gstmemory.c 18.2 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
/* GStreamer
 * Copyright (C) 2011 Wim Taymans <wim.taymans@gmail.be>
 *
 * gstmemory.c: memory block handling
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

Wim Taymans's avatar
Wim Taymans committed
22 23 24 25 26 27 28 29
/**
 * SECTION:gstmemory
 * @short_description: refcounted wrapper for memory blocks
 * @see_also: #GstBuffer
 *
 * GstMemory is a lightweight refcounted object that wraps a region of memory.
 * They are typically used to manage the data of a #GstBuffer.
 *
30 31 32 33 34 35 36
 * Memory is usually created by allocators with a gst_memory_allocator_alloc()
 * method call. When NULL is used as the allocator, the default allocator will
 * be used.
 *
 * New allocators can be registered with gst_memory_allocator_register().
 * Allocators are identified by name and can be retrieved with
 * gst_memory_allocator_find().
37
 *
Wim Taymans's avatar
Wim Taymans committed
38
 * New memory can be created with gst_memory_new_wrapped() that wraps the memory
39
 * allocated elsewhere.
Wim Taymans's avatar
Wim Taymans committed
40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57
 *
 * Refcounting of the memory block is performed with gst_memory_ref() and
 * gst_memory_unref().
 *
 * The size of the memory can be retrieved and changed with
 * gst_memory_get_sizes() and gst_memory_resize() respectively.
 *
 * Getting access to the data of the memory is performed with gst_memory_map().
 * After the memory access is completed, gst_memory_unmap() should be called.
 *
 * Memory can be copied with gst_memory_copy(), which will returnn a writable
 * copy. gst_memory_share() will create a new memory block that shares the
 * memory with an existing memory block at a custom offset and with a custom
 * size.
 *
 * Memory can be efficiently merged when gst_memory_is_span() returns TRUE and
 * with the function gst_memory_span().
 *
58
 * Last reviewed on 2011-06-08 (0.11.0)
Wim Taymans's avatar
Wim Taymans committed
59
 */
60

Wim Taymans's avatar
Wim Taymans committed
61
#include "config.h"
62 63 64
#include "gst_private.h"
#include "gstmemory.h"

Wim Taymans's avatar
Wim Taymans committed
65

66
struct _GstMemoryAllocator
67 68 69 70 71 72
{
  GQuark name;

  GstMemoryInfo info;
};

Wim Taymans's avatar
Wim Taymans committed
73
/* default memory implementation */
74 75 76
typedef struct
{
  GstMemory mem;
Wim Taymans's avatar
Wim Taymans committed
77
  gsize slice_size;
78 79 80 81 82 83 84
  guint8 *data;
  GFreeFunc free_func;
  gsize maxsize;
  gsize offset;
  gsize size;
} GstMemoryDefault;

85 86 87 88 89 90
/* the default allocator */
static const GstMemoryAllocator *_default_allocator;

/* our predefined allocators */
static const GstMemoryAllocator *_default_mem_impl;
static const GstMemoryAllocator *_default_share_impl;
Wim Taymans's avatar
Wim Taymans committed
91

Wim Taymans's avatar
Wim Taymans committed
92
/* initialize the fields */
Wim Taymans's avatar
Wim Taymans committed
93
static void
94 95 96
_default_mem_init (GstMemoryDefault * mem, GstMemoryFlags flags,
    GstMemory * parent, gsize slice_size, gpointer data,
    GFreeFunc free_func, gsize maxsize, gsize offset, gsize size)
Wim Taymans's avatar
Wim Taymans committed
97
{
98
  mem->mem.allocator = data ? _default_mem_impl : _default_share_impl;
99
  mem->mem.flags = flags;
Wim Taymans's avatar
Wim Taymans committed
100
  mem->mem.refcount = 1;
Wim Taymans's avatar
Wim Taymans committed
101 102 103 104 105 106 107 108 109
  mem->mem.parent = parent ? gst_memory_ref (parent) : NULL;
  mem->slice_size = slice_size;
  mem->data = data;
  mem->free_func = free_func;
  mem->maxsize = maxsize;
  mem->offset = offset;
  mem->size = size;
}

