2 * Copyright (C) 2011 Wim Taymans <wim.taymans@gmail.be>
4 * gstmemory.c: memory block handling
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Library General Public
8 * License as published by the Free Software Foundation; either
9 * version 2 of the License, or (at your option) any later version.
11 * This library 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 GNU
14 * Library General Public License for more details.
16 * You should have received a copy of the GNU Library General Public
17 * License along with this library; if not, write to the
18 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
19 * Boston, MA 02111-1307, USA.
24 * @short_description: refcounted wrapper for memory blocks
25 * @see_also: #GstBuffer
27 * GstMemory is a lightweight refcounted object that wraps a region of memory.
28 * They are typically used to manage the data of a #GstBuffer.
30 * A GstMemory object has an allocated region of memory of maxsize. The maximum
31 * size does not change during the lifetime of the memory object. The memory
32 * also has an offset and size property that specifies the valid range of memory
33 * in the allocated region.
35 * Memory is usually created by allocators with a gst_allocator_alloc()
36 * method call. When NULL is used as the allocator, the default allocator will
39 * New allocators can be registered with gst_allocator_register().
40 * Allocators are identified by name and can be retrieved with
41 * gst_allocator_find(). gst_allocator_set_default() can be used to change the
44 * New memory can be created with gst_memory_new_wrapped() that wraps the memory
45 * allocated elsewhere.
47 * Refcounting of the memory block is performed with gst_memory_ref() and
50 * The size of the memory can be retrieved and changed with
51 * gst_memory_get_sizes() and gst_memory_resize() respectively.
53 * Getting access to the data of the memory is performed with gst_memory_map().
54 * The call will return a pointer to offset bytes into the region of memory.
55 * After the memory access is completed, gst_memory_unmap() should be called.
57 * Memory can be copied with gst_memory_copy(), which will return a writable
58 * copy. gst_memory_share() will create a new memory block that shares the
59 * memory with an existing memory block at a custom offset and with a custom
62 * Memory can be efficiently merged when gst_memory_is_span() returns TRUE.
64 * Last reviewed on 2012-03-28 (0.11.3)
71 #include "gst_private.h"
72 #include "gstmemory.h"
74 GST_DEFINE_MINI_OBJECT_TYPE (GstMemory, gst_memory);
76 GST_DEFINE_MINI_OBJECT_TYPE (GstAllocator, gst_allocator);
78 G_DEFINE_BOXED_TYPE (GstAllocationParams, gst_allocation_params,
79 (GBoxedCopyFunc) gst_allocation_params_copy,
80 (GBoxedFreeFunc) gst_allocation_params_free);
82 #if defined(MEMORY_ALIGNMENT_MALLOC)
83 size_t gst_memory_alignment = 7;
84 #elif defined(MEMORY_ALIGNMENT_PAGESIZE)
85 /* we fill this in in the _init method */
86 size_t gst_memory_alignment = 0;
87 #elif defined(MEMORY_ALIGNMENT)
88 size_t gst_memory_alignment = MEMORY_ALIGNMENT - 1;
90 #error "No memory alignment configured"
91 size_t gst_memory_alignment = 0;
96 GstMiniObject mini_object;
103 GDestroyNotify notify;
106 /* default memory implementation */
113 GDestroyNotify notify;
116 /* the default allocator */
117 static GstAllocator *_default_allocator;
119 /* our predefined allocators */
120 static GstAllocator *_default_mem_impl;
123 _gst_memory_copy (GstMemory * mem)
125 return gst_memory_copy (mem, 0, -1);
