diff --git a/acc_user.h b/acc_user.h
index 995257c23..02118143c 100644
--- a/acc_user.h
+++ b/acc_user.h
@@ -19,7 +19,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: acc_user.h,v 1.11 2003/04/24 18:57:05 steve Exp $"
+#ident "$Id: acc_user.h,v 1.12 2003/05/18 00:16:35 steve Exp $"
 #endif
 
 /*
@@ -84,11 +84,39 @@ typedef struct __vpiHandle *handle;
 #define accStringVal 8
 #define accVectorVal 9
 
+/* Scalar values */
+#define acc0 0
+#define acc1 1
+#define accX 2
+#define accZ 3
+
 /* type VALUES FOR t_acc_time STRUCTURE */
 #define accTime 1
 #define accSimTime 2
 #define accRealTime 3
 
+/* reason codes */
+#define logic_value_change     1
+#define strength_value_change  2
+#define real_value_change      3
+#define vector_value_change    4
+#define event_value_change     5
+#define integer_value_change   6
+#define time_value_change      7
+#define sregister_value_change 8
+#define vregister_value_change 9
+#define realtime_value_change 10
+
+/* VCL strength values */
+#define vclSupply  7
+#define vclStrong  6
+#define vclPull    5
+#define vclLarge   4
+#define vclWeak    3
+#define vclMedium  2
+#define vclSmall   1
+#define vclHighZ   0
+
 /* Constants used by acc_vcl_add */
 #define vcl_verilog_logic 2
 #define VCL_VERILOG_LOGIC vcl_verilog_logic
@@ -141,6 +169,7 @@ typedef struct t_vc_record {
       } out_value;
 } s_vc_record, *p_vc_record;
 
+
 typedef struct t_location {
       PLI_INT32 line_no;
       const char*filename;
@@ -214,6 +243,12 @@ EXTERN_C_END
 
 /*
  * $Log: acc_user.h,v $
+ * Revision 1.12  2003/05/18 00:16:35  steve
+ *  Add PLI_TRACE tracing of PLI1 modules.
+ *
+ *  Add tf_isetdelay and friends, and add
+ *  callback return values for acc_vcl support.
+ *
  * Revision 1.11  2003/04/24 18:57:05  steve
  *  Add acc_fetch_fulltype function.
  *
diff --git a/libveriuser/Makefile.in b/libveriuser/Makefile.in
index a19eb126d..f89a61362 100644
--- a/libveriuser/Makefile.in
+++ b/libveriuser/Makefile.in
@@ -16,7 +16,7 @@
 #    59 Temple Place - Suite 330
 #    Boston, MA 02111-1307, USA
 #
-#ident "$Id: Makefile.in,v 1.22 2003/05/16 03:23:17 steve Exp $"
+#ident "$Id: Makefile.in,v 1.23 2003/05/18 00:16:35 steve Exp $"
 #
 #
 SHELL = /bin/sh
@@ -51,7 +51,7 @@ a_fetch_type.o a_fetch_type_str.o a_fetch_value.o \
 a_handle_object.o a_handle_parent.o a_handle_tfarg.o \
 a_initialize.o a_next_topmod.o a_object_of_type.o a_product_version.o \
 a_set_value.o a_vcl.o a_version.o
-O = asynch.o finish.o getcstringp.o getinstance.o getlongp.o \
+O = asynch.o delay.o finish.o getcstringp.o getinstance.o getlongp.o \
 getp.o getsimtime.o io_print.o math.o mc_scan_plusargs.o nump.o putlongp.o \
 putp.o spname.o typep.o workarea.o veriusertfs.o priv.o $A
 
diff --git a/libveriuser/a_close.c b/libveriuser/a_close.c
index 087b7629c..b2e0159b9 100644
--- a/libveriuser/a_close.c
+++ b/libveriuser/a_close.c
@@ -17,15 +17,28 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: a_close.c,v 1.2 2002/08/12 01:35:02 steve Exp $"
+#ident "$Id: a_close.c,v 1.3 2003/05/18 00:16:35 steve Exp $"
 #endif
 
 # include  <acc_user.h>
+# include  "priv.h"
 
-void acc_close(void) { }
+void acc_close(void)
+{
+      if (pli_trace) {
+	    fprintf(pli_trace, "acc_close()\n");
+	    fflush(pli_trace);
+      }
+}
 
