/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * 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, MERCHANTIBILITY
 * 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.
 */

/*
 * Defintions for the Atheros Wireless LAN controller driver.
 */
#ifndef _DEV_ATH_RATE_SAMPLE_H
#define _DEV_ATH_RATE_SAMPLE_H

/* per-device state */
struct sample_softc {
        struct ath_ratectrl arc;        /* base class */
        int     smoothing_rate;         /* ewma percentage [0..99] */
        int     smoothing_minpackets;
        int     sample_rate;            /* %time to try different tx rates */
        int     max_successive_failures;
        int     stale_failure_timeout;  /* how long to honor max_successive_failures */
        int     min_switch;             /* min time between rate changes */
        int     min_good_pct;           /* min good percentage for a rate to be considered */
};
#define ATH_SOFTC_SAMPLE(sc)    ((struct sample_softc *)sc->sc_rc)

struct rate_stats {     
        unsigned average_tx_time;
        int successive_failures;
        uint64_t tries;
        uint64_t total_packets; /* pkts total since assoc */
        uint64_t packets_acked; /* pkts acked since assoc */
        int ewma_pct;   /* EWMA percentage */
        unsigned perfect_tx_time; /* transmit time for 0 retries */
        int last_tx;
};

struct txschedule {
        uint8_t t0, r0;         /* series 0: tries, rate code */
        uint8_t t1, r1;         /* series 1: tries, rate code */
        uint8_t t2, r2;         /* series 2: tries, rate code */
        uint8_t t3, r3;         /* series 3: tries, rate code */
};

/*
 * We track performance for eight different packet size buckets.
 */
#define NUM_PACKET_SIZE_BINS 7

static const int packet_size_bins[NUM_PACKET_SIZE_BINS]  = { 250, 1600, 4096, 8192, 16384, 32768, 65536 };

static inline int
bin_to_size(int index)
{
        return packet_size_bins[index];
}

/* per-node state */
struct sample_node {
        int static_rix;                 /* rate index of fixed tx rate */
#define SAMPLE_MAXRATES 64              /* NB: corresponds to hal info[32] */
        uint64_t ratemask;              /* bit mask of valid rate indices */
        const struct txschedule *sched; /* tx schedule table */

        const HAL_RATE_TABLE *currates;

        struct rate_stats stats[NUM_PACKET_SIZE_BINS][SAMPLE_MAXRATES];
        int last_sample_rix[NUM_PACKET_SIZE_BINS];

        int current_sample_rix[NUM_PACKET_SIZE_BINS];       
        int packets_sent[NUM_PACKET_SIZE_BINS];

        int current_rix[NUM_PACKET_SIZE_BINS];
        int packets_since_switch[NUM_PACKET_SIZE_BINS];
        int ticks_since_switch[NUM_PACKET_SIZE_BINS];

        int packets_since_sample[NUM_PACKET_SIZE_BINS];
        unsigned sample_tt[NUM_PACKET_SIZE_BINS];
};

#ifdef  _KERNEL

#define ATH_NODE_SAMPLE(an)     ((struct sample_node *)&(an)[1])
#define IS_RATE_DEFINED(sn, rix)        (((uint64_t) (sn)->ratemask & (1ULL<<((uint64_t) rix))) != 0)

#ifndef MIN
#define MIN(a,b)        ((a) < (b) ? (a) : (b))
#endif
#ifndef MAX
#define MAX(a,b)        ((a) > (b) ? (a) : (b))
#endif

#define WIFI_CW_MIN 31
#define WIFI_CW_MAX 1023

/*
 * Calculate the transmit duration of a frame.
 */
static unsigned calc_usecs_unicast_packet(struct ath_softc *sc,
                                int length,
                                int rix, int short_retries,
                                int long_retries, int is_ht40)
{
        const HAL_RATE_TABLE *rt = sc->sc_currates;
        struct ieee80211com *ic = &sc->sc_ic;
        int rts, cts;

        unsigned t_slot = 20;
        unsigned t_difs = 50; 
        unsigned t_sifs = 10; 
        int tt = 0;
        int x = 0;
        int cw = WIFI_CW_MIN;
        int cix;

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

        if (rix >= rt->rateCount) {
                printf("bogus rix %d, max %u, mode %u\n",
                       rix, rt->rateCount, sc->sc_curmode);
                return 0;
        }
        cix = rt->info[rix].controlRate;
        /* 
         * XXX getting mac/phy level timings should be fixed for turbo
         * rates, and there is probably a way to get this from the
         * hal...
         */
        switch (rt->info[rix].phy) {
        case IEEE80211_T_OFDM:
                t_slot = 9;
                t_sifs = 16;
                t_difs = 28;
                /* fall through */
        case IEEE80211_T_TURBO:
                t_slot = 9;
                t_sifs = 8;
                t_difs = 28;
                break;
        case IEEE80211_T_HT:
                t_slot = 9;
                t_sifs = 8;
                t_difs = 28;
                break;
        case IEEE80211_T_DS:
                /* fall through to default */
        default:
                /* pg 205 ieee.802.11.pdf */
                t_slot = 20;
                t_difs = 50;
                t_sifs = 10;
        }

        rts = cts = 0;

        if ((ic->ic_flags & IEEE80211_F_USEPROT) &&
            rt->info[rix].phy == IEEE80211_T_OFDM) {
                if (ic->ic_protmode == IEEE80211_PROT_RTSCTS)
                        rts = 1;
                else if (ic->ic_protmode == IEEE80211_PROT_CTSONLY)
                        cts = 1;

                cix = rt->info[sc->sc_protrix].controlRate;
        }

        if (0 /*length > ic->ic_rtsthreshold */) {
                rts = 1;
        }

        if (rts || cts) {
                int ctsrate;
                int ctsduration = 0;

                /* NB: this is intentionally not a runtime check */
                KASSERT(cix < rt->rateCount,
                    ("bogus cix %d, max %u, mode %u\n", cix, rt->rateCount,
                     sc->sc_curmode));

                ctsrate = rt->info[cix].rateCode | rt->info[cix].shortPreamble;
                if (rts)                /* SIFS + CTS */
                        ctsduration += rt->info[cix].spAckDuration;

                /* XXX assumes short preamble, include SIFS */
                ctsduration += ath_hal_pkt_txtime(sc->sc_ah, rt, length, rix,
                    is_ht40, 0, 1);

                if (cts)        /* SIFS + ACK */
                        ctsduration += rt->info[cix].spAckDuration;

                tt += (short_retries + 1) * ctsduration;
        }
        tt += t_difs;

        /* XXX assumes short preamble, include SIFS */
        tt += (long_retries+1)*ath_hal_pkt_txtime(sc->sc_ah, rt, length, rix,
            is_ht40, 0, 1);

        tt += (long_retries+1)*(t_sifs + rt->info[rix].spAckDuration);

        for (x = 0; x <= short_retries + long_retries; x++) {
                cw = MIN(WIFI_CW_MAX, (cw + 1) * 2);
                tt += (t_slot * cw/2);
        }
        return tt;
}

#endif  /* _KERNEL */

#endif /* _DEV_ATH_RATE_SAMPLE_H */