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) 2007   The University of Aberdeen, Scotland, UK
   7  *  Copyright (c) 2005-6 The University of Waikato, Hamilton, New Zealand.
   8  *  Copyright (c) 2005-6 Ian McDonald <ian.mcdonald@jandi.co.nz>
   9  *  Copyright (c) 2005   Arnaldo Carvalho de Melo <acme@conectiva.com.br>
  10  *  Copyright (c) 2003   Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
  11  *
  12  *  This program is free software; you can redistribute it and/or modify
  13  *  it under the terms of the GNU General Public License as published by
  14  *  the Free Software Foundation; either version 2 of the License, or
  15  *  (at your option) any later version.
  16  */
  17 #include <linux/types.h>
  18 #include <asm/div64.h>
  19 #include "../../dccp.h"
  20 /* internal includes that this module exports: */
  21 #include "loss_interval.h"
  22 #include "packet_history.h"
  23
  24 #ifdef CONFIG_IP_DCCP_TFRC_DEBUG
  25 extern int tfrc_debug;
  26 #define tfrc_pr_debug(format, a...)     DCCP_PR_DEBUG(tfrc_debug, format, ##a)
  27 #else
  28 #define tfrc_pr_debug(format, a...)
  29 #endif
  30
  31 /* integer-arithmetic divisions of type (a * 1000000)/b */
  32 static inline u64 scaled_div(u64 a, u32 b)
  33 {
  34         BUG_ON(b==0);
  35         a *= 1000000;
  36         do_div(a, b);
  37         return a;
  38 }
  39
  40 static inline u32 scaled_div32(u64 a, u32 b)
  41 {
  42         u64 result = scaled_div(a, b);
  43
  44         if (result > UINT_MAX) {
  45                 DCCP_CRIT("Overflow: a(%llu)/b(%u) > ~0U",
  46                           (unsigned long long)a, b);
  47                 return UINT_MAX;
  48         }
  49         return result;
  50 }
  51
  52 /**
  53  * tfrc_ewma  -  Exponentially weighted moving average
  54  * @weight: Weight to be used as damping factor, in units of 1/10
  55  */
  56 static inline u32 tfrc_ewma(const u32 avg, const u32 newval, const u8 weight)
  57 {
  58         return avg ? (weight * avg + (10 - weight) * newval) / 10 : newval;
  59 }
  60
  61 extern u32 tfrc_calc_x(u16 s, u32 R, u32 p);
  62 extern u32 tfrc_calc_x_reverse_lookup(u32 fvalue);
  63
  64 #endif /* _TFRC_H_ */