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Linux/sound/core/seq/seq_fifo.c

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  1 /*
  2  *   ALSA sequencer FIFO
  3  *   Copyright (c) 1998 by Frank van de Pol <fvdpol@coil.demon.nl>
  4  *
  5  *
  6  *   This program is free software; you can redistribute it and/or modify
  7  *   it under the terms of the GNU General Public License as published by
  8  *   the Free Software Foundation; either version 2 of the License, or
  9  *   (at your option) any later version.
 10  *
 11  *   This program is distributed in the hope that it will be useful,
 12  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 13  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 14  *   GNU General Public License for more details.
 15  *
 16  *   You should have received a copy of the GNU General Public License
 17  *   along with this program; if not, write to the Free Software
 18  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 19  *
 20  */
 21 
 22 #include <sound/core.h>
 23 #include <linux/slab.h>
 24 #include "seq_fifo.h"
 25 #include "seq_lock.h"
 26 
 27 
 28 /* FIFO */
 29 
 30 /* create new fifo */
 31 struct snd_seq_fifo *snd_seq_fifo_new(int poolsize)
 32 {
 33         struct snd_seq_fifo *f;
 34 
 35         f = kzalloc(sizeof(*f), GFP_KERNEL);
 36         if (!f)
 37                 return NULL;
 38 
 39         f->pool = snd_seq_pool_new(poolsize);
 40         if (f->pool == NULL) {
 41                 kfree(f);
 42                 return NULL;
 43         }
 44         if (snd_seq_pool_init(f->pool) < 0) {
 45                 snd_seq_pool_delete(&f->pool);
 46                 kfree(f);
 47                 return NULL;
 48         }
 49 
 50         spin_lock_init(&f->lock);
 51         snd_use_lock_init(&f->use_lock);
 52         init_waitqueue_head(&f->input_sleep);
 53         atomic_set(&f->overflow, 0);
 54 
 55         f->head = NULL;
 56         f->tail = NULL;
 57         f->cells = 0;
 58         
 59         return f;
 60 }
 61 
 62 void snd_seq_fifo_delete(struct snd_seq_fifo **fifo)
 63 {
 64         struct snd_seq_fifo *f;
 65 
 66         if (snd_BUG_ON(!fifo))
 67                 return;
 68         f = *fifo;
 69         if (snd_BUG_ON(!f))
 70                 return;
 71         *fifo = NULL;
 72 
 73         if (f->pool)
 74                 snd_seq_pool_mark_closing(f->pool);
 75 
 76         snd_seq_fifo_clear(f);
 77 
 78         /* wake up clients if any */
 79         if (waitqueue_active(&f->input_sleep))
 80                 wake_up(&f->input_sleep);
 81 
 82         /* release resources...*/
 83         /*....................*/
 84 
 85         if (f->pool) {
 86                 snd_seq_pool_done(f->pool);
 87                 snd_seq_pool_delete(&f->pool);
 88         }
 89         
 90         kfree(f);
 91 }
 92 
 93 static struct snd_seq_event_cell *fifo_cell_out(struct snd_seq_fifo *f);
 94 
 95 /* clear queue */
 96 void snd_seq_fifo_clear(struct snd_seq_fifo *f)
 97 {
 98         struct snd_seq_event_cell *cell;
 99         unsigned long flags;
100 
101         /* clear overflow flag */
102         atomic_set(&f->overflow, 0);
103 
104         snd_use_lock_sync(&f->use_lock);
105         spin_lock_irqsave(&f->lock, flags);
106         /* drain the fifo */
107         while ((cell = fifo_cell_out(f)) != NULL) {
108                 snd_seq_cell_free(cell);
109         }
110         spin_unlock_irqrestore(&f->lock, flags);
111 }
112 
113 
114 /* enqueue event to fifo */
115 int snd_seq_fifo_event_in(struct snd_seq_fifo *f,
116                           struct snd_seq_event *event)
117 {
118         struct snd_seq_event_cell *cell;
119         unsigned long flags;
120         int err;
121 
122         if (snd_BUG_ON(!f))
123                 return -EINVAL;
124 
125         snd_use_lock_use(&f->use_lock);
126         err = snd_seq_event_dup(f->pool, event, &cell, 1, NULL); /* always non-blocking */
127         if (err < 0) {
128                 if ((err == -ENOMEM) || (err == -EAGAIN))
129                         atomic_inc(&f->overflow);
130                 snd_use_lock_free(&f->use_lock);
131                 return err;
132         }
133                 
134         /* append new cells to fifo */
135         spin_lock_irqsave(&f->lock, flags);
136         if (f->tail != NULL)
137                 f->tail->next = cell;
138         f->tail = cell;
139         if (f->head == NULL)
140                 f->head = cell;
141         cell->next = NULL;
142         f->cells++;
143         spin_unlock_irqrestore(&f->lock, flags);
144 
