diff --git a/ivl.def b/ivl.def
index 2467f695a..274a14284 100644
--- a/ivl.def
+++ b/ivl.def
@@ -62,6 +62,8 @@ ivl_logic_udp
 ivl_lpm_aset_value
 ivl_lpm_async_clr
 ivl_lpm_async_set
+ivl_lpm_attr_cnt
+ivl_lpm_attr_val
 ivl_lpm_basename
 ivl_lpm_clk
 ivl_lpm_data
diff --git a/ivl_target.h b/ivl_target.h
index e9a68579c..b7eefdf46 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
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: ivl_target.h,v 1.126.2.1 2006/02/19 00:11:31 steve Exp $"
+#ident "$Id: ivl_target.h,v 1.126.2.2 2006/02/25 05:03:28 steve Exp $"
 #endif
 
 #ifdef __cplusplus
@@ -630,6 +630,11 @@ extern const char* ivl_udp_name(ivl_udp_t net);
  *    the LPM type, but it generally has to do with the width of the
  *    output data path.
  *
+ * ivl_lpm_attr_cnt
+ * ivl_lpm_attr_val
+ *    These functions access attributes attached to LPM devices. These
+ *    attributes may be explicit attributes collected from the Verilog
+ *    source, or implicit attributes generated by the compiler.
  *
  * These functions apply to a subset of the LPM devices, or may have
  * varying meaning depending on the device:
@@ -667,11 +672,19 @@ extern const char* ivl_udp_name(ivl_udp_t net);
  *
  * SEMANTIC NOTES:
  *
+ * - IVL_LPM_FF
  * The IVL_LPM_FF and IVL_LPM_DECODE devices are closely related. If
  * the ivl_lpm_decode function returns a non-nil value, then the
  * decoder represents an extra ENABLE-like input, where exactly one(1)
  * bit of the width of the FF is enabled. The decoder inputs are and
  * address that selects the FF to be enabled.
+ *
+ * The core compiler generates these attributes in certain cases:
+ *
+ *  - ivl:clock_polarity
+ *    If present, the string value can be "INVERT". That indicates
+ *    that the clock is negedge sensitive instead of the default
+ *    posedge sensitive.
  */
 
 extern const char*    ivl_lpm_name(ivl_lpm_t net); /* (Obsolete) */
@@ -681,6 +694,9 @@ extern int            ivl_lpm_signed(ivl_lpm_t net);
 extern ivl_lpm_type_t ivl_lpm_type(ivl_lpm_t net);
 extern unsigned       ivl_lpm_width(ivl_lpm_t net);
 
+extern unsigned        ivl_lpm_attr_cnt(ivl_lpm_t net);
+extern ivl_attribute_t ivl_lpm_attr_val(ivl_lpm_t net, unsigned idx);
+
   /* IVL_LPM_FF */
 extern ivl_nexus_t ivl_lpm_async_clr(ivl_lpm_t net);
 extern ivl_nexus_t ivl_lpm_async_set(ivl_lpm_t net);
@@ -1252,6 +1268,9 @@ _END_DECL
 
 /*
  * $Log: ivl_target.h,v $
+ * Revision 1.126.2.2  2006/02/25 05:03:28  steve
+ *  Add support for negedge FFs by using attributes.
+ *
  * Revision 1.126.2.1  2006/02/19 00:11:31  steve
  *  Handle synthesis of FF vectors with l-value decoder.
  *
diff --git a/synth2.cc b/synth2.cc
index d912e152e..299e7e57a 100644
--- a/synth2.cc
+++ b/synth2.cc
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: synth2.cc,v 1.39.2.21 2006/02/19 00:11:33 steve Exp $"
+#ident "$Id: synth2.cc,v 1.39.2.22 2006/02/25 05:03:29 steve Exp $"
 #endif
 
 # include "config.h"
@@ -1458,7 +1458,7 @@ bool NetEvWait::synth_sync(Design*des, NetScope*scope,
       NetFF*ff = nex_ff[0].ff;
       connect(ff->pin_Clock(), pclk->pin(0));
       if (pclk->edge() == NetEvProbe::NEGEDGE)
-	    ff->attribute(perm_string::literal("Clock:LPM_Polarity"), verinum("INVERT"));
+	    ff->attribute(perm_string::literal("ivl:clock_polarity"), verinum("INVERT"));
 
