diff --git a/vvp/Makefile.in b/vvp/Makefile.in
index c80ddd462..3f453b7cf 100644
--- a/vvp/Makefile.in
+++ b/vvp/Makefile.in
@@ -16,7 +16,7 @@
 #    59 Temple Place - Suite 330
 #    Boston, MA 02111-1307, USA
 #
-#ident "$Id: Makefile.in,v 1.67 2005/04/28 04:59:53 steve Exp $"
+#ident "$Id: Makefile.in,v 1.68 2005/05/24 01:43:27 steve Exp $"
 #
 #
 SHELL = /bin/sh
@@ -82,7 +82,7 @@ vpi_memory.o vpi_vthr_vector.o vpip_bin.o vpip_hex.o vpip_oct.o \
 vpip_to_dec.o vpip_format.o vvp_vpi.o
 
 O = main.o parse.o parse_misc.o lexor.o arith.o bufif.o compile.o concat.o \
-dff.o functor.o npmos.o part.o reduce.o resolv.o stop.o symbols.o \
+dff.o extend.o functor.o npmos.o part.o reduce.o resolv.o stop.o symbols.o \
 ufunc.o codes.o \
 vthread.o schedule.o statistics.o tables.o udp.o vvp_net.o memory.o \
 event.o logic.o delay.o words.o $V
diff --git a/vvp/README.txt b/vvp/README.txt
index 0aa9c93e4..2becd6c4d 100644
--- a/vvp/README.txt
+++ b/vvp/README.txt
@@ -1,7 +1,7 @@
 /*
  * Copyright (c) 2001 Stephen Williams (steve@icarus.com)
  *
- *  $Id: README.txt,v 1.66 2005/05/08 23:40:14 steve Exp $
+ *  $Id: README.txt,v 1.67 2005/05/24 01:43:27 steve Exp $
  */
 
 VVP SIMULATION ENGINE
@@ -524,6 +524,16 @@ the device has a single input, which is a vector of any width. The
 device performs the logic on all the bits of the vector (a la Verilog)
 and produces and propagates a single bit width vector.
 
+EXPANSION LOGIC
+
+Sign extension nodes are the opposite of reduction logic, in that they
+take a narrow vector, or single bit, and pad it out to a wider
+vector.
+
+        <label> .expand/s <wid>, <symbol> ;
+
+The .expand/s node takes an input symbol and sign-extends it to the
+given width.
 
 FORCE STATEMENTS (old method - remove me):
 
diff --git a/vvp/compile.cc b/vvp/compile.cc
index a07bdab3f..1a67a23fc 100644
--- a/vvp/compile.cc
+++ b/vvp/compile.cc
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: compile.cc,v 1.201 2005/05/18 03:46:01 steve Exp $"
+#ident "$Id: compile.cc,v 1.202 2005/05/24 01:43:27 steve Exp $"
 #endif
 
 # include  "arith.h"
@@ -1037,6 +1037,23 @@ void compile_cmp_gt(char*label, long wid, bool signed_flag,
       make_arith(arith, label, wid, argc, argv);
 }
 
+/*
+ * Extend nodes.
+ */
+void compile_extend_signed(char*label, long wid, struct symb_s arg)
+{
+      assert(wid >= 0);
+
+      vvp_fun_extend_signed*fun = new vvp_fun_extend_signed(wid);
+      vvp_net_t*ptr = new vvp_net_t;
+      ptr->fun = fun;
+
+      define_functor_symbol(label, ptr);
+      free(label);
+
+      input_connect(ptr, 0, arg.text);
+}
+
 /*
  * A .shift/l statement creates an array of functors for the
  * width. The 0 input is the data vector to be shifted and the 1 input
@@ -1526,6 +1543,9 @@ void compile_param_string(char*label, char*name, char*str, char*value)
 