129 _gst_memory_free (GstMemory * mem)
131 /* there should be no outstanding mappings */
132 g_return_if_fail (g_atomic_int_get (&mem->state) < 4);
133 mem->allocator->info.mem_free (mem);
136 /* initialize the fields */
138 _default_mem_init (GstMemoryDefault * mem, GstMemoryFlags flags,
139 GstMemory * parent, gsize slice_size, gpointer data,
140 gsize maxsize, gsize offset, gsize size, gsize align,
141 gpointer user_data, GDestroyNotify notify)
143 gst_mini_object_init (GST_MINI_OBJECT_CAST (mem), GST_TYPE_MEMORY);
145 mem->mem.mini_object.copy = (GstMiniObjectCopyFunction) _gst_memory_copy;
146 mem->mem.mini_object.dispose = NULL;
147 mem->mem.mini_object.free = (GstMiniObjectFreeFunction) _gst_memory_free;
148 mem->mem.mini_object.flags = flags;
150 mem->mem.allocator = _default_mem_impl;
151 mem->mem.parent = parent ? gst_memory_ref (parent) : NULL;
152 mem->mem.state = (flags & GST_MEMORY_FLAG_READONLY ? 0x1 : 0);
153 mem->mem.maxsize = maxsize;
154 mem->mem.align = align;
155 mem->mem.offset = offset;
156 mem->mem.size = size;
157 mem->slice_size = slice_size;
159 mem->user_data = user_data;
160 mem->notify = notify;
162 GST_CAT_DEBUG (GST_CAT_MEMORY, "new memory %p, maxsize:%" G_GSIZE_FORMAT
163 " offset:%" G_GSIZE_FORMAT " size:%" G_GSIZE_FORMAT, mem, maxsize,
167 /* create a new memory block that manages the given memory */
168 static GstMemoryDefault *
169 _default_mem_new (GstMemoryFlags flags, GstMemory * parent, gpointer data,
170 gsize maxsize, gsize offset, gsize size, gsize align, gpointer user_data,
171 GDestroyNotify notify)
173 GstMemoryDefault *mem;
176 slice_size = sizeof (GstMemoryDefault);
178 mem = g_slice_alloc (slice_size);
179 _default_mem_init (mem, flags, parent, slice_size,
180 data, maxsize, offset, size, align, user_data, notify);
185 /* allocate the memory and structure in one block */
186 static GstMemoryDefault *
187 _default_mem_new_block (GstMemoryFlags flags, gsize maxsize, gsize align,
188 gsize offset, gsize size)
190 GstMemoryDefault *mem;
191 gsize aoffset, slice_size, padding;
194 /* ensure configured alignment */
195 align |= gst_memory_alignment;
196 /* allocate more to compensate for alignment */
198 /* alloc header and data in one block */
199 slice_size = sizeof (GstMemoryDefault) + maxsize;
201 mem = g_slice_alloc (slice_size);
205 data = (guint8 *) mem + sizeof (GstMemoryDefault);
208 if ((aoffset = ((guintptr) data & align))) {
209 aoffset = (align + 1) - aoffset;
214 if (offset && (flags & GST_MEMORY_FLAG_ZERO_PREFIXED))
215 memset (data, 0, offset);
217 padding = maxsize - (offset + size);
218 if (padding && (flags & GST_MEMORY_FLAG_ZERO_PADDED))
219 memset (data + offset + size, 0, padding);
221 _default_mem_init (mem, flags, NULL, slice_size, data, maxsize,
222 offset, size, align, NULL, NULL);
228 _default_alloc_alloc (GstAllocator * allocator, gsize size,
229 GstAllocationParams * params, gpointer user_data)
231 gsize maxsize = size + params->prefix + params->padding;
233 return (GstMemory *) _default_mem_new_block (params->flags,
234 maxsize, params->align, params->prefix, size);
238 _default_mem_map (GstMemoryDefault * mem, gsize maxsize, GstMapFlags flags)
244 _default_mem_unmap (GstMemoryDefault * mem)
250 _default_mem_free (GstMemoryDefault * mem)
252 GST_CAT_DEBUG (GST_CAT_MEMORY, "free memory %p", mem);
255 gst_memory_unref (mem->mem.parent);
258 mem->notify (mem->user_data);
260 g_slice_free1 (mem->slice_size, mem);
263 static GstMemoryDefault *