 	/* Synthesize the input to the DFF. */
       bool flag = statement_->synth_sync(des, scope, nex_ff,
@@ -1639,6 +1639,9 @@ void synth2(Design*des)
 
 /*
  * $Log: synth2.cc,v $
+ * Revision 1.39.2.22  2006/02/25 05:03:29  steve
+ *  Add support for negedge FFs by using attributes.
+ *
  * Revision 1.39.2.21  2006/02/19 00:11:33  steve
  *  Handle synthesis of FF vectors with l-value decoder.
  *
diff --git a/t-dll-api.cc b/t-dll-api.cc
index 1214861d2..bcc48784b 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
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: t-dll-api.cc,v 1.108.2.1 2006/02/19 00:11:33 steve Exp $"
+#ident "$Id: t-dll-api.cc,v 1.108.2.2 2006/02/25 05:03:29 steve Exp $"
 #endif
 
 # include "config.h"
@@ -620,6 +620,19 @@ extern "C" const char* ivl_udp_name(ivl_udp_t net)
       return net->name;
 }
 
+extern "C" unsigned ivl_lpm_attr_cnt(ivl_lpm_t net)
+{
+      return net->nattr;
+}
+
+extern "C" ivl_attribute_t ivl_lpm_attr_val(ivl_lpm_t net, unsigned idx)
+{
+      if (idx >= net->nattr)
+	    return 0;
+      else
+	    return net->attr + idx;
+}
+
 extern "C" const char* ivl_lpm_basename(ivl_lpm_t net)
 {
       return net->name;
@@ -1951,6 +1964,9 @@ extern "C" ivl_variable_type_t ivl_variable_type(ivl_variable_t net)
 
 /*
  * $Log: t-dll-api.cc,v $
+ * Revision 1.108.2.2  2006/02/25 05:03:29  steve
+ *  Add support for negedge FFs by using attributes.
+ *
  * Revision 1.108.2.1  2006/02/19 00:11:33  steve
  *  Handle synthesis of FF vectors with l-value decoder.
  *
diff --git a/t-dll.cc b/t-dll.cc
index 72dfecd7b..7f0c5578a 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
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: t-dll.cc,v 1.131.2.3 2006/02/19 00:11:34 steve Exp $"
+#ident "$Id: t-dll.cc,v 1.131.2.4 2006/02/25 05:03:29 steve Exp $"
 #endif
 
 # include "config.h"
@@ -967,6 +967,8 @@ bool dll_target::net_function(const NetUserFunc*net)
       obj->type = IVL_LPM_UFUNC;
       obj->name  = net->name();
       obj->scope = find_scope(des_, net->scope());
+      obj->attr = 0;
+      obj->nattr = 0;
       assert(obj->scope);
 
 	/* Get the definition of the function and save it. */
@@ -1109,6 +1111,8 @@ void dll_target::lpm_add_sub(const NetAddSub*net)
       obj->name = net->name(); // NetAddSub names are permallocated
       assert(net->scope());
       obj->scope = find_scope(des_, net->scope());
+      obj->attr  = 0;
+      obj->nattr = 0;
       assert(obj->scope);
 
       obj->u_.arith.signed_flag = 0;
@@ -1178,6 +1182,8 @@ void dll_target::lpm_clshift(const NetCLShift*net)
       ivl_lpm_t obj = new struct ivl_lpm_s;
       obj->type = IVL_LPM_SHIFTL;
       obj->name = net->name();
+      obj->attr  = 0;
+      obj->nattr = 0;
       assert(net->scope());
       obj->scope = find_scope(des_, net->scope());
       assert(obj->scope);
@@ -1245,6 +1251,8 @@ void dll_target::lpm_clshift(const NetCLShift*net)
 void dll_target::lpm_compare(const NetCompare*net)
 {
       ivl_lpm_t obj = new struct ivl_lpm_s;
+      obj->attr  = 0;
+      obj->nattr = 0;
       obj->name = net->name(); // NetCompare names are permallocated
       assert(net->scope());
       obj->scope = find_scope(des_, net->scope());
@@ -1359,6 +1367,8 @@ void dll_target::lpm_divide(const NetDivide*net)
       ivl_lpm_t obj = new struct ivl_lpm_s;
       obj->type  = IVL_LPM_DIVIDE;
       obj->name  = net->name();
+      obj->attr  = 0;
+      obj->nattr = 0;
       assert(net->scope());
       obj->scope = find_scope(des_, net->scope());
       assert(obj->scope);
@@ -1429,6 +1439,8 @@ void dll_target::lpm_modulo(const NetModulo*net)
       ivl_lpm_t obj = new struct ivl_lpm_s;
       obj->type  = IVL_LPM_MOD;
       obj->name  = net->name();
+      obj->attr  = 0;
+      obj->nattr = 0;
       assert(net->scope());
       obj->scope = find_scope(des_, net->scope());
       assert(obj->scope);
@@ -1504,6 +1516,8 @@ ivl_lpm_t dll_target::lpm_decode_ff_(const NetDecode*net)
       ivl_lpm_t obj = new struct ivl_lpm_s;
       obj->type  = IVL_LPM_DECODE;
       obj->name  = net->name();
+      obj->attr  = 0;
+      obj->nattr = 0;
       obj->scope = find_scope(des_, net->scope());
 
