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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         snd_seq_fifo_clear(f);
 74 
 75         /* wake up clients if any */
 76         if (waitqueue_active(&f->input_sleep))
 77                 wake_up(&f->input_sleep);
 78 
 79         /* release resources...*/
 80         /*....................*/
 81 
 82         if (f->pool) {
 83                 snd_seq_pool_done(f->pool);
 84                 snd_seq_pool_delete(&f->pool);
 85         }
 86         
 87         kfree(f);
 88 }
 89 
 90 static struct snd_seq_event_cell *fifo_cell_out(struct snd_seq_fifo *f);
 91 
 92 /* clear queue */
 93 void snd_seq_fifo_clear(struct snd_seq_fifo *f)
 94 {
 95         struct snd_seq_event_cell *cell;
 96         unsigned long flags;
 97 
 98         /* clear overflow flag */
 99         atomic_set(&f->overflow, 0);
100 
101         snd_use_lock_sync(&f->use_lock);
102         spin_lock_irqsave(&f->lock, flags);
103         /* drain the fifo */
104         while ((cell = fifo_cell_out(f)) != NULL) {
105                 snd_seq_cell_free(cell);
106         }
107         spin_unlock_irqrestore(&f->lock, flags);
108 }
109 
110 
111 /* enqueue event to fifo */
112 int snd_seq_fifo_event_in(struct snd_seq_fifo *f,
113                           struct snd_seq_event *event)
114 {
115         struct snd_seq_event_cell *cell;
116         unsigned long flags;
117         int err;
118 
119         if (snd_BUG_ON(!f))
120                 return -EINVAL;
121 
122         snd_use_lock_use(&f->use_lock);
123         err = snd_seq_event_dup(f->pool, event, &cell, 1, NULL); /* always non-blocking */
124         if (err < 0) {
125                 if ((err == -ENOMEM) || (err == -EAGAIN))
126                         atomic_inc(&f->overflow);
127                 snd_use_lock_free(&f->use_lock);
128                 return err;
129         }
130                 
131         /* append new cells to fifo */
132         spin_lock_irqsave(&f->lock, flags);
133         if (f->tail != NULL)
134                 f->tail->next = cell;
135         f->tail = cell;
136         if (f->head == NULL)
137                 f->head = cell;
138         f->cells++;
139         spin_unlock_irqrestore(&f->lock, flags);
140 
141         /* wakeup client */
142         if (waitqueue_active(&f->input_sleep))
143                 wake_up(&f->input_sleep);
144 
145         snd_use_lock_free(&f->use_lock);
146 
147         return 0; /* success */
148 
149 }
150 
151 /* dequeue cell from fifo */
152 static struct snd_seq_event_cell *fifo_cell_out(struct snd_seq_fifo *f)
153 {
154         struct snd_seq_event_cell *cell;
155 
156         if ((cell = f->head) != NULL) {
157                 f->head = cell->next;
158 
159                 /* reset tail if this was the last element */
160                 if (f->tail == cell)
161                         f->tail = NULL;
162 
163                 cell->next = NULL;
164                 f->cells--;
165         }
166 
167         return cell;
168 }
169 
170 /* dequeue cell from fifo and copy on user space */
171 int snd_seq_fifo_cell_out(struct snd_seq_fifo *f,
172                           struct snd_seq_event_cell **cellp, int nonblock)
173 {
174         struct snd_seq_event_cell *cell;
175         unsigned long flags;
176         wait_queue_t wait;
177 
178         if (snd_BUG_ON(!f))
179                 return -EINVAL;
180 
181         *cellp = NULL;
182         init_waitqueue_entry(&wait, current);
183         spin_lock_irqsave(&f->lock, flags);
184         while ((cell = fifo_cell_out(f)) == NULL) {
185                 if (nonblock) {
186                         /* non-blocking - return immediately */
187                         spin_unlock_irqrestore(&f->lock, flags);
188                         return -EAGAIN;
189                 }
190                 set_current_state(TASK_INTERRUPTIBLE);
191                 add_wait_queue(&f->input_sleep, &wait);
192                 spin_unlock_irq(&f->lock);
193                 schedule();
194                 spin_lock_irq(&f->lock);
195                 remove_wait_queue(&f->input_sleep, &wait);
196                 if (signal_pending(current)) {
197                         spin_unlock_irqrestore(&f->lock, flags);
198                         return -ERESTARTSYS;
199                 }
200         }
201         spin_unlock_irqrestore(&f->lock, flags);
202         *cellp = cell;
203 
204         return 0;
205 }
206 
207 
208 void snd_seq_fifo_cell_putback(struct snd_seq_fifo *f,
209                                struct snd_seq_event_cell *cell)
210 {
211         unsigned long flags;
212 
213         if (cell) {
214                 spin_lock_irqsave(&f->lock, flags);
215                 cell->next = f->head;
216                 f->head = cell;
217                 f->cells++;
218                 spin_unlock_irqrestore(&f->lock, flags);
219         }
220 }
221 
222 
223 /* polling; return non-zero if queue is available */
224 int snd_seq_fifo_poll_wait(struct snd_seq_fifo *f, struct file *file,
225                            poll_table *wait)
226 {
227         poll_wait(file, &f->input_sleep, wait);
228         return (f->cells > 0);
229 }
230 
231 /* change the size of pool; all old events are removed */
232 int snd_seq_fifo_resize(struct snd_seq_fifo *f, int poolsize)
233 {
234         unsigned long flags;
235         struct snd_seq_pool *newpool, *oldpool;
236         struct snd_seq_event_cell *cell, *next, *oldhead;
237 
238         if (snd_BUG_ON(!f || !f->pool))
239                 return -EINVAL;
240 
241         /* allocate new pool */
242         newpool = snd_seq_pool_new(poolsize);
243         if (newpool == NULL)
244                 return -ENOMEM;
245         if (snd_seq_pool_init(newpool) < 0) {
246                 snd_seq_pool_delete(&newpool);
247                 return -ENOMEM;
248         }
249 
250         spin_lock_irqsave(&f->lock, flags);
251         /* remember old pool */
252         oldpool = f->pool;
253         oldhead = f->head;
254         /* exchange pools */
255         f->pool = newpool;
256         f->head = NULL;
257         f->tail = NULL;
258         f->cells = 0;
259         /* NOTE: overflow flag is not cleared */
260         spin_unlock_irqrestore(&f->lock, flags);
261 
262         /* release cells in old pool */
263         for (cell = oldhead; cell; cell = next) {
264                 next = cell->next;
265                 snd_seq_cell_free(cell);
266         }
267         snd_seq_pool_delete(&oldpool);
268 
269         return 0;
270 }
271 

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