From 4b829bf04f71a1ff8bb07fd7736aa629896135bf Mon Sep 17 00:00:00 2001
From: steve <steve>
Date: Sat, 20 Jan 2007 02:10:45 +0000
Subject: [PATCH]  Get argument widths right for shift results.

---
 elab_net.cc   | 12 +++++++++++-
 expr_synth.cc | 29 ++++++++++++++++++++++++++---
 2 files changed, 37 insertions(+), 4 deletions(-)

diff --git a/elab_net.cc b/elab_net.cc
index 71d10eac7..289f6aefe 100644
--- a/elab_net.cc
+++ b/elab_net.cc
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: elab_net.cc,v 1.193 2007/01/19 04:26:24 steve Exp $"
+#ident "$Id: elab_net.cc,v 1.194 2007/01/20 02:10:45 steve Exp $"
 #endif
 
 # include "config.h"
@@ -1141,6 +1141,13 @@ NetNet* PEBinary::elaborate_net_shift_(Design*des, NetScope*scope,
 
 	    des->add_node(part);
 
+	    if (debug_elaborate) {
+		  cerr << get_line() << ": debug: Elaborate shift "
+		       << "(" << op_ << ") as concatenation of "
+		       << pad_width << " zeros with " << part_width
+		       << " bits of expression." << endl;
+	    }
+
 	      /* Attach a signal to the part select output (NetConcat
 		 input) */
 	    NetNet*tmp = new NetNet(scope, scope->local_symbol(),
@@ -2887,6 +2894,9 @@ NetNet* PEUnary::elaborate_net(Design*des, NetScope*scope,
 
 /*
  * $Log: elab_net.cc,v $
+ * Revision 1.194  2007/01/20 02:10:45  steve
+ *  Get argument widths right for shift results.
+ *
  * Revision 1.193  2007/01/19 04:26:24  steve
  *  Fix missing data_type mark for array words.
  *
diff --git a/expr_synth.cc b/expr_synth.cc
index 23926c426..60a604017 100644
--- a/expr_synth.cc
+++ b/expr_synth.cc
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: expr_synth.cc,v 1.81 2007/01/16 05:44:15 steve Exp $"
+#ident "$Id: expr_synth.cc,v 1.82 2007/01/20 02:10:45 steve Exp $"
 #endif
 
 # include "config.h"
@@ -449,10 +449,14 @@ NetNet* NetEBShift::synthesize(Design*des)
 	    osig->data_type(expr_type());
 	    osig->local_flag(true);
 
+	      // ushift is the amount of pad created by the shift.
 	    unsigned long ushift = shift>=0? shift : -shift;
 	    if (ushift > osig->vector_width())
 		  ushift = osig->vector_width();
 
+	      // part_width is the bits of the vector that survive the shift.
+	    unsigned long part_width = osig->vector_width() - ushift;
+
 	    verinum znum (verinum::V0, ushift, true);
 	    NetConst*zcon = new NetConst(scope, scope->local_symbol(),
 					 znum);
@@ -471,6 +475,20 @@ NetNet* NetEBShift::synthesize(Design*des)
 	    zsig->data_type(osig->data_type());
 	    connect(zcon->pin(0), zsig->pin(0));
 
+	      /* Create a part select to reduce the width of the lsig
+	         to the amount left by the shift. */
+	    NetPartSelect*psel = new NetPartSelect(lsig, shift<0? ushift : 0,
+						   part_width,
+						   NetPartSelect::VP);
+	    des->add_node(psel);
+
+	    NetNet*psig = new NetNet(scope, scope->local_symbol(),
+				     NetNet::IMPLICIT, part_width);
+	    psig->data_type(expr_type());
+	    psig->local_flag(true);
+	    psig->set_line(*this);
+	    connect(psig->pin(0), psel->pin(0));
+
 	    NetConcat*ccat = new NetConcat(scope, scope->local_symbol(),
 					   osig->vector_width(), 2);
 	    ccat->set_line(*this);
@@ -478,10 +496,12 @@ NetNet* NetEBShift::synthesize(Design*des)
 
 	    connect(ccat->pin(0), osig->pin(0));
 	    if (shift > 0) {
+		    // Left shift.
 		  connect(ccat->pin(1), zsig->pin(0));
-		  connect(ccat->pin(2), lsig->pin(0));
+		  connect(ccat->pin(2), psig->pin(0));
 	    } else {
-		  connect(ccat->pin(1), lsig->pin(0));
+		    // Right shift
+		  connect(ccat->pin(1), psig->pin(0));
 		  connect(ccat->pin(2), zsig->pin(0));
 	    }
 
@@ -890,6 +910,9 @@ NetNet* NetESignal::synthesize(Design*des)
 
 /*
  * $Log: expr_synth.cc,v $
+ * Revision 1.82  2007/01/20 02:10:45  steve
+ *  Get argument widths right for shift results.
+ *
  * Revision 1.81  2007/01/16 05:44:15  steve
  *  Major rework of array handling. Memories are replaced with the
  *  more general concept of arrays. The NetMemory and NetEMemory