sound/core/seq/seq_prioq.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *   ALSA sequencer Priority Queue
   4  *   Copyright (c) 1998-1999 by Frank van de Pol <fvdpol@coil.demon.nl>
   5  */
   6
   7 #include <linux/time.h>
   8 #include <linux/slab.h>
   9 #include <sound/core.h>
  10 #include "seq_timer.h"
  11 #include "seq_prioq.h"
  12
  13
  14 /* Implementation is a simple linked list for now...
  15
  16    This priority queue orders the events on timestamp. For events with an
  17    equeal timestamp the queue behaves as a FIFO.
  18
  19    *
  20    *           +-------+
  21    *  Head --> | first |
  22    *           +-------+
  23    *                 |next
  24    *           +-----v-+
  25    *           |       |
  26    *           +-------+
  27    *                 |
  28    *           +-----v-+
  29    *           |       |
  30    *           +-------+
  31    *                 |
  32    *           +-----v-+
  33    *  Tail --> | last  |
  34    *           +-------+
  35    *
  36
  37  */
  38
  39
  40
  41 /* create new prioq (constructor) */
  42 struct snd_seq_prioq *snd_seq_prioq_new(void)
  43 {
  44         struct snd_seq_prioq *f;
  45
  46         f = kzalloc(sizeof(*f), GFP_KERNEL);
  47         if (!f)
  48                 return NULL;
  49
  50         spin_lock_init(&f->lock);
  51         f->head = NULL;
  52         f->tail = NULL;
  53         f->cells = 0;
  54
  55         return f;
  56 }
  57
  58 /* delete prioq (destructor) */
  59 void snd_seq_prioq_delete(struct snd_seq_prioq **fifo)
  60 {
  61         struct snd_seq_prioq *f = *fifo;
  62         *fifo = NULL;
  63
  64         if (f == NULL) {
  65                 pr_debug("ALSA: seq: snd_seq_prioq_delete() called with NULL prioq\n");
  66                 return;
  67         }
  68
  69         /* release resources...*/
  70         /*....................*/
  71
  72         if (f->cells > 0) {
  73                 /* drain prioQ */
  74                 while (f->cells > 0)
  75                         snd_seq_cell_free(snd_seq_prioq_cell_out(f, NULL));
  76         }
  77
  78         kfree(f);
  79 }
  80
  81
  82
  83
  84 /* compare timestamp between events */
  85 /* return 1 if a >= b; 0 */
  86 static inline int compare_timestamp(struct snd_seq_event *a,
  87                                     struct snd_seq_event *b)
  88 {
  89         if ((a->flags & SNDRV_SEQ_TIME_STAMP_MASK) == SNDRV_SEQ_TIME_STAMP_TICK) {
  90                 /* compare ticks */
  91                 return (snd_seq_compare_tick_time(&a->time.tick, &b->time.tick));
  92         } else {
  93                 /* compare real time */
  94                 return (snd_seq_compare_real_time(&a->time.time, &b->time.time));
  95         }
  96 }
  97
  98 /* compare timestamp between events */
  99 /* return negative if a < b;
 100  *        zero     if a = b;
 101  *        positive if a > b;
 102  */
 103 static inline int compare_timestamp_rel(struct snd_seq_event *a,
 104                                         struct snd_seq_event *b)
 105 {
 106         if ((a->flags & SNDRV_SEQ_TIME_STAMP_MASK) == SNDRV_SEQ_TIME_STAMP_TICK) {
 107                 /* compare ticks */
 108                 if (a->time.tick > b->time.tick)
 109                         return 1;
 110                 else if (a->time.tick == b->time.tick)
 111                         return 0;
 112                 else
 113                         return -1;
 114         } else {
 115                 /* compare real time */
 116                 if (a->time.time.tv_sec > b->time.time.tv_sec)
 117                         return 1;
 118                 else if (a->time.time.tv_sec == b->time.time.tv_sec) {
 119                         if (a->time.time.tv_nsec > b->time.time.tv_nsec)
 120                                 return 1;
 121                         else if (a->time.time.tv_nsec == b->time.time.tv_nsec)
 122                                 return 0;
 123                         else
 124                                 return -1;
 125                 } else
 126                         return -1;
 127         }
 128 }
 129
 130 /* enqueue cell to prioq */
