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seq_prioq.c

/*
 *   ALSA sequencer Priority Queue
 *   Copyright (c) 1998-1999 by Frank van de Pol <fvdpol@coil.demon.nl>
 *
 *
 *   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;
      }
}



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