aboutsummaryrefslogtreecommitdiffstats
path: root/sound/core/seq/seq_fifo.c
blob: 53a403e17c5bba08a755da454dfee3d5829c2cc9 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
/*
 *   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/core.h>
#include <linux/slab.h>
#include "seq_fifo.h"
#include "seq_lock.h"


/* FIFO */

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

	f = kzalloc(sizeof(*f), GFP_KERNEL);
	if (f == NULL) {
		pr_debug("ALSA: seq: 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(struct snd_seq_fifo **fifo)
{
	struct snd_seq_fifo *f;

	if (snd_BUG_ON(!fifo))
		return;
	f = *fifo;
	if (snd_BUG_ON(!f))
		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 struct snd_seq_event_cell *fifo_cell_out(struct snd_seq_fifo *f);

/* clear queue */
void snd_seq_fifo_clear(struct snd_seq_fifo *f)
{
	struct snd_seq_event_cell *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(struct snd_seq_fifo *f,
			  struct snd_seq_event *event)
{
	struct snd_seq_event_cell *cell;
	unsigned long flags;
	int err;

	if (snd_BUG_ON(!f))
		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) || (err == -EAGAIN))
			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 struct snd_seq_event_cell *fifo_cell_out(struct snd_seq_fifo *f)
{
	struct snd_seq_event_cell *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(struct snd_seq_fifo *f,
			  struct snd_seq_event_cell **cellp, int nonblock)
{
	struct snd_seq_event_cell *cell;
	unsigned long flags;
	wait_queue_t wait;

	if (snd_BUG_ON(!f))
		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(struct snd_seq_fifo *f,
			       struct snd_seq_event_cell *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(struct snd_seq_fifo *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(struct snd_seq_fifo *f, int poolsize)
{
	unsigned long flags;
	struct snd_seq_pool *newpool, *oldpool;
	struct snd_seq_event_cell *cell, *next, *oldhead;

	if (snd_BUG_ON(!f || !f->pool))
		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;
}