/*-
 * Copyright (c) 2005 John Bicket
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer,
 *    without modification.
 * 2. Redistributions in binary form must reproduce at minimum a disclaimer
 *    similar to the "NO WARRANTY" disclaimer below ("Disclaimer") and any
 *    redistribution must be conditioned upon including a substantially
 *    similar Disclaimer requirement for further binary redistribution.
 * 3. Neither the names of the above-listed copyright holders nor the names
 *    of any contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * NO WARRANTY
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF NONINFRINGEMENT, MERCHANTABILITY
 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
 * THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY,
 * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
 * IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGES.
 *
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

/*
 * John Bicket's SampleRate control algorithm.
 */
#include "opt_ath.h"
#include "opt_inet.h"
#include "opt_wlan.h"
#include "opt_ah.h"

#include <sys/param.h>
#include <sys/systm.h> 
#include <sys/sysctl.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/errno.h>

#if defined(__DragonFly__)
/* empty */
#else
#include <machine/bus.h>
#include <machine/resource.h>
#endif
#include <sys/bus.h>

#include <sys/socket.h>
 
#include <net/if.h>
#include <net/if_var.h>
#include <net/if_media.h>
#include <net/if_arp.h>
#include <net/ethernet.h>               /* XXX for ether_sprintf */

#include <netproto/802_11/ieee80211_var.h>

#include <net/bpf.h>

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

#include <dev/netif/ath/ath/if_athvar.h>
#include <dev/netif/ath/ath_rate/sample/sample.h>
#include <dev/netif/ath/ath_hal/ah_desc.h>
#include <dev/netif/ath/ath_rate/sample/tx_schedules.h>

#if defined(__DragonFly__)
extern const char* ath_hal_ether_sprintf(const uint8_t *mac);
#endif

/*
 * This file is an implementation of the SampleRate algorithm
 * in "Bit-rate Selection in Wireless Networks"
 * (http://www.pdos.lcs.mit.edu/papers/jbicket-ms.ps)
 *
 * SampleRate chooses the bit-rate it predicts will provide the most
 * throughput based on estimates of the expected per-packet
 * transmission time for each bit-rate.  SampleRate periodically sends
 * packets at bit-rates other than the current one to estimate when
 * another bit-rate will provide better performance. SampleRate
 * switches to another bit-rate when its estimated per-packet
 * transmission time becomes smaller than the current bit-rate's.
 * SampleRate reduces the number of bit-rates it must sample by
 * eliminating those that could not perform better than the one
 * currently being used.  SampleRate also stops probing at a bit-rate
 * if it experiences several successive losses.
 *
 * The difference between the algorithm in the thesis and the one in this
 * file is that the one in this file uses a ewma instead of a window.
 *
 * Also, this implementation tracks the average transmission time for
 * a few different packet sizes independently for each link.
 */

static void     ath_rate_ctl_reset(struct ath_softc *, struct ieee80211_node *);

static __inline int
size_to_bin(int size) 
{
#if NUM_PACKET_SIZE_BINS > 1
        if (size <= packet_size_bins[0])
                return 0;
#endif
#if NUM_PACKET_SIZE_BINS > 2
        if (size <= packet_size_bins[1])
                return 1;
#endif
#if NUM_PACKET_SIZE_BINS > 3
        if (size <= packet_size_bins[2])
                return 2;
#endif
#if NUM_PACKET_SIZE_BINS > 4
#error "add support for more packet sizes"
#endif
        return NUM_PACKET_SIZE_BINS-1;
}

void
ath_rate_node_init(struct ath_softc *sc, struct ath_node *an)
{
        /* NB: assumed to be zero'd by caller */
}

void
ath_rate_node_cleanup(struct ath_softc *sc, struct ath_node *an)
{
}

static int
dot11rate(const HAL_RATE_TABLE *rt, int rix)
{
        if (rix < 0)
                return -1;
        return rt->info[rix].phy == IEEE80211_T_HT ?
            rt->info[rix].dot11Rate : (rt->info[rix].dot11Rate & IEEE80211_RATE_VAL) / 2;
}

static const char *
dot11rate_label(const HAL_RATE_TABLE *rt, int rix)
{
        if (rix < 0)
                return "";
        return rt->info[rix].phy == IEEE80211_T_HT ? "MCS" : "Mb ";
}

/*
 * Return the rix with the lowest average_tx_time,
 * or -1 if all the average_tx_times are 0.
 */
static __inline int
pick_best_rate(struct ath_node *an, const HAL_RATE_TABLE *rt,
    int size_bin, int require_acked_before)
{
        struct sample_node *sn = ATH_NODE_SAMPLE(an);
        int best_rate_rix, best_rate_tt, best_rate_pct;
        uint64_t mask;
        int rix, tt, pct;

        best_rate_rix = 0;
        best_rate_tt = 0;
        best_rate_pct = 0;
        for (mask = sn->ratemask, rix = 0; mask != 0; mask >>= 1, rix++) {
                if ((mask & 1) == 0)            /* not a supported rate */
                        continue;

                /* Don't pick a non-HT rate for a HT node */
                if ((an->an_node.ni_flags & IEEE80211_NODE_HT) &&
                    (rt->info[rix].phy != IEEE80211_T_HT)) {
                        continue;
                }

                tt = sn->stats[size_bin][rix].average_tx_time;
                if (tt <= 0 ||
                    (require_acked_before &&
                     !sn->stats[size_bin][rix].packets_acked))
                        continue;

                /* Calculate percentage if possible */
                if (sn->stats[size_bin][rix].total_packets > 0) {
                        pct = sn->stats[size_bin][rix].ewma_pct;
                } else {
                        /* XXX for now, assume 95% ok */
                        pct = 95;
                }

                /* don't use a bit-rate that has been failing */
                if (sn->stats[size_bin][rix].successive_failures > 3)
                        continue;

                /*
                 * For HT, Don't use a bit rate that is much more
                 * lossy than the best.
                 *
                 * XXX this isn't optimal; it's just designed to
                 * eliminate rates that are going to be obviously
                 * worse.
                 */
                if (an->an_node.ni_flags & IEEE80211_NODE_HT) {
                        if (best_rate_pct > (pct + 50))
                                continue;
                }

                /*
                 * For non-MCS rates, use the current average txtime for
                 * comparison.
                 */
                if (! (an->an_node.ni_flags & IEEE80211_NODE_HT)) {
                        if (best_rate_tt == 0 || tt <= best_rate_tt) {
                                best_rate_tt = tt;
                                best_rate_rix = rix;
                                best_rate_pct = pct;
                        }
                }

                /*
                 * Since 2 stream rates have slightly higher TX times,
                 * allow a little bit of leeway. This should later
                 * be abstracted out and properly handled.
                 */
                if (an->an_node.ni_flags & IEEE80211_NODE_HT) {
                        if (best_rate_tt == 0 || (tt * 8 <= best_rate_tt * 10)) {
                                best_rate_tt = tt;
                                best_rate_rix = rix;
                                best_rate_pct = pct;
                        }
                }
        }
        return (best_rate_tt ? best_rate_rix : -1);
}

