/*      $NetBSD: ieee80211_amrr.c,v 1.3 2015/08/24 20:58:47 pooka Exp $ */
/*      $OpenBSD: ieee80211_amrr.c,v 1.1 2006/06/17 19:07:19 damien Exp $       */

/*-
 * Copyright (c) 2006
 *      Damien Bergamini <damien.bergamini@free.fr>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: ieee80211_amrr.c,v 1.3 2015/08/24 20:58:47 pooka Exp $");

#ifdef _KERNEL_OPT
#include "opt_inet.h"
#endif

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/socket.h>
#include <sys/sysctl.h>

#include <net/if.h>
#include <net/if_ether.h>
#include <net/if_media.h>

#ifdef INET
#include <netinet/in.h>
#endif

#include <net80211/ieee80211.h>
#include <net80211/ieee80211_var.h>
#include <net80211/ieee80211_amrr.h>

#define is_success(amn) \
        ((amn)->amn_retrycnt < (amn)->amn_txcnt / 10)
#define is_failure(amn) \
        ((amn)->amn_retrycnt > (amn)->amn_txcnt / 3)
#define is_enough(amn)          \
        ((amn)->amn_txcnt > 10)
#define is_min_rate(ni)         \
        ((ni)->ni_txrate == 0)
#define is_max_rate(ni)         \
        ((ni)->ni_txrate == (ni)->ni_rates.rs_nrates - 1)
#define increase_rate(ni)       \
        ((ni)->ni_txrate++)
#define decrease_rate(ni)       \
        ((ni)->ni_txrate--)
#define reset_cnt(amn)          \
        do { (amn)->amn_txcnt = (amn)->amn_retrycnt = 0; } while (0)

void
ieee80211_amrr_node_init(struct ieee80211_amrr *amrr,
    struct ieee80211_amrr_node *amn)
{
        amn->amn_success = 0;
        amn->amn_recovery = 0;
        amn->amn_txcnt = amn->amn_retrycnt = 0;
        amn->amn_success_threshold = amrr->amrr_min_success_threshold;
}

/*
 * Update ni->ni_txrate.
 */
void
ieee80211_amrr_choose(struct ieee80211_amrr *amrr, struct ieee80211_node *ni,
    struct ieee80211_amrr_node *amn)
{
        int need_change = 0;

        if (is_success(amn) && is_enough(amn)) {
                amn->amn_success++;
                if (amn->amn_success >= amn->amn_success_threshold &&
                    !is_max_rate(ni)) {
                        amn->amn_recovery = 1;
                        amn->amn_success = 0;
                        increase_rate(ni);
                        IEEE80211_DPRINTF(ni->ni_ic, IEEE80211_MSG_DEBUG,
                            "AMRR increasing rate %d (txcnt=%d retrycnt=%d)\n",
                            ni->ni_rates.rs_rates[ni->ni_txrate] &
                                IEEE80211_RATE_VAL,
                            amn->amn_txcnt, amn->amn_retrycnt);
                        need_change = 1;
                } else {
                        amn->amn_recovery = 0;
                }
        } else if (is_failure(amn)) {
                amn->amn_success = 0;
                if (!is_min_rate(ni)) {
                        if (amn->amn_recovery) {
                                amn->amn_success_threshold *= 2;
                                if (amn->amn_success_threshold >
                                    amrr->amrr_max_success_threshold)
                                        amn->amn_success_threshold =
                                            amrr->amrr_max_success_threshold;
                        } else {
                                amn->amn_success_threshold =
                                    amrr->amrr_min_success_threshold;
                        }
                        decrease_rate(ni);
                        IEEE80211_DPRINTF(ni->ni_ic, IEEE80211_MSG_DEBUG,
                            "AMRR decreasing rate %d (txcnt=%d retrycnt=%d)\n",
                            ni->ni_rates.rs_rates[ni->ni_txrate] &
                                IEEE80211_RATE_VAL,
                            amn->amn_txcnt, amn->amn_retrycnt);
                        need_change = 1;
                }
                amn->amn_recovery = 0;
        }

        if (is_enough(amn) || need_change)
                reset_cnt(amn);
}