 /*
  * $Log: a_close.c,v $
+ * Revision 1.3  2003/05/18 00:16:35  steve
+ *  Add PLI_TRACE tracing of PLI1 modules.
+ *
+ *  Add tf_isetdelay and friends, and add
+ *  callback return values for acc_vcl support.
+ *
  * Revision 1.2  2002/08/12 01:35:02  steve
  *  conditional ident string using autoconfig.
  *
diff --git a/libveriuser/a_configure.c b/libveriuser/a_configure.c
index 483ab8184..5e30be592 100644
--- a/libveriuser/a_configure.c
+++ b/libveriuser/a_configure.c
@@ -17,11 +17,12 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: a_configure.c,v 1.1 2003/02/17 06:39:47 steve Exp $"
+#ident "$Id: a_configure.c,v 1.2 2003/05/18 00:16:35 steve Exp $"
 #endif
 
 #include  <acc_user.h>
 #include  <vpi_user.h>
+#include  "priv.h"
 
 int acc_configure(PLI_INT32 config_param, const char*value)
 {
@@ -30,9 +31,23 @@ int acc_configure(PLI_INT32 config_param, const char*value)
 	  case accDevelopmentVersion:
 	    vpi_printf("Request PLI Development Version %s\n", value);
 	    rc = 1;
+
+	    if (pli_trace) {
+		  fprintf(pli_trace,
+			  "acc_configure(accDevelopmentVersion, %s)\n",
+			  value);
+		  fflush(pli_trace);
+	    }
 	    break;
 
 	  default:
+
+	    if (pli_trace) {
+		  fprintf(pli_trace, "acc_configure(config=%d, %s)\n",
+			  config_param, value);
+		  fflush(pli_trace);
+	    }
+
 	    vpi_printf("XXXX acc_configure(%d, %s)\n", config_param, value);
 	    rc = 0;
 	    break;
@@ -43,6 +58,12 @@ int acc_configure(PLI_INT32 config_param, const char*value)
 
 /*
  * $Log: a_configure.c,v $
+ * Revision 1.2  2003/05/18 00:16:35  steve
+ *  Add PLI_TRACE tracing of PLI1 modules.
+ *
+ *  Add tf_isetdelay and friends, and add
+ *  callback return values for acc_vcl support.
+ *
  * Revision 1.1  2003/02/17 06:39:47  steve
  *  Add at least minimal implementations for several
  *  acc_ functions. Add support for standard ACC
diff --git a/libveriuser/a_fetch_param.c b/libveriuser/a_fetch_param.c
index a94780e62..827d101d9 100644
--- a/libveriuser/a_fetch_param.c
+++ b/libveriuser/a_fetch_param.c
@@ -17,12 +17,13 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: a_fetch_param.c,v 1.2 2003/03/14 04:59:54 steve Exp $"
+#ident "$Id: a_fetch_param.c,v 1.3 2003/05/18 00:16:35 steve Exp $"
 #endif
 
 #include  <assert.h>
 #include  <vpi_user.h>
 #include  <acc_user.h>
+#include  "priv.h"
 
 double acc_fetch_paramval(handle object)
 {
@@ -34,6 +35,11 @@ double acc_fetch_paramval(handle object)
       switch (val.format) {
 
 	  case vpiStringVal:
+	    if (pli_trace) {
+		  fprintf(pli_trace, "acc_fetch_paramval(%s) --> \"%s\"\n",
+			  vpi_get_str(vpiName, object), val.value.str);
+		  fflush(pli_trace);
+	    }
 	    return (double) (long)val.value.str;
 
 	  default:
@@ -46,6 +52,12 @@ double acc_fetch_paramval(handle object)
 
 /*
  * $Log: a_fetch_param.c,v $
+ * Revision 1.3  2003/05/18 00:16:35  steve
+ *  Add PLI_TRACE tracing of PLI1 modules.
+ *
+ *  Add tf_isetdelay and friends, and add
+ *  callback return values for acc_vcl support.
+ *
  * Revision 1.2  2003/03/14 04:59:54  steve
  *  Better message when asserting funky value type.
  *
diff --git a/libveriuser/a_fetch_tfarg.c b/libveriuser/a_fetch_tfarg.c
index f46010ee0..7f71483fe 100644
--- a/libveriuser/a_fetch_tfarg.c
+++ b/libveriuser/a_fetch_tfarg.c
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: a_fetch_tfarg.c,v 1.5 2003/03/14 04:58:50 steve Exp $"
+#ident "$Id: a_fetch_tfarg.c,v 1.6 2003/05/18 00:16:35 steve Exp $"
 #endif
 
 #include  <vpi_user.h>
@@ -48,6 +48,13 @@ int acc_fetch_tfarg_int(int n)
 	    rtn = 0;
       }
 
+
+      if (pli_trace) {
+	    fprintf(pli_trace, "%s: acc_fetch_tfarg_int(%d) --> %d\n",
+		    vpi_get_str(vpiName, sys_h), n, rtn);
+	    fflush(pli_trace);
+      }
+
       return rtn;
 }
 