 131 int snd_seq_prioq_cell_in(struct snd_seq_prioq * f,
 132                           struct snd_seq_event_cell * cell)
 133 {
 134         struct snd_seq_event_cell *cur, *prev;
 135         unsigned long flags;
 136         int count;
 137         int prior;
 138
 139         if (snd_BUG_ON(!f || !cell))
 140                 return -EINVAL;
 141
 142         /* check flags */
 143         prior = (cell->event.flags & SNDRV_SEQ_PRIORITY_MASK);
 144
 145         spin_lock_irqsave(&f->lock, flags);
 146
 147         /* check if this element needs to inserted at the end (ie. ordered
 148            data is inserted) This will be very likeley if a sequencer
 149            application or midi file player is feeding us (sequential) data */
 150         if (f->tail && !prior) {
 151                 if (compare_timestamp(&cell->event, &f->tail->event)) {
 152                         /* add new cell to tail of the fifo */
 153                         f->tail->next = cell;
 154                         f->tail = cell;
 155                         cell->next = NULL;
 156                         f->cells++;
 157                         spin_unlock_irqrestore(&f->lock, flags);
 158                         return 0;
 159                 }
 160         }
 161         /* traverse list of elements to find the place where the new cell is
 162            to be inserted... Note that this is a order n process ! */
 163
 164         prev = NULL;            /* previous cell */
 165         cur = f->head;          /* cursor */
 166
 167         count = 10000; /* FIXME: enough big, isn't it? */
 168         while (cur != NULL) {
 169                 /* compare timestamps */
 170                 int rel = compare_timestamp_rel(&cell->event, &cur->event);
 171                 if (rel < 0)
 172                         /* new cell has earlier schedule time, */
 173                         break;
 174                 else if (rel == 0 && prior)
 175                         /* equal schedule time and prior to others */
 176                         break;
 177                 /* new cell has equal or larger schedule time, */
 178                 /* move cursor to next cell */
 179                 prev = cur;
 180                 cur = cur->next;
 181                 if (! --count) {
 182                         spin_unlock_irqrestore(&f->lock, flags);
 183                         pr_err("ALSA: seq: cannot find a pointer.. infinite loop?\n");
 184                         return -EINVAL;
 185                 }
 186         }
 187
 188         /* insert it before cursor */
 189         if (prev != NULL)
 190                 prev->next = cell;
 191         cell->next = cur;
 192
 193         if (f->head == cur) /* this is the first cell, set head to it */
 194                 f->head = cell;
 195         if (cur == NULL) /* reached end of the list */
 196                 f->tail = cell;
 197         f->cells++;
 198         spin_unlock_irqrestore(&f->lock, flags);
 199         return 0;
 200 }
 201
 202 /* return 1 if the current time >= event timestamp */
 203 static int event_is_ready(struct snd_seq_event *ev, void *current_time)
 204 {
 205         if ((ev->flags & SNDRV_SEQ_TIME_STAMP_MASK) == SNDRV_SEQ_TIME_STAMP_TICK)
 206                 return snd_seq_compare_tick_time(current_time, &ev->time.tick);
 207         else
 208                 return snd_seq_compare_real_time(current_time, &ev->time.time);
 209 }
 210
 211 /* dequeue cell from prioq */
 212 struct snd_seq_event_cell *snd_seq_prioq_cell_out(struct snd_seq_prioq *f,
 213                                                   void *current_time)
 214 {
 215         struct snd_seq_event_cell *cell;
 216         unsigned long flags;
 217
 218         if (f == NULL) {
 219                 pr_debug("ALSA: seq: snd_seq_prioq_cell_in() called with NULL prioq\n");
 220                 return NULL;
 221         }
 222         spin_lock_irqsave(&f->lock, flags);
 223
 224         cell = f->head;
 225         if (cell && current_time && !event_is_ready(&cell->event, current_time))
 226                 cell = NULL;
 227         if (cell) {
 228                 f->head = cell->next;
