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| author | Gerrit Renker <gerrit@erg.abdn.ac.uk> | 2006-12-03 14:52:01 -0200 |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@mandriva.com> | 2006-12-03 14:52:01 -0200 |
| commit | 90fb0e60dd9178dbca2e42c682c483cdb7ea9f2d (patch) | |
| tree | 09e750ded7fb3b34a0b146ef96a03a9495a9c37f /net | |
| parent | 50ab46c790a3408c441ba4c2faa9555cacc20028 (diff) | |
| download | blackbird-op-linux-90fb0e60dd9178dbca2e42c682c483cdb7ea9f2d.tar.gz blackbird-op-linux-90fb0e60dd9178dbca2e42c682c483cdb7ea9f2d.zip | |
[DCCP] tfrc: Fix small error in reverse lookup of p for given f(p)
This fixes the following small error in tfrc_calc_x_reverse_lookup.
1) The table is generated by the following equations:
lookup[index][0] = g((index+1) * 1000000/TFRC_CALC_X_ARRSIZE);
lookup[index][1] = g((index+1) * TFRC_CALC_X_SPLIT/TFRC_CALC_X_ARRSIZE);
where g(q) is 1E6 * f(q/1E6)
2) The reverse lookup assigns an entry in lookup[index][small]
3) This index needs to match the above, i.e.
* if small=0 then
p = (index + 1) * 1000000/TFRC_CALC_X_ARRSIZE
* if small=1 then
p = (index+1) * TFRC_CALC_X_SPLIT/TFRC_CALC_X_ARRSIZE
These are exactly the changes that the patch makes; previously the code did
not conform to the way the lookup table was generated (this difference resulted
in a mean error of about 1.12%).
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Diffstat (limited to 'net')
| -rw-r--r-- | net/dccp/ccids/lib/tfrc_equation.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/net/dccp/ccids/lib/tfrc_equation.c b/net/dccp/ccids/lib/tfrc_equation.c index 57665e979308..78bdf3489162 100644 --- a/net/dccp/ccids/lib/tfrc_equation.c +++ b/net/dccp/ccids/lib/tfrc_equation.c @@ -667,9 +667,9 @@ u32 tfrc_calc_x_reverse_lookup(u32 fvalue) ctr++; if (small) - return TFRC_CALC_X_SPLIT * ctr / TFRC_CALC_X_ARRSIZE; + return (ctr + 1) * TFRC_CALC_X_SPLIT / TFRC_CALC_X_ARRSIZE; else - return 1000000 * ctr / TFRC_CALC_X_ARRSIZE; + return (ctr + 1) * 1000000 / TFRC_CALC_X_ARRSIZE; } EXPORT_SYMBOL_GPL(tfrc_calc_x_reverse_lookup); |