@@ -74,11 +81,23 @@ char *acc_fetch_tfarg_str(int n)
 	    rtn = (char *) 0;
       }
 
+      if (pli_trace) {
+	    fprintf(pli_trace, "%s: acc_fetch_tfarg_str(%d) --> \"%s\"\n",
+		    vpi_get_str(vpiName, sys_h), n, rtn? rtn : "");
+	    fflush(pli_trace);
+      }
+
       return rtn;
 }
 
 /*
  * $Log: a_fetch_tfarg.c,v $
+ * Revision 1.6  2003/05/18 00:16:35  steve
+ *  Add PLI_TRACE tracing of PLI1 modules.
+ *
+ *  Add tf_isetdelay and friends, and add
+ *  callback return values for acc_vcl support.
+ *
  * Revision 1.5  2003/03/14 04:58:50  steve
  *  Free the iterator when Im done.
  *
diff --git a/libveriuser/a_fetch_value.c b/libveriuser/a_fetch_value.c
index 5efee7278..1fbf013fd 100644
--- a/libveriuser/a_fetch_value.c
+++ b/libveriuser/a_fetch_value.c
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: a_fetch_value.c,v 1.3 2003/04/24 02:02:37 steve Exp $"
+#ident "$Id: a_fetch_value.c,v 1.4 2003/05/18 00:16:35 steve Exp $"
 #endif
 
 # include  <acc_user.h>
@@ -35,19 +35,58 @@ static char* fetch_struct_value(handle obj, s_acc_value*value)
 	  case accScalarVal:
 	    val.format = vpiScalarVal;
 	    vpi_get_value(obj, &val);
-	    value->value.scalar = val.value.scalar;
+	    switch (val.value.scalar) {
+		case vpi0:
+		  value->value.scalar = acc0;
+		  break;
+		case vpi1:
+		  value->value.scalar = acc1;
+		  break;
+		case vpiX:
+		  value->value.scalar = accX;
+		  break;
+		case vpiZ:
+		  value->value.scalar = accZ;
+		  break;
+		default:
+		  assert(0);
+	    }
+
+	    if (pli_trace) {
+		  fprintf(pli_trace, "acc_fetch_value(<%s>, "
+			  "accScalarVal) --> %d\n",
+			  vpi_get_str(vpiFullName,obj),
+			  value->value.scalar);
+		  fflush(pli_trace);
+	    }
 	    break;
 
 	  case accIntVal:
 	    val.format = vpiIntVal;
 	    vpi_get_value(obj, &val);
 	    value->value.integer = val.value.integer;
+
+	    if (pli_trace) {
+		  fprintf(pli_trace, "acc_fetch_value(<%s>, "
+			  "accIntVal) --> %d\n",
+			  vpi_get_str(vpiFullName,obj),
+			  value->value.integer);
+		  fflush(pli_trace);
+	    }
 	    break;
 
 	  case accRealVal:
 	    val.format = vpiRealVal;
 	    vpi_get_value(obj, &val);
 	    value->value.real = val.value.real;
+
+	    if (pli_trace) {
+		  fprintf(pli_trace, "acc_fetch_value(<%s>, "
+			  "accRealVal) --> %g\n",
+			  vpi_get_str(vpiFullName,obj),
+			  value->value.real);
+		  fflush(pli_trace);
+	    }
 	    break;
 
 	  default:
@@ -70,6 +109,12 @@ static char* fetch_strength_value(handle obj)
 
       vpip_format_strength(str, &val);
 
+      if (pli_trace) {
+	    fprintf(pli_trace, "acc_fetch_value(<%s>, \"%%v\") --> %s\n",
+		    vpi_get_str(vpiFullName,obj), str);
+	    fflush(pli_trace);
+      }
+
       return __acc_newstring(str);
 }
 
@@ -88,6 +133,12 @@ char* acc_fetch_value(handle obj, const char*fmt, s_acc_value*value)
 
 /*
  * $Log: a_fetch_value.c,v $
+ * Revision 1.4  2003/05/18 00:16:35  steve
+ *  Add PLI_TRACE tracing of PLI1 modules.
+ *
+ *  Add tf_isetdelay and friends, and add
+ *  callback return values for acc_vcl support.
+ *
  * Revision 1.3  2003/04/24 02:02:37  steve
  *  Clean up some simple warnings.
  *
diff --git a/libveriuser/a_set_value.c b/libveriuser/a_set_value.c
index 6031a172a..7e842255f 100644
--- a/libveriuser/a_set_value.c
+++ b/libveriuser/a_set_value.c
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: a_set_value.c,v 1.2 2002/08/12 01:35:02 steve Exp $"
+#ident "$Id: a_set_value.c,v 1.3 2003/05/18 00:16:35 steve Exp $"
 #endif
 