Wim Taymans's avatar
Wim Taymans committed
110
/* create a new memory block that manages the given memory */
Wim Taymans's avatar
Wim Taymans committed
111
static GstMemoryDefault *
112
_default_mem_new (GstMemoryFlags flags, GstMemory * parent, gpointer data,
Wim Taymans's avatar
Wim Taymans committed
113 114 115
    GFreeFunc free_func, gsize maxsize, gsize offset, gsize size)
{
  GstMemoryDefault *mem;
Wim Taymans's avatar
Wim Taymans committed
116
  gsize slice_size;
Wim Taymans's avatar
Wim Taymans committed
117

Wim Taymans's avatar
Wim Taymans committed
118 119 120
  slice_size = sizeof (GstMemoryDefault);

  mem = g_slice_alloc (slice_size);
121
  _default_mem_init (mem, flags, parent, slice_size,
Wim Taymans's avatar
Wim Taymans committed
122 123 124 125
      data, free_func, maxsize, offset, size);

  return mem;
}
126

Wim Taymans's avatar
Wim Taymans committed
127
/* allocate the memory and structure in one block */
Wim Taymans's avatar
Wim Taymans committed
128 129 130 131 132 133 134
static GstMemoryDefault *
_default_mem_new_block (gsize maxsize, gsize align, gsize offset, gsize size)
{
  GstMemoryDefault *mem;
  gsize aoffset, slice_size;
  guint8 *data;

Wim Taymans's avatar
Wim Taymans committed
135 136
  /* allocate more to compensate for alignment */
  maxsize += align;
Wim Taymans's avatar
Wim Taymans committed
137
  /* alloc header and data in one block */
Wim Taymans's avatar
Wim Taymans committed
138
  slice_size = sizeof (GstMemoryDefault) + maxsize;
Wim Taymans's avatar
Wim Taymans committed
139 140 141 142 143 144 145 146

  mem = g_slice_alloc (slice_size);
  if (mem == NULL)
    return NULL;

  data = (guint8 *) mem + sizeof (GstMemoryDefault);

  if ((aoffset = ((guintptr) data & align)))
147
    aoffset = (align + 1) - aoffset;
Wim Taymans's avatar
Wim Taymans committed
148

Wim Taymans's avatar
Wim Taymans committed
149
  _default_mem_init (mem, 0, NULL, slice_size, data, NULL, maxsize,
Wim Taymans's avatar
Wim Taymans committed
150 151 152 153 154
      aoffset + offset, size);

  return mem;
}

155 156 157 158 159 160 161
static GstMemory *
_default_mem_alloc (const GstMemoryAllocator * allocator, gsize maxsize,
    gsize align)
{
  return (GstMemory *) _default_mem_new_block (maxsize, align, 0, maxsize);
}

162
static gsize
Wim Taymans's avatar
Wim Taymans committed
163
_default_mem_get_sizes (GstMemoryDefault * mem, gsize * maxsize)
164
{
Wim Taymans's avatar
Wim Taymans committed
165 166
  if (maxsize)
    *maxsize = mem->maxsize;
167

Wim Taymans's avatar
Wim Taymans committed
168 169 170 171
  return mem->size;
}

static void
Wim Taymans's avatar
Wim Taymans committed
172
_default_mem_resize (GstMemoryDefault * mem, gsize offset, gsize size)
Wim Taymans's avatar
Wim Taymans committed
173
{
Wim Taymans's avatar
Wim Taymans committed
174
  g_return_if_fail (size + mem->offset + offset <= mem->maxsize);
Wim Taymans's avatar
Wim Taymans committed
175 176 177 178 179 180 181 182 183 184 185

  mem->offset += offset;
  mem->size = size;
}

static gpointer
_default_mem_map (GstMemoryDefault * mem, gsize * size, gsize * maxsize,
    GstMapFlags flags)
{
  if (size)
    *size = mem->size;
186
  if (maxsize)
Wim Taymans's avatar
Wim Taymans committed
187
    *maxsize = mem->maxsize;
188

Wim Taymans's avatar
Wim Taymans committed
189
  return mem->data + mem->offset;
190 191 192
}

static gpointer
Wim Taymans's avatar
Wim Taymans committed
193
_default_share_map (GstMemoryDefault * mem, gsize * size, gsize * maxsize,
Wim Taymans's avatar
Wim Taymans committed
194
    GstMapFlags flags)
195
{
Wim Taymans's avatar
Wim Taymans committed
196 197 198
  guint8 *data;

  data = gst_memory_map (mem->mem.parent, size, maxsize, flags);
199 200

  if (size)
Wim Taymans's avatar
Wim Taymans committed
201
    *size = mem->size;
202
  if (maxsize)
Wim Taymans's avatar
Wim Taymans committed
203
    *maxsize -= mem->offset;
204

