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 } 268