 /*
  * $Log: compile.cc,v $
+ * Revision 1.202  2005/05/24 01:43:27  steve
+ *  Add a sign-extension node.
+ *
  * Revision 1.201  2005/05/18 03:46:01  steve
  *  Fixup structural GT comparators.
  *
@@ -1583,32 +1603,5 @@ void compile_param_string(char*label, char*name, char*str, char*value)
  *
  * Revision 1.184  2005/01/29 17:53:25  steve
  *  Use scheduler to initialize constant functor inputs.
- *
- * Revision 1.183  2005/01/28 05:34:25  steve
- *  Add vector4 implementation of .arith/mult.
- *
- * Revision 1.182  2005/01/22 16:21:11  steve
- *  Implement vectored CMP_EQ and NE
- *
- * Revision 1.181  2005/01/22 01:06:20  steve
- *  Implement the .cmp/eeq LPM node.
- *
- * Revision 1.180  2005/01/16 04:19:08  steve
- *  Reimplement comparators as vvp_vector4_t nodes.
- *
- * Revision 1.179  2004/12/31 05:54:46  steve
- *  Fix uninitialized fun pointer for resolver nodes.
- *
- * Revision 1.178  2004/12/17 04:47:47  steve
- *  Replace single release with release/net and release/reg.
- *
- * Revision 1.177  2004/12/15 17:17:42  steve
- *  Add the force/v instruction.
- *
- * Revision 1.176  2004/12/11 02:31:29  steve
- *  Rework of internals to carry vectors through nexus instead
- *  of single bits. Make the ivl, tgt-vvp and vvp initial changes
- *  down this path.
- *
  */
 
diff --git a/vvp/compile.h b/vvp/compile.h
index 0e9bab531..676edb423 100644
--- a/vvp/compile.h
+++ b/vvp/compile.h
@@ -19,7 +19,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: compile.h,v 1.71 2005/05/08 23:40:14 steve Exp $"
+#ident "$Id: compile.h,v 1.72 2005/05/24 01:43:27 steve Exp $"
 #endif
 
 # include  <stdio.h>
@@ -154,6 +154,8 @@ extern void compile_reduce_nand(char*label, struct symb_s arg);
 extern void compile_reduce_nor(char*label, struct symb_s arg);
 extern void compile_reduce_xnor(char*label, struct symb_s arg);
 
+extern void compile_extend_signed(char*label, long width, struct symb_s arg);
+
 extern void compile_repeat(char*label, long width, long repeat,
 			   struct symb_s arg);
 
@@ -311,6 +313,9 @@ extern void compile_net(char*label, char*name,
 
 /*
  * $Log: compile.h,v $
+ * Revision 1.72  2005/05/24 01:43:27  steve
+ *  Add a sign-extension node.
+ *
  * Revision 1.71  2005/05/08 23:40:14  steve
  *  Add support for variable part select.
  *
diff --git a/vvp/extend.cc b/vvp/extend.cc
new file mode 100644
index 000000000..774e6e90c
--- /dev/null
+++ b/vvp/extend.cc
@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2005 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: extend.cc,v 1.1 2005/05/24 01:43:27 steve Exp $"
+#endif
+
+# include  "vvp_net.h"
+# include  "compile.h"
+# include  <string.h>
+# include  <stream.h>
+# include  <assert.h>
+
+vvp_fun_extend_signed::vvp_fun_extend_signed(unsigned wid)
+: width_(wid)
+{
+}
+
+vvp_fun_extend_signed::~vvp_fun_extend_signed()
+{
+}
+
+void vvp_fun_extend_signed::recv_vec4(vvp_net_ptr_t port, vvp_vector4_t bit)
+{
+      if (bit.size() >= width_) {
+	    vvp_send_vec4(port.ptr()->out, bit);
+	    return;
+      }
+
+      vvp_vector4_t res (width_);
+
+      for (unsigned idx = 0 ;  idx < bit.size() ;  idx += 1)
+	    res.set_bit(idx, bit.value(idx));
+
+      vvp_bit4_t pad = bit.size() > 0? bit.value(bit.size()-1) : BIT4_0;
+      for (unsigned idx = bit.size() ;  idx < res.size() ;  idx += 1)
+	    res.set_bit(idx, pad);
+
+      vvp_send_vec4(port.ptr()->out, res);
+}
diff --git a/vvp/lexor.lex b/vvp/lexor.lex
index 75e74b714..0f60d3e46 100644
--- a/vvp/lexor.lex
+++ b/vvp/lexor.lex
@@ -19,7 +19,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: lexor.lex,v 1.53 2005/05/08 23:40:14 steve Exp $"
+#ident "$Id: lexor.lex,v 1.54 2005/05/24 01:43:27 steve Exp $"
 #endif
 
 # include  "parse_misc.h"
@@ -101,6 +101,7 @@
 ".dff"      { return K_DFF; }
 ".event"    { return K_EVENT; }
 ".event/or" { return K_EVENT_OR; }
+".extend/s" { return K_EXTEND_S; }
 ".functor"  { return K_FUNCTOR; }
 ".net"      { return K_NET; }
 ".net/s"    { return K_NET_S; }
@@ -195,6 +196,9 @@ int yywrap()
 
