/*
 * CoDel - The Controlled-Delay Active Queue Management algorithm
 *
 *  Copyright (C) 2013 Ermal Luçi <eri@FreeBSD.org>
 *  Copyright (C) 2011-2012 Kathleen Nichols <nichols@pollere.com>
 *  Copyright (C) 2011-2012 Van Jacobson <van@pollere.net>
 *  Copyright (C) 2012 Michael D. Taht <dave.taht@bufferbloat.net>
 *  Copyright (C) 2012 Eric Dumazet <edumazet@google.com>
 *
 * 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 the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The names of the authors may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * Alternatively, provided that this notice is retained in full, this
 * software may be distributed under the terms of the GNU General
 * Public License ("GPL") version 2, in which case the provisions of the
 * GPL apply INSTEAD OF those given above.
 *
 * 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 MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * 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
 * DAMAGE.
 */

#ifndef _ALTQ_ALTQ_CODEL_H_
#define _ALTQ_ALTQ_CODEL_H_

struct codel_stats {
        u_int32_t       maxpacket;
        struct pktcntr  drop_cnt;
        u_int           marked_packets;
};

struct codel_ifstats {
        u_int                   qlength;
        u_int                   qlimit;
        struct codel_stats      stats;
        struct pktcntr  cl_xmitcnt;     /* transmitted packet counter */
        struct pktcntr  cl_dropcnt;     /* dropped packet counter */
};

/*
 * CBQ_STATS_VERSION is defined in altq.h to work around issues stemming
 * from mixing of public-API and internal bits in each scheduler-specific
 * header.
 */

#ifdef _KERNEL
#include <net/altq/altq_classq.h>

/**
 * struct codel_params - contains codel parameters
 *  <at> target:        target queue size (in time units)
 *  <at> interval:      width of moving time window
 *  <at> ecn:   is Explicit Congestion Notification enabled
 */
struct codel_params {
        u_int64_t       target;
        u_int64_t       interval;
        int             ecn;
};

/**
 * struct codel_vars - contains codel variables
 *  <at> count:         how many drops we've done since the last time we
 *                      entered dropping state
 *  <at> lastcount:     count at entry to dropping state
 *  <at> dropping:      set to true if in dropping state
 *  <at> rec_inv_sqrt:  reciprocal value of sqrt(count) >> 1
 *  <at> first_above_time:      when we went (or will go) continuously above
 *                              target for interval
 *  <at> drop_next:     time to drop next packet, or when we dropped last
 *  <at> ldelay:        sojourn time of last dequeued packet
 */
struct codel_vars {
        u_int32_t       count;
        u_int32_t       lastcount;
        int             dropping;
        u_int16_t       rec_inv_sqrt;
        u_int64_t       first_above_time;
        u_int64_t       drop_next;
        u_int64_t       ldelay;
};
        
struct codel {
        int                     last_pps;
        struct codel_params     params;
        struct codel_vars       vars;
        struct codel_stats      stats;
        struct timeval          last_log;
        u_int32_t               drop_overlimit;
};

/*
 * codel interface state
 */
struct codel_if {
        struct codel_if         *cif_next;      /* interface state list */
        struct ifaltq           *cif_ifq;       /* backpointer to ifaltq */
        u_int                   cif_bandwidth;  /* link bandwidth in bps */

        class_queue_t   *cl_q;          /* class queue structure */
        struct codel    codel;

        /* statistics */
        struct codel_ifstats cl_stats;
};

struct codel    *codel_alloc(int, int, int);
void             codel_destroy(struct codel *);
int              codel_addq(struct codel *, class_queue_t *, struct mbuf *);
struct mbuf     *codel_getq(struct codel *, class_queue_t *);
void             codel_getstats(struct codel *, struct codel_stats *);

#endif /* _KERNEL */

#endif /* _ALTQ_ALTQ_CODEL_H_ */