/*
 * Pick a good "random" bit-rate to sample other than the current one.
 */
static __inline int
pick_sample_rate(struct sample_softc *ssc , struct ath_node *an,
    const HAL_RATE_TABLE *rt, int size_bin)
{
#define DOT11RATE(ix)   (rt->info[ix].dot11Rate & IEEE80211_RATE_VAL)
#define MCS(ix)         (rt->info[ix].dot11Rate | IEEE80211_RATE_MCS)
        struct sample_node *sn = ATH_NODE_SAMPLE(an);
        int current_rix, rix;
        unsigned current_tt;
        uint64_t mask;
        
        current_rix = sn->current_rix[size_bin];
        if (current_rix < 0) {
                /* no successes yet, send at the lowest bit-rate */
                /* XXX should return MCS0 if HT */
                return 0;
        }

        current_tt = sn->stats[size_bin][current_rix].average_tx_time;

        rix = sn->last_sample_rix[size_bin]+1;  /* next sample rate */
        mask = sn->ratemask &~ ((uint64_t) 1<<current_rix);/* don't sample current rate */
        while (mask != 0) {
                if ((mask & ((uint64_t) 1<<rix)) == 0) {        /* not a supported rate */
        nextrate:
                        if (++rix >= rt->rateCount)
                                rix = 0;
                        continue;
                }

                /*
                 * The following code stops trying to sample
                 * non-MCS rates when speaking to an MCS node.
                 * However, at least for CCK rates in 2.4GHz mode,
                 * the non-MCS rates MAY actually provide better
                 * PER at the very far edge of reception.
                 *
                 * However! Until ath_rate_form_aggr() grows
                 * some logic to not form aggregates if the
                 * selected rate is non-MCS, this won't work.
                 *
                 * So don't disable this code until you've taught
                 * ath_rate_form_aggr() to drop out if any of
                 * the selected rates are non-MCS.
                 */
#if 1
                /* if the node is HT and the rate isn't HT, don't bother sample */
                if ((an->an_node.ni_flags & IEEE80211_NODE_HT) &&
                    (rt->info[rix].phy != IEEE80211_T_HT)) {
                        mask &= ~((uint64_t) 1<<rix);
                        goto nextrate;
                }
#endif

                /* this bit-rate is always worse than the current one */
                if (sn->stats[size_bin][rix].perfect_tx_time > current_tt) {
                        mask &= ~((uint64_t) 1<<rix);
                        goto nextrate;
                }

                /* rarely sample bit-rates that fail a lot */
                if (sn->stats[size_bin][rix].successive_failures > ssc->max_successive_failures &&
                    ticks - sn->stats[size_bin][rix].last_tx < ssc->stale_failure_timeout) {
                        mask &= ~((uint64_t) 1<<rix);
                        goto nextrate;
                }

                /*
                 * For HT, only sample a few rates on either side of the
                 * current rix; there's quite likely a lot of them.
                 */
                if (an->an_node.ni_flags & IEEE80211_NODE_HT) {
                        if (rix < (current_rix - 3) ||
                            rix > (current_rix + 3)) {
                                mask &= ~((uint64_t) 1<<rix);
                                goto nextrate;
                        }
                }

                /* Don't sample more than 2 rates higher for rates > 11M for non-HT rates */
                if (! (an->an_node.ni_flags & IEEE80211_NODE_HT)) {
                        if (DOT11RATE(rix) > 2*11 && rix > current_rix + 2) {
                                mask &= ~((uint64_t) 1<<rix);
                                goto nextrate;
                        }
                }

                sn->last_sample_rix[size_bin] = rix;
                return rix;
        }
        return current_rix;
#undef DOT11RATE
#undef  MCS
}

static int
ath_rate_get_static_rix(struct ath_softc *sc, const struct ieee80211_node *ni)
{
#define RATE(_ix)       (ni->ni_rates.rs_rates[(_ix)] & IEEE80211_RATE_VAL)
#define DOT11RATE(_ix)  (rt->info[(_ix)].dot11Rate & IEEE80211_RATE_VAL)
#define MCS(_ix)        (ni->ni_htrates.rs_rates[_ix] | IEEE80211_RATE_MCS)
        const struct ieee80211_txparam *tp = ni->ni_txparms;
        int srate;

        /* Check MCS rates */
        for (srate = ni->ni_htrates.rs_nrates - 1; srate >= 0; srate--) {
                if (MCS(srate) == tp->ucastrate)
                        return sc->sc_rixmap[tp->ucastrate];
        }

        /* Check legacy rates */
        for (srate = ni->ni_rates.rs_nrates - 1; srate >= 0; srate--) {
                if (RATE(srate) == tp->ucastrate)
                        return sc->sc_rixmap[tp->ucastrate];
        }
        return -1;
#undef  RATE
#undef  DOT11RATE
#undef  MCS
}

static void
ath_rate_update_static_rix(struct ath_softc *sc, struct ieee80211_node *ni)
{
        struct ath_node *an = ATH_NODE(ni);
        const struct ieee80211_txparam *tp = ni->ni_txparms;
        struct sample_node *sn = ATH_NODE_SAMPLE(an);

        if (tp != NULL && tp->ucastrate != IEEE80211_FIXED_RATE_NONE) {
                /*
                 * A fixed rate is to be used; ucastrate is the IEEE code
                 * for this rate (sans basic bit).  Check this against the
                 * negotiated rate set for the node.  Note the fixed rate
                 * may not be available for various reasons so we only
                 * setup the static rate index if the lookup is successful.
                 */
                sn->static_rix = ath_rate_get_static_rix(sc, ni);
        } else {
                sn->static_rix = -1;
        }
}

/*
 * Pick a non-HT rate to begin using.
 */
static int
ath_rate_pick_seed_rate_legacy(struct ath_softc *sc, struct ath_node *an,
    int frameLen)
{
#define DOT11RATE(ix)   (rt->info[ix].dot11Rate & IEEE80211_RATE_VAL)
#define MCS(ix)         (rt->info[ix].dot11Rate | IEEE80211_RATE_MCS)
#define RATE(ix)        (DOT11RATE(ix) / 2)
        int rix = -1;
        const HAL_RATE_TABLE *rt = sc->sc_currates;
        struct sample_node *sn = ATH_NODE_SAMPLE(an);
        const int size_bin = size_to_bin(frameLen);

        /* no packet has been sent successfully yet */
        for (rix = rt->rateCount-1; rix > 0; rix--) {
                if ((sn->ratemask & ((uint64_t) 1<<rix)) == 0)
                        continue;

                /* Skip HT rates */
                if (rt->info[rix].phy == IEEE80211_T_HT)
                        continue;

                /*
                 * Pick the highest rate <= 36 Mbps
                 * that hasn't failed.
                 */
                if (DOT11RATE(rix) <= 72 &&
                    sn->stats[size_bin][rix].successive_failures == 0) {
                        break;
                }
        }
        return rix;
#undef  RATE
#undef  MCS
#undef  DOT11RATE
}

