include/nucleus/schedqueue.h

/*
 * Copyright (C) 2008 Philippe Gerum <rpm@xenomai.org>.
 *
 * Xenomai is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2 of the License,
 * or (at your option) any later version.
 *
 * Xenomai is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Xenomai; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.
 */

#ifndef _XENO_NUCLEUS_SCHEDQUEUE_H
#define _XENO_NUCLEUS_SCHEDQUEUE_H

#include <nucleus/queue.h>

#ifdef CONFIG_XENO_OPT_SCALABLE_SCHED
/*
 * Multi-level priority queue, suitable for handling the runnable
 * thread queue of a scheduling class with O(1) property. We only
 * manage a descending queuing order, i.e. highest numbered priorities
 * come first.
 */
#define XNSCHED_MLQ_LEVELS  264

#if BITS_PER_LONG * BITS_PER_LONG < XNSCHED_MLQ_LEVELS
#error "Internal bitmap cannot hold so many priority levels"
#endif

#define __MLQ_LONGS ((XNSCHED_MLQ_LEVELS+BITS_PER_LONG-1)/BITS_PER_LONG)

struct xnsched_mlq {

        int loprio, hiprio, elems;
        unsigned long himap, lomap[__MLQ_LONGS];
        struct xnqueue queue[XNSCHED_MLQ_LEVELS];

};

#undef __MLQ_LONGS

void initmlq(struct xnsched_mlq *q, int loprio, int hiprio);

void addmlq(struct xnsched_mlq *q,
            struct xnpholder *holder, int idx, int lifo);

void removemlq(struct xnsched_mlq *q, struct xnpholder *holder);

struct xnpholder *findmlqh(struct xnsched_mlq *q, int prio);

struct xnpholder *getheadmlq(struct xnsched_mlq *q);

struct xnpholder *getmlq(struct xnsched_mlq *q);

struct xnpholder *nextmlq(struct xnsched_mlq *q,
                          struct xnpholder *h);

static inline int countmlq(struct xnsched_mlq *q)
{
        return q->elems;
}

static inline int emptymlq_p(struct xnsched_mlq *q)
{
        return q->himap == 0;
}

static inline int indexmlq(struct xnsched_mlq *q, int prio)
{
        XENO_ASSERT(QUEUES, 
                    prio >= q->loprio && prio <= q->hiprio,
                    xnpod_fatal("priority level %d is out of range ", prio));
        /*
         * BIG FAT WARNING: We need to rescale the priority level to a
         * 0-based range. We use ffnz() to scan the bitmap which MUST
         * be based on a bit scan forward op. Therefore, the lower the
         * index value, the higher the priority (since least
         * significant bits will be found first when scanning the
         * bitmaps).
         */
        return q->hiprio - prio;
}

static inline int ffsmlq(struct xnsched_mlq *q)
{
        int hi = ffnz(q->himap);
        int lo = ffnz(q->lomap[hi]);
        return hi * BITS_PER_LONG + lo; /* Result is undefined if none set. */
}

static inline void insertmlql(struct xnsched_mlq *q,
                              struct xnpholder *holder, int prio)
{
        addmlq(q, holder, indexmlq(q, prio), 1);
}

static inline void insertmlqf(struct xnsched_mlq *q,
                              struct xnpholder *holder, int prio)
{
        addmlq(q, holder, indexmlq(q, prio), 0);
}

static inline void appendmlq(struct xnsched_mlq *q, struct xnpholder *holder)
{
        addmlq(q, holder, indexmlq(q, q->hiprio), 0);
}

static inline void prependmlq(struct xnsched_mlq *q, struct xnpholder *holder)
{
        addmlq(q, holder, indexmlq(q, q->loprio), 1);
}

typedef struct xnsched_mlq xnsched_queue_t;

#define sched_initpq            initmlq
#define sched_emptypq_p         emptymlq_p
#define sched_insertpql         insertmlql
#define sched_insertpqf         insertmlqf
#define sched_appendpq          appendmlq
#define sched_prependpq         prependmlq
#define sched_removepq          removemlq
#define sched_getheadpq         getheadmlq
#define sched_nextpq            nextmlq
#define sched_getpq             getmlq
#define sched_findpqh           findmlqh

#else /* ! CONFIG_XENO_OPT_SCALABLE_SCHED */

typedef xnpqueue_t xnsched_queue_t;

#define sched_initpq(q, minp, maxp)     initpq(q)
#define sched_emptypq_p                 emptypq_p
#define sched_insertpql                 insertpql
#define sched_insertpqf                 insertpqf
#define sched_appendpq                  appendpq
#define sched_prependpq                 prependpq
#define sched_removepq                  removepq
#define sched_getheadpq                 getheadpq
#define sched_nextpq                    nextpq
#define sched_getpq                     getpq
#define sched_findpqh                   findpqh

#endif /* !CONFIG_XENO_OPT_SCALABLE_SCHED */

#endif /* !_XENO_NUCLEUS_SCHEDQUEUE_H */

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