       switch (op_) {
 	  case 'e':
-	    natural_width(1);
+	    expr_width(1);
 	    break;
 	  default:
-	    natural_width(left_->natural_width() > right_->natural_width()
+	    expr_width(left_->expr_width() > right_->expr_width()
-			  ? left_->natural_width() : right_->natural_width());
+			  ? left_->expr_width() : right_->expr_width());
 	    break;
       }
 }
 
+void NetEBinary::set_width(unsigned w)
+{
+      switch (op_) {
+	      /* Comparison operators allow the subexpressions to have
+		 their own natural width. Do not recurse the
+		 set_width(). */
+	  case 'e':
+	    assert(w == 1);
+	    expr_width(w);
+	    break;;
+
+	      /* The default rule is that the operands of the binary
+		 operator might as well use the same width as the
+		 output from the binary operation. */
+	  default:
+	    cerr << "NetEBinary::set_width(): Using default for " <<
+		  op_ << "." << endl;
+
+	  case '+':
+	    left_->set_width(w);
+	    right_->set_width(w);
+	    expr_width(w);
+	    break;
+      }
+}
+
+NetEConst::~NetEConst()
+{
+}
+
+void NetEConst::set_width(unsigned w)
+{
+      assert(w <= value_.len());
+      expr_width(w);
+}
+
+NetESignal::~NetESignal()
+{
+}
+
+void NetESignal::set_width(unsigned w)
+{
+      assert(w == sig_->pin_count());
+      expr_width(w);
+}
+
+NetEUnary::~NetEUnary()
+{
+}
+
+void NetEUnary::set_width(unsigned w)
+{
+      expr_->set_width(w);
+      expr_width(w);
+}
+
 void Design::add_signal(NetNet*net)
 {
       assert(net->design_ == 0);
@@ -253,6 +317,9 @@ void Design::add_process(NetProcTop*pro)
 
 /*
  * $Log: netlist.cc,v $
+ * Revision 1.3  1998/11/07 19:17:10  steve
+ *  Calculate expression widths at elaboration time.
+ *
  * Revision 1.2  1998/11/07 17:05:05  steve
  *  Handle procedural conditional, and some
  *  of the conditional expressions.

netlist.h

@@ -19,7 +19,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #if !defined(WINNT)
-#ident "$Id: netlist.h,v 1.2 1998/11/07 17:05:05 steve Exp $"
+#ident "$Id: netlist.h,v 1.3 1998/11/07 19:17:10 steve Exp $"
 #endif
 
 /*
@@ -475,6 +475,13 @@ class NetProcTop {
 /* =========
  * There are cases where expressions need to be represented. The
  * NetExpr class is the root of a heirarchy that serves that purpose.
+ *
+ * The expr_width() is the width of the expression, that accounts
+ * for the widths of the sub-expressions I might have. It is up to the
+ * derived classes to properly set the expr width, if need be. The
+ * set_width() method is used to compel an expression to have a
+ * certain width, and is used particulary when the expression is an
+ * rvalue in an assignment statement.
  */
 class NetExpr {
     public:
@@ -484,10 +491,11 @@ class NetExpr {
       virtual void expr_scan(struct expr_scan_t*) const =0;
       virtual void dump(ostream&) const;
 
-      unsigned natural_width() const { return width_; }
+      unsigned expr_width() const { return width_; }
+      virtual void set_width(unsigned);
 
     protected:
-      void natural_width(unsigned w) { width_ = w; }
+      void expr_width(unsigned w) { width_ = w; }
 
     private:
       unsigned width_;
@@ -508,6 +516,8 @@ class NetEBinary  : public NetExpr {
 
       char op() const { return op_; }
 
+      void set_width(unsigned w);
+
       virtual void expr_scan(struct expr_scan_t*) const;
       virtual void dump(ostream&) const;
 
@@ -526,6 +536,7 @@ class NetEConst  : public NetExpr {
 
       const verinum&value() const { return value_; }
 
+      virtual void set_width(unsigned w);
       virtual void expr_scan(struct expr_scan_t*) const;
       virtual void dump(ostream&) const;
 
@@ -537,11 +548,14 @@ class NetEUnary  : public NetExpr {
 
     public:
       NetEUnary(char op, NetExpr*ex)
-      : NetExpr(ex->natural_width()), op_(op), expr_(ex) { }
+      : NetExpr(ex->expr_width()), op_(op), expr_(ex) { }
+      ~NetEUnary();
 
       char op() const { return op_; }
       const NetExpr* expr() const { return expr_; }
 
+      void set_width(unsigned w);
+
       virtual void expr_scan(struct expr_scan_t*) const;
       virtual void dump(ostream&) const;
 
@@ -574,9 +588,12 @@ class NetESignal  : public NetExpr {
     public:
       NetESignal(NetNet*n)
       : NetExpr(n->pin_count()), sig_(n) { }
+      ~NetESignal();
 
       const string& name() const { return sig_->name(); }
 
+      virtual void set_width(unsigned);
+
       virtual void expr_scan(struct expr_scan_t*) const;
       virtual void dump(ostream&) const;
 
@@ -653,6 +670,9 @@ inline ostream& operator << (ostream&o, const NetExpr&exp)
 
 /*
  * $Log: netlist.h,v $
+ * Revision 1.3  1998/11/07 19:17:10  steve
+ *  Calculate expression widths at elaboration time.
+ *
  * Revision 1.2  1998/11/07 17:05:05  steve
  *  Handle procedural conditional, and some
  *  of the conditional expressions.

