diff options
author | David S. Miller <davem@davemloft.net> | 2008-09-08 17:28:59 -0700 |
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committer | David S. Miller <davem@davemloft.net> | 2008-09-08 17:28:59 -0700 |
commit | 0a68a20cc3eafa73bb54097c28b921147d7d3685 (patch) | |
tree | 8e5f315226b618cb8e050a0c7653c8ec134501e3 /net/dccp/ccids/lib/tfrc.h | |
parent | 17dce5dfe38ae2fb359b61e855f5d8a3a8b7892b (diff) | |
parent | a3cbdde8e9c38b66b4f13ac5d6ff1939ded0ff20 (diff) |
Merge branch 'dccp' of git://eden-feed.erg.abdn.ac.uk/dccp_exp
Conflicts:
net/dccp/input.c
net/dccp/options.c
Diffstat (limited to 'net/dccp/ccids/lib/tfrc.h')
-rw-r--r-- | net/dccp/ccids/lib/tfrc.h | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/net/dccp/ccids/lib/tfrc.h b/net/dccp/ccids/lib/tfrc.h index ed9857527ac..ede12f53de5 100644 --- a/net/dccp/ccids/lib/tfrc.h +++ b/net/dccp/ccids/lib/tfrc.h @@ -48,6 +48,21 @@ static inline u32 scaled_div32(u64 a, u64 b) } /** + * tfrc_scaled_sqrt - Compute scaled integer sqrt(x) for 0 < x < 2^22-1 + * Uses scaling to improve accuracy of the integer approximation of sqrt(). The + * scaling factor of 2^10 limits the maximum @sample to 4e6; this is okay for + * clamped RTT samples (dccp_sample_rtt). + * Should best be used for expressions of type sqrt(x)/sqrt(y), since then the + * scaling factor is neutralised. For this purpose, it avoids returning zero. + */ +static inline u16 tfrc_scaled_sqrt(const u32 sample) +{ + const unsigned long non_zero_sample = sample ? : 1; + + return int_sqrt(non_zero_sample << 10); +} + +/** * tfrc_ewma - Exponentially weighted moving average * @weight: Weight to be used as damping factor, in units of 1/10 */ @@ -58,6 +73,7 @@ static inline u32 tfrc_ewma(const u32 avg, const u32 newval, const u8 weight) extern u32 tfrc_calc_x(u16 s, u32 R, u32 p); extern u32 tfrc_calc_x_reverse_lookup(u32 fvalue); +extern u32 tfrc_invert_loss_event_rate(u32 loss_event_rate); extern int tfrc_tx_packet_history_init(void); extern void tfrc_tx_packet_history_exit(void); |