/*
 * Pick a HT rate to begin using.
 *
 * Don't use any non-HT rates; only consider HT rates.
 */
static int
ath_rate_pick_seed_rate_ht(struct ath_softc *sc, struct ath_node *an,
    int frameLen)
{
#define DOT11RATE(ix)   (rt->info[ix].dot11Rate & IEEE80211_RATE_VAL)
#define MCS(ix)         (rt->info[ix].dot11Rate | IEEE80211_RATE_MCS)
#define RATE(ix)        (DOT11RATE(ix) / 2)
        int rix = -1, ht_rix = -1;
        const HAL_RATE_TABLE *rt = sc->sc_currates;
        struct sample_node *sn = ATH_NODE_SAMPLE(an);
        const int size_bin = size_to_bin(frameLen);

        /* no packet has been sent successfully yet */
        for (rix = rt->rateCount-1; rix > 0; rix--) {
                /* Skip rates we can't use */
                if ((sn->ratemask & ((uint64_t) 1<<rix)) == 0)
                        continue;

                /* Keep a copy of the last seen HT rate index */
                if (rt->info[rix].phy == IEEE80211_T_HT)
                        ht_rix = rix;

                /* Skip non-HT rates */
                if (rt->info[rix].phy != IEEE80211_T_HT)
                        continue;

                /*
                 * Pick a medium-speed rate regardless of stream count
                 * which has not seen any failures. Higher rates may fail;
                 * we'll try them later.
                 */
                if (((MCS(rix) & 0x7) <= 4) &&
                    sn->stats[size_bin][rix].successive_failures == 0) {
                        break;
                }
        }

        /*
         * If all the MCS rates have successive failures, rix should be
         * > 0; otherwise use the lowest MCS rix (hopefully MCS 0.)
         */
        return MAX(rix, ht_rix);
#undef  RATE
#undef  MCS
#undef  DOT11RATE
}


void
ath_rate_findrate(struct ath_softc *sc, struct ath_node *an,
                  int shortPreamble, size_t frameLen,
                  u_int8_t *rix0, int *try0, u_int8_t *txrate)
{
#define DOT11RATE(ix)   (rt->info[ix].dot11Rate & IEEE80211_RATE_VAL)
#define MCS(ix)         (rt->info[ix].dot11Rate | IEEE80211_RATE_MCS)
#define RATE(ix)        (DOT11RATE(ix) / 2)
        struct sample_node *sn = ATH_NODE_SAMPLE(an);
        struct sample_softc *ssc = ATH_SOFTC_SAMPLE(sc);
        struct ieee80211com *ic = &sc->sc_ic;
        const HAL_RATE_TABLE *rt = sc->sc_currates;
        const int size_bin = size_to_bin(frameLen);
        int rix, mrr, best_rix, change_rates;
        unsigned average_tx_time;

        ath_rate_update_static_rix(sc, &an->an_node);

        if (sn->currates != sc->sc_currates) {
                device_printf(sc->sc_dev, "%s: currates != sc_currates!\n",
                    __func__);
                rix = 0;
                *try0 = ATH_TXMAXTRY;
                goto done;
        }

        if (sn->static_rix != -1) {
                rix = sn->static_rix;
                *try0 = ATH_TXMAXTRY;
                goto done;
        }

        mrr = sc->sc_mrretry;
        /* XXX check HT protmode too */
        if (mrr && (ic->ic_flags & IEEE80211_F_USEPROT && !sc->sc_mrrprot))
                mrr = 0;

        best_rix = pick_best_rate(an, rt, size_bin, !mrr);
        if (best_rix >= 0) {
                average_tx_time = sn->stats[size_bin][best_rix].average_tx_time;
        } else {
                average_tx_time = 0;
        }
        /*
         * Limit the time measuring the performance of other tx
         * rates to sample_rate% of the total transmission time.
         */
        if (sn->sample_tt[size_bin] < average_tx_time * (sn->packets_since_sample[size_bin]*ssc->sample_rate/100)) {
                rix = pick_sample_rate(ssc, an, rt, size_bin);
                IEEE80211_NOTE(an->an_node.ni_vap, IEEE80211_MSG_RATECTL,
                     &an->an_node, "att %d sample_tt %d size %u sample rate %d %s current rate %d %s",
                     average_tx_time,
                     sn->sample_tt[size_bin],
                     bin_to_size(size_bin),
                     dot11rate(rt, rix),
                     dot11rate_label(rt, rix),
                     dot11rate(rt, sn->current_rix[size_bin]),
                     dot11rate_label(rt, sn->current_rix[size_bin]));
                if (rix != sn->current_rix[size_bin]) {
                        sn->current_sample_rix[size_bin] = rix;
                } else {
                        sn->current_sample_rix[size_bin] = -1;
                }
                sn->packets_since_sample[size_bin] = 0;
        } else {
                change_rates = 0;
                if (!sn->packets_sent[size_bin] || best_rix == -1) {
                        /* no packet has been sent successfully yet */
                        change_rates = 1;
                        if (an->an_node.ni_flags & IEEE80211_NODE_HT)
                                best_rix =
                                    ath_rate_pick_seed_rate_ht(sc, an, frameLen);
                        else
                                best_rix =
                                    ath_rate_pick_seed_rate_legacy(sc, an, frameLen);
                } else if (sn->packets_sent[size_bin] < 20) {
                        /* let the bit-rate switch quickly during the first few packets */
                        IEEE80211_NOTE(an->an_node.ni_vap,
                            IEEE80211_MSG_RATECTL, &an->an_node,
                            "%s: switching quickly..", __func__);
                        change_rates = 1;
                } else if (ticks - ssc->min_switch > sn->ticks_since_switch[size_bin]) {
                        /* min_switch seconds have gone by */
                        IEEE80211_NOTE(an->an_node.ni_vap,
                            IEEE80211_MSG_RATECTL, &an->an_node,
                            "%s: min_switch %d > ticks_since_switch %d..",
                            __func__, ticks - ssc->min_switch, sn->ticks_since_switch[size_bin]);
                        change_rates = 1;
                } else if ((! (an->an_node.ni_flags & IEEE80211_NODE_HT)) &&
                    (2*average_tx_time < sn->stats[size_bin][sn->current_rix[size_bin]].average_tx_time)) {
                        /* the current bit-rate is twice as slow as the best one */
                        IEEE80211_NOTE(an->an_node.ni_vap,
                            IEEE80211_MSG_RATECTL, &an->an_node,
                            "%s: 2x att (= %d) < cur_rix att %d",
                            __func__,
                            2 * average_tx_time, sn->stats[size_bin][sn->current_rix[size_bin]].average_tx_time);
                        change_rates = 1;
                } else if ((an->an_node.ni_flags & IEEE80211_NODE_HT)) {
                        int cur_rix = sn->current_rix[size_bin];
                        int cur_att = sn->stats[size_bin][cur_rix].average_tx_time;
                        /*
                         * If the node is HT, upgrade it if the MCS rate is
                         * higher and the average tx time is within 20% of
                         * the current rate. It can fail a little.
                         *
                         * This is likely not optimal!
                         */
#if 0
                        kprintf("cur rix/att %x/%d, best rix/att %x/%d\n",
                            MCS(cur_rix), cur_att, MCS(best_rix), average_tx_time);
#endif
                        if ((MCS(best_rix) > MCS(cur_rix)) &&
                            (average_tx_time * 8) <= (cur_att * 10)) {
                                IEEE80211_NOTE(an->an_node.ni_vap,
                                    IEEE80211_MSG_RATECTL, &an->an_node,
                                    "%s: HT: best_rix 0x%d > cur_rix 0x%x, average_tx_time %d, cur_att %d",
                                    __func__,
                                    MCS(best_rix), MCS(cur_rix), average_tx_time, cur_att);
                                change_rates = 1;
                        }
                }