 229
 230                 /* reset tail if this was the last element */
 231                 if (f->tail == cell)
 232                         f->tail = NULL;
 233
 234                 cell->next = NULL;
 235                 f->cells--;
 236         }
 237
 238         spin_unlock_irqrestore(&f->lock, flags);
 239         return cell;
 240 }
 241
 242 /* return number of events available in prioq */
 243 int snd_seq_prioq_avail(struct snd_seq_prioq * f)
 244 {
 245         if (f == NULL) {
 246                 pr_debug("ALSA: seq: snd_seq_prioq_cell_in() called with NULL prioq\n");
 247                 return 0;
 248         }
 249         return f->cells;
 250 }
 251
 252 static inline int prioq_match(struct snd_seq_event_cell *cell,
 253                               int client, int timestamp)
 254 {
 255         if (cell->event.source.client == client ||
 256             cell->event.dest.client == client)
 257                 return 1;
 258         if (!timestamp)
 259                 return 0;
 260         switch (cell->event.flags & SNDRV_SEQ_TIME_STAMP_MASK) {
 261         case SNDRV_SEQ_TIME_STAMP_TICK:
 262                 if (cell->event.time.tick)
 263                         return 1;
 264                 break;
 265         case SNDRV_SEQ_TIME_STAMP_REAL:
 266                 if (cell->event.time.time.tv_sec ||
 267                     cell->event.time.time.tv_nsec)
 268                         return 1;
 269                 break;
 270         }
 271         return 0;
 272 }
 273
 274 /* remove cells for left client */
 275 void snd_seq_prioq_leave(struct snd_seq_prioq * f, int client, int timestamp)
 276 {
 277         register struct snd_seq_event_cell *cell, *next;
 278         unsigned long flags;
 279         struct snd_seq_event_cell *prev = NULL;
 280         struct snd_seq_event_cell *freefirst = NULL, *freeprev = NULL, *freenext;
 281
 282         /* collect all removed cells */
 283         spin_lock_irqsave(&f->lock, flags);
 284         cell = f->head;
 285         while (cell) {
 286                 next = cell->next;
 287                 if (prioq_match(cell, client, timestamp)) {
 288                         /* remove cell from prioq */
 289                         if (cell == f->head) {
 290                                 f->head = cell->next;
 291                         } else {
 292                                 prev->next = cell->next;
 293                         }
 294                         if (cell == f->tail)
 295                                 f->tail = cell->next;
 296                         f->cells--;
 297                         /* add cell to free list */
 298                         cell->next = NULL;
 299                         if (freefirst == NULL) {
 300                                 freefirst = cell;
 301                         } else {
 302                                 freeprev->next = cell;
 303                         }
 304                         freeprev = cell;
 305                 } else {
 306 #if 0
 307                         pr_debug("ALSA: seq: type = %i, source = %i, dest = %i, "
 308                                "client = %i\n",
 309                                 cell->event.type,
 310                                 cell->event.source.client,
 311                                 cell->event.dest.client,
 312                                 client);
 313 #endif
 314                         prev = cell;
 315                 }
 316                 cell = next;
 317         }
 318         spin_unlock_irqrestore(&f->lock, flags);
 319
 320         /* remove selected cells */
 321         while (freefirst) {
 322                 freenext = freefirst->next;
 323                 snd_seq_cell_free(freefirst);
 324                 freefirst = freenext;
 325         }
 326 }
 327
 328 static int prioq_remove_match(struct snd_seq_remove_events *info,
 329                               struct snd_seq_event *ev)
 330 {
 331         int res;
 332
 333         if (info->remove_mode & SNDRV_SEQ_REMOVE_DEST) {
 334                 if (ev->dest.client != info->dest.client ||
 335                                 ev->dest.port != info->dest.port)
