net/dccp/ccids/lib/tfrc.h

   1 #ifndef _TFRC_H_
   2 #define _TFRC_H_
   3 /*
   4  *  net/dccp/ccids/lib/tfrc.h
   5  *
   6  *  Copyright (c) 2005 The University of Waikato, Hamilton, New Zealand.
   7  *  Copyright (c) 2005 Ian McDonald <ian.mcdonald@jandi.co.nz>
   8  *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
   9  *  Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
  10  *
  11  *  This program is free software; you can redistribute it and/or modify
  12  *  it under the terms of the GNU General Public License as published by
  13  *  the Free Software Foundation; either version 2 of the License, or
  14  *  (at your option) any later version.
  15  */
  16 #include <linux/types.h>
  17 #include <asm/div64.h>
  18
  19 /* integer-arithmetic divisions of type (a * 1000000)/b */
  20 static inline u64 scaled_div(u64 a, u32 b)
  21 {
  22         BUG_ON(b==0);
  23         a *= 1000000;
  24         do_div(a, b);
  25         return a;
  26 }
  27
  28 static inline u32 scaled_div32(u64 a, u32 b)
  29 {
  30         u64 result = scaled_div(a, b);
  31
  32         if (result > UINT_MAX) {
  33                 DCCP_CRIT("Overflow: a(%llu)/b(%u) > ~0U",
  34                           (unsigned long long)a, b);
  35                 return UINT_MAX;
  36         }
  37         return result;
  38 }
  39
  40 /**
  41  * tfrc_ewma  -  Exponentially weighted moving average
  42  * @weight: Weight to be used as damping factor, in units of 1/10
  43  */
  44 static inline u32 tfrc_ewma(const u32 avg, const u32 newval, const u8 weight)
  45 {
  46         return avg ? (weight * avg + (10 - weight) * newval) / 10 : newval;
  47 }
  48
  49 extern u32 tfrc_calc_x(u16 s, u32 R, u32 p);
  50 extern u32 tfrc_calc_x_reverse_lookup(u32 fvalue);
  51
  52 #endif /* _TFRC_H_ */