                sn->packets_since_sample[size_bin]++;
                
                if (change_rates) {
                        if (best_rix != sn->current_rix[size_bin]) {
                                IEEE80211_NOTE(an->an_node.ni_vap,
                                    IEEE80211_MSG_RATECTL,
                                    &an->an_node,
"%s: size %d switch rate %d (%d/%d) -> %d (%d/%d) after %d packets mrr %d",
                                    __func__,
                                    bin_to_size(size_bin),
                                    RATE(sn->current_rix[size_bin]),
                                    sn->stats[size_bin][sn->current_rix[size_bin]].average_tx_time,
                                    sn->stats[size_bin][sn->current_rix[size_bin]].perfect_tx_time,
                                    RATE(best_rix),
                                    sn->stats[size_bin][best_rix].average_tx_time,
                                    sn->stats[size_bin][best_rix].perfect_tx_time,
                                    sn->packets_since_switch[size_bin],
                                    mrr);
                        }
                        sn->packets_since_switch[size_bin] = 0;
                        sn->current_rix[size_bin] = best_rix;
                        sn->ticks_since_switch[size_bin] = ticks;
                        /* 
                         * Set the visible txrate for this node.
                         */
                        an->an_node.ni_txrate = (rt->info[best_rix].phy == IEEE80211_T_HT) ?  MCS(best_rix) : DOT11RATE(best_rix);
                }
                rix = sn->current_rix[size_bin];
                sn->packets_since_switch[size_bin]++;
        }
        *try0 = mrr ? sn->sched[rix].t0 : ATH_TXMAXTRY;
done:

        /*
         * This bug totally sucks and should be fixed.
         *
         * For now though, let's not panic, so we can start to figure
         * out how to better reproduce it.
         */
        if (rix < 0 || rix >= rt->rateCount) {
                kprintf("%s: ERROR: rix %d out of bounds (rateCount=%d)\n",
                    __func__,
                    rix,
                    rt->rateCount);
                    rix = 0;    /* XXX just default for now */
        }
        KASSERT(rix >= 0 && rix < rt->rateCount, ("rix is %d", rix));

        *rix0 = rix;
        *txrate = rt->info[rix].rateCode
                | (shortPreamble ? rt->info[rix].shortPreamble : 0);
        sn->packets_sent[size_bin]++;
#undef DOT11RATE
#undef MCS
#undef RATE
}

/*
 * Get the TX rates. Don't fiddle with short preamble flags for them;
 * the caller can do that.
 */
void
ath_rate_getxtxrates(struct ath_softc *sc, struct ath_node *an,
    uint8_t rix0, struct ath_rc_series *rc)
{
        struct sample_node *sn = ATH_NODE_SAMPLE(an);
        const struct txschedule *sched = &sn->sched[rix0];

        KASSERT(rix0 == sched->r0, ("rix0 (%x) != sched->r0 (%x)!\n",
            rix0, sched->r0));

        rc[0].flags = rc[1].flags = rc[2].flags = rc[3].flags = 0;

        rc[0].rix = sched->r0;
        rc[1].rix = sched->r1;
        rc[2].rix = sched->r2;
        rc[3].rix = sched->r3;

        rc[0].tries = sched->t0;
        rc[1].tries = sched->t1;
        rc[2].tries = sched->t2;
        rc[3].tries = sched->t3;
}

void
ath_rate_setupxtxdesc(struct ath_softc *sc, struct ath_node *an,
                      struct ath_desc *ds, int shortPreamble, u_int8_t rix)
{
        struct sample_node *sn = ATH_NODE_SAMPLE(an);
        const struct txschedule *sched = &sn->sched[rix];
        const HAL_RATE_TABLE *rt = sc->sc_currates;
        uint8_t rix1, s1code, rix2, s2code, rix3, s3code;

        /* XXX precalculate short preamble tables */
        rix1 = sched->r1;
        s1code = rt->info[rix1].rateCode
               | (shortPreamble ? rt->info[rix1].shortPreamble : 0);
        rix2 = sched->r2;
        s2code = rt->info[rix2].rateCode
               | (shortPreamble ? rt->info[rix2].shortPreamble : 0);
        rix3 = sched->r3;
        s3code = rt->info[rix3].rateCode
               | (shortPreamble ? rt->info[rix3].shortPreamble : 0);
        ath_hal_setupxtxdesc(sc->sc_ah, ds,
            s1code, sched->t1,          /* series 1 */
            s2code, sched->t2,          /* series 2 */
            s3code, sched->t3);         /* series 3 */
}

static void
update_stats(struct ath_softc *sc, struct ath_node *an, 
                  int frame_size,
                  int rix0, int tries0,
                  int rix1, int tries1,
                  int rix2, int tries2,
                  int rix3, int tries3,
                  int short_tries, int tries, int status,
                  int nframes, int nbad)
{
        struct sample_node *sn = ATH_NODE_SAMPLE(an);
        struct sample_softc *ssc = ATH_SOFTC_SAMPLE(sc);
#ifdef IEEE80211_DEBUG
        const HAL_RATE_TABLE *rt = sc->sc_currates;
#endif
        const int size_bin = size_to_bin(frame_size);
        const int size = bin_to_size(size_bin);
        int tt, tries_so_far;
        int is_ht40 = (an->an_node.ni_chw == 40);
        int pct;

        if (!IS_RATE_DEFINED(sn, rix0))
                return;
        tt = calc_usecs_unicast_packet(sc, size, rix0, short_tries,
                MIN(tries0, tries) - 1, is_ht40);
        tries_so_far = tries0;

        if (tries1 && tries_so_far < tries) {
                if (!IS_RATE_DEFINED(sn, rix1))
                        return;
                tt += calc_usecs_unicast_packet(sc, size, rix1, short_tries,
                        MIN(tries1 + tries_so_far, tries) - tries_so_far - 1, is_ht40);
                tries_so_far += tries1;
        }

