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/*
* ALSA sequencer FIFO
* Copyright (c) 1998 by Frank van de Pol <F.K.W.van.de.Pol@inter.nl.net>
*
*
* 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., 675 Mass Ave, Cambridge, MA 02139, USA.
*
*/
#include "driver.h"
#include "seq_fifo.h"
/* FIFO */
/* create new fifo */
fifo_t *snd_seq_fifo_new(void)
{
fifo_t *f;
unsigned long flags;
f = snd_malloc(sizeof(fifo_t));
if (f == NULL) {
snd_printk("malloc failed for snd_seq_fifo_new() \n");
return NULL;
}
/* clear unused variables */
memset(f, 0, sizeof(fifo_t));
snd_spin_prepare(f, lock);
snd_sleep_prepare(f, input);
f->flags = 0;
snd_spin_lock(f, lock, &flags);
f->head = NULL;
f->tail = NULL;
f->cells = 0;
snd_spin_unlock(f, lock, &flags);
return f;
}
void snd_seq_fifo_delete(fifo_t **fifo)
{
fifo_t *f = *fifo;
*fifo = NULL;
if (f == NULL) {
snd_printk("oops: snd_seq_fifo_delete() called with NULL fifo\n");
return;
}
/* release resources...*/
/*....................*/
if (f->cells > 0) {
/* should drain the fifo */
snd_printk("warning: releasing non-empty fifo\n");
}
snd_free(f,sizeof(fifo_t));
}
/* enqueue cell to fifo */
void snd_seq_fifo_cell_in(fifo_t * f, snd_seq_event_cell_t * cell)
{
unsigned long flags;
if (f == NULL) {
snd_printk("oops: snd_seq_fifo_cell_in() called with NULL fifo\n");
return;
}
if (cell == NULL) {
snd_printk("oops: snd_seq_fifo_cell_in() called with NULL cell\n");
return;
}
snd_spin_lock(f, lock, &flags);
/* add new cell to tail of the fifo */
if (f->tail != NULL)
f->tail->ptr_l = cell;
f->tail = cell;
cell->ptr_l = NULL;
/* register if this is the first element */
if (f->head == NULL)
f->head = cell;
f->cells++;
snd_spin_unlock(f, lock, &flags);
/* wakeup clients */
if (f->flags & SND_WK_SLEEP)
snd_wakeup(f, input);
}
/* dequeue cell from fifo */
snd_seq_event_cell_t *snd_seq_fifo_cell_out(fifo_t * f)
{
snd_seq_event_cell_t *cell;
unsigned long flags;
if (f == NULL) {
snd_printk("oops: snd_seq_fifo_cell_out() called with NULL fifo\n");
return NULL;
}
snd_spin_lock(f, lock, &flags);
if (f->head != NULL) {
cell = f->head;
f->head = cell->ptr_l;
/* reset tail if this was the last element */
if (f->tail == cell)
f->tail = NULL;
cell->ptr_l = NULL;
f->cells--;
} else {
/* empty queue */
snd_spin_unlock(f, lock, &flags);
return NULL;
}
snd_spin_unlock(f, lock, &flags);
return cell;
}
/* return number of events available in fifo */
int snd_seq_fifo_avail(fifo_t * f)
{
if (f == NULL) {
snd_printk("oops: snd_seq_fifo_avail() called with NULL fifo\n");
return 0;
}
return f->cells;
}
/* peek at cell at the head of the fifo */
snd_seq_event_cell_t *snd_seq_fifo_cell_peek(fifo_t * f)
{
if (f == NULL) {
snd_printk("oops: snd_seq_fifo_avail() called with NULL fifo\n");
return 0;
}
return f->head;
}
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