 #include  <assert.h>
@@ -101,7 +101,11 @@ int acc_set_value(handle object, p_setval_value value, p_setval_delay delay)
 		  val.format = vpiVectorVal;
 		  val.value.vector = (p_vpi_vecval)value->value.vector;
 		  break;
-	    default: assert(0); break;
+	    default:
+	      vpi_printf("XXXX acc_set_value(value->format=%d)\n",
+			 value->format);
+	      assert(0);
+	      break;
       }
 
       /* put value */
@@ -112,6 +116,12 @@ int acc_set_value(handle object, p_setval_value value, p_setval_delay delay)
 
 /*
  * $Log: a_set_value.c,v $
+ * Revision 1.3  2003/05/18 00:16:35  steve
+ *  Add PLI_TRACE tracing of PLI1 modules.
+ *
+ *  Add tf_isetdelay and friends, and add
+ *  callback return values for acc_vcl support.
+ *
  * Revision 1.2  2002/08/12 01:35:02  steve
  *  conditional ident string using autoconfig.
  *
diff --git a/libveriuser/a_vcl.c b/libveriuser/a_vcl.c
index 9126a4be7..923f3c5f0 100644
--- a/libveriuser/a_vcl.c
+++ b/libveriuser/a_vcl.c
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: a_vcl.c,v 1.4 2003/04/30 01:09:29 steve Exp $"
+#ident "$Id: a_vcl.c,v 1.5 2003/05/18 00:16:35 steve Exp $"
 #endif
 
 #include  <vpi_user.h>
@@ -27,11 +27,25 @@
 #include  <malloc.h>
 #endif
 #include  "priv.h"
+#include  <assert.h>
 
+/*
+ * This is the structure of a record that I use locally to hold the
+ * information about a VCL. This record includes a pointer to the vpi
+ * callback that is actually watching the value, and that callback has
+ * a pointer to this record in its user_data so that I can get to it
+ * when the value changes.
+ *
+ * Keep all these records in a vcl_list so that I can get access to
+ * them for the vcl_delete.
+ */
 struct vcl_record {
+	/* Object who's value I'm watching. */
       vpiHandle obj;
+	/* User's callback routine. */
       PLI_INT32(*consumer)(p_vc_record);
       void*user_data;
+
       PLI_INT32 vcl_flag;
 
       vpiHandle callback;
@@ -40,13 +54,109 @@ struct vcl_record {
 
 static struct vcl_record*vcl_list = 0;
 
+static int vpi_strength_to_vcl(int vs)
+{
+      switch (vs) {
+	  case vpiSupplyDrive:
+	    return vclSupply;
+	  case vpiStrongDrive:
+	    return vclStrong;
+	  case vpiPullDrive:
+	    return vclPull;
+	  case vpiLargeCharge:
+	    return vclLarge;
+	  case vpiWeakDrive:
+	    return vclWeak;
+	  case vpiMediumCharge:
+	    return vclMedium;
+	  case vpiSmallCharge:
+	    return vclSmall;
+	  case vpiHiZ:
+	    return vclHighZ;
+	  default:
+	    return -1;
+      }
+}
+
+/*
+ * This is a VPI callback that notices the value change. This function
+ * further dispatches the information about the callback to the
+ * consumer function.
+ */
 static PLI_INT32 vcl_value_callback(struct t_cb_data*cb)
 {
+      s_vpi_time sim_time;
+      s_vpi_value obj_value;
+      struct t_vc_record vcr;
       struct vcl_record*cur = (struct vcl_record*)cb->user_data;
 
-      vpi_printf("XXXX Call vcl_callback(<type=%d>);\n",
-		 vpi_get(vpiType, cur->obj));
+      sim_time.type = vpiSimTime;
+      vpi_get_time(cur->obj, &sim_time);
 
