diff --git a/ivl_target.h b/ivl_target.h
index c63b3598f..128c05e33 100644
--- a/ivl_target.h
+++ b/ivl_target.h
@@ -19,7 +19,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #if !defined(WINNT) && !defined(macintosh)
-#ident "$Id: ivl_target.h,v 1.64 2001/06/07 02:12:43 steve Exp $"
+#ident "$Id: ivl_target.h,v 1.65 2001/06/07 03:09:37 steve Exp $"
 #endif
 
 #ifdef __cplusplus
@@ -203,7 +203,8 @@ typedef enum ivl_logic_e {
 typedef enum ivl_lpm_type_e {
       IVL_LPM_ADD,
       IVL_LPM_FF,
-      IVL_LPM_MUX
+      IVL_LPM_MUX,
+      IVL_LPM_SUB
 } ivl_lpm_type_t;
 
 /* Processes are initial or always blocks with a statement. This is
@@ -510,13 +511,13 @@ extern unsigned       ivl_lpm_width(ivl_lpm_t net);
 
   /* IVL_LPM_FF */
 extern ivl_nexus_t ivl_lpm_clk(ivl_lpm_t net);
-  /* IVL_LPM_ADD IVL_LPM_FF */
+  /* IVL_LPM_ADD IVL_LPM_FF IVL_LPM_SUB */
 extern ivl_nexus_t ivl_lpm_data(ivl_lpm_t net, unsigned idx);
-  /* IVL_LPM_ADD */
+  /* IVL_LPM_ADD IVL_LPM_SUB */
 extern ivl_nexus_t ivl_lpm_datab(ivl_lpm_t net, unsigned idx);
   /* IVL_LPM_MUX */
 extern ivl_nexus_t ivl_lpm_data2(ivl_lpm_t net, unsigned sdx, unsigned idx);
-  /* IVL_LPM_ADD IVL_LPM_FF */
+  /* IVL_LPM_ADD IVL_LPM_FF IVL_LPM_SUB */
 extern ivl_nexus_t ivl_lpm_q(ivl_lpm_t net, unsigned idx);
   /* IVL_LPM_MUX */
 extern unsigned ivl_lpm_selects(ivl_lpm_t net);
@@ -872,6 +873,9 @@ _END_DECL
 
 /*
  * $Log: ivl_target.h,v $
+ * Revision 1.65  2001/06/07 03:09:37  steve
+ *  support subtraction in tgt-vvp.
+ *
  * Revision 1.64  2001/06/07 02:12:43  steve
  *  Support structural addition.
  *
diff --git a/t-dll-api.cc b/t-dll-api.cc
index ecdf2704c..59444e090 100644
--- a/t-dll-api.cc
+++ b/t-dll-api.cc
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #if !defined(WINNT) && !defined(macintosh)
-#ident "$Id: t-dll-api.cc,v 1.47 2001/06/07 02:12:43 steve Exp $"
+#ident "$Id: t-dll-api.cc,v 1.48 2001/06/07 03:09:37 steve Exp $"
 #endif
 
 # include  "t-dll.h"
@@ -450,6 +450,7 @@ extern "C" ivl_nexus_t ivl_lpm_data(ivl_lpm_t net, unsigned idx)
       assert(net);
       switch (net->type) {
 	  case IVL_LPM_ADD:
+	  case IVL_LPM_SUB:
 	    assert(idx < net->u_.arith.width);
 	    return net->u_.arith.a[idx];
 
@@ -472,6 +473,7 @@ extern "C" ivl_nexus_t ivl_lpm_datab(ivl_lpm_t net, unsigned idx)
       switch (net->type) {
 
 	  case IVL_LPM_ADD:
+	  case IVL_LPM_SUB:
 	    assert(idx < net->u_.arith.width);
 	    return net->u_.arith.b[idx];
 
@@ -507,6 +509,7 @@ extern "C" ivl_nexus_t ivl_lpm_q(ivl_lpm_t net, unsigned idx)
 
       switch (net->type) {
 	  case IVL_LPM_ADD:
+	  case IVL_LPM_SUB:
 	    assert(idx < net->u_.arith.width);
 	    return net->u_.arith.q[idx];
 
@@ -582,6 +585,7 @@ extern "C" unsigned ivl_lpm_width(ivl_lpm_t net)
 	  case IVL_LPM_MUX:
 	    return net->u_.mux.width;
 	  case IVL_LPM_ADD:
+	  case IVL_LPM_SUB:
 	    return net->u_.arith.width;
 	  default:
 	    assert(0);
@@ -1171,6 +1175,9 @@ extern "C" ivl_statement_t ivl_stmt_sub_stmt(ivl_statement_t net)
 
 /*
  * $Log: t-dll-api.cc,v $
+ * Revision 1.48  2001/06/07 03:09:37  steve
+ *  support subtraction in tgt-vvp.
+ *
  * Revision 1.47  2001/06/07 02:12:43  steve
  *  Support structural addition.
  *
diff --git a/t-dll.cc b/t-dll.cc
index 274fb889f..205e04441 100644
--- a/t-dll.cc
+++ b/t-dll.cc
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #if !defined(WINNT) && !defined(macintosh)
-#ident "$Id: t-dll.cc,v 1.43 2001/06/07 02:12:43 steve Exp $"
+#ident "$Id: t-dll.cc,v 1.44 2001/06/07 03:09:37 steve Exp $"
 #endif
 
