From 301bbe94a0a8902a651c3dfa297c3ced3a617e8a Mon Sep 17 00:00:00 2001
From: Cary R <cygcary@yahoo.com>
Date: Thu, 1 Apr 2010 17:46:43 -0700
Subject: [PATCH] Set negative absolute SDF delays to zero.

The SDF standard allows negative absolute delays, but simulation
tools cannot handle this so set negative delays to zero.
---
 vpi/sys_sdf.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/vpi/sys_sdf.c b/vpi/sys_sdf.c
index 82f46644e..139ebcc74 100644
--- a/vpi/sys_sdf.c
+++ b/vpi/sys_sdf.c
@@ -195,6 +195,10 @@ void sdf_iopath_delays(int vpi_edge, const char*src, const char*dst,
 		  delay_vals[idx].type = vpiScaledRealTime;
 		  if (delval_list->val[idx].defined) {
 			delay_vals[idx].real = delval_list->val[idx].value;
+			  /* Simulation cannot support negative delays. */
+			if (delay_vals[idx].real < 0.0)  {
+			      delay_vals[idx].real = 0.0;
+			}
 		  }
  
 	    }