Revert "Switch to TCP conventions for the RTT decay factor"

This reverts commit bf8555b2.

babeld.man

@@ -342,9 +342,9 @@ otherwise.
 .TP
 .BI rtt\-exponential\-decay " decay"
 This specifies the decay factor for the exponential moving average of
-RTT samples, in units of 1/256.  Must be between 0 and 255, inclusive.
-Lower values discard old samples faster.  The default is
-.BR 214 .
+RTT samples, in units of 1/256.  Must be between 1 and 256, inclusive.
+Higher values discard old samples faster.  The default is
+.BR 42 .
 .TP
 .BI rtt\-min " rtt"
 This specifies the minimum RTT, in milliseconds, starting from which

interface.c

@@ -307,7 +307,7 @@ interface_up(struct interface *ifp, int up)
 
         ifp->rtt_exponential_decay =
             IF_CONF(ifp, rtt_exponential_decay) > 0 ?
-            IF_CONF(ifp, rtt_exponential_decay) : 214;
+            IF_CONF(ifp, rtt_exponential_decay) : 42;
 
         ifp->rtt_min =
             IF_CONF(ifp, rtt_min) > 0 ?

message.c

@@ -618,8 +618,8 @@ parse_packet(const unsigned char *from, struct interface *ifp,
         old_rttcost = neighbour_rttcost(neigh);
         if (valid_rtt(neigh)) {
             /* Running exponential average. */
-            smoothed_rtt = ((256 - ifp->rtt_exponential_decay) * rtt
-                            + ifp->rtt_exponential_decay * neigh->rtt);
+            smoothed_rtt = (ifp->rtt_exponential_decay * rtt
+                            + (256 - ifp->rtt_exponential_decay) * neigh->rtt);
             /* Rounding (up or down) to get closer to the sample. */
             neigh->rtt = (neigh->rtt >= rtt) ? smoothed_rtt / 256 :
                 (smoothed_rtt + 255) / 256;