264 _default_mem_copy (GstMemoryDefault * mem, gssize offset, gsize size)
266 GstMemoryDefault *copy;
269 size = mem->mem.size > offset ? mem->mem.size - offset : 0;
272 _default_mem_new_block (0, mem->mem.maxsize, 0, mem->mem.offset + offset,
274 GST_CAT_DEBUG (GST_CAT_PERFORMANCE,
275 "memcpy %" G_GSIZE_FORMAT " memory %p -> %p", mem->mem.maxsize, mem,
277 memcpy (copy->data, mem->data, mem->mem.maxsize);
282 static GstMemoryDefault *
283 _default_mem_share (GstMemoryDefault * mem, gssize offset, gsize size)
285 GstMemoryDefault *sub;
288 /* find the real parent */
289 if ((parent = mem->mem.parent) == NULL)
290 parent = (GstMemory *) mem;
293 size = mem->mem.size - offset;
296 _default_mem_new (GST_MINI_OBJECT_FLAGS (parent), parent, mem->data,
297 mem->mem.maxsize, mem->mem.offset + offset, size, mem->mem.align, NULL,
304 _default_mem_is_span (GstMemoryDefault * mem1, GstMemoryDefault * mem2,
309 GstMemoryDefault *parent;
311 parent = (GstMemoryDefault *) mem1->mem.parent;
313 *offset = mem1->mem.offset - parent->mem.offset;
316 /* and memory is contiguous */
317 return mem1->data + mem1->mem.offset + mem1->mem.size ==
318 mem2->data + mem2->mem.offset;
322 _fallback_mem_copy (GstMemory * mem, gssize offset, gssize size)
325 GstMapInfo sinfo, dinfo;
326 GstAllocationParams params = { 0, 0, 0, mem->align, };
328 if (!gst_memory_map (mem, &sinfo, GST_MAP_READ))
332 size = sinfo.size > offset ? sinfo.size - offset : 0;
334 /* use the same allocator as the memory we copy */
335 copy = gst_allocator_alloc (mem->allocator, size, ¶ms);
336 if (!gst_memory_map (copy, &dinfo, GST_MAP_WRITE)) {
337 GST_CAT_WARNING (GST_CAT_MEMORY, "could not write map memory %p", copy);
338 gst_memory_unmap (mem, &sinfo);
342 GST_CAT_DEBUG (GST_CAT_PERFORMANCE,
343 "memcpy %" G_GSSIZE_FORMAT " memory %p -> %p", size, mem, copy);
344 memcpy (dinfo.data, sinfo.data + offset, size);
345 gst_memory_unmap (copy, &dinfo);
346 gst_memory_unmap (mem, &sinfo);
352 _fallback_mem_is_span (GstMemory * mem1, GstMemory * mem2, gsize * offset)
358 static GHashTable *allocators;
361 _priv_sysmem_notify (gpointer user_data)
363 g_warning ("The default memory allocator was freed!");
367 _priv_gst_memory_initialize (void)
369 static const GstMemoryInfo _mem_info = {
370 GST_ALLOCATOR_SYSMEM,
371 (GstAllocatorAllocFunction) _default_alloc_alloc,
372 (GstMemoryMapFunction) _default_mem_map,
373 (GstMemoryUnmapFunction) _default_mem_unmap,
374 (GstMemoryFreeFunction) _default_mem_free,
375 (GstMemoryCopyFunction) _default_mem_copy,
376 (GstMemoryShareFunction) _default_mem_share,
377 (GstMemoryIsSpanFunction) _default_mem_is_span,
380 g_rw_lock_init (&lock);
381 allocators = g_hash_table_new (g_str_hash, g_str_equal);
383 #ifdef HAVE_GETPAGESIZE
384 #ifdef MEMORY_ALIGNMENT_PAGESIZE
385 gst_memory_alignment = getpagesize () - 1;
389 GST_CAT_DEBUG (GST_CAT_MEMORY, "memory alignment: %" G_GSIZE_FORMAT,
390 gst_memory_alignment);
392 _default_mem_impl = gst_allocator_new (&_mem_info, NULL, _priv_sysmem_notify);
394 _default_allocator = gst_allocator_ref (_default_mem_impl);
395 gst_allocator_register (GST_ALLOCATOR_SYSMEM,
396 gst_allocator_ref (_default_mem_impl));
400 * gst_memory_new_wrapped:
401 * @flags: #GstMemoryFlags
402 * @data: data to wrap
403 * @maxsize: allocated size of @data
404 * @offset: offset in @data
405 * @size: size of valid data
406 * @user_data: user_data
407 * @notify: called with @user_data when the memory is freed
409 * Allocate a new memory block that wraps the given @data.