 /*
  * $Log: lexor.lex,v $
+ * Revision 1.54  2005/05/24 01:43:27  steve
+ *  Add a sign-extension node.
+ *
  * Revision 1.53  2005/05/08 23:40:14  steve
  *  Add support for variable part select.
  *
diff --git a/vvp/parse.y b/vvp/parse.y
index 878e12c38..66e675e96 100644
--- a/vvp/parse.y
+++ b/vvp/parse.y
@@ -19,7 +19,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: parse.y,v 1.74 2005/05/08 23:40:14 steve Exp $"
+#ident "$Id: parse.y,v 1.75 2005/05/24 01:43:27 steve Exp $"
 #endif
 
 # include  "parse_misc.h"
@@ -62,7 +62,8 @@ extern FILE*yyin;
 %token K_CMP_EEQ K_CMP_EQ K_CMP_NEE K_CMP_NE
 %token K_CMP_GE K_CMP_GE_S K_CMP_GT K_CMP_GT_S
 %token K_CONCAT K_DFF
-%token K_EVENT K_EVENT_OR K_FUNCTOR K_NET K_NET_S K_PARAM K_PART K_PART_PV
+%token K_EVENT K_EVENT_OR K_EXTEND_S K_FUNCTOR K_NET K_NET_S
+%token K_PARAM K_PART K_PART_PV
 %token K_PART_V K_REDUCE_AND K_REDUCE_OR K_REDUCE_XOR
 %token K_REDUCE_NAND K_REDUCE_NOR K_REDUCE_XNOR K_REPEAT
 %token K_RESOLV K_SCOPE K_SHIFTL K_SHIFTR K_THREAD K_TIMESCALE K_UFUNC
@@ -301,6 +302,13 @@ statement
         | T_LABEL K_REPEAT T_NUMBER ',' T_NUMBER ',' symbol ';'
                 { compile_repeat($1, $3, $5, $7); }
 
+  /* The extend nodes take a width and a symbol. */
+
+        | T_LABEL K_EXTEND_S T_NUMBER ',' symbol ';'
+                { compile_extend_signed($1, $3, $5); }
+
+  /* Shift nodes. */
+
 	| T_LABEL K_SHIFTL T_NUMBER ',' symbols ';'
 		{ struct symbv_s obj = $5;
 		  compile_shiftl($1, $3, obj.cnt, obj.vect);
@@ -681,6 +689,9 @@ int compile_design(const char*path)
 
 /*
  * $Log: parse.y,v $
+ * Revision 1.75  2005/05/24 01:43:27  steve
+ *  Add a sign-extension node.
+ *
  * Revision 1.74  2005/05/08 23:40:14  steve
  *  Add support for variable part select.
  *
diff --git a/vvp/vvp_net.h b/vvp/vvp_net.h
index 734786699..f36d634c0 100644
--- a/vvp/vvp_net.h
+++ b/vvp/vvp_net.h
@@ -18,7 +18,7 @@
  *    along with this program; if not, write to the Free Software
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
-#ident "$Id: vvp_net.h,v 1.27 2005/05/09 00:36:58 steve Exp $"
+#ident "$Id: vvp_net.h,v 1.28 2005/05/24 01:43:27 steve Exp $"
 
 # include  "config.h"
 # include  <assert.h>
@@ -490,6 +490,24 @@ class vvp_fun_drive  : public vvp_net_fun_t {
       unsigned char drive1_;
 };
 
+/*
+ * EXTEND functors expand an input vector to the desired output
+ * width. The extend_signed functor sign extends the input. If the
+ * input is already wider then the desired output, then it is passed
+ * unmodified.
+ */
+class vvp_fun_extend_signed  : public vvp_net_fun_t {
+
+    public:
+      explicit vvp_fun_extend_signed(unsigned wid);
+      ~vvp_fun_extend_signed();
+
+      void recv_vec4(vvp_net_ptr_t port, vvp_vector4_t bit);
+
+    private:
+      unsigned width_;
+};
+
 /* vvp_fun_part
  * This node takes a part select of the input vector. Input 0 is the
  * vector to be selected from, and input 1 is the location where the
@@ -721,6 +739,9 @@ class vvp_wide_fun_t : public vvp_net_fun_t {
 
 /*
  * $Log: vvp_net.h,v $
+ * Revision 1.28  2005/05/24 01:43:27  steve
+ *  Add a sign-extension node.
+ *
  * Revision 1.27  2005/05/09 00:36:58  steve
  *  Force part base out of bounds if index is invalid.
  *