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;
101 GDestroyNotify notify;
104 /* default memory implementation */
111 GDestroyNotify notify;
114 /* the default allocator */
115 static GstAllocator *_default_allocator;
117 /* our predefined allocators */
118 static GstAllocator *_default_mem_impl;
121 _gst_memory_copy (GstMemory * mem)
123 return gst_memory_copy (mem, 0, -1);
127 _gst_memory_free (GstMemory * mem)
129 /* there should be no outstanding mappings */
130 g_return_if_fail (g_atomic_int_get (&mem->state) < 4);
131 mem->allocator->info.mem_free (mem);
134 /* initialize the fields */
136 _default_mem_init (GstMemoryDefault * mem, GstMemoryFlags flags,
137 GstMemory * parent, gsize slice_size, gpointer data,
138 gsize maxsize, gsize offset, gsize size, gsize align,
139 gpointer user_data, GDestroyNotify notify)
141 gst_mini_object_init (GST_MINI_OBJECT_CAST (mem), GST_TYPE_MEMORY);
143 mem->mem.mini_object.copy = (GstMiniObjectCopyFunction) _gst_memory_copy;
144 mem->mem.mini_object.dispose = NULL;
145 mem->mem.mini_object.free = (GstMiniObjectFreeFunction) _gst_memory_free;
146 mem->mem.mini_object.flags = flags;
148 mem->mem.allocator = _default_mem_impl;
149 mem->mem.parent = parent ? gst_memory_ref (parent) : NULL;
150 mem->mem.state = (flags & GST_MEMORY_FLAG_READONLY ? 0x1 : 0);
151 mem->mem.maxsize = maxsize;
152 mem->mem.align = align;
153 mem->mem.offset = offset;
154 mem->mem.size = size;
155 mem->slice_size = slice_size;
157 mem->user_data = user_data;
158 mem->notify = notify;
160 GST_CAT_DEBUG (GST_CAT_MEMORY, "new memory %p, maxsize:%" G_GSIZE_FORMAT
161 " offset:%" G_GSIZE_FORMAT " size:%" G_GSIZE_FORMAT, mem, maxsize,
165 /* create a new memory block that manages the given memory */
166 static GstMemoryDefault *
167 _default_mem_new (GstMemoryFlags flags, GstMemory * parent, gpointer data,
168 gsize maxsize, gsize offset, gsize size, gsize align, gpointer user_data,
169 GDestroyNotify notify)
171 GstMemoryDefault *mem;
174 slice_size = sizeof (GstMemoryDefault);
176 mem = g_slice_alloc (slice_size);
177 _default_mem_init (mem, flags, parent, slice_size,
178 data, maxsize, offset, size, align, user_data, notify);
183 /* allocate the memory and structure in one block */
184 static GstMemoryDefault *
185 _default_mem_new_block (GstMemoryFlags flags, gsize maxsize, gsize align,
186 gsize offset, gsize size)
188 GstMemoryDefault *mem;
189 gsize aoffset, slice_size, padding;
192 /* ensure configured alignment */
193 align |= gst_memory_alignment;
194 /* allocate more to compensate for alignment */
196 /* alloc header and data in one block */
197 slice_size = sizeof (GstMemoryDefault) + maxsize;
199 mem = g_slice_alloc (slice_size);
203 data = (guint8 *) mem + sizeof (GstMemoryDefault);
206 if ((aoffset = ((guintptr) data & align))) {
207 aoffset = (align + 1) - aoffset;
212 if (offset && (flags & GST_MEMORY_FLAG_ZERO_PREFIXED))
213 memset (data, 0, offset);
215 padding = maxsize - (offset + size);
216 if (padding && (flags & GST_MEMORY_FLAG_ZERO_PADDED))
217 memset (data + offset + size, 0, padding);
219 _default_mem_init (mem, flags, NULL, slice_size, data, maxsize,
220 offset, size, align, NULL, NULL);
226 _default_alloc_alloc (GstAllocator * allocator, gsize size,
227 GstAllocationParams * params, gpointer user_data)
229 gsize maxsize = size + params->prefix + params->padding;
231 return (GstMemory *) _default_mem_new_block (params->flags,
232 maxsize, params->align, params->prefix, size);
236 _default_mem_map (GstMemoryDefault * mem, gsize maxsize, GstMapFlags flags)
242 _default_mem_unmap (GstMemoryDefault * mem)
248 _default_mem_free (GstMemoryDefault * mem)
250 GST_CAT_DEBUG (GST_CAT_MEMORY, "free memory %p", mem);
253 gst_memory_unref (mem->mem.parent);
256 mem->notify (mem->user_data);
258 g_slice_free1 (mem->slice_size, mem);
261 static GstMemoryDefault *
262 _default_mem_copy (GstMemoryDefault * mem, gssize offset, gsize size)
264 GstMemoryDefault *copy;
267 size = mem->mem.size > offset ? mem->mem.size - offset : 0;
270 _default_mem_new_block (0, mem->mem.maxsize, 0, mem->mem.offset + offset,
272 GST_CAT_DEBUG (GST_CAT_PERFORMANCE,
273 "memcpy %" G_GSIZE_FORMAT " memory %p -> %p", mem->mem.maxsize, mem,
275 memcpy (copy->data, mem->data, mem->mem.maxsize);
280 static GstMemoryDefault *
281 _default_mem_share (GstMemoryDefault * mem, gssize offset, gsize size)
283 GstMemoryDefault *sub;