 336                         return 0;
 337         }
 338         if (info->remove_mode & SNDRV_SEQ_REMOVE_DEST_CHANNEL) {
 339                 if (! snd_seq_ev_is_channel_type(ev))
 340                         return 0;
 341                 /* data.note.channel and data.control.channel are identical */
 342                 if (ev->data.note.channel != info->channel)
 343                         return 0;
 344         }
 345         if (info->remove_mode & SNDRV_SEQ_REMOVE_TIME_AFTER) {
 346                 if (info->remove_mode & SNDRV_SEQ_REMOVE_TIME_TICK)
 347                         res = snd_seq_compare_tick_time(&ev->time.tick, &info->time.tick);
 348                 else
 349                         res = snd_seq_compare_real_time(&ev->time.time, &info->time.time);
 350                 if (!res)
 351                         return 0;
 352         }
 353         if (info->remove_mode & SNDRV_SEQ_REMOVE_TIME_BEFORE) {
 354                 if (info->remove_mode & SNDRV_SEQ_REMOVE_TIME_TICK)
 355                         res = snd_seq_compare_tick_time(&ev->time.tick, &info->time.tick);
 356                 else
 357                         res = snd_seq_compare_real_time(&ev->time.time, &info->time.time);
 358                 if (res)
 359                         return 0;
 360         }
 361         if (info->remove_mode & SNDRV_SEQ_REMOVE_EVENT_TYPE) {
 362                 if (ev->type != info->type)
 363                         return 0;
 364         }
 365         if (info->remove_mode & SNDRV_SEQ_REMOVE_IGNORE_OFF) {
 366                 /* Do not remove off events */
 367                 switch (ev->type) {
 368                 case SNDRV_SEQ_EVENT_NOTEOFF:
 369                 /* case SNDRV_SEQ_EVENT_SAMPLE_STOP: */
 370                         return 0;
 371                 default:
 372                         break;
 373                 }
 374         }
 375         if (info->remove_mode & SNDRV_SEQ_REMOVE_TAG_MATCH) {
 376                 if (info->tag != ev->tag)
 377                         return 0;
 378         }
 379
 380         return 1;
 381 }
 382
 383 /* remove cells matching remove criteria */
 384 void snd_seq_prioq_remove_events(struct snd_seq_prioq * f, int client,
 385                                  struct snd_seq_remove_events *info)
 386 {
 387         struct snd_seq_event_cell *cell, *next;
 388         unsigned long flags;
 389         struct snd_seq_event_cell *prev = NULL;
 390         struct snd_seq_event_cell *freefirst = NULL, *freeprev = NULL, *freenext;
 391
 392         /* collect all removed cells */
 393         spin_lock_irqsave(&f->lock, flags);
 394         cell = f->head;
 395
 396         while (cell) {
 397                 next = cell->next;
 398                 if (cell->event.source.client == client &&
 399                         prioq_remove_match(info, &cell->event)) {
 400
 401                         /* remove cell from prioq */
 402                         if (cell == f->head) {
 403                                 f->head = cell->next;
 404                         } else {
 405                                 prev->next = cell->next;
 406                         }
 407
 408                         if (cell == f->tail)
 409                                 f->tail = cell->next;
 410                         f->cells--;
 411
 412                         /* add cell to free list */
 413                         cell->next = NULL;
 414                         if (freefirst == NULL) {
 415                                 freefirst = cell;
 416                         } else {
 417                                 freeprev->next = cell;
 418                         }
 419
 420                         freeprev = cell;
 421                 } else {
 422                         prev = cell;
 423                 }
 424                 cell = next;
 425         }
 426         spin_unlock_irqrestore(&f->lock, flags);
 427
 428         /* remove selected cells */
 429         while (freefirst) {
 430                 freenext = freefirst->next;
 431                 snd_seq_cell_free(freefirst);
 432                 freefirst = freenext;
 433         }
 434 }
 435
 436