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         snd_assert(fifo != NULL, return);
  69         f = *fifo;
  70         snd_assert(f != NULL, 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         snd_assert(f != NULL, return -EINVAL);
 120
 121         snd_use_lock_use(&f->use_lock);
 122         err = snd_seq_event_dup(f->pool, event, &cell, 1, NULL); /* always non-blocking */
 123         if (err < 0) {
 124                 if (err == -ENOMEM)
 125                         atomic_inc(&f->overflow);
 126                 snd_use_lock_free(&f->use_lock);
 127                 return err;
 128         }
 129
 130         /* append new cells to fifo */
 131         spin_lock_irqsave(&f->lock, flags);
 132         if (f->tail != NULL)
 133                 f->tail->next = cell;
 134         f->tail = cell;
 135         if (f->head == NULL)
 136                 f->head = cell;
 137         f->cells++;
 138         spin_unlock_irqrestore(&f->lock, flags);
 139
 140         /* wakeup client */
 141         if (waitqueue_active(&f->input_sleep))
 142                 wake_up(&f->input_sleep);
 143
 144         snd_use_lock_free(&f->use_lock);
 145
 146         return 0; /* success */
 147
 148 }
 149
 150 /* dequeue cell from fifo */
 151 static struct snd_seq_event_cell *fifo_cell_out(struct snd_seq_fifo *f)
 152 {
 153         struct snd_seq_event_cell *cell;
 154
 155         if ((cell = f->head) != NULL) {
 156                 f->head = cell->next;
 157
 158                 /* reset tail if this was the last element */
 159                 if (f->tail == cell)
 160                         f->tail = NULL;
 161
 162                 cell->next = NULL;
 163                 f->cells--;
 164         }
 165
 166         return cell;
 167 }
 168
 169 /* dequeue cell from fifo and copy on user space */
 170 int snd_seq_fifo_cell_out(struct snd_seq_fifo *f,
 171                           struct snd_seq_event_cell **cellp, int nonblock)
 172 {
 173         struct snd_seq_event_cell *cell;
 174         unsigned long flags;
 175         wait_queue_t wait;
 176
 177         snd_assert(f != NULL, return -EINVAL);
 178
 179         *cellp = NULL;
 180         init_waitqueue_entry(&wait, current);
 181         spin_lock_irqsave(&f->lock, flags);
 182         while ((cell = fifo_cell_out(f)) == NULL) {
 183                 if (nonblock) {
 184                         /* non-blocking - return immediately */
 185                         spin_unlock_irqrestore(&f->lock, flags);
 186                         return -EAGAIN;
 187                 }
 188                 set_current_state(TASK_INTERRUPTIBLE);
 189                 add_wait_queue(&f->input_sleep, &wait);
 190                 spin_unlock_irq(&f->lock);
 191                 schedule();
 192                 spin_lock_irq(&f->lock);
 193                 remove_wait_queue(&f->input_sleep, &wait);
 194                 if (signal_pending(current)) {
 195                         spin_unlock_irqrestore(&f->lock, flags);
 196                         return -ERESTARTSYS;
 197                 }
 198         }
 199         spin_unlock_irqrestore(&f->lock, flags);
 200         *cellp = cell;
 201
 202         return 0;
 203 }
 204
 205
 206 void snd_seq_fifo_cell_putback(struct snd_seq_fifo *f,
 207                                struct snd_seq_event_cell *cell)
 208 {
 209         unsigned long flags;
 210
 211         if (cell) {
 212                 spin_lock_irqsave(&f->lock, flags);
 213                 cell->next = f->head;
 214                 f->head = cell;
 215                 f->cells++;
 216                 spin_unlock_irqrestore(&f->lock, flags);
 217         }
 218 }
 219
 220
 221 /* polling; return non-zero if queue is available */
 222 int snd_seq_fifo_poll_wait(struct snd_seq_fifo *f, struct file *file,
 223                            poll_table *wait)
 224 {
 225         poll_wait(file, &f->input_sleep, wait);
 226         return (f->cells > 0);
 227 }
 228
 229 /* change the size of pool; all old events are removed */
 230 int snd_seq_fifo_resize(struct snd_seq_fifo *f, int poolsize)
 231 {
 232         unsigned long flags;
 233         struct snd_seq_pool *newpool, *oldpool;
 234         struct snd_seq_event_cell *cell, *next, *oldhead;
 235
 236         snd_assert(f != NULL && f->pool != NULL, return -EINVAL);
 237
 238         /* allocate new pool */
 239         newpool = snd_seq_pool_new(poolsize);
 240         if (newpool == NULL)
 241                 return -ENOMEM;
 242         if (snd_seq_pool_init(newpool) < 0) {
 243                 snd_seq_pool_delete(&newpool);
 244                 return -ENOMEM;
 245         }
 246
 247         spin_lock_irqsave(&f->lock, flags);
 248         /* remember old pool */
 249         oldpool = f->pool;
 250         oldhead = f->head;
 251         /* exchange pools */
 252         f->pool = newpool;
 253         f->head = NULL;
 254         f->tail = NULL;
 255         f->cells = 0;
 256         /* NOTE: overflow flag is not cleared */
 257         spin_unlock_irqrestore(&f->lock, flags);
 258
 259         /* release cells in old pool */
 260         for (cell = oldhead; cell; cell = next) {
 261                 next = cell->next;
 262                 snd_seq_cell_free(cell);
 263         }
 264         snd_seq_pool_delete(&oldpool);
 265
 266         return 0;
 267 }