411 * The prefix/padding must be filled with 0 if @flags contains
412 * #GST_MEMORY_FLAG_ZERO_PREFIXED and #GST_MEMORY_FLAG_ZERO_PADDED respectively.
414 * Returns: a new #GstMemory.
417 gst_memory_new_wrapped (GstMemoryFlags flags, gpointer data,
418 gsize maxsize, gsize offset, gsize size, gpointer user_data,
419 GDestroyNotify notify)
421 GstMemoryDefault *mem;
423 g_return_val_if_fail (data != NULL, NULL);
424 g_return_val_if_fail (offset + size <= maxsize, NULL);
427 _default_mem_new (flags, NULL, data, maxsize, offset, size, 0, user_data,
430 return (GstMemory *) mem;
434 * gst_memory_is_exclusive:
437 * Check if the current ref to @mem is exclusive, this means that no other
438 * references exist other than @mem.
441 gst_memory_is_exclusive (GstMemory * mem)
443 g_return_val_if_fail (mem != NULL, FALSE);
445 return GST_MINI_OBJECT_REFCOUNT_VALUE (mem) == 1;
449 * gst_memory_get_sizes:
451 * @offset: pointer to offset
452 * @maxsize: pointer to maxsize
454 * Get the current @size, @offset and @maxsize of @mem.
456 * Returns: the current sizes of @mem
459 gst_memory_get_sizes (GstMemory * mem, gsize * offset, gsize * maxsize)
461 g_return_val_if_fail (mem != NULL, 0);
464 *offset = mem->offset;
466 *maxsize = mem->maxsize;
474 * @offset: a new offset
477 * Resize the memory region. @mem should be writable and offset + size should be
478 * less than the maxsize of @mem.
480 * #GST_MEMORY_FLAG_ZERO_PREFIXED and #GST_MEMORY_FLAG_ZERO_PADDED will be
481 * cleared when offset or padding is increased respectively.
484 gst_memory_resize (GstMemory * mem, gssize offset, gsize size)
486 g_return_if_fail (mem != NULL);
487 g_return_if_fail (offset >= 0 || mem->offset >= -offset);
488 g_return_if_fail (size + mem->offset + offset <= mem->maxsize);
490 /* if we increase the prefix, we can't guarantee it is still 0 filled */
491 if ((offset > 0) && GST_MEMORY_IS_ZERO_PREFIXED (mem))
492 GST_MEMORY_FLAG_UNSET (mem, GST_MEMORY_FLAG_ZERO_PREFIXED);
494 /* if we increase the padding, we can't guarantee it is still 0 filled */
495 if ((offset + size < mem->size) && GST_MEMORY_IS_ZERO_PADDED (mem))
496 GST_MEMORY_FLAG_UNSET (mem, GST_MEMORY_FLAG_ZERO_PADDED);
498 mem->offset += offset;
503 gst_memory_lock (GstMemory * mem, GstMapFlags flags)
505 gint access_mode, state, newstate;
507 access_mode = flags & 3;
510 state = g_atomic_int_get (&mem->state);
512 /* nothing mapped, set access_mode and refcount */
513 newstate = 4 | access_mode;
515 /* access_mode must match */
516 if ((state & access_mode) != access_mode)
518 /* increase refcount */
519 newstate = state + 4;
521 } while (!g_atomic_int_compare_and_exchange (&mem->state, state, newstate));
527 GST_CAT_DEBUG (GST_CAT_MEMORY, "lock failed %p: state %d, access_mode %d",
528 mem, state, access_mode);
534 gst_memory_unlock (GstMemory * mem)
536 gint state, newstate;
539 state = g_atomic_int_get (&mem->state);
540 /* decrease the refcount */
541 newstate = state - 4;
542 /* last refcount, unset access_mode */
545 } while (!g_atomic_int_compare_and_exchange (&mem->state, state, newstate));
550 * gst_memory_make_mapped:
551 * @mem: (transfer full): a #GstMemory
552 * @info: (out): pointer for info
553 * @flags: mapping flags
555 * Create a #GstMemory object that is mapped with @flags. If @mem is mappable
556 * with @flags, this function returns the mapped @mem directly. Otherwise a
557 * mapped copy of @mem is returned.