       obj->u_.mux.swid  = net->awidth();
@@ -1538,12 +1552,17 @@ void dll_target::lpm_ff(const NetFF*net)
       ivl_lpm_t obj = new struct ivl_lpm_s;
       obj->type  = IVL_LPM_FF;
       obj->name  = net->name();
+      obj->attr  = 0;
+      obj->nattr = 0;
       obj->scope = find_scope(des_, net->scope());
       obj->u_.ff.a.decode = lpm_decode_ff_(net->get_demux());
       assert(obj->scope);
 
       obj->u_.ff.width = net->width();
 
+      obj->nattr = net->attr_cnt();
+      obj->attr = fill_in_attributes(net);
+
       scope_add_lpm(obj->scope, obj);
 
       const Nexus*nex;
@@ -1655,6 +1674,8 @@ void dll_target::lpm_ram_dq(const NetRamDq*net)
       ivl_lpm_t obj = new struct ivl_lpm_s;
       obj->type  = IVL_LPM_RAM;
       obj->name  = net->name();
+      obj->attr  = 0;
+      obj->nattr = 0;
       obj->u_.ff.a.mem = find_memory(des_, net->mem());
       assert(obj->u_.ff.a.mem);
       obj->scope = find_scope(des_, net->mem()->scope());
@@ -1769,6 +1790,8 @@ void dll_target::lpm_mult(const NetMult*net)
       ivl_lpm_t obj = new struct ivl_lpm_s;
       obj->type  = IVL_LPM_MULT;
       obj->name  = net->name();
+      obj->attr  = 0;
+      obj->nattr = 0;
       assert(net->scope());
       obj->scope = find_scope(des_, net->scope());
       assert(obj->scope);
@@ -1849,6 +1872,8 @@ void dll_target::lpm_mux(const NetMux*net)
       ivl_lpm_t obj = new struct ivl_lpm_s;
       obj->type  = IVL_LPM_MUX;
       obj->name  = net->name(); // NetMux names are permallocated
+      obj->attr  = 0;
+      obj->nattr = 0;
       obj->scope = find_scope(des_, net->scope());
       assert(obj->scope);
 
@@ -2225,6 +2250,9 @@ extern const struct target tgt_dll = { "dll", &dll_target_obj };
 
 /*
  * $Log: t-dll.cc,v $
+ * Revision 1.131.2.4  2006/02/25 05:03:29  steve
+ *  Add support for negedge FFs by using attributes.
+ *
  * Revision 1.131.2.3  2006/02/19 00:11:34  steve
  *  Handle synthesis of FF vectors with l-value decoder.
  *
diff --git a/t-dll.h b/t-dll.h
index 5db0bdc94..db2067a6d 100644
--- a/t-dll.h
+++ b/t-dll.h
@@ -19,7 +19,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: t-dll.h,v 1.115.2.1 2006/02/19 00:11:34 steve Exp $"
+#ident "$Id: t-dll.h,v 1.115.2.2 2006/02/25 05:03:30 steve Exp $"
 #endif
 
 # include  "target.h"
@@ -293,6 +293,9 @@ struct ivl_lpm_s {
       ivl_scope_t scope;
       perm_string name;
 
+      struct ivl_attribute_s*attr;
+      unsigned nattr;
+
       union {
 	    struct ivl_lpm_ff_s {
 		  unsigned width;
@@ -690,6 +693,9 @@ struct ivl_variable_s {
 
