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 == NULL) {
  37                 snd_printd("malloc failed for snd_seq_fifo_new() \n");
  38                 return NULL;
  39         }
  40
  41         f->pool = snd_seq_pool_new(poolsize);
  42         if (f->pool == NULL) {
  43                 kfree(f);
  44                 return NULL;
  45         }
  46         if (snd_seq_pool_init(f->pool) < 0) {
  47                 snd_seq_pool_delete(&f->pool);
  48                 kfree(f);
  49                 return NULL;
  50         }
  51
  52         spin_lock_init(&f->lock);
  53         snd_use_lock_init(&f->use_lock);
  54         init_waitqueue_head(&f->input_sleep);
  55         atomic_set(&f->overflow, 0);
  56
  57         f->head = NULL;
  58         f->tail = NULL;
  59         f->cells = 0;
  60
  61         return f;
  62 }
  63
  64 void snd_seq_fifo_delete(struct snd_seq_fifo **fifo)
  65 {
  66         struct snd_seq_fifo *f;
  67
  68         if (snd_BUG_ON(!fifo))
  69                 return;
  70         f = *fifo;
  71         if (snd_BUG_ON(!f))
  72                 return;
  73         *fifo = NULL;
  74
  75         snd_seq_fifo_clear(f);
  76
  77         /* wake up clients if any */
  78         if (waitqueue_active(&f->input_sleep))
  79                 wake_up(&f->input_sleep);
  80
  81         /* release resources...*/
  82         /*....................*/
  83
  84         if (f->pool) {
  85                 snd_seq_pool_done(f->pool);
  86                 snd_seq_pool_delete(&f->pool);
  87         }
  88
  89         kfree(f);
  90 }
  91
  92 static struct snd_seq_event_cell *fifo_cell_out(struct snd_seq_fifo *f);
  93
  94 /* clear queue */
  95 void snd_seq_fifo_clear(struct snd_seq_fifo *f)
  96 {
  97         struct snd_seq_event_cell *cell;
  98         unsigned long flags;
  99
 100         /* clear overflow flag */
 101         atomic_set(&f->overflow, 0);
 102
 103         snd_use_lock_sync(&f->use_lock);
 104         spin_lock_irqsave(&f->lock, flags);
 105         /* drain the fifo */
 106         while ((cell = fifo_cell_out(f)) != NULL) {
 107                 snd_seq_cell_free(cell);
 108         }
 109         spin_unlock_irqrestore(&f->lock, flags);
 110 }
 111
 112
 113 /* enqueue event to fifo */
 114 int snd_seq_fifo_event_in(struct snd_seq_fifo *f,
 115                           struct snd_seq_event *event)
 116 {
 117         struct snd_seq_event_cell *cell;
 118         unsigned long flags;
 119         int err;
 120
 121         if (snd_BUG_ON(!f))
 122                 return -EINVAL;
 123
 124         snd_use_lock_use(&f->use_lock);
 125         err = snd_seq_event_dup(f->pool, event, &cell, 1, NULL); /* always non-blocking */
 126         if (err < 0) {
 127                 if (err == -ENOMEM)
 128                         atomic_inc(&f->overflow);
 129                 snd_use_lock_free(&f->use_lock);
 130                 return err;
 131         }
 132
 133         /* append new cells to fifo */
 134         spin_lock_irqsave(&f->lock, flags);
 135         if (f->tail != NULL)
 136                 f->tail->next = cell;
 137         f->tail = cell;
 138         if (f->head == NULL)
 139                 f->head = cell;
 140         f->cells++;
 141         spin_unlock_irqrestore(&f->lock, flags);
 142
 143         /* wakeup client */
 144         if (waitqueue_active(&f->input_sleep))
 145                 wake_up(&f->input_sleep);
 146
 147         snd_use_lock_free(&f->use_lock);
 148
 149         return 0; /* success */
 150
 151 }
 152
 153 /* dequeue cell from fifo */
 154 static struct snd_seq_event_cell *fifo_cell_out(struct snd_seq_fifo *f)
 155 {
 156         struct snd_seq_event_cell *cell;
 157
 158         if ((cell = f->head) != NULL) {
 159                 f->head = cell->next;
 160
 161                 /* reset tail if this was the last element */
