xref: /kernel/linux/linux-5.10/net/dccp/ccids/lib/tfrc.h

/* SPDX-License-Identifier: GPL-2.0-or-later */
#ifndef _TFRC_H_
#define _TFRC_H_
/*
 *  Copyright (c) 2007   The University of Aberdeen, Scotland, UK
 *  Copyright (c) 2005-6 The University of Waikato, Hamilton, New Zealand.
 *  Copyright (c) 2005-6 Ian McDonald <ian.mcdonald@jandi.co.nz>
 *  Copyright (c) 2005   Arnaldo Carvalho de Melo <acme@conectiva.com.br>
 *  Copyright (c) 2003   Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
 */
#include <linux/types.h>
#include <linux/math64.h>
#include "../../dccp.h"

/* internal includes that this library exports: */
#include "loss_interval.h"
#include "packet_history.h"

#ifdef CONFIG_IP_DCCP_TFRC_DEBUG
extern bool tfrc_debug;
#define tfrc_pr_debug(format, a...)	DCCP_PR_DEBUG(tfrc_debug, format, ##a)
#else
#define tfrc_pr_debug(format, a...)
#endif

/* integer-arithmetic divisions of type (a * 1000000)/b */
static inline u64 scaled_div(u64 a, u64 b)
{
	BUG_ON(b == 0);
	return div64_u64(a * 1000000, b);
}

static inline u32 scaled_div32(u64 a, u64 b)
{
	u64 result = scaled_div(a, b);

	if (result > UINT_MAX) {
		DCCP_CRIT("Overflow: %llu/%llu > UINT_MAX",
			  (unsigned long long)a, (unsigned long long)b);
		return UINT_MAX;
	}
	return result;
}

/**
 * tfrc_ewma  -  Exponentially weighted moving average
 * @weight: Weight to be used as damping factor, in units of 1/10
 */
static inline u32 tfrc_ewma(const u32 avg, const u32 newval, const u8 weight)
{
	return avg ? (weight * avg + (10 - weight) * newval) / 10 : newval;
}

u32 tfrc_calc_x(u16 s, u32 R, u32 p);
u32 tfrc_calc_x_reverse_lookup(u32 fvalue);
u32 tfrc_invert_loss_event_rate(u32 loss_event_rate);

int tfrc_tx_packet_history_init(void);
void tfrc_tx_packet_history_exit(void);
int tfrc_rx_packet_history_init(void);
void tfrc_rx_packet_history_exit(void);

int tfrc_li_init(void);
void tfrc_li_exit(void);

#ifdef CONFIG_IP_DCCP_TFRC_LIB
int tfrc_lib_init(void);
void tfrc_lib_exit(void);
#else
#define tfrc_lib_init() (0)
#define tfrc_lib_exit()
#endif
#endif /* _TFRC_H_ */