+      switch (cur->vcl_flag) {
+	  case VCL_VERILOG_LOGIC:
+	    vpi_printf("XXXX vcl_value_callback(%s=%d);\n",
+		       vpi_get_str(vpiName, cur->obj), -1);
+
+	    vcr.vc_reason = logic_value_change;
+	    break;
+
+	  case VCL_VERILOG_STRENGTH:
+	    vcr.vc_reason = strength_value_change;
+	    obj_value.format = vpiStrengthVal;
+	    vpi_get_value(cur->obj, &obj_value);
+	    assert(obj_value.format == vpiStrengthVal);
+	    switch (obj_value.value.strength[0].logic) {
+		case vpi0:
+		  vcr.out_value.strengths_s.logic_value = acc0;
+		  vcr.out_value.strengths_s.strength1 =
+			vpi_strength_to_vcl(obj_value.value.strength[0].s0);
+		  vcr.out_value.strengths_s.strength2 =
+			vpi_strength_to_vcl(obj_value.value.strength[0].s0);
+		  break;
+		case vpi1:
+		  vcr.out_value.strengths_s.logic_value = acc1;
+		  vcr.out_value.strengths_s.strength1 =
+			vpi_strength_to_vcl(obj_value.value.strength[0].s1);
+		  vcr.out_value.strengths_s.strength2 =
+			vpi_strength_to_vcl(obj_value.value.strength[0].s1);
+		  break;
+		case vpiX:
+		  vcr.out_value.strengths_s.logic_value = accX;
+		  vcr.out_value.strengths_s.strength1 =
+			vpi_strength_to_vcl(obj_value.value.strength[0].s1);
+		  vcr.out_value.strengths_s.strength2 =
+			vpi_strength_to_vcl(obj_value.value.strength[0].s0);
+		  break;
+		case vpiZ:
+		  vcr.out_value.strengths_s.logic_value = accZ;
+		  vcr.out_value.strengths_s.strength1 = vclHighZ;
+		  vcr.out_value.strengths_s.strength2 = vclHighZ;
+		  break;
+		default:
+		  assert(0);
+	    }
+
+	    if (pli_trace) {
+		  fprintf(pli_trace,
+			  "Call vcl_value_callback(%s=%d <s1=%d,s2=%d>)\n",
+			  vpi_get_str(vpiFullName, cur->obj),
+			  vcr.out_value.strengths_s.logic_value,
+			  vcr.out_value.strengths_s.strength1,
+			  vcr.out_value.strengths_s.strength2);
+		  fflush(pli_trace);
+	    }
+	    break;
+
+	  default:
+	    assert(0);
+      }
+
+      vcr.vc_hightime = sim_time.high;
+      vcr.vc_lowtime  = sim_time.low;
+      vcr.user_data = cur->user_data;
+      
+      (cur->consumer) (&vcr);
       return 0;
 }
 
@@ -69,12 +179,20 @@ void acc_vcl_add(handle obj, PLI_INT32(*consumer)(p_vc_record),
 	    cb.reason = cbValueChange;
 	    cb.cb_rtn = vcl_value_callback;
 	    cb.obj = obj;
+	    cb.time = 0;
+	    cb.value = 0;
 	    cb.user_data = (void*)cur;
 	    cur->callback = vpi_register_cb(&cb);
+
+	    if (pli_trace) {
+		  fprintf(pli_trace, "acc_vcl_add(<%s>, ..., %p, %d)\n",
+			  vpi_get_str(vpiFullName, obj), data, vcl_flag);
+		  fflush(pli_trace);
+	    }
 	    break;
 
 	  default:
-	    vpi_printf("XXXX Call acc_vcl_add(<type=%d>, ..., %d);\n",
+	    vpi_printf("XXXX acc_vcl_add(<type=%d>, ..., %d);\n",
 		       vpi_get(vpiType, obj), vcl_flag);
 	    break;
       }
@@ -84,12 +202,18 @@ void acc_vcl_add(handle obj, PLI_INT32(*consumer)(p_vc_record),
 void acc_vcl_delete(handle obj, PLI_INT32(*consumer)(p_vc_record),
 		    void*data, PLI_INT32 vcl_flag)
 {
-      vpi_printf("XXXX Call acc_vcl_delete\n");
+      vpi_printf("XXXX acc_vcl_delete(...)\n");
 }
 