Wim Taymans's avatar
Wim Taymans committed
205
  return data + mem->offset;
206 207 208
}

static gboolean
Wim Taymans's avatar
Wim Taymans committed
209
_default_mem_unmap (GstMemoryDefault * mem, gpointer data, gsize size)
210
{
Wim Taymans's avatar
Wim Taymans committed
211 212
  if (size != -1)
    mem->size = size;
Wim Taymans's avatar
Wim Taymans committed
213 214
  return TRUE;
}
215

Wim Taymans's avatar
Wim Taymans committed
216
static gboolean
Wim Taymans's avatar
Wim Taymans committed
217
_default_share_unmap (GstMemoryDefault * mem, gpointer data, gsize size)
Wim Taymans's avatar
Wim Taymans committed
218 219 220
{
  gboolean res;
  guint8 *ptr = data;
221

Wim Taymans's avatar
Wim Taymans committed
222 223 224 225
  if (size != -1)
    mem->size = size;
  else
    size = mem->size - mem->offset;
Wim Taymans's avatar
Wim Taymans committed
226 227 228 229 230

  res =
      gst_memory_unmap (mem->mem.parent, ptr - mem->offset, size + mem->offset);

  return res;
231 232 233
}

static void
Wim Taymans's avatar
Wim Taymans committed
234
_default_mem_free (GstMemoryDefault * mem)
235
{
Wim Taymans's avatar
Wim Taymans committed
236 237 238 239 240
  if (mem->mem.parent)
    gst_memory_unref (mem->mem.parent);

  if (mem->free_func)
    mem->free_func (mem->data);
241

Wim Taymans's avatar
Wim Taymans committed
242
  g_slice_free1 (mem->slice_size, mem);
243 244
}

Wim Taymans's avatar
Wim Taymans committed
245
static GstMemoryDefault *
246
_default_mem_copy (GstMemoryDefault * mem, gsize offset, gsize size)
247 248 249
{
  GstMemoryDefault *copy;

Wim Taymans's avatar
Wim Taymans committed
250 251
  if (size == -1)
    size = mem->size > offset ? mem->size - offset : 0;
Wim Taymans's avatar
Wim Taymans committed
252

253 254
  copy = _default_mem_new_block (mem->maxsize, 0, mem->offset + offset, size);
  memcpy (copy->data, mem->data, mem->maxsize);
255

Wim Taymans's avatar
Wim Taymans committed
256
  return copy;
257 258
}

Wim Taymans's avatar
Wim Taymans committed
259
static GstMemoryDefault *
Wim Taymans's avatar
Wim Taymans committed
260
_default_mem_share (GstMemoryDefault * mem, gsize offset, gsize size)
Wim Taymans's avatar
Wim Taymans committed
261 262 263 264 265 266 267 268
{
  GstMemoryDefault *sub;
  GstMemory *parent;

  /* find the real parent */
  if ((parent = mem->mem.parent) == NULL)
    parent = (GstMemory *) mem;

269 270 271
  if (size == -1)
    size = mem->size - offset;

272
  sub = _default_mem_new (parent->flags, parent, mem->data, NULL, mem->maxsize,
Wim Taymans's avatar
Wim Taymans committed
273 274 275
      mem->offset + offset, size);

  return sub;
276 277
}

Wim Taymans's avatar
Wim Taymans committed
278
static gboolean
Wim Taymans's avatar
Wim Taymans committed
279 280
_default_mem_is_span (GstMemoryDefault * mem1, GstMemoryDefault * mem2,
    gsize * offset)
281
{
Wim Taymans's avatar
Wim Taymans committed
282 283
  if (offset)
    *offset = mem1->offset;
284

Wim Taymans's avatar
Wim Taymans committed
285
  /* and memory is contiguous */
Wim Taymans's avatar
Wim Taymans committed
286
  return mem1->data + mem1->offset + mem1->size == mem2->data + mem2->offset;
287 288 289
}

static GstMemory *
290
_fallback_copy (GstMemory * mem, gsize offset, gsize size)
291
{
292 293
  GstMemory *copy;
  guint8 *data, *dest;
294
  gsize msize;
295

