[PATCH 24/25]: Macro for moving average

[Gerrit Renker]

[CCID 3]: Macro for moving average

The moving average computation occurs so frequently in the CCID 3 code that
it merits a macro of its own.

Signed-off-by: Gerrit Renker <[EMAIL PROTECTED]>
---
 net/dccp/ccids/ccid3.c    |    8 +++-----
 net/dccp/ccids/lib/tfrc.h |    8 ++++++++
 2 files changed, 11 insertions(+), 5 deletions(-)

--- a/net/dccp/ccids/lib/tfrc.h
+++ b/net/dccp/ccids/lib/tfrc.h
@@ -37,6 +37,14 @@ static inline u32 scaled_div32(u64 a, u3
        return result;
 }
 
+/**
+ * Macro for exponentially weighted moving average
+ * @weight: Weight to be used as damping factor, in units of 1/10
+ * Beware that @val is evaluated multiple times.
+ */
+#define TFRC_EWMA(val, newval, weight) \
+       val = val? ((weight) * val + (10 - (weight)) * (newval)) / 10 : (newval)
+
 extern u32 tfrc_calc_x(u16 s, u32 R, u32 p);
 extern u32 tfrc_calc_x_reverse_lookup(u32 fvalue);
 
--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -183,7 +183,7 @@ static inline void ccid3_hc_tx_update_s(
 {
        const u16 old_s = hctx->ccid3hctx_s;
 
-       hctx->ccid3hctx_s = old_s == 0 ? len : (9 * old_s + len) / 10;
+       TFRC_EWMA(hctx->ccid3hctx_s, len, 9);
 
        if (hctx->ccid3hctx_s != old_s)
                ccid3_update_send_interval(hctx);
@@ -474,8 +474,7 @@ static void ccid3_hc_tx_packet_recv(stru
         *
         * q is a constant, RFC 3448 recommends 0.9
         */
-       hctx->ccid3hctx_rtt = hctx->ccid3hctx_rtt == 0 ?  r_sample
-                           : (9 * hctx->ccid3hctx_rtt + r_sample) / 10;
+       TFRC_EWMA(hctx->ccid3hctx_rtt, r_sample, 9);
 
        /*
         * Update allowed sending rate as per draft rfc3448bis, 4.2/4.3
@@ -724,8 +723,7 @@ static inline void ccid3_hc_rx_update_s(
        if (unlikely(len == 0)) /* don't update on empty packets (e.g. ACKs) */
                ccid3_pr_debug("Packet payload length is 0 - not updating\n");
        else
-               hcrx->ccid3hcrx_s = hcrx->ccid3hcrx_s == 0 ? len :
-                                   (9 * hcrx->ccid3hcrx_s + len) / 10;
+               TFRC_EWMA(hcrx->ccid3hcrx_s, len, 9);
 }
 
 static void ccid3_hc_rx_send_feedback(struct sock *sk)
-
To unsubscribe from this list: send the line "unsubscribe dccp" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at  http://vger.kernel.org/majordomo-info.html