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/driver.h>
  23 #include <sound/core.h>
  24 #include <linux/slab.h>
  25 #include "seq_fifo.h"
  26 #include "seq_lock.h"
  27
  28
  29 /* FIFO */
  30
  31 /* create new fifo */
  32 struct snd_seq_fifo *snd_seq_fifo_new(int poolsize)
  33 {
  34         struct snd_seq_fifo *f;
  35
  36         f = kzalloc(sizeof(*f), GFP_KERNEL);
  37         if (f == NULL) {
  38                 snd_printd("malloc failed for snd_seq_fifo_new() \n");
  39                 return NULL;
  40         }
  41
  42         f->pool = snd_seq_pool_new(poolsize);
  43         if (f->pool == NULL) {
  44                 kfree(f);
  45                 return NULL;
  46         }
  47         if (snd_seq_pool_init(f->pool) < 0) {
  48                 snd_seq_pool_delete(&f->pool);
  49                 kfree(f);
  50                 return NULL;
  51         }
  52
  53         spin_lock_init(&f->lock);
  54         snd_use_lock_init(&f->use_lock);
  55         init_waitqueue_head(&f->input_sleep);
  56         atomic_set(&f->overflow, 0);
  57
  58         f->head = NULL;
  59         f->tail = NULL;
  60         f->cells = 0;
  61
  62         return f;
  63 }
  64
  65 void snd_seq_fifo_delete(struct snd_seq_fifo **fifo)
  66 {
  67         struct snd_seq_fifo *f;
  68
  69         snd_assert(fifo != NULL, return);
  70         f = *fifo;
  71         snd_assert(f != NULL, return);
  72         *fifo = NULL;
  73
  74         snd_seq_fifo_clear(f);
  75
  76         /* wake up clients if any */
  77         if (waitqueue_active(&f->input_sleep))
  78                 wake_up(&f->input_sleep);
  79
  80         /* release resources...*/
  81         /*....................*/
  82
  83         if (f->pool) {
  84                 snd_seq_pool_done(f->pool);
  85                 snd_seq_pool_delete(&f->pool);
  86         }
  87
  88         kfree(f);
  89 }
  90
  91 static struct snd_seq_event_cell *fifo_cell_out(struct snd_seq_fifo *f);
  92
  93 /* clear queue */
  94 void snd_seq_fifo_clear(struct snd_seq_fifo *f)
  95 {
  96         struct snd_seq_event_cell *cell;
  97         unsigned long flags;
  98
  99         /* clear overflow flag */
 100         atomic_set(&f->overflow, 0);
 101
 102         snd_use_lock_sync(&f->use_lock);
 103         spin_lock_irqsave(&f->lock, flags);
 104         /* drain the fifo */
 105         while ((cell = fifo_cell_out(f)) != NULL) {
 106                 snd_seq_cell_free(cell);
 107         }
 108         spin_unlock_irqrestore(&f->lock, flags);
 109 }
 110
 111
 112 /* enqueue event to fifo */
 113 int snd_seq_fifo_event_in(struct snd_seq_fifo *f,
 114                           struct snd_seq_event *event)
 115 {
 116         struct snd_seq_event_cell *cell;
 117         unsigned long flags;
 118         int err;
 119
 120         snd_assert(f != NULL, 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)
 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         snd_assert(f != NULL, return -EINVAL);
 179
 180         *cellp = NULL;
 181         init_waitqueue_entry(&wait, current);
 182         spin_lock_irqsave(&f->lock, flags);
 183         while ((cell = fifo_cell_out(f)) == NULL) {
 184                 if (nonblock) {
 185                         /* non-blocking - return immediately */
 186                         spin_unlock_irqrestore(&f->lock, flags);
 187                         return -EAGAIN;
 188                 }
 189                 set_current_state(TASK_INTERRUPTIBLE);
 190                 add_wait_queue(&f->input_sleep, &wait);
 191                 spin_unlock_irq(&f->lock);
 192                 schedule();
 193                 spin_lock_irq(&f->lock);
 194                 remove_wait_queue(&f->input_sleep, &wait);
 195                 if (signal_pending(current)) {
 196                         spin_unlock_irqrestore(&f->lock, flags);
 197                         return -ERESTARTSYS;
 198                 }
 199         }
 200         spin_unlock_irqrestore(&f->lock, flags);
 201         *cellp = cell;
 202
 203         return 0;
 204 }
 205
 206
 207 void snd_seq_fifo_cell_putback(struct snd_seq_fifo *f,
 208                                struct snd_seq_event_cell *cell)
 209 {
 210         unsigned long flags;
 211
 212         if (cell) {
 213                 spin_lock_irqsave(&f->lock, flags);
 214                 cell->next = f->head;
 215                 f->head = cell;
 216                 f->cells++;
 217                 spin_unlock_irqrestore(&f->lock, flags);
 218         }
 219 }
 220
 221
 222 /* polling; return non-zero if queue is available */
 223 int snd_seq_fifo_poll_wait(struct snd_seq_fifo *f, struct file *file,
 224                            poll_table *wait)
 225 {
 226         poll_wait(file, &f->input_sleep, wait);
 227         return (f->cells > 0);
 228 }
 229
 230 /* change the size of pool; all old events are removed */
 231 int snd_seq_fifo_resize(struct snd_seq_fifo *f, int poolsize)
 232 {
 233         unsigned long flags;
 234         struct snd_seq_pool *newpool, *oldpool;
 235         struct snd_seq_event_cell *cell, *next, *oldhead;
 236
 237         snd_assert(f != NULL && f->pool != NULL, return -EINVAL);
 238
 239         /* allocate new pool */
 240         newpool = snd_seq_pool_new(poolsize);
 241         if (newpool == NULL)
 242                 return -ENOMEM;
 243         if (snd_seq_pool_init(newpool) < 0) {
 244                 snd_seq_pool_delete(&newpool);
 245                 return -ENOMEM;
 246         }
 247
 248         spin_lock_irqsave(&f->lock, flags);
 249         /* remember old pool */
 250         oldpool = f->pool;
 251         oldhead = f->head;
 252         /* exchange pools */
 253         f->pool = newpool;
 254         f->head = NULL;
 255         f->tail = NULL;
 256         f->cells = 0;
 257         /* NOTE: overflow flag is not cleared */
 258         spin_unlock_irqrestore(&f->lock, flags);
 259
 260         /* release cells in old pool */
 261         for (cell = oldhead; cell; cell = next) {
 262                 next = cell->next;
 263                 snd_seq_cell_free(cell);
 264         }
 265         snd_seq_pool_delete(&oldpool);
 266
 267         return 0;
 268 }