seq_prioq.c

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/*
 *   ALSA sequencer Priority Queue
 *   Copyright (c) 1998-1999 by Frank van de Pol <[email protected]>
 *
 *
 *   This program 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.
 *
 *   This program 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 this program; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 *
 */

#include <linux/time.h>
#include <linux/slab.h>
#include <sound/core.h>
#include "seq_timer.h"
#include "seq_prioq.h"


/* Implementation is a simple linked list for now...

   This priority queue orders the events on timestamp. For events with an
   equeal timestamp the queue behaves as a FIFO. 

   *
   *           +-------+
   *  Head --> | first |
   *           +-------+
   *                 |next
   *           +-----v-+
   *           |       |
   *           +-------+
   *                 |
   *           +-----v-+
   *           |       |
   *           +-------+
   *                 |
   *           +-----v-+
   *  Tail --> | last  |
   *           +-------+
   *

 */



/* create new prioq (constructor) */
struct snd_seq_prioq *snd_seq_prioq_new(void)
{
    struct snd_seq_prioq *f;

    f = kzalloc(sizeof(*f), GFP_KERNEL);
    if (f == NULL) {
        snd_printd("oops: malloc failed for snd_seq_prioq_new()\n");
        return NULL;
    }
    
    spin_lock_init(&f->lock);
    f->head = NULL;
    f->tail = NULL;
    f->cells = 0;
    
    return f;
}

/* delete prioq (destructor) */
void snd_seq_prioq_delete(struct snd_seq_prioq **fifo)
{
    struct snd_seq_prioq *f = *fifo;
    *fifo = NULL;

    if (f == NULL) {
        snd_printd("oops: snd_seq_prioq_delete() called with NULL prioq\n");
        return;
    }

    /* release resources...*/
    /*....................*/
    
    if (f->cells > 0) {
        /* drain prioQ */
        while (f->cells > 0)
            snd_seq_cell_free(snd_seq_prioq_cell_out(f));
    }
    
    kfree(f);
}




/* compare timestamp between events */
/* return 1 if a >= b; 0 */
static inline int compare_timestamp(struct snd_seq_event *a,
                    struct snd_seq_event *b)
{
    if ((a->flags & SNDRV_SEQ_TIME_STAMP_MASK) == SNDRV_SEQ_TIME_STAMP_TICK) {
        /* compare ticks */
        return (snd_seq_compare_tick_time(&a->time.tick, &b->time.tick));
    } else {
        /* compare real time */
        return (snd_seq_compare_real_time(&a->time.time, &b->time.time));
    }
}

/* compare timestamp between events */
/* return negative if a < b;
 *        zero     if a = b;
 *        positive if a > b;
 */
static inline int compare_timestamp_rel(struct snd_seq_event *a,
                    struct snd_seq_event *b)
{
    if ((a->flags & SNDRV_SEQ_TIME_STAMP_MASK) == SNDRV_SEQ_TIME_STAMP_TICK) {
        /* compare ticks */
        if (a->time.tick > b->time.tick)
            return 1;
        else if (a->time.tick == b->time.tick)
            return 0;
        else
            return -1;
    } else {
        /* compare real time */
        if (a->time.time.tv_sec > b->time.time.tv_sec)
            return 1;
        else if (a->time.time.tv_sec == b->time.time.tv_sec) {
            if (a->time.time.tv_nsec > b->time.time.tv_nsec)
                return 1;
            else if (a->time.time.tv_nsec == b->time.time.tv_nsec)
                return 0;
            else
                return -1;
        } else
            return -1;
    }
}

/* enqueue cell to prioq */
int snd_seq_prioq_cell_in(struct snd_seq_prioq * f,
              struct snd_seq_event_cell * cell)
{
    struct snd_seq_event_cell *cur, *prev;
    unsigned long flags;
    int count;
    int prior;

    if (snd_BUG_ON(!f || !cell))
        return -EINVAL;
    
    /* check flags */
    prior = (cell->event.flags & SNDRV_SEQ_PRIORITY_MASK);

    spin_lock_irqsave(&f->lock, flags);