145         /* wakeup client */
146         if (waitqueue_active(&f->input_sleep))
147                 wake_up(&f->input_sleep);
148 
149         snd_use_lock_free(&f->use_lock);
150 
151         return 0; /* success */
152 
153 }
154 
155 /* dequeue cell from fifo */
156 static struct snd_seq_event_cell *fifo_cell_out(struct snd_seq_fifo *f)
157 {
158         struct snd_seq_event_cell *cell;
159 
160         if ((cell = f->head) != NULL) {
161                 f->head = cell->next;
162 
163                 /* reset tail if this was the last element */
164                 if (f->tail == cell)
165                         f->tail = NULL;
166 
167                 cell->next = NULL;
168                 f->cells--;
169         }
170 
171         return cell;
172 }
173 
174 /* dequeue cell from fifo and copy on user space */
175 int snd_seq_fifo_cell_out(struct snd_seq_fifo *f,
176                           struct snd_seq_event_cell **cellp, int nonblock)
177 {
178         struct snd_seq_event_cell *cell;
179         unsigned long flags;
180         wait_queue_t wait;
181 
182         if (snd_BUG_ON(!f))
183                 return -EINVAL;
184 
185         *cellp = NULL;
186         init_waitqueue_entry(&wait, current);
187         spin_lock_irqsave(&f->lock, flags);
188         while ((cell = fifo_cell_out(f)) == NULL) {
189                 if (nonblock) {
190                         /* non-blocking - return immediately */
191                         spin_unlock_irqrestore(&f->lock, flags);
192                         return -EAGAIN;
193                 }
194                 set_current_state(TASK_INTERRUPTIBLE);
195                 add_wait_queue(&f->input_sleep, &wait);
196                 spin_unlock_irq(&f->lock);
197                 schedule();
198                 spin_lock_irq(&f->lock);
199                 remove_wait_queue(&f->input_sleep, &wait);
200                 if (signal_pending(current)) {
201                         spin_unlock_irqrestore(&f->lock, flags);
202                         return -ERESTARTSYS;
203                 }
204         }
205         spin_unlock_irqrestore(&f->lock, flags);
206         *cellp = cell;
207 
208         return 0;
209 }
210 
211 
212 void snd_seq_fifo_cell_putback(struct snd_seq_fifo *f,
213                                struct snd_seq_event_cell *cell)
214 {
215         unsigned long flags;
216 
217         if (cell) {
218                 spin_lock_irqsave(&f->lock, flags);
219                 cell->next = f->head;
220                 f->head = cell;
221                 if (!f->tail)
222                         f->tail = cell;
223                 f->cells++;
224                 spin_unlock_irqrestore(&f->lock, flags);
225         }
226 }
227 
228 
229 /* polling; return non-zero if queue is available */
230 int snd_seq_fifo_poll_wait(struct snd_seq_fifo *f, struct file *file,
231                            poll_table *wait)
232 {
233         poll_wait(file, &f->input_sleep, wait);
234         return (f->cells > 0);
235 }
236 
237 /* change the size of pool; all old events are removed */
238 int snd_seq_fifo_resize(struct snd_seq_fifo *f, int poolsize)
239 {
240         unsigned long flags;
241         struct snd_seq_pool *newpool, *oldpool;
242         struct snd_seq_event_cell *cell, *next, *oldhead;
243 
244         if (snd_BUG_ON(!f || !f->pool))
245                 return -EINVAL;
246 
247         /* allocate new pool */
248         newpool = snd_seq_pool_new(poolsize);
249         if (newpool == NULL)
250                 return -ENOMEM;
251         if (snd_seq_pool_init(newpool) < 0) {
252                 snd_seq_pool_delete(&newpool);
253                 return -ENOMEM;
254         }
255 
256         spin_lock_irqsave(&f->lock, flags);
257         /* remember old pool */
258         oldpool = f->pool;
259         oldhead = f->head;
260         /* exchange pools */
261         f->pool = newpool;
262         f->head = NULL;
263         f->tail = NULL;
264         f->cells = 0;
265         /* NOTE: overflow flag is not cleared */
266         spin_unlock_irqrestore(&f->lock, flags);
267 
268         /* close the old pool and wait until all users are gone */
269         snd_seq_pool_mark_closing(oldpool);
270         snd_use_lock_sync(&f->use_lock);
271 
272         /* release cells in old pool */
273         for (cell = oldhead; cell; cell = next) {
274                 next = cell->next;
275                 snd_seq_cell_free(cell);
276         }
277         snd_seq_pool_delete(&oldpool);
278 
279         return 0;
280 }
281 

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