From 1f350adf14c7f1b371a9a2930ad5b61fc6472650 Mon Sep 17 00:00:00 2001
From: Sebastien Bourdeauducq <sebastien@milkymist.org>
Date: Fri, 14 Dec 2012 23:56:03 +0100
Subject: [PATCH] actorlib/sim/SimActor: do not drive busy low when generator
 yields None

---
 migen/actorlib/sim.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/migen/actorlib/sim.py b/migen/actorlib/sim.py
index 67f8689eb..d99b909d8 100644
--- a/migen/actorlib/sim.py
+++ b/migen/actorlib/sim.py
@@ -60,7 +60,7 @@ class TokenExchanger(PureSimulable):
 			self.active = set()
 		else:
 			raise TypeError
-		if all(transaction.idle_wait for transaction in self.active):
+		if self.active and all(transaction.idle_wait for transaction in self.active):
 			self.busy = False
 	
 	def do_simulation(self, s):