diff options
Diffstat (limited to 'net/dccp/ccids/lib/tfrc.h')
-rw-r--r-- | net/dccp/ccids/lib/tfrc.h | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/net/dccp/ccids/lib/tfrc.h b/net/dccp/ccids/lib/tfrc.h index bb47146ac7d1..ede12f53de5a 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) | |||
48 | } | 48 | } |
49 | 49 | ||
50 | /** | 50 | /** |
51 | * tfrc_scaled_sqrt - Compute scaled integer sqrt(x) for 0 < x < 2^22-1 | ||
52 | * Uses scaling to improve accuracy of the integer approximation of sqrt(). The | ||
53 | * scaling factor of 2^10 limits the maximum @sample to 4e6; this is okay for | ||
54 | * clamped RTT samples (dccp_sample_rtt). | ||
55 | * Should best be used for expressions of type sqrt(x)/sqrt(y), since then the | ||
56 | * scaling factor is neutralised. For this purpose, it avoids returning zero. | ||
57 | */ | ||
58 | static inline u16 tfrc_scaled_sqrt(const u32 sample) | ||
59 | { | ||
60 | const unsigned long non_zero_sample = sample ? : 1; | ||
61 | |||
62 | return int_sqrt(non_zero_sample << 10); | ||
63 | } | ||
64 | |||
65 | /** | ||
51 | * tfrc_ewma - Exponentially weighted moving average | 66 | * tfrc_ewma - Exponentially weighted moving average |
52 | * @weight: Weight to be used as damping factor, in units of 1/10 | 67 | * @weight: Weight to be used as damping factor, in units of 1/10 |
53 | */ | 68 | */ |