296
  data = gst_memory_map (mem, &msize, NULL, GST_MAP_READ);
Wim Taymans's avatar
Wim Taymans committed
297 298
  if (size == -1)
    size = msize > offset ? msize - offset : 0;
299 300 301 302 303 304
  /* use the same allocator as the memory we copy, FIXME, alignment?  */
  copy = gst_memory_allocator_alloc (mem->allocator, size, 1);
  dest = gst_memory_map (copy, NULL, NULL, GST_MAP_WRITE);
  memcpy (dest, data + offset, size);
  gst_memory_unmap (copy, dest, size);

305
  gst_memory_unmap (mem, data, msize);
306

Wim Taymans's avatar
Wim Taymans committed
307
  return (GstMemory *) copy;
308 309 310
}

static GstMemory *
Wim Taymans's avatar
Wim Taymans committed
311
_fallback_share (GstMemory * mem, gsize offset, gsize size)
312 313 314
{
  GstMemoryDefault *sub;

315
  sub = _default_mem_new (0, mem, NULL, NULL, size, offset, size);
316 317 318 319 320

  return (GstMemory *) sub;
}

static gboolean
Wim Taymans's avatar
Wim Taymans committed
321
_fallback_is_span (GstMemory * mem1, GstMemory * mem2, gsize * offset)
322 323 324 325
{
  return FALSE;
}

326 327 328
static GStaticRWLock lock = G_STATIC_RW_LOCK_INIT;
static GHashTable *memoryimpl;

Wim Taymans's avatar
Wim Taymans committed
329 330 331 332
void
_gst_memory_init (void)
{
  static const GstMemoryInfo _mem_info = {
333
    (GstMemoryAllocFunction) _default_mem_alloc,
Wim Taymans's avatar
Wim Taymans committed
334
    (GstMemoryGetSizesFunction) _default_mem_get_sizes,
Wim Taymans's avatar
Wim Taymans committed
335
    (GstMemoryResizeFunction) _default_mem_resize,
Wim Taymans's avatar
Wim Taymans committed
336 337 338 339
    (GstMemoryMapFunction) _default_mem_map,
    (GstMemoryUnmapFunction) _default_mem_unmap,
    (GstMemoryFreeFunction) _default_mem_free,
    (GstMemoryCopyFunction) _default_mem_copy,
Wim Taymans's avatar
Wim Taymans committed
340
    (GstMemoryShareFunction) _default_mem_share,
341 342
    (GstMemoryIsSpanFunction) _default_mem_is_span,
    NULL
Wim Taymans's avatar
Wim Taymans committed
343
  };
Wim Taymans's avatar
Wim Taymans committed
344
  static const GstMemoryInfo _share_info = {
345
    (GstMemoryAllocFunction) _default_mem_alloc,
Wim Taymans's avatar
Wim Taymans committed
346
    (GstMemoryGetSizesFunction) _default_mem_get_sizes,
Wim Taymans's avatar
Wim Taymans committed
347 348 349
    (GstMemoryResizeFunction) _default_mem_resize,
    (GstMemoryMapFunction) _default_share_map,
    (GstMemoryUnmapFunction) _default_share_unmap,
Wim Taymans's avatar
Wim Taymans committed
350 351 352
    (GstMemoryFreeFunction) _default_mem_free,
    NULL,
    NULL,
353
    NULL,
Wim Taymans's avatar
Wim Taymans committed
354 355 356
    NULL
  };

357
  memoryimpl = g_hash_table_new (g_str_hash, g_str_equal);
358

359 360 361 362
  _default_mem_impl =
      gst_memory_allocator_register ("GstMemoryDefault", &_mem_info);
  _default_share_impl =
      gst_memory_allocator_register ("GstMemorySharebuffer", &_share_info);
363

364
  _default_allocator = _default_mem_impl;
365 366
}

Wim Taymans's avatar
Wim Taymans committed
367 368 369 370 371 372 373 374 375 376 377 378 379
/**
 * gst_memory_new_wrapped:
 * @flags: #GstMemoryFlags
 * @data: data to wrap
 * @free_func: function to free @data
 * @maxsize: allocated size of @data
 * @offset: offset in @data
 * @size: size of valid data
 *
 * Allocate a new memory block that wraps the given @data.
 *
 * Returns: a new #GstMemory.
 */
Wim Taymans's avatar
Wim Taymans committed
380 381 382
GstMemory *
gst_memory_new_wrapped (GstMemoryFlags flags, gpointer data,
    GFreeFunc free_func, gsize maxsize, gsize offset, gsize size)
383
{
Wim Taymans's avatar
Wim Taymans committed
384
  GstMemoryDefault *mem;
Wim Taymans's avatar
Wim Taymans committed
385