        if (tries2 && tries_so_far < tries) {
                if (!IS_RATE_DEFINED(sn, rix2))
                        return;
                tt += calc_usecs_unicast_packet(sc, size, rix2, short_tries,
                        MIN(tries2 + tries_so_far, tries) - tries_so_far - 1, is_ht40);
                tries_so_far += tries2;
        }

        if (tries3 && tries_so_far < tries) {
                if (!IS_RATE_DEFINED(sn, rix3))
                        return;
                tt += calc_usecs_unicast_packet(sc, size, rix3, short_tries,
                        MIN(tries3 + tries_so_far, tries) - tries_so_far - 1, is_ht40);
        }

        if (sn->stats[size_bin][rix0].total_packets < ssc->smoothing_minpackets) {
                /* just average the first few packets */
                int avg_tx = sn->stats[size_bin][rix0].average_tx_time;
                int packets = sn->stats[size_bin][rix0].total_packets;
                sn->stats[size_bin][rix0].average_tx_time = (tt+(avg_tx*packets))/(packets+nframes);
        } else {
                /* use a ewma */
                sn->stats[size_bin][rix0].average_tx_time = 
                        ((sn->stats[size_bin][rix0].average_tx_time * ssc->smoothing_rate) + 
                         (tt * (100 - ssc->smoothing_rate))) / 100;
        }
        
        /*
         * XXX Don't mark the higher bit rates as also having failed; as this
         * unfortunately stops those rates from being tasted when trying to
         * TX. This happens with 11n aggregation.
         */
        if (nframes == nbad) {
#if 0
                int y;
#endif
                sn->stats[size_bin][rix0].successive_failures += nbad;
#if 0
                for (y = size_bin+1; y < NUM_PACKET_SIZE_BINS; y++) {
                        /*
                         * Also say larger packets failed since we
                         * assume if a small packet fails at a
                         * bit-rate then a larger one will also.
                         */
                        sn->stats[y][rix0].successive_failures += nbad;
                        sn->stats[y][rix0].last_tx = ticks;
                        sn->stats[y][rix0].tries += tries;
                        sn->stats[y][rix0].total_packets += nframes;
                }
#endif
        } else {
                sn->stats[size_bin][rix0].packets_acked += (nframes - nbad);
                sn->stats[size_bin][rix0].successive_failures = 0;
        }
        sn->stats[size_bin][rix0].tries += tries;
        sn->stats[size_bin][rix0].last_tx = ticks;
        sn->stats[size_bin][rix0].total_packets += nframes;

        /* update EWMA for this rix */

        /* Calculate percentage based on current rate */
        if (nframes == 0)
                nframes = nbad = 1;
        pct = ((nframes - nbad) * 1000) / nframes;

        if (sn->stats[size_bin][rix0].total_packets <
            ssc->smoothing_minpackets) {
                /* just average the first few packets */
                int a_pct = (sn->stats[size_bin][rix0].packets_acked * 1000) /
                    (sn->stats[size_bin][rix0].total_packets);
                sn->stats[size_bin][rix0].ewma_pct = a_pct;
        } else {
                /* use a ewma */
                sn->stats[size_bin][rix0].ewma_pct =
                        ((sn->stats[size_bin][rix0].ewma_pct * ssc->smoothing_rate) +
                         (pct * (100 - ssc->smoothing_rate))) / 100;
        }


        if (rix0 == sn->current_sample_rix[size_bin]) {
                IEEE80211_NOTE(an->an_node.ni_vap, IEEE80211_MSG_RATECTL,
                   &an->an_node,
"%s: size %d %s sample rate %d %s tries (%d/%d) tt %d avg_tt (%d/%d) nfrm %d nbad %d", 
                    __func__, 
                    size,
                    status ? "FAIL" : "OK",
                    dot11rate(rt, rix0),
                    dot11rate_label(rt, rix0),
                    short_tries, tries, tt, 
                    sn->stats[size_bin][rix0].average_tx_time,
                    sn->stats[size_bin][rix0].perfect_tx_time,
                    nframes, nbad);
                sn->sample_tt[size_bin] = tt;
                sn->current_sample_rix[size_bin] = -1;
        }
}

static void
badrate(struct ath_softc *sc, int series, int hwrate, int tries, int status)
{

        device_printf(sc->sc_dev,
            "bad series%d hwrate 0x%x, tries %u ts_status 0x%x\n",
            series, hwrate, tries, status);
}

void
ath_rate_tx_complete(struct ath_softc *sc, struct ath_node *an,
        const struct ath_rc_series *rc, const struct ath_tx_status *ts,
        int frame_size, int nframes, int nbad)
{
        struct ieee80211com *ic = &sc->sc_ic;
        struct sample_node *sn = ATH_NODE_SAMPLE(an);
        int final_rix, short_tries, long_tries;
        const HAL_RATE_TABLE *rt = sc->sc_currates;
        int status = ts->ts_status;
        int mrr;

        final_rix = rt->rateCodeToIndex[ts->ts_rate];
        short_tries = ts->ts_shortretry;
        long_tries = ts->ts_longretry + 1;

        if (nframes == 0) {
                device_printf(sc->sc_dev, "%s: nframes=0?\n", __func__);
                return;
        }

        if (frame_size == 0)                /* NB: should not happen */
                frame_size = 1500;

        if (sn->ratemask == 0) {
                IEEE80211_NOTE(an->an_node.ni_vap, IEEE80211_MSG_RATECTL,
                    &an->an_node,
                    "%s: size %d %s rate/try %d/%d no rates yet", 
                    __func__,
                    bin_to_size(size_to_bin(frame_size)),
                    status ? "FAIL" : "OK",
                    short_tries, long_tries);
                return;
        }
        mrr = sc->sc_mrretry;
        /* XXX check HT protmode too */
        if (mrr && (ic->ic_flags & IEEE80211_F_USEPROT && !sc->sc_mrrprot))
                mrr = 0;

        if (!mrr || ts->ts_finaltsi == 0) {
                if (!IS_RATE_DEFINED(sn, final_rix)) {
                        device_printf(sc->sc_dev,
                            "%s: ts_rate=%d ts_finaltsi=%d, final_rix=%d\n",
                            __func__, ts->ts_rate, ts->ts_finaltsi, final_rix);
                        badrate(sc, 0, ts->ts_rate, long_tries, status);
                        return;
                }
                /*
                 * Only one rate was used; optimize work.
                 */
                IEEE80211_NOTE(an->an_node.ni_vap, IEEE80211_MSG_RATECTL,
                     &an->an_node, "%s: size %d (%d bytes) %s rate/short/long %d %s/%d/%d nframes/nbad [%d/%d]",
                     __func__,
                     bin_to_size(size_to_bin(frame_size)),
                     frame_size,
                     status ? "FAIL" : "OK",
                     dot11rate(rt, final_rix), dot11rate_label(rt, final_rix),
                     short_tries, long_tries, nframes, nbad);
                update_stats(sc, an, frame_size, 
                             final_rix, long_tries,
                             0, 0,
                             0, 0,
                             0, 0,
                             short_tries, long_tries, status,
                             nframes, nbad);