 /*
  * $Log: t-dll.h,v $
+ * Revision 1.115.2.2  2006/02/25 05:03:30  steve
+ *  Add support for negedge FFs by using attributes.
+ *
  * Revision 1.115.2.1  2006/02/19 00:11:34  steve
  *  Handle synthesis of FF vectors with l-value decoder.
  *
diff --git a/tgt-stub/stub.c b/tgt-stub/stub.c
index f67f7cbaa..c686216ce 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
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: stub.c,v 1.90.2.5 2006/02/19 00:11:34 steve Exp $"
+#ident "$Id: stub.c,v 1.90.2.6 2006/02/25 05:03:30 steve Exp $"
 #endif
 
 # include "config.h"
@@ -35,6 +35,23 @@
 
 static FILE*out;
 
+static void show_attribute(ivl_attribute_t attr, unsigned ind)
+{
+      switch (attr->type) {
+	  case IVL_ATT_VOID:
+	    fprintf(out, "%*s(* %s *)\n", ind,"", attr->key);
+	    break;
+	  case IVL_ATT_STR:
+	    fprintf(out, "%*s(* %s = \"%s\" *)\n", ind,"", attr->key,
+		    attr->val.str);
+	    break;
+	  case IVL_ATT_NUM:
+	    fprintf(out, "%*s(* %s = %ld *)\n", ind,"", attr->key,
+		    attr->val.num);
+	    break;
+      }
+}
+
 static void show_expression(ivl_expr_t net, unsigned ind)
 {
       unsigned idx;
@@ -433,6 +450,11 @@ static void show_lpm(ivl_lpm_t net)
 		    ivl_lpm_width(net),
 		    ivl_lpm_signed(net));
       }
+
+      for (idx = 0 ;  idx < ivl_lpm_attr_cnt(net) ;  idx += 1) {
+	    ivl_attribute_t atr = ivl_lpm_attr_val(net,idx);
+	    show_attribute(atr, 4);
+      }
 }
 
 static void show_assign_lval(ivl_lval_t lval, unsigned ind)
@@ -643,19 +665,7 @@ static int show_process(ivl_process_t net, void*x)
 
       for (idx = 0 ;  idx < ivl_process_attr_cnt(net) ;  idx += 1) {
 	    ivl_attribute_t attr = ivl_process_attr_val(net, idx);
-	    switch (attr->type) {
-		case IVL_ATT_VOID:
-		  fprintf(out, "    (* %s *)\n", attr->key);
-		  break;
-		case IVL_ATT_STR:
-		  fprintf(out, "    (* %s = \"%s\" *)\n", attr->key,
-			  attr->val.str);
-		  break;
-		case IVL_ATT_NUM:
-		  fprintf(out, "    (* %s = %ld *)\n", attr->key,
-			  attr->val.num);
-		  break;
-	    }
+	    show_attribute(attr,4);
       }
 
       show_statement(ivl_process_stmt(net), 4);
@@ -1023,6 +1033,9 @@ int target_design(ivl_design_t des)
 
 /*
  * $Log: stub.c,v $
+ * Revision 1.90.2.6  2006/02/25 05:03:30  steve
+ *  Add support for negedge FFs by using attributes.
+ *
  * Revision 1.90.2.5  2006/02/19 00:11:34  steve
  *  Handle synthesis of FF vectors with l-value decoder.
  *
diff --git a/tgt-vvp/vvp_scope.c b/tgt-vvp/vvp_scope.c
index b90d24465..7c496d878 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
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: vvp_scope.c,v 1.103.2.2 2006/02/19 00:11:35 steve Exp $"
+#ident "$Id: vvp_scope.c,v 1.103.2.3 2006/02/25 05:03:30 steve Exp $"
 #endif
 
 # include  "vvp_priv.h"
@@ -38,6 +38,18 @@ inline static char hex_digit(unsigned i)
       return i>=10 ? i-10+'A' : i+'0';
 }
 
+ivl_attribute_t find_lpm_attr(ivl_lpm_t net, const char*key)
+{
+      unsigned idx;
+      for (idx = 0 ;  idx < ivl_lpm_attr_cnt(net) ;  idx += 1) {
+	    ivl_attribute_t atr = ivl_lpm_attr_val(net, idx);
+	    if (strcmp(key,atr->key) == 0)
+		  return atr;
+      }
+
+      return 0;
+}
+
 const char *vvp_mangle_id(const char *id)
 {
       static char *out = 0x0;
@@ -1304,26 +1316,45 @@ static void draw_lpm_ff(ivl_lpm_t net)
       const char*aset_bits = 0;
 
       unsigned width, idx;
+      ivl_attribute_t clock_pol = find_lpm_attr(net, "ivl:clock_polarity");
 
       width = ivl_lpm_width(net);
 
