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
20extern 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 */
27static inline u64 scaled_div(u64 a, u64 b)
28{
29	BUG_ON(b == 0);
30	return div64_u64(a * 1000000, b);
31}
32
33static 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 */
49static 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
54u32 tfrc_calc_x(u16 s, u32 R, u32 p);
55u32 tfrc_calc_x_reverse_lookup(u32 fvalue);
56u32 tfrc_invert_loss_event_rate(u32 loss_event_rate);
57
58int tfrc_tx_packet_history_init(void);
59void tfrc_tx_packet_history_exit(void);
60int tfrc_rx_packet_history_init(void);
61void tfrc_rx_packet_history_exit(void);
62
63int tfrc_li_init(void);
64void tfrc_li_exit(void);
65
66#ifdef CONFIG_IP_DCCP_TFRC_LIB
67int tfrc_lib_init(void);
68void tfrc_lib_exit(void);
69#else
70#define tfrc_lib_init() (0)
71#define tfrc_lib_exit()
72#endif
73#endif /* _TFRC_H_ */
74