        } else {
                int finalTSIdx = ts->ts_finaltsi;
                int i;

                /*
                 * Process intermediate rates that failed.
                 */

                IEEE80211_NOTE(an->an_node.ni_vap, IEEE80211_MSG_RATECTL,
                    &an->an_node,
"%s: size %d (%d bytes) finaltsidx %d short %d long %d %s rate/try [%d %s/%d %d %s/%d %d %s/%d %d %s/%d] nframes/nbad [%d/%d]", 
                     __func__,
                     bin_to_size(size_to_bin(frame_size)),
                     frame_size,
                     finalTSIdx,
                     short_tries,
                     long_tries,
                     status ? "FAIL" : "OK",
                     dot11rate(rt, rc[0].rix),
                      dot11rate_label(rt, rc[0].rix), rc[0].tries,
                     dot11rate(rt, rc[1].rix),
                      dot11rate_label(rt, rc[1].rix), rc[1].tries,
                     dot11rate(rt, rc[2].rix),
                      dot11rate_label(rt, rc[2].rix), rc[2].tries,
                     dot11rate(rt, rc[3].rix),
                      dot11rate_label(rt, rc[3].rix), rc[3].tries,
                     nframes, nbad);

                for (i = 0; i < 4; i++) {
                        if (rc[i].tries && !IS_RATE_DEFINED(sn, rc[i].rix))
                                badrate(sc, 0, rc[i].ratecode, rc[i].tries,
                                    status);
                }

                /*
                 * NB: series > 0 are not penalized for failure
                 * based on the try counts under the assumption
                 * that losses are often bursty and since we
                 * sample higher rates 1 try at a time doing so
                 * may unfairly penalize them.
                 */
                if (rc[0].tries) {
                        update_stats(sc, an, frame_size,
                                     rc[0].rix, rc[0].tries,
                                     rc[1].rix, rc[1].tries,
                                     rc[2].rix, rc[2].tries,
                                     rc[3].rix, rc[3].tries,
                                     short_tries, long_tries,
                                     long_tries > rc[0].tries,
                                     nframes, nbad);
                        long_tries -= rc[0].tries;
                }
                
                if (rc[1].tries && finalTSIdx > 0) {
                        update_stats(sc, an, frame_size,
                                     rc[1].rix, rc[1].tries,
                                     rc[2].rix, rc[2].tries,
                                     rc[3].rix, rc[3].tries,
                                     0, 0,
                                     short_tries, long_tries,
                                     status,
                                     nframes, nbad);
                        long_tries -= rc[1].tries;
                }

                if (rc[2].tries && finalTSIdx > 1) {
                        update_stats(sc, an, frame_size,
                                     rc[2].rix, rc[2].tries,
                                     rc[3].rix, rc[3].tries,
                                     0, 0,
                                     0, 0,
                                     short_tries, long_tries,
                                     status,
                                     nframes, nbad);
                        long_tries -= rc[2].tries;
                }

                if (rc[3].tries && finalTSIdx > 2) {
                        update_stats(sc, an, frame_size,
                                     rc[3].rix, rc[3].tries,
                                     0, 0,
                                     0, 0,
                                     0, 0,
                                     short_tries, long_tries,
                                     status,
                                     nframes, nbad);
                }
        }
}

void
ath_rate_newassoc(struct ath_softc *sc, struct ath_node *an, int isnew)
{
        if (isnew)
                ath_rate_ctl_reset(sc, &an->an_node);
}

static const struct txschedule *mrr_schedules[IEEE80211_MODE_MAX+2] = {
        NULL,           /* IEEE80211_MODE_AUTO */
        series_11a,     /* IEEE80211_MODE_11A */
        series_11g,     /* IEEE80211_MODE_11B */
        series_11g,     /* IEEE80211_MODE_11G */
        NULL,           /* IEEE80211_MODE_FH */
        series_11a,     /* IEEE80211_MODE_TURBO_A */
        series_11g,     /* IEEE80211_MODE_TURBO_G */
        series_11a,     /* IEEE80211_MODE_STURBO_A */
        series_11na,    /* IEEE80211_MODE_11NA */
        series_11ng,    /* IEEE80211_MODE_11NG */
        series_half,    /* IEEE80211_MODE_HALF */
        series_quarter, /* IEEE80211_MODE_QUARTER */
};

/*
 * Initialize the tables for a node.
 */
static void
ath_rate_ctl_reset(struct ath_softc *sc, struct ieee80211_node *ni)
{
#define RATE(_ix)       (ni->ni_rates.rs_rates[(_ix)] & IEEE80211_RATE_VAL)
#define DOT11RATE(_ix)  (rt->info[(_ix)].dot11Rate & IEEE80211_RATE_VAL)
#define MCS(_ix)        (ni->ni_htrates.rs_rates[_ix] | IEEE80211_RATE_MCS)
        struct ath_node *an = ATH_NODE(ni);
        struct sample_node *sn = ATH_NODE_SAMPLE(an);
        const HAL_RATE_TABLE *rt = sc->sc_currates;
        int x, y, rix;

        KASSERT(rt != NULL, ("no rate table, mode %u", sc->sc_curmode));

        KASSERT(sc->sc_curmode < IEEE80211_MODE_MAX+2,
            ("curmode %u", sc->sc_curmode));

        sn->sched = mrr_schedules[sc->sc_curmode];
        KASSERT(sn->sched != NULL,
            ("no mrr schedule for mode %u", sc->sc_curmode));

        sn->static_rix = -1;
        ath_rate_update_static_rix(sc, ni);

        sn->currates = sc->sc_currates;

        /*
         * Construct a bitmask of usable rates.  This has all
         * negotiated rates minus those marked by the hal as
         * to be ignored for doing rate control.
         */
        sn->ratemask = 0;
        /* MCS rates */
        if (ni->ni_flags & IEEE80211_NODE_HT) {
                for (x = 0; x < ni->ni_htrates.rs_nrates; x++) {
                        rix = sc->sc_rixmap[MCS(x)];
                        if (rix == 0xff)
                                continue;
                        /* skip rates marked broken by hal */
                        if (!rt->info[rix].valid)
                                continue;
                        KASSERT(rix < SAMPLE_MAXRATES,
                            ("mcs %u has rix %d", MCS(x), rix));
                        sn->ratemask |= (uint64_t) 1<<rix;
                }
        }

        /* Legacy rates */
        for (x = 0; x < ni->ni_rates.rs_nrates; x++) {
                rix = sc->sc_rixmap[RATE(x)];
                if (rix == 0xff)
                        continue;
                /* skip rates marked broken by hal */
                if (!rt->info[rix].valid)
                        continue;
                KASSERT(rix < SAMPLE_MAXRATES,
                    ("rate %u has rix %d", RATE(x), rix));
                sn->ratemask |= (uint64_t) 1<<rix;
        }
#ifdef IEEE80211_DEBUG
        if (ieee80211_msg(ni->ni_vap, IEEE80211_MSG_RATECTL)) {
                uint64_t mask;