 # include  "compiler.h"
@@ -609,7 +609,10 @@ void dll_target::memory(const NetMemory*net)
 void dll_target::lpm_add_sub(const NetAddSub*net)
 {
       ivl_lpm_t obj = new struct ivl_lpm_s;
-      obj->type = IVL_LPM_ADD;
+      if (net->attribute("LPM_Direction") == "SUB")
+	    obj->type = IVL_LPM_SUB;
+      else
+	    obj->type = IVL_LPM_ADD;
       obj->name = strdup(net->name());
       assert(net->scope());
       obj->scope = find_scope(des_.root_, net->scope());
@@ -1063,6 +1066,9 @@ extern const struct target tgt_dll = { "dll", &dll_target_obj };
 
 /*
  * $Log: t-dll.cc,v $
+ * Revision 1.44  2001/06/07 03:09:37  steve
+ *  support subtraction in tgt-vvp.
+ *
  * Revision 1.43  2001/06/07 02:12:43  steve
  *  Support structural addition.
  *
diff --git a/tgt-stub/stub.c b/tgt-stub/stub.c
index 7a1c25681..aa8b36310 100644
--- a/tgt-stub/stub.c
+++ b/tgt-stub/stub.c
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #if !defined(WINNT) && !defined(macintosh)
-#ident "$Id: stub.c,v 1.43 2001/06/07 02:12:43 steve Exp $"
+#ident "$Id: stub.c,v 1.44 2001/06/07 03:09:37 steve Exp $"
 #endif
 
 /*
@@ -115,6 +115,21 @@ static void show_lpm(ivl_lpm_t net)
 		break;
 	  }
 
+	  case IVL_LPM_SUB: {
+		fprintf(out, "  LPM_SUB %s: <width=%u>\n",
+			ivl_lpm_name(net), width);
+		for (idx = 0 ;  idx < width ;  idx += 1)
+		      fprintf(out, "    Q %u: %s\n", idx,
+			      ivl_nexus_name(ivl_lpm_q(net, idx)));
+		for (idx = 0 ;  idx < width ;  idx += 1)
+		      fprintf(out, "    Data A %u: %s\n", idx,
+			      ivl_nexus_name(ivl_lpm_data(net, idx)));
+		for (idx = 0 ;  idx < width ;  idx += 1)
+		      fprintf(out, "    Data B %u: %s\n", idx,
+			      ivl_nexus_name(ivl_lpm_datab(net, idx)));
+		break;
+	  }
+
 	  case IVL_LPM_FF: {
 
 		fprintf(out, "  LPM_FF %s: <width=%u>\n",
@@ -566,6 +581,9 @@ DECLARE_CYGWIN_DLL(DllMain);
 
 /*
  * $Log: stub.c,v $
+ * Revision 1.44  2001/06/07 03:09:37  steve
+ *  support subtraction in tgt-vvp.
+ *
  * Revision 1.43  2001/06/07 02:12:43  steve
  *  Support structural addition.
  *
diff --git a/tgt-vvp/vvp_scope.c b/tgt-vvp/vvp_scope.c
index c1f00b9be..b65be02cd 100644
--- a/tgt-vvp/vvp_scope.c
+++ b/tgt-vvp/vvp_scope.c
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #if !defined(WINNT)
-#ident "$Id: vvp_scope.c,v 1.29 2001/06/07 02:12:43 steve Exp $"
+#ident "$Id: vvp_scope.c,v 1.30 2001/06/07 03:09:37 steve Exp $"
 #endif
 
 # include  "vvp_priv.h"
@@ -115,6 +115,7 @@ static const char* draw_net_input_drive(ivl_nexus_t nex, ivl_nexus_ptr_t nptr)
 		  }
 
 	  case IVL_LPM_ADD:
+	  case IVL_LPM_SUB:
 	    for (idx = 0 ;  idx < ivl_lpm_width(lpm) ;  idx += 1)
 		  if (ivl_lpm_q(lpm, idx) == nex) {
 			sprintf(result, "L_%s[%u]",
@@ -609,10 +610,22 @@ static void draw_event_in_scope(ivl_event_t obj)
 static void draw_lpm_add(ivl_lpm_t net)
 {
       unsigned idx, width;
+      const char*type = "";
 
       width = ivl_lpm_width(net);
 
-      fprintf(vvp_out, "L_%s .arith/sum %u", ivl_lpm_name(net), width);
+      switch (ivl_lpm_type(net)) {
+	  case IVL_LPM_ADD:
+	    type = "sum";
+	    break;
+	  case IVL_LPM_SUB:
+	    type = "sub";
+	    break;
+	  default:
+	    assert(0);
+      }
+
+      fprintf(vvp_out, "L_%s .arith/%s %u", ivl_lpm_name(net), type, width);
 
       for (idx = 0 ;  idx < width ;  idx += 1) {
 	    ivl_nexus_t a = ivl_lpm_data(net, idx);
@@ -660,6 +673,7 @@ static void draw_lpm_in_scope(ivl_lpm_t net)
 {
       switch (ivl_lpm_type(net)) {
 	  case IVL_LPM_ADD:
+	  case IVL_LPM_SUB:
 	    draw_lpm_add(net);
 	    return;
 
@@ -752,6 +766,9 @@ int draw_scope(ivl_scope_t net, ivl_scope_t parent)
 
 /*
  * $Log: vvp_scope.c,v $
+ * Revision 1.30  2001/06/07 03:09:37  steve
+ *  support subtraction in tgt-vvp.
+ *
  * Revision 1.29  2001/06/07 02:12:43  steve
  *  Support structural addition.
  *