Accept do faster ETX caclculation after last ETX probe or unicast traffic.

Added definition for define how many accelerated ETX update will be done before start follow cached value.

Change-Id: I59ba142ff0ee3a8b46566c7d4a2b7b98abe692b0

Author: Juha Heiskanen

source/Service_Libs/etx/etx.c

@@ -131,7 +131,7 @@ static bool etx_update_possible(etx_sample_storage_t *storage, etx_storage_t *en
         }
     }
 
-    if (entry->etx_samples == 7) {
+    if (entry->etx_samples > ETX_ACCELERATED_SAMPLE_COUNT) {
         //Slower ETX update phase
         if (storage->sample_count < etx_info.min_sample_count || storage->etx_timer) {
             if (storage->sample_count < 0xff) {
@@ -140,7 +140,7 @@ static bool etx_update_possible(etx_sample_storage_t *storage, etx_storage_t *en
         }
     } else {
         //Accelerated ETX at for new neighbor
-        if (storage->sample_count < 3) {
+        if (storage->sample_count < ETX_ACCELERATED_INTERVAL) {
             return false;
         }
     }

source/Service_Libs/etx/etx.h

@@ -31,6 +31,25 @@
    Range for value can be from 1 to 11 */
 #define ETX_MOVING_AVERAGE_FRACTION      3     // n >> 3, 1/8
 
+/* ETX cache configuration definitions */
+
+/* Amount of accelerated ETX samples
+ * After this value is received the ETX calculation starts to follow the
+ * slower ETX cache configuration values.
+ *
+ * Maximum value is 7
+ */
+#define ETX_ACCELERATED_SAMPLE_COUNT      3
+
+/* Amount of samples before updating the ETX value when in accelerated mode.
+ *
+ * if set to 1 every sample updates an ETX value. if set to 2 every second
+ * ETX sample updates the ETX value.
+ *
+ * This value should be smaller than ETX_ACCELERATED_SAMPLE_COUNT
+ */
+#define ETX_ACCELERATED_INTERVAL          2
+
 typedef struct etx_storage_s {
     uint16_t        etx;                       /*!< 12 bits fraction */
     uint16_t        stored_diff_etx;           /*!< 12 bits fraction */