/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2010 Riccardo Panicucci, Universita` di Pisa
 * 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.
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 */

/*
 */
#ifdef _KERNEL
#include <sys/malloc.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mbuf.h>
#include <sys/module.h>
#include <sys/rwlock.h>
#include <net/if.h>     /* IFNAMSIZ */
#include <netinet/in.h>
#include <netinet/ip_var.h>             /* ipfw_rule_ref */
#include <netinet/ip_fw.h>      /* flow_id */
#include <netinet/ip_dummynet.h>
#include <netpfil/ipfw/ip_fw_private.h>
#include <netpfil/ipfw/dn_heap.h>
#include <netpfil/ipfw/ip_dn_private.h>
#ifdef NEW_AQM
#include <netpfil/ipfw/dn_aqm.h>
#endif
#include <netpfil/ipfw/dn_sched.h>
#else
#include <dn_test.h>
#endif

#define DN_SCHED_PRIO   5 //XXX

#if !defined(_KERNEL) || !defined(__linux__)
#define test_bit(ix, pData)     ((*pData) & (1<<(ix)))
#define __set_bit(ix, pData)    (*pData) |= (1<<(ix))
#define __clear_bit(ix, pData)  (*pData) &= ~(1<<(ix))
#endif

#ifdef __MIPSEL__
#define __clear_bit(ix, pData)  (*pData) &= ~(1<<(ix))
#endif

/* Size of the array of queues pointers. */
#define BITMAP_T        unsigned long
#define MAXPRIO         (sizeof(BITMAP_T) * 8)

/*
 * The scheduler instance contains an array of pointers to queues,
 * one for each priority, and a bitmap listing backlogged queues.
 */
struct prio_si {
        BITMAP_T bitmap;                        /* array bitmap */
        struct dn_queue *q_array[MAXPRIO];      /* Array of queues pointers */
};

/*
 * If a queue with the same priority is already backlogged, use
 * that one instead of the queue passed as argument.
 */
static int 
prio_enqueue(struct dn_sch_inst *_si, struct dn_queue *q, struct mbuf *m)
{
        struct prio_si *si = (struct prio_si *)(_si + 1);
        int prio = q->fs->fs.par[0];

        if (test_bit(prio, &si->bitmap) == 0) {
                /* No queue with this priority, insert */
                __set_bit(prio, &si->bitmap);
                si->q_array[prio] = q;
        } else { /* use the existing queue */
                q = si->q_array[prio];
        }
        if (dn_enqueue(q, m, 0))
                return 1;
        return 0;
}

/*
 * Packets are dequeued only from the highest priority queue.
 * The function ffs() return the lowest bit in the bitmap that rapresent
 * the array index (-1) which contains the pointer to the highest priority
 * queue.
 * After the dequeue, if this queue become empty, it is index is removed
 * from the bitmap.
 * Scheduler is idle if the bitmap is empty
 *
 * NOTE: highest priority is 0, lowest is sched->max_prio_q
 */
static struct mbuf *
prio_dequeue(struct dn_sch_inst *_si)
{
        struct prio_si *si = (struct prio_si *)(_si + 1);
        struct mbuf *m;
        struct dn_queue *q;
        int prio;

        if (si->bitmap == 0) /* scheduler idle */
                return NULL;

        prio = ffs(si->bitmap) - 1;

        /* Take the highest priority queue in the scheduler */
        q = si->q_array[prio];
        // assert(q)

        m = dn_dequeue(q);
        if (q->mq.head == NULL) {
                /* Queue is now empty, remove from scheduler
                 * and mark it
                 */
                si->q_array[prio] = NULL;
                __clear_bit(prio, &si->bitmap);
        }
        return m;
}

static int
prio_new_sched(struct dn_sch_inst *_si)
{
        struct prio_si *si = (struct prio_si *)(_si + 1);

        bzero(si->q_array, sizeof(si->q_array));
        si->bitmap = 0;

        return 0;
}

static int
prio_new_fsk(struct dn_fsk *fs)
{
        /* Check if the prioritiy is between 0 and MAXPRIO-1 */
        ipdn_bound_var(&fs->fs.par[0], 0, 0, MAXPRIO - 1, "PRIO priority");
        return 0;
}

static int
prio_new_queue(struct dn_queue *q)
{
        struct prio_si *si = (struct prio_si *)(q->_si + 1);
        int prio = q->fs->fs.par[0];
        struct dn_queue *oldq;

        q->ni.oid.subtype = DN_SCHED_PRIO;

        if (q->mq.head == NULL)
                return 0;

        /* Queue already full, must insert in the scheduler or append
         * mbufs to existing queue. This partly duplicates prio_enqueue
         */
        if (test_bit(prio, &si->bitmap) == 0) {
                /* No queue with this priority, insert */
                __set_bit(prio, &si->bitmap);
                si->q_array[prio] = q;
        } else if ( (oldq = si->q_array[prio]) != q) {
                /* must append to the existing queue.
                 * can simply append q->mq.head to q2->...
                 * and add the counters to those of q2
                 */
                oldq->mq.tail->m_nextpkt = q->mq.head;
                oldq->mq.tail = q->mq.tail;
                oldq->ni.length += q->ni.length;
                q->ni.length = 0;
                oldq->ni.len_bytes += q->ni.len_bytes;
                q->ni.len_bytes = 0;
                q->mq.tail = q->mq.head = NULL;
        }
        return 0;
}

static int
prio_free_queue(struct dn_queue *q)
{
        int prio = q->fs->fs.par[0];
        struct prio_si *si = (struct prio_si *)(q->_si + 1);

        if (si->q_array[prio] == q) {
                si->q_array[prio] = NULL;
                __clear_bit(prio, &si->bitmap);
        }
        return 0;
}

static struct dn_alg prio_desc = {
        _SI( .type = ) DN_SCHED_PRIO,
        _SI( .name = ) "PRIO",
        _SI( .flags = ) DN_MULTIQUEUE,

        /* we need extra space in the si and the queue */
        _SI( .schk_datalen = ) 0,
        _SI( .si_datalen = ) sizeof(struct prio_si),
        _SI( .q_datalen = ) 0,

        _SI( .enqueue = ) prio_enqueue,
        _SI( .dequeue = ) prio_dequeue,

        _SI( .config = )  NULL,
        _SI( .destroy = )  NULL,
        _SI( .new_sched = ) prio_new_sched,
        _SI( .free_sched = ) NULL,

        _SI( .new_fsk = ) prio_new_fsk,
        _SI( .free_fsk = )  NULL,

        _SI( .new_queue = ) prio_new_queue,
        _SI( .free_queue = ) prio_free_queue,
#ifdef NEW_AQM
        _SI( .getconfig = )  NULL,
#endif
};

DECLARE_DNSCHED_MODULE(dn_prio, &prio_desc);