-	/*        Q   C   CE  D   RS  --> Q+ */
-      fprintf(vvp_out, "L_%s.%s/def .udp/sequ \"DFF\", 5, 2,"
-	      " \"?" "r" "1" "0" "00"    "0\","
-	      " \"?" "r" "1" "1" "00"    "1\","
-	      " \"?" "r" "1" "x" "00"    "x\","
-	      " \"0" "r" "x" "0" "00"    "0\","
-	      " \"1" "r" "x" "1" "00"    "1\","
-	      " \"?" "*" "0" "?" "00"    "-\","
-	      " \"?" "_" "?" "?" "00"    "-\","
-	      " \"?" "?" "?" "?" "01"    "1\","
-	      " \"?" "?" "?" "?" "1?"    "0\","
-	      " \"?" "?" "1" "?" "00"    "-\","
-	      " \"?" "?" "?" "?" "00"    "-\""
-	      ";\n",
-	      vvp_mangle_id(ivl_scope_name(ivl_lpm_scope(net))),
-	      vvp_mangle_id(ivl_lpm_basename(net)));
-
+      if (clock_pol) {
+	      /*        Q   C   CE  D   RS  --> Q+ */
+	    fprintf(vvp_out, "L_%s.%s/def .udp/sequ \"DFF\", 5, 2,"
+		    " \"?" "f" "1" "0" "00"    "0\","
+		    " \"?" "f" "1" "1" "00"    "1\","
+		    " \"?" "f" "1" "x" "00"    "x\","
+		    " \"0" "f" "x" "0" "00"    "0\","
+		    " \"1" "f" "x" "1" "00"    "1\","
+		    " \"?" "*" "0" "?" "00"    "-\","
+		    " \"?" "_" "?" "?" "00"    "-\","
+		    " \"?" "?" "?" "?" "01"    "1\","
+		    " \"?" "?" "?" "?" "1?"    "0\","
+		    " \"?" "?" "1" "?" "00"    "-\","
+		    " \"?" "?" "?" "?" "00"    "-\""
+		    ";\n",
+		    vvp_mangle_id(ivl_scope_name(ivl_lpm_scope(net))),
+		    vvp_mangle_id(ivl_lpm_basename(net)));
+      } else {
+	      /*        Q   C   CE  D   RS  --> Q+ */
+	    fprintf(vvp_out, "L_%s.%s/def .udp/sequ \"DFF\", 5, 2,"
+		    " \"?" "r" "1" "0" "00"    "0\","
+		    " \"?" "r" "1" "1" "00"    "1\","
+		    " \"?" "r" "1" "x" "00"    "x\","
+		    " \"0" "r" "x" "0" "00"    "0\","
+		    " \"1" "r" "x" "1" "00"    "1\","
+		    " \"?" "*" "0" "?" "00"    "-\","
+		    " \"?" "_" "?" "?" "00"    "-\","
+		    " \"?" "?" "?" "?" "01"    "1\","
+		    " \"?" "?" "?" "?" "1?"    "0\","
+		    " \"?" "?" "1" "?" "00"    "-\","
+		    " \"?" "?" "?" "?" "00"    "-\""
+		    ";\n",
+		    vvp_mangle_id(ivl_scope_name(ivl_lpm_scope(net))),
+		    vvp_mangle_id(ivl_lpm_basename(net)));
+      }
       aset_expr = ivl_lpm_aset_value(net);
       if (aset_expr) {
 	    assert(ivl_expr_width(aset_expr) == width);
@@ -1745,6 +1776,9 @@ int draw_scope(ivl_scope_t net, ivl_scope_t parent)
 
 /*
  * $Log: vvp_scope.c,v $
+ * Revision 1.103.2.3  2006/02/25 05:03:30  steve
+ *  Add support for negedge FFs by using attributes.
+ *
  * Revision 1.103.2.2  2006/02/19 00:11:35  steve
  *  Handle synthesis of FF vectors with l-value decoder.
  *