#if defined(__DragonFly__)
                ieee80211_note(ni->ni_vap, "[%s] %s: size 1600 rate/tt",
                    ath_hal_ether_sprintf(ni->ni_macaddr), __func__);
#else
                ieee80211_note(ni->ni_vap, "[%6D] %s: size 1600 rate/tt",
                    ni->ni_macaddr, ":", __func__);
#endif
                for (mask = sn->ratemask, rix = 0; mask != 0; mask >>= 1, rix++) {
                        if ((mask & 1) == 0)
                                continue;
                        kprintf(" %d %s/%d", dot11rate(rt, rix), dot11rate_label(rt, rix),
                            calc_usecs_unicast_packet(sc, 1600, rix, 0,0,
                                (ni->ni_chw == 40)));
                }
                kprintf("\n");
        }
#endif
        for (y = 0; y < NUM_PACKET_SIZE_BINS; y++) {
                int size = bin_to_size(y);
                uint64_t mask;

                sn->packets_sent[y] = 0;
                sn->current_sample_rix[y] = -1;
                sn->last_sample_rix[y] = 0;
                /* XXX start with first valid rate */
                sn->current_rix[y] = ffs(sn->ratemask)-1;
                
                /*
                 * Initialize the statistics buckets; these are
                 * indexed by the rate code index.
                 */
                for (rix = 0, mask = sn->ratemask; mask != 0; rix++, mask >>= 1) {
                        if ((mask & 1) == 0)            /* not a valid rate */
                                continue;
                        sn->stats[y][rix].successive_failures = 0;
                        sn->stats[y][rix].tries = 0;
                        sn->stats[y][rix].total_packets = 0;
                        sn->stats[y][rix].packets_acked = 0;
                        sn->stats[y][rix].last_tx = 0;
                        sn->stats[y][rix].ewma_pct = 0;
                        
                        sn->stats[y][rix].perfect_tx_time =
                            calc_usecs_unicast_packet(sc, size, rix, 0, 0,
                            (ni->ni_chw == 40));
                        sn->stats[y][rix].average_tx_time =
                            sn->stats[y][rix].perfect_tx_time;
                }
        }
#if 0
        /* XXX 0, num_rates-1 are wrong */
        IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
            "%s: %d rates %d%sMbps (%dus)- %d%sMbps (%dus)", __func__, 
            sn->num_rates,
            DOT11RATE(0)/2, DOT11RATE(0) % 1 ? ".5" : "",
            sn->stats[1][0].perfect_tx_time,
            DOT11RATE(sn->num_rates-1)/2, DOT11RATE(sn->num_rates-1) % 1 ? ".5" : "",
            sn->stats[1][sn->num_rates-1].perfect_tx_time
        );
#endif
        /* set the visible bit-rate */
        if (sn->static_rix != -1)
                ni->ni_txrate = DOT11RATE(sn->static_rix);
        else
                ni->ni_txrate = RATE(0);
#undef RATE
#undef DOT11RATE
}

/*
 * Fetch the statistics for the given node.
 *
 * The ieee80211 node must be referenced and unlocked, however the ath_node
 * must be locked.
 *
 * The main difference here is that we convert the rate indexes
 * to 802.11 rates, or the userland output won't make much sense
 * as it has no access to the rix table.
 */
int
ath_rate_fetch_node_stats(struct ath_softc *sc, struct ath_node *an,
    struct ath_rateioctl *rs)
{
        struct sample_node *sn = ATH_NODE_SAMPLE(an);
        const HAL_RATE_TABLE *rt = sc->sc_currates;
        struct ath_rateioctl_tlv av;
        struct ath_rateioctl_rt *tv;
        int y;
        int o = 0;

        ATH_NODE_LOCK_ASSERT(an);

        /*
         * Ensure there's enough space for the statistics.
         */
        if (rs->len <
            sizeof(struct ath_rateioctl_tlv) +
            sizeof(struct ath_rateioctl_rt) +
            sizeof(struct ath_rateioctl_tlv) +
            sizeof(struct sample_node)) {
                device_printf(sc->sc_dev, "%s: len=%d, too short\n",
                    __func__,
                    rs->len);
                return (EINVAL);
        }

        /*
         * Take a temporary copy of the sample node state so we can
         * modify it before we copy it.
         */
#if defined(__DragonFly__)
        tv = kmalloc(sizeof(struct ath_rateioctl_rt), M_TEMP,
                M_INTWAIT | M_ZERO);
#else
        tv = malloc(sizeof(struct ath_rateioctl_rt), M_TEMP,
                M_NOWAIT | M_ZERO);
#endif
        if (tv == NULL) {
                return (ENOMEM);
        }

        /*
         * Populate the rate table mapping TLV.
         */
        tv->nentries = rt->rateCount;
        for (y = 0; y < rt->rateCount; y++) {
                tv->ratecode[y] = rt->info[y].dot11Rate & IEEE80211_RATE_VAL;
                if (rt->info[y].phy == IEEE80211_T_HT)
                        tv->ratecode[y] |= IEEE80211_RATE_MCS;
        }

        o = 0;
        /*
         * First TLV - rate code mapping
         */
        av.tlv_id = ATH_RATE_TLV_RATETABLE;
        av.tlv_len = sizeof(struct ath_rateioctl_rt);
        copyout(&av, rs->buf + o, sizeof(struct ath_rateioctl_tlv));
        o += sizeof(struct ath_rateioctl_tlv);
        copyout(tv, rs->buf + o, sizeof(struct ath_rateioctl_rt));
        o += sizeof(struct ath_rateioctl_rt);

        /*
         * Second TLV - sample node statistics
         */
        av.tlv_id = ATH_RATE_TLV_SAMPLENODE;
        av.tlv_len = sizeof(struct sample_node);
        copyout(&av, rs->buf + o, sizeof(struct ath_rateioctl_tlv));
        o += sizeof(struct ath_rateioctl_tlv);

