From f04fb0fc450b460ad8a52beb0f00db7f16228fc1 Mon Sep 17 00:00:00 2001
From: Cary R <cygcary@yahoo.com>
Date: Tue, 27 May 2008 15:11:17 -0700
Subject: [PATCH] System functions have a default return value.

If a system function does not call vpi_put_value it is
supposed to have a default return value of 0. This patch
adds this functionality.
---
 vvp/vpi_priv.h   |  1 +
 vvp/vpi_tasks.cc | 26 +++++++++++++++++++++++++-
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/vvp/vpi_priv.h b/vvp/vpi_priv.h
index fc43caeff..ab4e11658 100644
--- a/vvp/vpi_priv.h
+++ b/vvp/vpi_priv.h
@@ -368,6 +368,7 @@ struct __vpiSysTaskCall {
       class vvp_net_t*fnet;
       unsigned file_idx;
       unsigned lineno;
+      bool put_value;
 };
 
 extern struct __vpiSysTaskCall*vpip_cur_task;
diff --git a/vvp/vpi_tasks.cc b/vvp/vpi_tasks.cc
index f82a43c41..fdad4ffc3 100644
--- a/vvp/vpi_tasks.cc
+++ b/vvp/vpi_tasks.cc
@@ -167,6 +167,8 @@ static vpiHandle sysfunc_put_value(vpiHandle ref, p_vpi_value vp, int)
 
       struct __vpiSysTaskCall*rfp = (struct __vpiSysTaskCall*)ref;
 
+      rfp->put_value = true;
+
       assert(rfp->vbit >= 4);
 
       switch (vp->format) {
@@ -271,6 +273,8 @@ static vpiHandle sysfunc_put_real_value(vpiHandle ref, p_vpi_value vp, int)
 
       struct __vpiSysTaskCall*rfp = (struct __vpiSysTaskCall*)ref;
 
+      rfp->put_value = true;
+
 	/* Make sure this is a real valued function. */
       assert(rfp->vwid == -vpiRealConst);
 
@@ -297,6 +301,8 @@ static vpiHandle sysfunc_put_4net_value(vpiHandle ref, p_vpi_value vp, int)
 
       struct __vpiSysTaskCall*rfp = (struct __vpiSysTaskCall*)ref;
 
+      rfp->put_value = true;
+
       unsigned vwid = (unsigned) rfp->vwid;
       vvp_vector4_t val (vwid);
 
@@ -384,8 +390,10 @@ static vpiHandle sysfunc_put_rnet_value(vpiHandle ref, p_vpi_value vp, int)
       assert(ref->vpi_type->type_code == vpiSysFuncCall);
 
       struct __vpiSysTaskCall*rfp = (struct __vpiSysTaskCall*)ref;
-      double val;
 
+      rfp->put_value = true;
+
+      double val;
       switch (vp->format) {
 
 	  case vpiRealVal:
@@ -563,6 +571,7 @@ vpiHandle vpip_build_vpi_call(const char*name, unsigned vbit, int vwid,
       obj->file_idx  = (unsigned) file_idx;
       obj->lineno   = (unsigned) lineno;
       obj->userdata  = 0;
+      obj->put_value = false;
 
       compile_compiletf(obj);
 
@@ -590,8 +599,23 @@ void vpip_execute_vpi_call(vthread_t thr, vpiHandle ref)
       if (vpip_cur_task->defn->info.calltf) {
 	    assert(vpi_mode_flag == VPI_MODE_NONE);
 	    vpi_mode_flag = VPI_MODE_CALLTF;
+	    vpip_cur_task->put_value = false;
 	    vpip_cur_task->defn->info.calltf(vpip_cur_task->defn->info.user_data);
 	    vpi_mode_flag = VPI_MODE_NONE;
+	      /* If the function call did not set a value then put a
+	       * default value (0). */
+	    if (ref->vpi_type->type_code == vpiSysFuncCall &&
+	        !vpip_cur_task->put_value) {
+		  s_vpi_value val;
+		  if (vpip_cur_task->vwid == -vpiRealConst) {
+			val.format = vpiRealVal;
+			val.value.real = 0.0;
+		  } else {
+			val.format = vpiIntVal;
+			val.value.integer = 0;
+		  }
+		  vpi_put_value(ref, &val, 0, vpiNoDelay);
+	    }
       }
 }