From 97fca3fc4b4847d9030d3a4436a02ef90db030ae Mon Sep 17 00:00:00 2001
From: Cary R <cygcary@yahoo.com>
Date: Wed, 21 Oct 2015 22:00:50 -0700
Subject: [PATCH] Fix the modpath delay to ignore bits that are not changing

---
 vvp/delay.cc | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/vvp/delay.cc b/vvp/delay.cc
index 94c323f78..5bda67ad8 100644
--- a/vvp/delay.cc
+++ b/vvp/delay.cc
@@ -645,8 +645,11 @@ void vvp_fun_modpath::recv_vec4(vvp_net_ptr_t port, const vvp_vector4_t&bit,
 	   and schedule an event for each partial change. Hard! */
       for (unsigned idx = 1 ;  idx < bit.size() ;  idx += 1) {
 	    vvp_time64_t tmp = delay_from_edge(cur_vec4_.value(idx),
-					       bit.value(0),
+					       bit.value(idx),
 					       out_at);
+	      /* If the current and new bit values match then no delay
+	       * is needed for this bit. */
+	    if (cur_vec4_.value(idx) == bit.value(idx)) continue;
 	    assert(tmp == use_delay);
       }