net/dccp/ccids/lib/tfrc.h

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2 #ifndef _TFRC_H_
   3 #define _TFRC_H_
   4 /*
   5  *  Copyright (c) 2007   The University of Aberdeen, Scotland, UK
   6  *  Copyright (c) 2005-6 The University of Waikato, Hamilton, New Zealand.
   7  *  Copyright (c) 2005-6 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 #include <linux/types.h>
  12 #include <linux/math64.h>
  13 #include "../../dccp.h"
  14
  15 /* internal includes that this library exports: */
  16 #include "loss_interval.h"
  17 #include "packet_history.h"
  18
  19 #ifdef CONFIG_IP_DCCP_TFRC_DEBUG
  20 extern bool tfrc_debug;
  21 #define tfrc_pr_debug(format, a...)     DCCP_PR_DEBUG(tfrc_debug, format, ##a)
  22 #else
  23 #define tfrc_pr_debug(format, a...)
  24 #endif
  25
  26 /* integer-arithmetic divisions of type (a * 1000000)/b */
  27 static inline u64 scaled_div(u64 a, u64 b)
  28 {
  29         BUG_ON(b == 0);
  30         return div64_u64(a * 1000000, b);
  31 }
  32
  33 static inline u32 scaled_div32(u64 a, u64 b)
  34 {
  35         u64 result = scaled_div(a, b);
  36
  37         if (result > UINT_MAX) {
  38                 DCCP_CRIT("Overflow: %llu/%llu > UINT_MAX",
  39                           (unsigned long long)a, (unsigned long long)b);
  40                 return UINT_MAX;
  41         }
  42         return result;
  43 }
  44
  45 /**
  46  * tfrc_ewma  -  Exponentially weighted moving average
  47  * @weight: Weight to be used as damping factor, in units of 1/10
  48  */
  49 static inline u32 tfrc_ewma(const u32 avg, const u32 newval, const u8 weight)
  50 {
  51         return avg ? (weight * avg + (10 - weight) * newval) / 10 : newval;
  52 }
  53
  54 u32 tfrc_calc_x(u16 s, u32 R, u32 p);
  55 u32 tfrc_calc_x_reverse_lookup(u32 fvalue);
  56 u32 tfrc_invert_loss_event_rate(u32 loss_event_rate);
  57
  58 int tfrc_tx_packet_history_init(void);
  59 void tfrc_tx_packet_history_exit(void);
  60 int tfrc_rx_packet_history_init(void);
  61 void tfrc_rx_packet_history_exit(void);
  62
  63 int tfrc_li_init(void);
  64 void tfrc_li_exit(void);
  65
  66 #ifdef CONFIG_IP_DCCP_TFRC_LIB
  67 int tfrc_lib_init(void);
  68 void tfrc_lib_exit(void);
  69 #else
  70 #define tfrc_lib_init() (0)
  71 #define tfrc_lib_exit()
  72 #endif
  73 #endif /* _TFRC_H_ */