From a3a8c0e1799b231762a5b1def31f200a5a036e2c Mon Sep 17 00:00:00 2001
From: adamdunkels <adamdunkels>
Date: Fri, 19 Mar 2010 13:18:53 +0000
Subject: [PATCH] Safety check: only try to read a packet if it was preceeded
 by an interrupt (which sets the pending flag)

---
 core/dev/cc2420.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/core/dev/cc2420.c b/core/dev/cc2420.c
index 2d3d30fcf..d85bb7f2e 100644
--- a/core/dev/cc2420.c
+++ b/core/dev/cc2420.c
@@ -28,7 +28,7 @@
  *
  * This file is part of the Contiki operating system.
  *
- * @(#)$Id: cc2420.c,v 1.45 2010/03/16 18:10:09 adamdunkels Exp $
+ * @(#)$Id: cc2420.c,v 1.46 2010/03/19 13:18:53 adamdunkels Exp $
  */
 /*
  * This code is almost device independent and should be easy to port.
@@ -631,6 +631,10 @@ cc2420_read(void *buf, unsigned short bufsize)
   uint16_t checksum;
 #endif /* CC2420_CONF_CHECKSUM */
 
+  if(!pending) {
+    return 0;
+  }
+  
   pending = 0;
   
   GET_LOCK();