net/dccp/ccids/lib/tfrc.h

   1 #ifndef _TFRC_H_
   2 #define _TFRC_H_
   3 /*
   4  *  Copyright (c) 2007   The University of Aberdeen, Scotland, UK
   5  *  Copyright (c) 2005-6 The University of Waikato, Hamilton, New Zealand.
   6  *  Copyright (c) 2005-6 Ian McDonald <ian.mcdonald@jandi.co.nz>
   7  *  Copyright (c) 2005   Arnaldo Carvalho de Melo <acme@conectiva.com.br>
   8  *  Copyright (c) 2003   Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
   9  *
  10  *  This program is free software; you can redistribute it and/or modify
  11  *  it under the terms of the GNU General Public License as published by
  12  *  the Free Software Foundation; either version 2 of the License, or
  13  *  (at your option) any later version.
  14  */
  15 #include <linux/types.h>
  16 #include <linux/math64.h>
  17 #include "../../dccp.h"
  18
  19 /* internal includes that this library exports: */
  20 #include "loss_interval.h"
  21 #include "packet_history.h"
  22
  23 #ifdef CONFIG_IP_DCCP_TFRC_DEBUG
  24 extern bool tfrc_debug;
  25 #define tfrc_pr_debug(format, a...)     DCCP_PR_DEBUG(tfrc_debug, format, ##a)
  26 #else
  27 #define tfrc_pr_debug(format, a...)
  28 #endif
  29
  30 /* integer-arithmetic divisions of type (a * 1000000)/b */
  31 static inline u64 scaled_div(u64 a, u64 b)
  32 {
  33         BUG_ON(b == 0);
  34         return div64_u64(a * 1000000, b);
  35 }
  36
  37 static inline u32 scaled_div32(u64 a, u64 b)
  38 {
  39         u64 result = scaled_div(a, b);
  40
  41         if (result > UINT_MAX) {
  42                 DCCP_CRIT("Overflow: %llu/%llu > UINT_MAX",
  43                           (unsigned long long)a, (unsigned long long)b);
  44                 return UINT_MAX;
  45         }
  46         return result;
  47 }
  48
  49 /**
  50  * tfrc_ewma  -  Exponentially weighted moving average
  51  * @weight: Weight to be used as damping factor, in units of 1/10
  52  */
  53 static inline u32 tfrc_ewma(const u32 avg, const u32 newval, const u8 weight)
  54 {
  55         return avg ? (weight * avg + (10 - weight) * newval) / 10 : newval;
  56 }
  57
  58 extern u32  tfrc_calc_x(u16 s, u32 R, u32 p);
  59 extern u32  tfrc_calc_x_reverse_lookup(u32 fvalue);
  60 extern u32  tfrc_invert_loss_event_rate(u32 loss_event_rate);
  61
  62 extern int  tfrc_tx_packet_history_init(void);
  63 extern void tfrc_tx_packet_history_exit(void);
  64 extern int  tfrc_rx_packet_history_init(void);
  65 extern void tfrc_rx_packet_history_exit(void);
  66
  67 extern int  tfrc_li_init(void);
  68 extern void tfrc_li_exit(void);
  69
  70 #ifdef CONFIG_IP_DCCP_TFRC_LIB
  71 extern int  tfrc_lib_init(void);
  72 extern void tfrc_lib_exit(void);
  73 #else
  74 #define tfrc_lib_init() (0)
  75 #define tfrc_lib_exit()
  76 #endif
  77 #endif /* _TFRC_H_ */