Wim Taymans's avatar
Wim Taymans committed
386 387 388
  g_return_val_if_fail (data != NULL, NULL);
  g_return_val_if_fail (offset + size <= maxsize, NULL);

Wim Taymans's avatar
Wim Taymans committed
389 390 391 392 393 394 395 396 397
  mem = _default_mem_new (flags, NULL, data, free_func, maxsize, offset, size);

  return (GstMemory *) mem;
}

/**
 * gst_memory_ref:
 * @mem: a #GstMemory
 *
Wim Taymans's avatar
Wim Taymans committed
398 399
 * Increases the refcount of @mem.
 *
Wim Taymans's avatar
Wim Taymans committed
400 401
 * Returns: @mem with increased refcount
 */
402 403 404 405 406 407 408 409 410 411
GstMemory *
gst_memory_ref (GstMemory * mem)
{
  g_return_val_if_fail (mem != NULL, NULL);

  g_atomic_int_inc (&mem->refcount);

  return mem;
}

Wim Taymans's avatar
Wim Taymans committed
412 413 414
/**
 * gst_memory_unref:
 * @mem: a #GstMemory
Wim Taymans's avatar
Wim Taymans committed
415 416 417
 *
 * Decreases the refcount of @mem. When the refcount reaches 0, the free
 * function of @mem will be called.
Wim Taymans's avatar
Wim Taymans committed
418
 */
419 420 421 422
void
gst_memory_unref (GstMemory * mem)
{
  g_return_if_fail (mem != NULL);
423
  g_return_if_fail (mem->allocator != NULL);
424 425

  if (g_atomic_int_dec_and_test (&mem->refcount))
426
    mem->allocator->info.free (mem);
427 428
}

Wim Taymans's avatar
Wim Taymans committed
429 430 431 432 433
/**
 * gst_memory_get_sizes:
 * @mem: a #GstMemory
 * @maxsize: pointer to maxsize
 *
Wim Taymans's avatar
Wim Taymans committed
434 435 436
 * Get the current @size and @maxsize of @mem.
 *
 * Returns: the current sizes of @mem
Wim Taymans's avatar
Wim Taymans committed
437
 */
438 439 440 441 442
gsize
gst_memory_get_sizes (GstMemory * mem, gsize * maxsize)
{
  g_return_val_if_fail (mem != NULL, 0);

443
  return mem->allocator->info.get_sizes (mem, maxsize);
444 445
}

Wim Taymans's avatar
Wim Taymans committed
446 447 448 449 450 451 452 453 454 455 456 457 458 459 460
/**
 * gst_memory_resize:
 * @mem: a #GstMemory
 * @offset: a new offset
 * @size: a new size
 *
 * Resize the memory region. @mem should be writable and offset + size should be
 * less than the maxsize of @mem.
 */
void
gst_memory_resize (GstMemory * mem, gsize offset, gsize size)
{
  g_return_if_fail (mem != NULL);
  g_return_if_fail (GST_MEMORY_IS_WRITABLE (mem));

461
  mem->allocator->info.resize (mem, offset, size);
Wim Taymans's avatar
Wim Taymans committed
462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477
}

/**
 * gst_memory_map:
 * @mem: a #GstMemory
 * @size: pointer for size
 * @maxsize: pointer for maxsize
 * @flags: mapping flags
 *
 * Get a pointer to the memory of @mem that can be accessed according to @flags.
 *
 * @size and @maxsize will contain the size of the memory and the maximum
 * allocated memory of @mem respectively. They can be set to NULL.
 *
 * Returns: a pointer to the memory of @mem.
 */
478 479 480 481 482
gpointer
gst_memory_map (GstMemory * mem, gsize * size, gsize * maxsize,
    GstMapFlags flags)
{
  g_return_val_if_fail (mem != NULL, NULL);
Wim Taymans's avatar
Wim Taymans committed
483 484
  g_return_val_if_fail (!(flags & GST_MAP_WRITE) ||
      GST_MEMORY_IS_WRITABLE (mem), NULL);
485