t-vvm.cc

@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #if !defined(WINNT)
-#ident "$Id: t-vvm.cc,v 1.2 1998/11/07 17:05:06 steve Exp $"
+#ident "$Id: t-vvm.cc,v 1.3 1998/11/07 19:17:10 steve Exp $"
 #endif
 
 # include  <iostream>
@@ -69,14 +69,13 @@ class target_vvm : public target_t {
 class vvm_proc_rval  : public expr_scan_t {
 
     public:
-      explicit vvm_proc_rval(ostream&os, unsigned width)
+      explicit vvm_proc_rval(ostream&os)
-      : result(""), os_(os), width_(width) { }
+      : result(""), os_(os) { }
 
       string result;
 
     private:
       ostream&os_;
-      unsigned width_;
 
     private:
       virtual void expr_const(const NetEConst*);
@@ -89,8 +88,9 @@ class vvm_proc_rval  : public expr_scan_t {
 void vvm_proc_rval::expr_const(const NetEConst*expr)
 {
       string tname = make_temp();
-      os_ << "        vvm_bitset_t<" << width_ << "> " << tname << ";" << endl;
+      os_ << "        vvm_bitset_t<" << expr->expr_width() << "> "
-      for (unsigned idx = 0 ;  idx < width_ ;  idx += 1) {
+	  << tname << ";" << endl;
+      for (unsigned idx = 0 ;  idx < expr->expr_width() ;  idx += 1) {
 	    os_ << "        " << tname << "[" << idx << "] = ";
 	    switch (expr->value().get(idx)) {
 		case verinum::V0:
@@ -127,7 +127,8 @@ void vvm_proc_rval::expr_unary(const NetEUnary*expr)
       expr->expr()->expr_scan(this);
       string tname = make_temp();
 
-      os_ << "        vvm_bitset_t<" << width_ << "> " << tname << " = ";
+      os_ << "        vvm_bitset_t<" << expr->expr_width() << "> "
+	  << tname << " = ";
       switch (expr->op()) {
 	  case '~':
 	    os_ << "vvm_unop_not(" << result << ");"
@@ -145,22 +146,23 @@ void vvm_proc_rval::expr_unary(const NetEUnary*expr)
 
 void vvm_proc_rval::expr_binary(const NetEBinary*expr)
 {
-      if (width_ == 0) {
-	    width_ = expr->left()->natural_width();
-      }
-
       expr->left()->expr_scan(this);
       string lres = result;
 
       expr->right()->expr_scan(this);
       string rres = result;
 
+      result = make_temp();
+      os_ << "        vvm_bitset_t<" << expr->expr_width() << ">" <<
+	    result << ";" << endl;
       switch (expr->op()) {
 	  case 'e':
-	    result = string("vvm_binop_eq(") + lres + "," + rres + ")";
+	    os_ << "        " << result << " = vvm_binop_eq(" << lres
+		<< "," << rres << ");" << endl;
 	    break;
 	  case '+':
-	    result = string("vvm_binop_plus(") + lres + "," + rres + ")";
+	    os_ << "        " << result << " = vvm_binop_plus(" << lres
+		<< "," << rres << ");" << endl;
 	    break;
 	  default:
 	    cerr << "vvm: Unhandled binary op `" << expr->op() << "': "
@@ -171,9 +173,9 @@ void vvm_proc_rval::expr_binary(const NetEBinary*expr)
       }
 }
 
-static string emit_proc_rval(ostream&os, unsigned width, const NetExpr*expr)
+static string emit_proc_rval(ostream&os, const NetExpr*expr)
 {
-      vvm_proc_rval scan (os, width);
+      vvm_proc_rval scan (os);
       expr->expr_scan(&scan);
       return scan.result;
 }
@@ -400,7 +402,7 @@ void target_vvm::start_process(ostream&os, const NetProcTop*proc)
  */
 void target_vvm::proc_assign(ostream&os, const NetAssign*net)
 {
-      string rval = emit_proc_rval(os, net->lval()->pin_count(), net->rval());
+      string rval = emit_proc_rval(os, net->rval());
 
       os << "        // " << net->lval()->name() << " = ";
       net->rval()->dump(os);
@@ -419,7 +421,7 @@ void target_vvm::proc_assign(ostream&os, const NetAssign*net)
       for (unsigned idx = 0 ;  idx < net->pin_count() ;  idx += 1) {
 	    const NetObj*cur;
 	    unsigned pin;
-	    for (net->lval()->pin(0).next_link(cur, pin)
+	    for (net->lval()->pin(idx).next_link(cur, pin)
 		       ; cur != net->lval()
 		       ; cur->pin(pin).next_link(cur, pin)) {
 
@@ -450,7 +452,7 @@ void target_vvm::proc_block(ostream&os, const NetBlock*net)
 
 void target_vvm::proc_condit(ostream&os, const NetCondit*net)
 {
-      string expr = emit_proc_rval(os, 0, net->expr());
+      string expr = emit_proc_rval(os, net->expr());
       os << "        if (" << expr << "[0] == V1) {" << endl;
       net->emit_recurse_if(os, this);
       os << "        } else {" << endl;
@@ -543,6 +545,9 @@ extern const struct target tgt_vvm = {
 };
 /*
  * $Log: t-vvm.cc,v $
+ * Revision 1.3  1998/11/07 19:17:10  steve
+ *  Calculate expression widths at elaboration time.
+ *
  * Revision 1.2  1998/11/07 17:05:06  steve
  *  Handle procedural conditional, and some
  *  of the conditional expressions.