 
 /*
  * $Log: a_vcl.c,v $
+ * Revision 1.5  2003/05/18 00:16:35  steve
+ *  Add PLI_TRACE tracing of PLI1 modules.
+ *
+ *  Add tf_isetdelay and friends, and add
+ *  callback return values for acc_vcl support.
+ *
  * Revision 1.4  2003/04/30 01:09:29  steve
  *  Conditionally include malloc.h
  *
diff --git a/libveriuser/delay.c b/libveriuser/delay.c
new file mode 100644
index 000000000..01e097076
--- /dev/null
+++ b/libveriuser/delay.c
@@ -0,0 +1,91 @@
+/*
+ * Copyright (c) 2003 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: delay.c,v 1.1 2003/05/18 00:16:35 steve Exp $"
+#endif
+
+#include  <veriuser.h>
+#include  <vpi_user.h>
+#include  "priv.h"
+#include  <assert.h>
+
+static PLI_INT32 delay_callback(struct t_cb_data*cb)
+{
+      vpi_printf("XXXX delay_callback called.\n");
+}
+
+int tf_isetdelay(PLI_INT32 delay, void*ss)
+{
+      vpiHandle sys = (vpiHandle)ss;
+      int unit = vpi_get(vpiTimeUnit, sys);
+      int prec = vpi_get(vpiTimePrecision, 0);
+
+      struct t_cb_data cb;
+      struct t_vpi_time ct;
+
+      if (pli_trace) {
+	    fprintf(pli_trace, "%s: tf_isetdelay(%d, ...)"
+		    " <unit=%d, prec=%d>;\n",
+		    vpi_get_str(vpiName, sys), delay, unit, prec);
+	    fflush(pli_trace);
+      }
+
+
+	/* Convert the delay from the UNITS of the specified
+	   task/function to the precision of the simulation. */
+      assert(unit >= prec);
+
+      while (unit > prec) {
+	    PLI_INT32 tmp = delay * 10;
+	    assert(tmp > delay);
+	    delay = tmp;
+	    unit -= 1;
+      }
+
+	/* Create a VPI callback to schedule the delay. */
+      ct.type = vpiSimTime;
+      ct.high = 0;
+      ct.low  = delay;
+
+      cb.reason = cbAfterDelay;
+      cb.cb_rtn = delay_callback;
+      cb.obj = 0;
+      cb.time = &ct;
+      cb.value = 0;
+      cb.user_data = 0;
+      vpi_register_cb(&cb);
+
+      return 0;
+}
+
+int tf_setdelay(PLI_INT32 delay)
+{
+      return tf_isetdelay(delay, tf_getinstance());
+}
+
+/*
+ * $Log: delay.c,v $
+ * Revision 1.1  2003/05/18 00:16:35  steve
+ *  Add PLI_TRACE tracing of PLI1 modules.
+ *
+ *  Add tf_isetdelay and friends, and add
+ *  callback return values for acc_vcl support.
+ *
+ */
+
diff --git a/libveriuser/getinstance.c b/libveriuser/getinstance.c
index e1b770d5b..4fb4b26a1 100644
--- a/libveriuser/getinstance.c
+++ b/libveriuser/getinstance.c
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: getinstance.c,v 1.3 2002/08/12 01:35:02 steve Exp $"
+#ident "$Id: getinstance.c,v 1.4 2003/05/18 00:16:35 steve Exp $"
 #endif
 
 #include  <veriuser.h>
@@ -26,13 +26,19 @@
 /*
  * tf_getinstance implemented using VPI interface
  */
-char *tf_getinstance(void)
+PLI_BYTE8* tf_getinstance(void)
 {
       return (char *)vpi_handle(vpiSysTfCall, 0 /* NULL */);
 }
 
 /*
  * $Log: getinstance.c,v $
+ * Revision 1.4  2003/05/18 00:16:35  steve
+ *  Add PLI_TRACE tracing of PLI1 modules.
+ *
+ *  Add tf_isetdelay and friends, and add
+ *  callback return values for acc_vcl support.
+ *
  * Revision 1.3  2002/08/12 01:35:02  steve
  *  conditional ident string using autoconfig.
  *
diff --git a/libveriuser/priv.c b/libveriuser/priv.c
index ffcc77438..cd3355617 100644
--- a/libveriuser/priv.c
+++ b/libveriuser/priv.c
@@ -17,13 +17,15 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: priv.c,v 1.2 2003/03/13 05:07:46 steve Exp $"
+#ident "$Id: priv.c,v 1.3 2003/05/18 00:16:35 steve Exp $"
 #endif
 
 # include  "priv.h"
 # include  <string.h>
 # include  <assert.h>
 
+FILE* pli_trace = 0;
+
 static char string_buffer[8192];
 static unsigned string_fill = 0;
 
@@ -56,6 +58,12 @@ char* __acc_newstring(const char*txt)
 
 /*
  * $Log: priv.c,v $
+ * Revision 1.3  2003/05/18 00:16:35  steve
+ *  Add PLI_TRACE tracing of PLI1 modules.
+ *
+ *  Add tf_isetdelay and friends, and add
+ *  callback return values for acc_vcl support.
+ *
  * Revision 1.2  2003/03/13 05:07:46  steve
  *  Declaration warnings.
  *
diff --git a/libveriuser/priv.h b/libveriuser/priv.h
index a6f289ffb..c6db54313 100644
--- a/libveriuser/priv.h
+++ b/libveriuser/priv.h
@@ -19,9 +19,11 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: priv.h,v 1.1 2003/02/17 06:39:47 steve Exp $"
+#ident "$Id: priv.h,v 1.2 2003/05/18 00:16:35 steve Exp $"
 #endif
 