486
  return mem->allocator->info.map (mem, size, maxsize, flags);
487 488
}

Wim Taymans's avatar
Wim Taymans committed
489 490 491 492 493 494 495 496 497 498 499 500
/**
 * gst_memory_unmap:
 * @mem: a #GstMemory
 * @data: data to unmap
 * @size: new size of @mem
 *
 * Release the memory pointer obtained with gst_memory_map() and set the size of
 * the memory to @size. @size can be set to -1 when the size should not be
 * updated.
 *
 * Returns: TRUE when the memory was release successfully.
 */
501 502 503 504 505
gboolean
gst_memory_unmap (GstMemory * mem, gpointer data, gsize size)
{
  g_return_val_if_fail (mem != NULL, FALSE);

506
  return mem->allocator->info.unmap (mem, data, size);
507 508
}

Wim Taymans's avatar
Wim Taymans committed
509 510 511 512 513 514 515 516 517 518 519 520
/**
 * gst_memory_copy:
 * @mem: a #GstMemory
 * @offset: an offset to copy
 * @size: size to copy
 *
 * Return a copy of @size bytes from @mem starting from @offset. This copy is
 * guaranteed to be writable. @size can be set to -1 to return a copy all bytes
 * from @offset.
 *
 * Returns: a new #GstMemory.
 */
521
GstMemory *
522
gst_memory_copy (GstMemory * mem, gsize offset, gsize size)
523 524 525
{
  g_return_val_if_fail (mem != NULL, NULL);

526
  return mem->allocator->info.copy (mem, offset, size);
527 528
}

Wim Taymans's avatar
Wim Taymans committed
529 530 531 532 533 534 535 536 537 538 539 540 541
/**
 * gst_memory_share:
 * @mem: a #GstMemory
 * @offset: an offset to share
 * @size: size to share
 *
 * Return a shared copy of @size bytes from @mem starting from @offset. No memory
 * copy is performed and the memory region is simply shared. The result is
 * guaranteed to be not-writable. @size can be set to -1 to return a share all bytes
 * from @offset.
 *
 * Returns: a new #GstMemory.
 */
542
GstMemory *
Wim Taymans's avatar
Wim Taymans committed
543
gst_memory_share (GstMemory * mem, gsize offset, gsize size)
544 545 546
{
  g_return_val_if_fail (mem != NULL, NULL);

547
  return mem->allocator->info.share (mem, offset, size);
548 549
}

Wim Taymans's avatar
Wim Taymans committed
550 551 552 553 554 555 556 557 558 559 560 561 562 563 564
/**
 * gst_memory_is_span:
 * @mem1: a #GstMemory
 * @mem2: a #GstMemory
 * @offset: a pointer to a result offset
 *
 * Check if @mem1 and mem2 share the memory with a common parent memory object
 * and that the memory is contiguous.
 *
 * If this is the case, the memory of @mem1 and @mem2 can be merged
 * efficiently by performing gst_memory_share() on the parent object from
 * the returned @offset.
 *
 * Returns: %TRUE if the memory is contiguous and of a common parent.
 */
Wim Taymans's avatar
Wim Taymans committed
565
gboolean
566
gst_memory_is_span (GstMemory * mem1, GstMemory * mem2, gsize * offset)
Wim Taymans's avatar
Wim Taymans committed
567 568 569 570
{
  g_return_val_if_fail (mem1 != NULL, FALSE);
  g_return_val_if_fail (mem2 != NULL, FALSE);

571 572
  /* need to have the same allocators */
  if (mem1->allocator != mem2->allocator)
Wim Taymans's avatar
Wim Taymans committed
573 574
    return FALSE;

575 576 577
  /* need to have the same parent */
  if (mem1->parent == NULL || mem1->parent != mem2->parent)
    return FALSE;
Wim Taymans's avatar
Wim Taymans committed
578

579
  /* and memory is contiguous */
580
  if (!mem1->allocator->info.is_span (mem1, mem2, offset))
581 582 583
    return FALSE;

  return TRUE;
Wim Taymans's avatar
Wim Taymans committed
584
}
585 586 587 588 589 590 591 592 593