        /*
         * Copy the statistics over to the provided buffer.
         */
        copyout(sn, rs->buf + o, sizeof(struct sample_node));
        o += sizeof(struct sample_node);

        kfree(tv, M_TEMP);

        return (0);
}

static void
sample_stats(void *arg, struct ieee80211_node *ni)
{
        struct ath_softc *sc = arg;
        const HAL_RATE_TABLE *rt = sc->sc_currates;
        struct sample_node *sn = ATH_NODE_SAMPLE(ATH_NODE(ni));
        uint64_t mask;
        int rix, y;

        kprintf("\n[%s] refcnt %d static_rix (%d %s) ratemask 0x%jx\n",
            ether_sprintf(ni->ni_macaddr), ieee80211_node_refcnt(ni),
            dot11rate(rt, sn->static_rix),
            dot11rate_label(rt, sn->static_rix),
            (uintmax_t)sn->ratemask);
        for (y = 0; y < NUM_PACKET_SIZE_BINS; y++) {
                kprintf("[%4u] cur rix %d (%d %s) since switch: packets %d ticks %u\n",
                    bin_to_size(y), sn->current_rix[y],
                    dot11rate(rt, sn->current_rix[y]),
                    dot11rate_label(rt, sn->current_rix[y]),
                    sn->packets_since_switch[y], sn->ticks_since_switch[y]);
                kprintf("[%4u] last sample (%d %s) cur sample (%d %s) packets sent %d\n",
                    bin_to_size(y),
                    dot11rate(rt, sn->last_sample_rix[y]),
                    dot11rate_label(rt, sn->last_sample_rix[y]),
                    dot11rate(rt, sn->current_sample_rix[y]),
                    dot11rate_label(rt, sn->current_sample_rix[y]),
                    sn->packets_sent[y]);
                kprintf("[%4u] packets since sample %d sample tt %u\n",
                    bin_to_size(y), sn->packets_since_sample[y],
                    sn->sample_tt[y]);
        }
        for (mask = sn->ratemask, rix = 0; mask != 0; mask >>= 1, rix++) {
                if ((mask & 1) == 0)
                                continue;
                for (y = 0; y < NUM_PACKET_SIZE_BINS; y++) {
                        if (sn->stats[y][rix].total_packets == 0)
                                continue;
                        kprintf("[%2u %s:%4u] %8ju:%-8ju (%3d%%) (EWMA %3d.%1d%%) T %8ju F %4d avg %5u last %u\n",
                            dot11rate(rt, rix), dot11rate_label(rt, rix),
                            bin_to_size(y),
                            (uintmax_t) sn->stats[y][rix].total_packets,
                            (uintmax_t) sn->stats[y][rix].packets_acked,
                            (int) ((sn->stats[y][rix].packets_acked * 100ULL) /
                             sn->stats[y][rix].total_packets),
                            sn->stats[y][rix].ewma_pct / 10,
                            sn->stats[y][rix].ewma_pct % 10,
                            (uintmax_t) sn->stats[y][rix].tries,
                            sn->stats[y][rix].successive_failures,
                            sn->stats[y][rix].average_tx_time,
                            ticks - sn->stats[y][rix].last_tx);
                }
        }
}

static int
ath_rate_sysctl_stats(SYSCTL_HANDLER_ARGS)
{
        struct ath_softc *sc = arg1;
        struct ieee80211com *ic = &sc->sc_ic;
        int error, v;

        v = 0;
        error = sysctl_handle_int(oidp, &v, 0, req);
        if (error || !req->newptr)
                return error;
        ieee80211_iterate_nodes(&ic->ic_sta, sample_stats, sc);
        return 0;
}

static int
ath_rate_sysctl_smoothing_rate(SYSCTL_HANDLER_ARGS)
{
        struct sample_softc *ssc = arg1;
        int rate, error;

        rate = ssc->smoothing_rate;
        error = sysctl_handle_int(oidp, &rate, 0, req);
        if (error || !req->newptr)
                return error;
        if (!(0 <= rate && rate < 100))
                return EINVAL;
        ssc->smoothing_rate = rate;
        ssc->smoothing_minpackets = 100 / (100 - rate);
        return 0;
}

static int
ath_rate_sysctl_sample_rate(SYSCTL_HANDLER_ARGS)
{
        struct sample_softc *ssc = arg1;
        int rate, error;

        rate = ssc->sample_rate;
        error = sysctl_handle_int(oidp, &rate, 0, req);
        if (error || !req->newptr)
                return error;
        if (!(2 <= rate && rate <= 100))
                return EINVAL;
        ssc->sample_rate = rate;
        return 0;
}

static void
ath_rate_sysctlattach(struct ath_softc *sc, struct sample_softc *ssc)
{
        struct sysctl_ctx_list *ctx = device_get_sysctl_ctx(sc->sc_dev);
        struct sysctl_oid *tree = device_get_sysctl_tree(sc->sc_dev);

        SYSCTL_ADD_PROC(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
            "smoothing_rate", CTLTYPE_INT | CTLFLAG_RW, ssc, 0,
            ath_rate_sysctl_smoothing_rate, "I",
            "sample: smoothing rate for avg tx time (%%)");
        SYSCTL_ADD_PROC(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
            "sample_rate", CTLTYPE_INT | CTLFLAG_RW, ssc, 0,
            ath_rate_sysctl_sample_rate, "I",
            "sample: percent air time devoted to sampling new rates (%%)");
        /* XXX max_successive_failures, stale_failure_timeout, min_switch */
        SYSCTL_ADD_PROC(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
            "sample_stats", CTLTYPE_INT | CTLFLAG_RW, sc, 0,
            ath_rate_sysctl_stats, "I", "sample: print statistics");
}

struct ath_ratectrl *
ath_rate_attach(struct ath_softc *sc)
{
        struct sample_softc *ssc;
        
#if defined(__DragonFly__)
        ssc = kmalloc(sizeof(struct sample_softc), M_DEVBUF, M_INTWAIT|M_ZERO);
#else
        ssc = malloc(sizeof(struct sample_softc), M_DEVBUF, M_NOWAIT|M_ZERO);
#endif
        if (ssc == NULL)
                return NULL;
        ssc->arc.arc_space = sizeof(struct sample_node);
        ssc->smoothing_rate = 75;               /* ewma percentage ([0..99]) */
        ssc->smoothing_minpackets = 100 / (100 - ssc->smoothing_rate);
        ssc->sample_rate = 10;                  /* %time to try diff tx rates */
        ssc->max_successive_failures = 3;       /* threshold for rate sampling*/
        ssc->stale_failure_timeout = 10 * hz;   /* 10 seconds */
        ssc->min_switch = hz;                   /* 1 second */
        ath_rate_sysctlattach(sc, ssc);
        return &ssc->arc;
}

void
ath_rate_detach(struct ath_ratectrl *arc)
{
        struct sample_softc *ssc = (struct sample_softc *) arc;
        
        kfree(ssc, M_DEVBUF);
}

#if defined(__DragonFly__)

/*
 * Module glue.
 */
static int
sample_modevent(module_t mod, int type, void *unused)
{
        int error;

        wlan_serialize_enter();

        switch (type) {
        case MOD_LOAD:
                if (bootverbose) {
                        kprintf("ath_rate: <SampleRate bit-rate "
                                "selection algorithm>\n");
                }
                error = 0;
                break;
        case MOD_UNLOAD:
                error = 0;
                break;
        default:
                error = EINVAL;
                break;
        }
        wlan_serialize_exit();

        return error;
}

static moduledata_t sample_mod = {
        "ath_rate",
        sample_modevent,
        0
};

DECLARE_MODULE(ath_rate, sample_mod, SI_SUB_DRIVERS, SI_ORDER_FIRST);
MODULE_VERSION(ath_rate, 1);
MODULE_DEPEND(ath_rate, ath_hal, 1, 1, 1);
MODULE_DEPEND(ath_rate, wlan, 1, 1, 1);

#endif