+# include  <stdio.h>
+
 /*
  * This function implements the acc_ string buffer, by adding the
  * input string to the buffer, and returning a pointer to the first
@@ -29,8 +31,19 @@
  */
 extern char* __acc_newstring(const char*txt);
 
+/*
+ * Trace file for loggint ACC and TF calls.
+ */
+FILE* pli_trace;
+
 /*
  * $Log: priv.h,v $
+ * Revision 1.2  2003/05/18 00:16:35  steve
+ *  Add PLI_TRACE tracing of PLI1 modules.
+ *
+ *  Add tf_isetdelay and friends, and add
+ *  callback return values for acc_vcl support.
+ *
  * Revision 1.1  2003/02/17 06:39:47  steve
  *  Add at least minimal implementations for several
  *  acc_ functions. Add support for standard ACC
diff --git a/libveriuser/spname.c b/libveriuser/spname.c
index 17658a714..543cc6d87 100644
--- a/libveriuser/spname.c
+++ b/libveriuser/spname.c
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: spname.c,v 1.1 2003/03/13 04:35:09 steve Exp $"
+#ident "$Id: spname.c,v 1.2 2003/05/18 00:16:35 steve Exp $"
 #endif
 
 #include  <assert.h>
@@ -27,14 +27,30 @@
 
 char* tf_spname(void)
 {
+      char*rtn;
+
       vpiHandle sys = vpi_handle(vpiSysTfCall, 0);
       vpiHandle scope = vpi_handle(vpiScope, sys);
 
-      return __acc_newstring(vpi_get_str(vpiFullName, scope));
+      rtn = __acc_newstring(vpi_get_str(vpiFullName, scope));
+
+      if (pli_trace) {
+	    fprintf(pli_trace, "%s: tf_spname() --> %s\n",
+		    vpi_get_str(vpiName,sys), rtn);
+	    fflush(pli_trace);
+      }
+
+      return rtn;
 }
 
 /*
  * $Log: spname.c,v $
+ * Revision 1.2  2003/05/18 00:16:35  steve
+ *  Add PLI_TRACE tracing of PLI1 modules.
+ *
+ *  Add tf_isetdelay and friends, and add
+ *  callback return values for acc_vcl support.
+ *
  * Revision 1.1  2003/03/13 04:35:09  steve
  *  Add a bunch of new acc_ and tf_ functions.
  *
diff --git a/libveriuser/veriusertfs.c b/libveriuser/veriusertfs.c
index a4bb05fcc..475a7a9f2 100644
--- a/libveriuser/veriusertfs.c
+++ b/libveriuser/veriusertfs.c
@@ -18,7 +18,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: veriusertfs.c,v 1.7 2003/04/23 15:01:29 steve Exp $"
+#ident "$Id: veriusertfs.c,v 1.8 2003/05/18 00:16:35 steve Exp $"
 #endif
 
 /*
@@ -31,6 +31,7 @@
 # include <assert.h>
 # include "vpi_user.h"
 # include "veriuser.h"
+# include "priv.h"
 
 /*
  * local structure used to hold the persistent veriusertfs data
@@ -51,10 +52,18 @@ static int callback(p_cb_data);
  */
 void veriusertfs_register_table(p_tfcell vtable)
 {
+      const char*path;
       p_tfcell tf;
       s_vpi_systf_data tf_data;
       p_pli_data data;
 
+      if ((pli_trace == 0) && (path = getenv("PLI_TRACE"))) {
+	    if (strcmp(path,"-") == 0)
+		  pli_trace = stdout;
+	    else
+		  pli_trace = fopen(path, "w");
+      }
+
       for (tf = vtable; tf; tf++) {
 	    /* last element */
 	    if (tf->type == 0) break;
@@ -94,6 +103,14 @@ void veriusertfs_register_table(p_tfcell vtable)
 	    tf_data.sizetf = tf->sizetf;
 	    tf_data.user_data = (char *)data;
 
+	    if (pli_trace) {
+		  fprintf(pli_trace, "Registering system task/function\n");
+		  fprintf(pli_trace, "    tfname: %s\n", tf->tfname);
+		  fprintf(pli_trace, "    type:   %d\n", tf->type);
+		  fprintf(pli_trace, "    data:   %d\n", tf->data);
+		  fflush(pli_trace);
+	    }
+
 	    /* register */
 	    vpi_register_systf(&tf_data);
       }
@@ -162,8 +179,26 @@ static int compiletf(char *data)
        * Since we are in compiletf, checktf and misctf need to
        * be executed. Check runs first to match other simulators.
        */
-      rtn = (tf->checktf) ? tf->checktf(tf->data, reason_checktf) : 0;
-      if (tf->misctf) tf->misctf(tf->data, reason_endofcompile, 0);
+      if (tf->checktf) {
+	    if (pli_trace) {
+		  fprintf(pli_trace, "Call %s->checktf(reason_checktf)\n",
+			  tf->tfname);
+		  fflush(pli_trace);
+	    }
+
+	    rtn = tf->checktf(tf->data, reason_checktf);
+      }
+
+      if (tf->misctf) {
+	    if (pli_trace) {
+		  fprintf(pli_trace, "Call %s->misctf"
+			  "(user_data=%d, reason=%d, paramvc=%d);\n",
+			  tf->tfname, tf->data, reason_endofcompile, 0);
+		  fflush(pli_trace);
+	    }
+
+	    tf->misctf(tf->data, reason_endofcompile, 0);
+      }
 