 162                 if (f->tail == cell)
 163                         f->tail = NULL;
 164
 165                 cell->next = NULL;
 166                 f->cells--;
 167         }
 168
 169         return cell;
 170 }
 171
 172 /* dequeue cell from fifo and copy on user space */
 173 int snd_seq_fifo_cell_out(struct snd_seq_fifo *f,
 174                           struct snd_seq_event_cell **cellp, int nonblock)
 175 {
 176         struct snd_seq_event_cell *cell;
 177         unsigned long flags;
 178         wait_queue_t wait;
 179
 180         if (snd_BUG_ON(!f))
 181                 return -EINVAL;
 182
 183         *cellp = NULL;
 184         init_waitqueue_entry(&wait, current);
 185         spin_lock_irqsave(&f->lock, flags);
 186         while ((cell = fifo_cell_out(f)) == NULL) {
 187                 if (nonblock) {
 188                         /* non-blocking - return immediately */
 189                         spin_unlock_irqrestore(&f->lock, flags);
 190                         return -EAGAIN;
 191                 }
 192                 set_current_state(TASK_INTERRUPTIBLE);
 193                 add_wait_queue(&f->input_sleep, &wait);
 194                 spin_unlock_irq(&f->lock);
 195                 schedule();
 196                 spin_lock_irq(&f->lock);
 197                 remove_wait_queue(&f->input_sleep, &wait);
 198                 if (signal_pending(current)) {
 199                         spin_unlock_irqrestore(&f->lock, flags);
 200                         return -ERESTARTSYS;
 201                 }
 202         }
 203         spin_unlock_irqrestore(&f->lock, flags);
 204         *cellp = cell;
 205
 206         return 0;
 207 }
 208
 209
 210 void snd_seq_fifo_cell_putback(struct snd_seq_fifo *f,
 211                                struct snd_seq_event_cell *cell)
 212 {
 213         unsigned long flags;
 214
 215         if (cell) {
 216                 spin_lock_irqsave(&f->lock, flags);
 217                 cell->next = f->head;
 218                 f->head = cell;
 219                 f->cells++;
 220                 spin_unlock_irqrestore(&f->lock, flags);
 221         }
 222 }
 223
 224
 225 /* polling; return non-zero if queue is available */
 226 int snd_seq_fifo_poll_wait(struct snd_seq_fifo *f, struct file *file,
 227                            poll_table *wait)
 228 {
 229         poll_wait(file, &f->input_sleep, wait);
 230         return (f->cells > 0);
 231 }
 232
 233 /* change the size of pool; all old events are removed */
 234 int snd_seq_fifo_resize(struct snd_seq_fifo *f, int poolsize)
 235 {
 236         unsigned long flags;
 237         struct snd_seq_pool *newpool, *oldpool;
 238         struct snd_seq_event_cell *cell, *next, *oldhead;
 239
 240         if (snd_BUG_ON(!f || !f->pool))
 241                 return -EINVAL;
 242
 243         /* allocate new pool */
 244         newpool = snd_seq_pool_new(poolsize);
 245         if (newpool == NULL)
 246                 return -ENOMEM;
 247         if (snd_seq_pool_init(newpool) < 0) {
 248                 snd_seq_pool_delete(&newpool);
 249                 return -ENOMEM;
 250         }
 251
 252         spin_lock_irqsave(&f->lock, flags);
 253         /* remember old pool */
 254         oldpool = f->pool;
 255         oldhead = f->head;
 256         /* exchange pools */
 257         f->pool = newpool;
 258         f->head = NULL;
 259         f->tail = NULL;
 260         f->cells = 0;
 261         /* NOTE: overflow flag is not cleared */
 262         spin_unlock_irqrestore(&f->lock, flags);
 263
 264         /* release cells in old pool */
 265         for (cell = oldhead; cell; cell = next) {
 266                 next = cell->next;
 267                 snd_seq_cell_free(cell);
 268         }
 269         snd_seq_pool_delete(&oldpool);
 270
 271         return 0;
 272 }