sound/core/seq/seq_fifo.c

   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         cell->next = NULL;
 139         f->cells++;
 140         spin_unlock_irqrestore(&f->lock, flags);
 141
 142         /* wakeup client */
 143         if (waitqueue_active(&f->input_sleep))
 144                 wake_up(&f->input_sleep);
 145
 146         snd_use_lock_free(&f->use_lock);
 147
 148         return 0; /* success */
 149
 150 }
 151
 152 /* dequeue cell from fifo */
 153 static struct snd_seq_event_cell *fifo_cell_out(struct snd_seq_fifo *f)
 154 {
 155         struct snd_seq_event_cell *cell;
 156
 157         if ((cell = f->head) != NULL) {
 158                 f->head = cell->next;
 159
 160                 /* reset tail if this was the last element */
 161                 if (f->tail == cell)
 162                         f->tail = NULL;
 163
 164                 cell->next = NULL;
 165                 f->cells--;
 166         }
 167
 168         return cell;
 169 }
 170
 171 /* dequeue cell from fifo and copy on user space */
 172 int snd_seq_fifo_cell_out(struct snd_seq_fifo *f,
 173                           struct snd_seq_event_cell **cellp, int nonblock)
 174 {
 175         struct snd_seq_event_cell *cell;
 176         unsigned long flags;
 177         wait_queue_t wait;
 178
 179         if (snd_BUG_ON(!f))
 180                 return -EINVAL;
 181
 182         *cellp = NULL;
 183         init_waitqueue_entry(&wait, current);
 184         spin_lock_irqsave(&f->lock, flags);
 185         while ((cell = fifo_cell_out(f)) == NULL) {
 186                 if (nonblock) {
 187                         /* non-blocking - return immediately */
 188                         spin_unlock_irqrestore(&f->lock, flags);
 189                         return -EAGAIN;
 190                 }
 191                 set_current_state(TASK_INTERRUPTIBLE);
 192                 add_wait_queue(&f->input_sleep, &wait);
 193                 spin_unlock_irq(&f->lock);
 194                 schedule();
 195                 spin_lock_irq(&f->lock);
 196                 remove_wait_queue(&f->input_sleep, &wait);
 197                 if (signal_pending(current)) {
 198                         spin_unlock_irqrestore(&f->lock, flags);
 199                         return -ERESTARTSYS;
 200                 }
 201         }
 202         spin_unlock_irqrestore(&f->lock, flags);
 203         *cellp = cell;
 204
 205         return 0;
 206 }
 207
 208
 209 void snd_seq_fifo_cell_putback(struct snd_seq_fifo *f,
 210                                struct snd_seq_event_cell *cell)
 211 {
 212         unsigned long flags;
 213
 214         if (cell) {
 215                 spin_lock_irqsave(&f->lock, flags);
 216                 cell->next = f->head;
 217                 f->head = cell;
 218                 if (!f->tail)
 219                         f->tail = cell;
 220                 f->cells++;
 221                 spin_unlock_irqrestore(&f->lock, flags);
 222         }
 223 }
 224
 225
 226 /* polling; return non-zero if queue is available */
 227 int snd_seq_fifo_poll_wait(struct snd_seq_fifo *f, struct file *file,
 228                            poll_table *wait)
 229 {
 230         poll_wait(file, &f->input_sleep, wait);
 231         return (f->cells > 0);
 232 }
 233
 234 /* change the size of pool; all old events are removed */
 235 int snd_seq_fifo_resize(struct snd_seq_fifo *f, int poolsize)
 236 {
 237         unsigned long flags;
 238         struct snd_seq_pool *newpool, *oldpool;
 239         struct snd_seq_event_cell *cell, *next, *oldhead;
 240
 241         if (snd_BUG_ON(!f || !f->pool))
 242                 return -EINVAL;
 243
 244         /* allocate new pool */
 245         newpool = snd_seq_pool_new(poolsize);
 246         if (newpool == NULL)
 247                 return -ENOMEM;
 248         if (snd_seq_pool_init(newpool) < 0) {
 249                 snd_seq_pool_delete(&newpool);
 250                 return -ENOMEM;
 251         }
 252
 253         spin_lock_irqsave(&f->lock, flags);
 254         /* remember old pool */
 255         oldpool = f->pool;
 256         oldhead = f->head;
 257         /* exchange pools */
 258         f->pool = newpool;
 259         f->head = NULL;
 260         f->tail = NULL;
 261         f->cells = 0;
 262         /* NOTE: overflow flag is not cleared */
 263         spin_unlock_irqrestore(&f->lock, flags);
 264
 265         /* release cells in old pool */
 266         for (cell = oldhead; cell; cell = next) {
 267                 next = cell->next;
 268                 snd_seq_cell_free(cell);
 269         }
 270         snd_seq_pool_delete(&oldpool);
 271
 272         return 0;
 273 }