       return rtn;
 }
@@ -182,8 +217,15 @@ static int calltf(char *data)
       tf = pli->tf;
 
       /* execute calltf */
-      if (tf->calltf)
+      if (tf->calltf) {
+	    if (pli_trace) {
+		  fprintf(pli_trace, "Call %s->calltf(%d, %d)\n",
+			  tf->data, reason_calltf);
+		  fflush(pli_trace);
+	    }
+
 	    rc = tf->calltf(tf->data, reason_calltf);
+      }
 
       return rc;
 }
@@ -199,6 +241,7 @@ static int callback(p_cb_data data)
       p_tfcell tf;
       int reason;
       int paramvc = 0;
+      int rc;
 
 	/* not enabled */
       if (data->reason == cbValueChange && !async_misctf_enable)
@@ -223,8 +266,17 @@ static int callback(p_cb_data data)
 	    assert(0);
       }
 
+      if (pli_trace) {
+	    fprintf(pli_trace, "Call %s->misctf"
+		    "(user_data=%d, reason=%d, paramvc=%d);\n",
+		    tf->tfname, tf->data, reason, paramvc);
+	    fflush(pli_trace);
+      }
+
       /* execute misctf */
-      return (tf->misctf) ? tf->misctf(tf->data, reason, paramvc) : 0;
+      rc = (tf->misctf) ? tf->misctf(tf->data, reason, paramvc) : 0;
+
+      return rc;
 }
 
 PLI_INT32 tf_isynchronize(void*obj)
@@ -253,6 +305,12 @@ PLI_INT32 tf_synchronize(void)
 
 /*
  * $Log: veriusertfs.c,v $
+ * Revision 1.8  2003/05/18 00:16:35  steve
+ *  Add PLI_TRACE tracing of PLI1 modules.
+ *
+ *  Add tf_isetdelay and friends, and add
+ *  callback return values for acc_vcl support.
+ *
  * Revision 1.7  2003/04/23 15:01:29  steve
  *  Add tf_synchronize and tf_multiply_long.
  *
diff --git a/veriuser.h b/veriuser.h
index af7dafda6..8727c7286 100644
--- a/veriuser.h
+++ b/veriuser.h
@@ -19,7 +19,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: veriuser.h,v 1.24 2003/04/23 15:01:29 steve Exp $"
+#ident "$Id: veriuser.h,v 1.25 2003/05/18 00:16:35 steve Exp $"
 #endif
 
 /*
@@ -245,7 +245,7 @@ extern void tf_error(const char*, ...)
 
 extern char* tf_getcstringp(int nparam);
 
-extern char* tf_getinstance(void);
+extern PLI_BYTE8* tf_getinstance(void);
 
 extern int tf_getlongp(int*aof_highvalue, int pnum);
 
@@ -276,6 +276,13 @@ extern void tf_putlongp(int pnum, int lowvalue, int highvalue);
 
 extern void tf_putp(int pnum, int value);
 
+/* Activate the misctf function after a delay. The units are of the
+   current scope. The tf_isetdelay variant specifies a particular
+   system task instance to use as the context for the
+   units. tf_getinstance gets that value. */
+extern int tf_setdelay(PLI_INT32 delay);
+extern int tf_isetdelay(PLI_INT32 delay, void* sys);
+
 /* IEEE1364 NOTE: tf_setworkarea is listed as taking a PLI_BYTE8*, but
    that is silly, it really takes any kind of pointer. Taking void* is
    compatible with those who pass a PLI_BYTE8*. */
@@ -298,6 +305,12 @@ EXTERN_C_END
 
 /*
  * $Log: veriuser.h,v $
+ * Revision 1.25  2003/05/18 00:16:35  steve
+ *  Add PLI_TRACE tracing of PLI1 modules.
+ *
+ *  Add tf_isetdelay and friends, and add
+ *  callback return values for acc_vcl support.
+ *
  * Revision 1.24  2003/04/23 15:01:29  steve
  *  Add tf_synchronize and tf_multiply_long.
  *