/**
 * gst_memory_allocator_register:
 * @name: the name of the allocator
 * @info: #GstMemoryInfo
 *
 * Registers the memory allocator with @name and implementation functions
 * @info.
 *
594 595 596 597 598 599
 * All functions in @info are mandatory exept the copy, share and is_span
 * functions, which will have a default implementation when left NULL.
 *
 * The user_data field in @info will be passed to all calls of the alloc
 * function.
 *
600 601 602 603 604 605 606 607 608 609 610 611
 * Returns: a new #GstMemoryAllocator.
 */
const GstMemoryAllocator *
gst_memory_allocator_register (const gchar * name, const GstMemoryInfo * info)
{
  GstMemoryAllocator *allocator;

#define INSTALL_FALLBACK(_t) \
  if (allocator->info._t == NULL) allocator->info._t = _fallback_ ##_t;

  g_return_val_if_fail (name != NULL, NULL);
  g_return_val_if_fail (info != NULL, NULL);
612
  g_return_val_if_fail (info->alloc != NULL, NULL);
613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639
  g_return_val_if_fail (info->get_sizes != NULL, NULL);
  g_return_val_if_fail (info->resize != NULL, NULL);
  g_return_val_if_fail (info->map != NULL, NULL);
  g_return_val_if_fail (info->unmap != NULL, NULL);
  g_return_val_if_fail (info->free != NULL, NULL);

  allocator = g_slice_new (GstMemoryAllocator);
  allocator->name = g_quark_from_string (name);
  allocator->info = *info;
  INSTALL_FALLBACK (copy);
  INSTALL_FALLBACK (share);
  INSTALL_FALLBACK (is_span);
#undef INSTALL_FALLBACK

  GST_DEBUG ("register \"%s\" of size %" G_GSIZE_FORMAT, name);

  g_static_rw_lock_writer_lock (&lock);
  g_hash_table_insert (memoryimpl, (gpointer) name, (gpointer) allocator);
  g_static_rw_lock_writer_unlock (&lock);

  return allocator;
}

/**
 * gst_memory_allocator_find:
 * @name: the name of the allocator
 *
640 641
 * Find a previously registered allocator with @name. When @name is NULL, the
 * default allocator will be returned.
642 643 644 645 646 647 648
 *
 * Returns: a #GstMemoryAllocator or NULL when the allocator with @name was not
 * registered.
 */
const GstMemoryAllocator *
gst_memory_allocator_find (const gchar * name)
{
649
  const GstMemoryAllocator *allocator;
650

651 652 653 654 655 656 657
  g_static_rw_lock_reader_lock (&lock);
  if (name) {
    allocator = g_hash_table_lookup (memoryimpl, (gconstpointer) name);
  } else {
    allocator = _default_allocator;
  }
  g_static_rw_lock_reader_unlock (&lock);
658 659 660 661 662 663 664 665 666 667 668 669 670 671 672

  return allocator;
}

/**
 * gst_memory_allocator_set_default:
 * @allocator: a ##GstMemoryAllocator
 *
 * Set the default allocator.
 */
void
gst_memory_allocator_set_default (const GstMemoryAllocator * allocator)
{
  g_return_if_fail (allocator != NULL);

673
  g_static_rw_lock_writer_lock (&lock);
674
  _default_allocator = allocator;
675
  g_static_rw_lock_writer_unlock (&lock);
676 677 678 679 680 681 682 683 684 685 686
}

/**
 * gst_memory_allocator_alloc:
 * @allocator: a #GstMemoryAllocator to use
 * @maxsize: allocated size of @data
 * @align: alignment for the data
 *
 * Use @allocator to allocate a new memory block with memory that is at least
 * @maxsize big and has the given alignment.
 *
687 688
 * When @allocator is NULL, the default allocator will be used.
 *
689 690 691 692 693 694 695 696 697 698 699 700 701 702
 * @align is given as a bitmask so that @align + 1 equals the amount of bytes to
 * align to. For example, to align to 8 bytes, use an alignment of 7.
 *
 * Returns: a new #GstMemory.
 */
GstMemory *
gst_memory_allocator_alloc (const GstMemoryAllocator * allocator,
    gsize maxsize, gsize align)
{
  g_return_val_if_fail (((align + 1) & align) == 0, NULL);

  if (allocator == NULL)
    allocator = _default_allocator;

703 704
  return allocator->info.alloc (allocator, maxsize, align,
      allocator->info.user_data);
705
}