    /* check if this element needs to inserted at the end (ie. ordered 
       data is inserted) This will be very likeley if a sequencer 
       application or midi file player is feeding us (sequential) data */
    if (f->tail && !prior) {
        if (compare_timestamp(&cell->event, &f->tail->event)) {
            /* add new cell to tail of the fifo */
            f->tail->next = cell;
            f->tail = cell;
            cell->next = NULL;
            f->cells++;
            spin_unlock_irqrestore(&f->lock, flags);
            return 0;
        }
    }
    /* traverse list of elements to find the place where the new cell is
       to be inserted... Note that this is a order n process ! */

    prev = NULL;        /* previous cell */
    cur = f->head;      /* cursor */

    count = 10000; /* FIXME: enough big, isn't it? */
    while (cur != NULL) {
        /* compare timestamps */
        int rel = compare_timestamp_rel(&cell->event, &cur->event);
        if (rel < 0)
            /* new cell has earlier schedule time, */
            break;
        else if (rel == 0 && prior)
            /* equal schedule time and prior to others */
            break;
        /* new cell has equal or larger schedule time, */
        /* move cursor to next cell */
        prev = cur;
        cur = cur->next;
        if (! --count) {
            spin_unlock_irqrestore(&f->lock, flags);
            snd_printk(KERN_ERR "cannot find a pointer.. infinite loop?\n");
            return -EINVAL;
        }
    }

    /* insert it before cursor */
    if (prev != NULL)
        prev->next = cell;
    cell->next = cur;

    if (f->head == cur) /* this is the first cell, set head to it */
        f->head = cell;
    if (cur == NULL) /* reached end of the list */
        f->tail = cell;
    f->cells++;
    spin_unlock_irqrestore(&f->lock, flags);
    return 0;
}

/* dequeue cell from prioq */
struct snd_seq_event_cell *snd_seq_prioq_cell_out(struct snd_seq_prioq *f)
{
    struct snd_seq_event_cell *cell;
    unsigned long flags;

    if (f == NULL) {
        snd_printd("oops: snd_seq_prioq_cell_in() called with NULL prioq\n");
        return NULL;
    }
    spin_lock_irqsave(&f->lock, flags);

    cell = f->head;
    if (cell) {
        f->head = cell->next;

        /* reset tail if this was the last element */
        if (f->tail == cell)
            f->tail = NULL;

        cell->next = NULL;
        f->cells--;
    }

    spin_unlock_irqrestore(&f->lock, flags);
    return cell;
}

/* return number of events available in prioq */
int snd_seq_prioq_avail(struct snd_seq_prioq * f)
{
    if (f == NULL) {
        snd_printd("oops: snd_seq_prioq_cell_in() called with NULL prioq\n");
        return 0;
    }
    return f->cells;
}


/* peek at cell at the head of the prioq */
struct snd_seq_event_cell *snd_seq_prioq_cell_peek(struct snd_seq_prioq * f)
{
    if (f == NULL) {
        snd_printd("oops: snd_seq_prioq_cell_in() called with NULL prioq\n");
        return NULL;
    }
    return f->head;
}


static inline int prioq_match(struct snd_seq_event_cell *cell,
                  int client, int timestamp)
{
    if (cell->event.source.client == client ||
        cell->event.dest.client == client)
        return 1;
    if (!timestamp)
        return 0;
    switch (cell->event.flags & SNDRV_SEQ_TIME_STAMP_MASK) {
    case SNDRV_SEQ_TIME_STAMP_TICK:
        if (cell->event.time.tick)
            return 1;
        break;
    case SNDRV_SEQ_TIME_STAMP_REAL:
        if (cell->event.time.time.tv_sec ||
            cell->event.time.time.tv_nsec)
            return 1;
        break;
    }
    return 0;
}

/* remove cells for left client */
void snd_seq_prioq_leave(struct snd_seq_prioq * f, int client, int timestamp)
{
    register struct snd_seq_event_cell *cell, *next;
    unsigned long flags;
    struct snd_seq_event_cell *prev = NULL;
    struct snd_seq_event_cell *freefirst = NULL, *freeprev = NULL, *freenext;

