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Sourcecode: alsa-driver version File versions

seq_fifo.c

/*
 *   ALSA sequencer FIFO
 *   Copyright (c) 1998 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 <sound/driver.h>
#include <sound/core.h>
#include <linux/slab.h>
#include "seq_fifo.h"
#include "seq_lock.h"


/* FIFO */

/* create new fifo */
fifo_t *snd_seq_fifo_new(int poolsize)
{
      fifo_t *f;

      f = kcalloc(1, sizeof(*f), GFP_KERNEL);
      if (f == NULL) {
            snd_printd("malloc failed for snd_seq_fifo_new() \n");
            return NULL;
      }

      f->pool = snd_seq_pool_new(poolsize);
      if (f->pool == NULL) {
            kfree(f);
            return NULL;
      }
      if (snd_seq_pool_init(f->pool) < 0) {
            snd_seq_pool_delete(&f->pool);
            kfree(f);
            return NULL;
      }

      spin_lock_init(&f->lock);
      snd_use_lock_init(&f->use_lock);
      init_waitqueue_head(&f->input_sleep);
      atomic_set(&f->overflow, 0);

      f->head = NULL;
      f->tail = NULL;
      f->cells = 0;
      
      return f;
}

void snd_seq_fifo_delete(fifo_t **fifo)
{
      fifo_t *f;

      snd_assert(fifo != NULL, return);
      f = *fifo;
      snd_assert(f != NULL, return);
      *fifo = NULL;

      snd_seq_fifo_clear(f);

      /* wake up clients if any */
      if (waitqueue_active(&f->input_sleep))
            wake_up(&f->input_sleep);

      /* release resources...*/
      /*....................*/

      if (f->pool) {
            snd_seq_pool_done(f->pool);
            snd_seq_pool_delete(&f->pool);
      }
      
      kfree(f);
}

static snd_seq_event_cell_t *fifo_cell_out(fifo_t *f);

/* clear queue */
void snd_seq_fifo_clear(fifo_t *f)
{
      snd_seq_event_cell_t *cell;
      unsigned long flags;

      /* clear overflow flag */
      atomic_set(&f->overflow, 0);

      snd_use_lock_sync(&f->use_lock);
      spin_lock_irqsave(&f->lock, flags);
      /* drain the fifo */
      while ((cell = fifo_cell_out(f)) != NULL) {
            snd_seq_cell_free(cell);
      }
      spin_unlock_irqrestore(&f->lock, flags);
}


/* enqueue event to fifo */
int snd_seq_fifo_event_in(fifo_t *f, snd_seq_event_t *event)
{
      snd_seq_event_cell_t *cell;
      unsigned long flags;
      int err;

      snd_assert(f != NULL, return -EINVAL);

      snd_use_lock_use(&f->use_lock);
      err = snd_seq_event_dup(f->pool, event, &cell, 1, NULL); /* always non-blocking */
      if (err < 0) {
            if (err == -ENOMEM)
                  atomic_inc(&f->overflow);
            snd_use_lock_free(&f->use_lock);
            return err;
      }
            
      /* append new cells to fifo */
      spin_lock_irqsave(&f->lock, flags);
      if (f->tail != NULL)
            f->tail->next = cell;
      f->tail = cell;
      if (f->head == NULL)
            f->head = cell;
      f->cells++;
      spin_unlock_irqrestore(&f->lock, flags);

      /* wakeup client */
      if (waitqueue_active(&f->input_sleep))
            wake_up(&f->input_sleep);

      snd_use_lock_free(&f->use_lock);

      return 0; /* success */

}

/* dequeue cell from fifo */
static snd_seq_event_cell_t *fifo_cell_out(fifo_t *f)
{
      snd_seq_event_cell_t *cell;

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

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

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

      return cell;
}

/* dequeue cell from fifo and copy on user space */
int snd_seq_fifo_cell_out(fifo_t *f, snd_seq_event_cell_t **cellp, int nonblock)
{
      snd_seq_event_cell_t *cell;
      unsigned long flags;
      wait_queue_t wait;

      snd_assert(f != NULL, return -EINVAL);

      *cellp = NULL;
      init_waitqueue_entry(&wait, current);
      spin_lock_irqsave(&f->lock, flags);
      while ((cell = fifo_cell_out(f)) == NULL) {
            if (nonblock) {
                  /* non-blocking - return immediately */
                  spin_unlock_irqrestore(&f->lock, flags);
                  return -EAGAIN;
            }
            set_current_state(TASK_INTERRUPTIBLE);
            add_wait_queue(&f->input_sleep, &wait);
            spin_unlock_irq(&f->lock);
            schedule();
            spin_lock_irq(&f->lock);
            remove_wait_queue(&f->input_sleep, &wait);
            if (signal_pending(current)) {
                  spin_unlock_irqrestore(&f->lock, flags);
                  return -ERESTARTSYS;
            }
      }
      spin_unlock_irqrestore(&f->lock, flags);
      *cellp = cell;

      return 0;
}


void snd_seq_fifo_cell_putback(fifo_t *f, snd_seq_event_cell_t *cell)
{
      unsigned long flags;

      if (cell) {
            spin_lock_irqsave(&f->lock, flags);
            cell->next = f->head;
            f->head = cell;
            f->cells++;
            spin_unlock_irqrestore(&f->lock, flags);
      }
}


/* polling; return non-zero if queue is available */
int snd_seq_fifo_poll_wait(fifo_t *f, struct file *file, poll_table *wait)
{
      poll_wait(file, &f->input_sleep, wait);
      return (f->cells > 0);
}

/* change the size of pool; all old events are removed */
int snd_seq_fifo_resize(fifo_t *f, int poolsize)
{
      unsigned long flags;
      pool_t *newpool, *oldpool;
      snd_seq_event_cell_t *cell, *next, *oldhead;

      snd_assert(f != NULL && f->pool != NULL, return -EINVAL);

      /* allocate new pool */
      newpool = snd_seq_pool_new(poolsize);
      if (newpool == NULL)
            return -ENOMEM;
      if (snd_seq_pool_init(newpool) < 0) {
            snd_seq_pool_delete(&newpool);
            return -ENOMEM;
      }

      spin_lock_irqsave(&f->lock, flags);
      /* remember old pool */
      oldpool = f->pool;
      oldhead = f->head;
      /* exchange pools */
      f->pool = newpool;
      f->head = NULL;
      f->tail = NULL;
      f->cells = 0;
      /* NOTE: overflow flag is not cleared */
      spin_unlock_irqrestore(&f->lock, flags);

      /* release cells in old pool */
      for (cell = oldhead; cell; cell = next) {
            next = cell->next;
            snd_seq_cell_free(cell);
      }
      snd_seq_pool_delete(&oldpool);

      return 0;
}

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