559 * This function takes ownership of old @mem and returns a reference to a new
562 * Returns: (transfer full): a #GstMemory object mapped with @flags or NULL when
563 * a mapping is not possible.
566 gst_memory_make_mapped (GstMemory * mem, GstMapInfo * info, GstMapFlags flags)
570 if (gst_memory_map (mem, info, flags)) {
573 result = gst_memory_copy (mem, 0, -1);
574 gst_memory_unref (mem);
579 if (!gst_memory_map (result, info, flags))
587 GST_CAT_DEBUG (GST_CAT_MEMORY, "cannot copy memory %p", mem);
592 GST_CAT_DEBUG (GST_CAT_MEMORY, "cannot map memory %p with flags %d", mem,
594 gst_memory_unref (result);
602 * @info: (out): pointer for info
603 * @flags: mapping flags
605 * Fill @info with the pointer and sizes of the memory in @mem that can be
606 * accessed according to @flags.
608 * This function can return %FALSE for various reasons:
609 * - the memory backed by @mem is not accessible with the given @flags.
610 * - the memory was already mapped with a different mapping.
612 * @info and its contents remain valid for as long as @mem is valid and
613 * until gst_memory_unmap() is called.
615 * For each gst_memory_map() call, a corresponding gst_memory_unmap() call
618 * Returns: %TRUE if the map operation was successful.
621 gst_memory_map (GstMemory * mem, GstMapInfo * info, GstMapFlags flags)
623 g_return_val_if_fail (mem != NULL, FALSE);
624 g_return_val_if_fail (info != NULL, FALSE);
626 if (!gst_memory_lock (mem, flags))
629 info->data = mem->allocator->info.mem_map (mem, mem->maxsize, flags);
631 if (G_UNLIKELY (info->data == NULL))
636 info->size = mem->size;
637 info->maxsize = mem->maxsize - mem->offset;
638 info->data = info->data + mem->offset;
645 GST_CAT_DEBUG (GST_CAT_MEMORY, "mem %p: lock %d failed", mem, flags);
650 /* something went wrong, restore the orginal state again */
651 GST_CAT_ERROR (GST_CAT_MEMORY, "mem %p: map failed", mem);
652 gst_memory_unlock (mem);
660 * @info: a #GstMapInfo
662 * Release the memory obtained with gst_memory_map()
665 gst_memory_unmap (GstMemory * mem, GstMapInfo * info)
667 g_return_if_fail (mem != NULL);
668 g_return_if_fail (info != NULL);
669 g_return_if_fail (info->memory == mem);
670 /* there must be a ref */
671 g_return_if_fail (g_atomic_int_get (&mem->state) >= 4);
673 mem->allocator->info.mem_unmap (mem);
674 gst_memory_unlock (mem);
680 * @offset: an offset to copy
681 * @size: size to copy or -1 to copy all bytes from offset
683 * Return a copy of @size bytes from @mem starting from @offset. This copy is
684 * guaranteed to be writable. @size can be set to -1 to return a copy all bytes
687 * Returns: a new #GstMemory.
690 gst_memory_copy (GstMemory * mem, gssize offset, gssize size)
694 g_return_val_if_fail (mem != NULL, NULL);
696 copy = mem->allocator->info.mem_copy (mem, offset, size);
704 * @offset: an offset to share
705 * @size: size to share or -1 to share bytes from offset
707 * Return a shared copy of @size bytes from @mem starting from @offset. No
708 * memory copy is performed and the memory region is simply shared. The result
709 * is guaranteed to be not-writable. @size can be set to -1 to return a share
710 * all bytes from @offset.
712 * Returns: a new #GstMemory.