    /* collect all removed cells */
    spin_lock_irqsave(&f->lock, flags);
    cell = f->head;
    while (cell) {
        next = cell->next;
        if (prioq_match(cell, client, timestamp)) {
            /* remove cell from prioq */
            if (cell == f->head) {
                f->head = cell->next;
            } else {
                prev->next = cell->next;
            }
            if (cell == f->tail)
                f->tail = cell->next;
            f->cells--;
            /* add cell to free list */
            cell->next = NULL;
            if (freefirst == NULL) {
                freefirst = cell;
            } else {
                freeprev->next = cell;
            }
            freeprev = cell;
        } else {
#if 0
            printk(KERN_DEBUG "type = %i, source = %i, dest = %i, "
                   "client = %i\n",
                cell->event.type,
                cell->event.source.client,
                cell->event.dest.client,
                client);
#endif
            prev = cell;
        }
        cell = next;        
    }
    spin_unlock_irqrestore(&f->lock, flags);    

    /* remove selected cells */
    while (freefirst) {
        freenext = freefirst->next;
        snd_seq_cell_free(freefirst);
        freefirst = freenext;
    }
}

static int prioq_remove_match(struct snd_seq_remove_events *info,
                  struct snd_seq_event *ev)
{
    int res;

    if (info->remove_mode & SNDRV_SEQ_REMOVE_DEST) {
        if (ev->dest.client != info->dest.client ||
                ev->dest.port != info->dest.port)
            return 0;
    }
    if (info->remove_mode & SNDRV_SEQ_REMOVE_DEST_CHANNEL) {
        if (! snd_seq_ev_is_channel_type(ev))
            return 0;
        /* data.note.channel and data.control.channel are identical */
        if (ev->data.note.channel != info->channel)
            return 0;
    }
    if (info->remove_mode & SNDRV_SEQ_REMOVE_TIME_AFTER) {
        if (info->remove_mode & SNDRV_SEQ_REMOVE_TIME_TICK)
            res = snd_seq_compare_tick_time(&ev->time.tick, &info->time.tick);
        else
            res = snd_seq_compare_real_time(&ev->time.time, &info->time.time);
        if (!res)
            return 0;
    }
    if (info->remove_mode & SNDRV_SEQ_REMOVE_TIME_BEFORE) {
        if (info->remove_mode & SNDRV_SEQ_REMOVE_TIME_TICK)
            res = snd_seq_compare_tick_time(&ev->time.tick, &info->time.tick);
        else
            res = snd_seq_compare_real_time(&ev->time.time, &info->time.time);
        if (res)
            return 0;
    }
    if (info->remove_mode & SNDRV_SEQ_REMOVE_EVENT_TYPE) {
        if (ev->type != info->type)
            return 0;
    }
    if (info->remove_mode & SNDRV_SEQ_REMOVE_IGNORE_OFF) {
        /* Do not remove off events */
        switch (ev->type) {
        case SNDRV_SEQ_EVENT_NOTEOFF:
        /* case SNDRV_SEQ_EVENT_SAMPLE_STOP: */
            return 0;
        default:
            break;
        }
    }
    if (info->remove_mode & SNDRV_SEQ_REMOVE_TAG_MATCH) {
        if (info->tag != ev->tag)
            return 0;
    }

    return 1;
}

/* remove cells matching remove criteria */
void snd_seq_prioq_remove_events(struct snd_seq_prioq * f, int client,
                 struct snd_seq_remove_events *info)
{
    struct snd_seq_event_cell *cell, *next;
    unsigned long flags;
    struct snd_seq_event_cell *prev = NULL;
    struct snd_seq_event_cell *freefirst = NULL, *freeprev = NULL, *freenext;

    /* collect all removed cells */
    spin_lock_irqsave(&f->lock, flags);
    cell = f->head;

    while (cell) {
        next = cell->next;
        if (cell->event.source.client == client &&
            prioq_remove_match(info, &cell->event)) {

            /* remove cell from prioq */
            if (cell == f->head) {
                f->head = cell->next;
            } else {
                prev->next = cell->next;
            }

            if (cell == f->tail)
                f->tail = cell->next;
            f->cells--;

            /* add cell to free list */
            cell->next = NULL;
            if (freefirst == NULL) {
                freefirst = cell;
            } else {
                freeprev->next = cell;
            }

            freeprev = cell;
        } else {
            prev = cell;
        }
        cell = next;        
    }
    spin_unlock_irqrestore(&f->lock, flags);    

    /* remove selected cells */
    while (freefirst) {
        freenext = freefirst->next;
        snd_seq_cell_free(freefirst);
        freefirst = freenext;
    }
}