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authorGerrit Renker <gerrit@erg.abdn.ac.uk>2006-12-03 11:52:01 -0500
committerArnaldo Carvalho de Melo <acme@mandriva.com>2006-12-03 11:52:01 -0500
commit90fb0e60dd9178dbca2e42c682c483cdb7ea9f2d (patch)
tree09e750ded7fb3b34a0b146ef96a03a9495a9c37f /net
parent50ab46c790a3408c441ba4c2faa9555cacc20028 (diff)
[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.c4
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)
667 ctr++; 667 ctr++;
668 668
669 if (small) 669 if (small)
670 return TFRC_CALC_X_SPLIT * ctr / TFRC_CALC_X_ARRSIZE; 670 return (ctr + 1) * TFRC_CALC_X_SPLIT / TFRC_CALC_X_ARRSIZE;
671 else 671 else
672 return 1000000 * ctr / TFRC_CALC_X_ARRSIZE; 672 return (ctr + 1) * 1000000 / TFRC_CALC_X_ARRSIZE;
673} 673}
674 674
675EXPORT_SYMBOL_GPL(tfrc_calc_x_reverse_lookup); 675EXPORT_SYMBOL_GPL(tfrc_calc_x_reverse_lookup);