715 gst_memory_share (GstMemory * mem, gssize offset, gssize size)
719 g_return_val_if_fail (mem != NULL, NULL);
720 g_return_val_if_fail (!GST_MEMORY_FLAG_IS_SET (mem, GST_MEMORY_FLAG_NO_SHARE),
723 shared = mem->allocator->info.mem_share (mem, offset, size);
729 * gst_memory_is_span:
730 * @mem1: a #GstMemory
731 * @mem2: a #GstMemory
732 * @offset: a pointer to a result offset
734 * Check if @mem1 and mem2 share the memory with a common parent memory object
735 * and that the memory is contiguous.
737 * If this is the case, the memory of @mem1 and @mem2 can be merged
738 * efficiently by performing gst_memory_share() on the parent object from
739 * the returned @offset.
741 * Returns: %TRUE if the memory is contiguous and of a common parent.
744 gst_memory_is_span (GstMemory * mem1, GstMemory * mem2, gsize * offset)
746 g_return_val_if_fail (mem1 != NULL, FALSE);
747 g_return_val_if_fail (mem2 != NULL, FALSE);
749 /* need to have the same allocators */
750 if (mem1->allocator != mem2->allocator)
753 /* need to have the same parent */
754 if (mem1->parent == NULL || mem1->parent != mem2->parent)
757 /* and memory is contiguous */
758 if (!mem1->allocator->info.mem_is_span (mem1, mem2, offset))
765 _gst_allocator_free (GstAllocator * allocator)
767 if (allocator->notify)
768 allocator->notify (allocator->user_data);
770 g_slice_free1 (allocator->slice_size, allocator);
773 static GstAllocator *
774 _gst_allocator_copy (GstAllocator * allocator)
776 return gst_allocator_ref (allocator);
781 * @info: a #GstMemoryInfo
782 * @user_data: user data
783 * @notify: a #GDestroyNotify for @user_data
785 * Create a new memory allocator with @info and @user_data.
787 * All functions in @info are mandatory exept the copy and is_span
788 * functions, which will have a default implementation when left NULL.
790 * The @user_data will be passed to all calls of the alloc function. @notify
791 * will be called with @user_data when the allocator is freed.
793 * Returns: a new #GstAllocator.
796 gst_allocator_new (const GstMemoryInfo * info, gpointer user_data,
797 GDestroyNotify notify)
799 GstAllocator *allocator;
801 g_return_val_if_fail (info != NULL, NULL);
802 g_return_val_if_fail (info->alloc != NULL, NULL);
803 g_return_val_if_fail (info->mem_map != NULL, NULL);
804 g_return_val_if_fail (info->mem_unmap != NULL, NULL);
805 g_return_val_if_fail (info->mem_free != NULL, NULL);
806 g_return_val_if_fail (info->mem_share != NULL, NULL);
808 allocator = g_slice_new0 (GstAllocator);
810 gst_mini_object_init (GST_MINI_OBJECT_CAST (allocator), GST_TYPE_ALLOCATOR);
812 allocator->mini_object.copy = (GstMiniObjectCopyFunction) _gst_allocator_copy;
813 allocator->mini_object.free = (GstMiniObjectFreeFunction) _gst_allocator_free;
815 allocator->slice_size = sizeof (GstAllocator);
816 allocator->info = *info;
817 allocator->user_data = user_data;
818 allocator->notify = notify;
820 #define INSTALL_FALLBACK(_t) \
821 if (allocator->info._t == NULL) allocator->info._t = _fallback_ ##_t;
822 INSTALL_FALLBACK (mem_copy);
823 INSTALL_FALLBACK (mem_is_span);
824 #undef INSTALL_FALLBACK
826 GST_CAT_DEBUG (GST_CAT_MEMORY, "new allocator %p", allocator);
832 * gst_allocator_get_memory_type:
833 * @allocator: a #GstAllocator
835 * Get the memory type allocated by this allocator
837 * Returns: the memory type provided by @allocator
840 gst_allocator_get_memory_type (GstAllocator * allocator)
842 g_return_val_if_fail (allocator != NULL, NULL);
844 return allocator->info.mem_type;
848 * gst_allocator_register:
849 * @name: the name of the allocator
850 * @allocator: (transfer full): #GstAllocator
852 * Registers the memory @allocator with @name. This function takes ownership of
856 gst_allocator_register (const gchar * name, GstAllocator * allocator)
858 g_return_if_fail (name != NULL);
859 g_return_if_fail (allocator != NULL);
861 GST_CAT_DEBUG (GST_CAT_MEMORY, "registering allocator %p with name \"%s\"",
864 g_rw_lock_writer_lock (&lock);
865 g_hash_table_insert (allocators, (gpointer) name, (gpointer) allocator);
866 g_rw_lock_writer_unlock (&lock);
870 * gst_allocator_find:
871 * @name: the name of the allocator
873 * Find a previously registered allocator with @name. When @name is NULL, the
874 * default allocator will be returned.
