From 6d556d5c13399cb0cc2b4c96f319db5138dc35ad Mon Sep 17 00:00:00 2001
From: adamdunkels <adamdunkels>
Date: Thu, 25 Nov 2010 08:44:34 +0000
Subject: [PATCH] Fixed bug with link-layer ACKs. Refactored the ACK reception
 code.

---
 core/net/mac/lpp.c | 65 +++++++++++++++++++++++++++-------------------
 1 file changed, 39 insertions(+), 26 deletions(-)

diff --git a/core/net/mac/lpp.c b/core/net/mac/lpp.c
index d7dbc8c34..32584e7b4 100644
--- a/core/net/mac/lpp.c
+++ b/core/net/mac/lpp.c
@@ -28,7 +28,7 @@
  *
  * This file is part of the Contiki operating system.
  *
- * $Id: lpp.c,v 1.38 2010/10/20 15:23:43 adamdunkels Exp $
+ * $Id: lpp.c,v 1.39 2010/11/25 08:44:34 adamdunkels Exp $
  */
 
 /**
@@ -104,9 +104,9 @@
    is 0 which will make compilation fail due to a modulo operation in
    the code. To ensure that OFF_TIME is greater than zero, we use the
    construct below. */
-#if OFF_TIME == 0
+#if OFF_TIME < 2
 #undef OFF_TIME
-#define OFF_TIME 1
+#define OFF_TIME 2
 #endif
 
 struct announcement_data {
@@ -643,7 +643,7 @@ send_packet(mac_callback_t sent, void *ptr)
   packetbuf_compact();
 
   packetbuf_set_attr(PACKETBUF_ATTR_MAC_ACK, 1);
-  
+
   {
     int hdrlen = NETSTACK_FRAMER.create();
     if(hdrlen == 0) {
@@ -721,6 +721,40 @@ send_packet(mac_callback_t sent, void *ptr)
   }
 }
 /*---------------------------------------------------------------------------*/
+static int
+detect_ack(void)
+{
+#define INTER_PACKET_INTERVAL              RTIMER_ARCH_SECOND / 5000
+#define ACK_LEN 3
+#define AFTER_ACK_DETECTECT_WAIT_TIME      RTIMER_ARCH_SECOND / 1000
+  rtimer_clock_t wt;
+  uint8_t ack_received = 0;
+  
+  wt = RTIMER_NOW();
+  leds_on(LEDS_GREEN);
+  while(RTIMER_CLOCK_LT(RTIMER_NOW(), wt + INTER_PACKET_INTERVAL)) { }
+  leds_off(LEDS_GREEN);
+  /* Check for incoming ACK. */
+  if((NETSTACK_RADIO.receiving_packet() ||
+      NETSTACK_RADIO.pending_packet() ||
+      NETSTACK_RADIO.channel_clear() == 0)) {
+    int len;
+    uint8_t ackbuf[ACK_LEN + 2];
+    
+    wt = RTIMER_NOW();
+    while(RTIMER_CLOCK_LT(RTIMER_NOW(), wt + AFTER_ACK_DETECTECT_WAIT_TIME)) { }
+    
+    len = NETSTACK_RADIO.read(ackbuf, ACK_LEN);
+    if(len == ACK_LEN) {
+      ack_received = 1;
+    }
+  }
+  if(ack_received) {
+    leds_toggle(LEDS_RED);
+  }
+  return ack_received;
+}
+/*---------------------------------------------------------------------------*/
 /**
  * Read a packet from the underlying radio driver. If the incoming
  * packet is a probe packet and the sender of the probe matches the
@@ -830,28 +864,7 @@ input_packet(void)
              neighbors, and are dequeued by the dutycycling function
              instead, after the appropriate time. */
           if(!rimeaddr_cmp(receiver, &rimeaddr_null)) {
-#define INTER_PACKET_INTERVAL              RTIMER_ARCH_SECOND / 5000
-#define ACK_LEN 3
-#define AFTER_ACK_DETECTECT_WAIT_TIME      RTIMER_ARCH_SECOND / 1000
-            rtimer_clock_t wt;
-            uint8_t ack_received = 0;
-            
-            wt = RTIMER_NOW();
-            while(RTIMER_CLOCK_LT(RTIMER_NOW(), wt + INTER_PACKET_INTERVAL)) { }
-            /* Check for incoming ACK. */
-            if((NETSTACK_RADIO.receiving_packet() ||
-                NETSTACK_RADIO.pending_packet() ||
-                NETSTACK_RADIO.channel_clear() == 0)) {
-              int len;
-              uint8_t ackbuf[ACK_LEN];
-
-              wt = RTIMER_NOW();
-              while(RTIMER_CLOCK_LT(RTIMER_NOW(), wt + AFTER_ACK_DETECTECT_WAIT_TIME)) { }
-
-              len = NETSTACK_RADIO.read(ackbuf, ACK_LEN);
-
-            }
-            if(ack_received) {
+            if(detect_ack()) {
               remove_queued_packet(i, 1);
             } else {
               remove_queued_packet(i, 0);