876 * Returns: (transfer full): a #GstAllocator or NULL when the allocator with @name was not
877 * registered. Use gst_allocator_unref() to release the allocator after usage.
880 gst_allocator_find (const gchar * name)
882 GstAllocator *allocator;
884 g_rw_lock_reader_lock (&lock);
886 allocator = g_hash_table_lookup (allocators, (gconstpointer) name);
888 allocator = _default_allocator;
891 gst_allocator_ref (allocator);
892 g_rw_lock_reader_unlock (&lock);
898 * gst_allocator_set_default:
899 * @allocator: (transfer full): a #GstAllocator
901 * Set the default allocator. This function takes ownership of @allocator.
904 gst_allocator_set_default (GstAllocator * allocator)
907 g_return_if_fail (allocator != NULL);
909 g_rw_lock_writer_lock (&lock);
910 old = _default_allocator;
911 _default_allocator = allocator;
912 g_rw_lock_writer_unlock (&lock);
915 gst_allocator_unref (old);
919 * gst_allocation_params_init:
920 * @params: a #GstAllocationParams
922 * Initialize @params to its default values
925 gst_allocation_params_init (GstAllocationParams * params)
927 g_return_if_fail (params != NULL);
929 memset (params, 0, sizeof (GstAllocationParams));
933 * gst_allocation_params_copy:
934 * @params: (transfer none): a #GstAllocationParams
936 * Create a copy of @params.
938 * Free-function: gst_allocation_params_free
940 * Returns: (transfer full): a new ##GstAllocationParams, free with
941 * gst_allocation_params_free().
943 GstAllocationParams *
944 gst_allocation_params_copy (const GstAllocationParams * params)
946 GstAllocationParams *result = NULL;
950 (GstAllocationParams *) g_slice_copy (sizeof (GstAllocationParams),
957 * gst_allocation_params_free:
958 * @params: (in) (transfer full): a #GstAllocationParams
963 gst_allocation_params_free (GstAllocationParams * params)
965 g_slice_free (GstAllocationParams, params);
969 * gst_allocator_alloc:
970 * @allocator: (transfer none) (allow-none): a #GstAllocator to use
971 * @size: size of the visible memory area
972 * @params: (transfer none) (allow-none): optional parameters
974 * Use @allocator to allocate a new memory block with memory that is at least
977 * The optional @params can specify the prefix and padding for the memory. If
978 * NULL is passed, no flags, no extra prefix/padding and a default alignment is
981 * The prefix/padding will be filled with 0 if flags contains
982 * #GST_MEMORY_FLAG_ZERO_PREFIXED and #GST_MEMORY_FLAG_ZERO_PADDED respectively.
984 * When @allocator is NULL, the default allocator will be used.
986 * The alignment in @params is given as a bitmask so that @align + 1 equals
987 * the amount of bytes to align to. For example, to align to 8 bytes,
988 * use an alignment of 7.
990 * Returns: (transfer full): a new #GstMemory.
993 gst_allocator_alloc (GstAllocator * allocator, gsize size,
994 GstAllocationParams * params)
997 static GstAllocationParams defparams = { 0, 0, 0, 0, };
1000 g_return_val_if_fail (((params->align + 1) & params->align) == 0, NULL);
1002 params = &defparams;
1005 if (allocator == NULL)
1006 allocator = _default_allocator;
1008 mem = allocator->info.alloc (allocator, size, params, allocator->user_data);