286 /* find the real parent */
287 if ((parent = mem->mem.parent) == NULL)
288 parent = (GstMemory *) mem;
291 size = mem->mem.size - offset;
294 _default_mem_new (GST_MINI_OBJECT_FLAGS (parent), parent, mem->data,
295 mem->mem.maxsize, mem->mem.offset + offset, size, mem->mem.align, NULL,
302 _default_mem_is_span (GstMemoryDefault * mem1, GstMemoryDefault * mem2,
307 GstMemoryDefault *parent;
309 parent = (GstMemoryDefault *) mem1->mem.parent;
311 *offset = mem1->mem.offset - parent->mem.offset;
314 /* and memory is contiguous */
315 return mem1->data + mem1->mem.offset + mem1->mem.size ==
316 mem2->data + mem2->mem.offset;
320 _fallback_mem_copy (GstMemory * mem, gssize offset, gssize size)
323 GstMapInfo sinfo, dinfo;
324 GstAllocationParams params = { 0, 0, 0, mem->align, };
326 if (!gst_memory_map (mem, &sinfo, GST_MAP_READ))
330 size = sinfo.size > offset ? sinfo.size - offset : 0;
332 /* use the same allocator as the memory we copy */
333 copy = gst_allocator_alloc (mem->allocator, size, ¶ms);
334 if (!gst_memory_map (copy, &dinfo, GST_MAP_WRITE)) {
335 GST_CAT_WARNING (GST_CAT_MEMORY, "could not write map memory %p", copy);
336 gst_memory_unmap (mem, &sinfo);
340 GST_CAT_DEBUG (GST_CAT_PERFORMANCE,
341 "memcpy %" G_GSSIZE_FORMAT " memory %p -> %p", size, mem, copy);
342 memcpy (dinfo.data, sinfo.data + offset, size);
343 gst_memory_unmap (copy, &dinfo);
344 gst_memory_unmap (mem, &sinfo);
350 _fallback_mem_is_span (GstMemory * mem1, GstMemory * mem2, gsize * offset)
356 static GHashTable *allocators;
359 _priv_sysmem_notify (gpointer user_data)
361 g_warning ("The default memory allocator was freed!");
365 _priv_gst_memory_initialize (void)
367 static const GstMemoryInfo _mem_info = {
368 GST_ALLOCATOR_SYSMEM,
369 (GstAllocatorAllocFunction) _default_alloc_alloc,
370 (GstMemoryMapFunction) _default_mem_map,
371 (GstMemoryUnmapFunction) _default_mem_unmap,
372 (GstMemoryFreeFunction) _default_mem_free,
373 (GstMemoryCopyFunction) _default_mem_copy,
374 (GstMemoryShareFunction) _default_mem_share,
375 (GstMemoryIsSpanFunction) _default_mem_is_span,
378 g_rw_lock_init (&lock);
379 allocators = g_hash_table_new (g_str_hash, g_str_equal);
381 #ifdef HAVE_GETPAGESIZE
382 #ifdef MEMORY_ALIGNMENT_PAGESIZE
383 gst_memory_alignment = getpagesize () - 1;
387 GST_CAT_DEBUG (GST_CAT_MEMORY, "memory alignment: %" G_GSIZE_FORMAT,
388 gst_memory_alignment);
390 _default_mem_impl = gst_allocator_new (&_mem_info, NULL, _priv_sysmem_notify);
392 _default_allocator = gst_allocator_ref (_default_mem_impl);
393 gst_allocator_register (GST_ALLOCATOR_SYSMEM,
394 gst_allocator_ref (_default_mem_impl));
398 * gst_memory_new_wrapped:
399 * @flags: #GstMemoryFlags
400 * @data: data to wrap
401 * @maxsize: allocated size of @data
402 * @offset: offset in @data
403 * @size: size of valid data
404 * @user_data: user_data
405 * @notify: called with @user_data when the memory is freed
407 * Allocate a new memory block that wraps the given @data.
409 * The prefix/padding must be filled with 0 if @flags contains
410 * #GST_MEMORY_FLAG_ZERO_PREFIXED and #GST_MEMORY_FLAG_ZERO_PADDED respectively.
412 * Returns: a new #GstMemory.
415 gst_memory_new_wrapped (GstMemoryFlags flags, gpointer data,
416 gsize maxsize, gsize offset, gsize size, gpointer user_data,
417 GDestroyNotify notify)
419 GstMemoryDefault *mem;
421 g_return_val_if_fail (data != NULL, NULL);
422 g_return_val_if_fail (offset + size <= maxsize, NULL);
425 _default_mem_new (flags, NULL, data, maxsize, offset, size, 0, user_data,
428 return (GstMemory *) mem;
432 * gst_memory_is_exclusive:
435 * Check if the current ref to @mem is exclusive, this means that no other
436 * references exist other than @mem.
439 gst_memory_is_exclusive (GstMemory * mem)
441 g_return_val_if_fail (mem != NULL, FALSE);
443 return GST_MINI_OBJECT_REFCOUNT_VALUE (mem) == 1;
447 * gst_memory_get_sizes:
449 * @offset: pointer to offset
450 * @maxsize: pointer to maxsize
452 * Get the current @size, @offset and @maxsize of @mem.
454 * Returns: the current sizes of @mem
457 gst_memory_get_sizes (GstMemory * mem, gsize * offset, gsize * maxsize)
459 g_return_val_if_fail (mem != NULL, 0);
462 *offset = mem->offset;
464 *maxsize = mem->maxsize;
472 * @offset: a new offset
475 * Resize the memory region. @mem should be writable and offset + size should be
476 * less than the maxsize of @mem.
478 * #GST_MEMORY_FLAG_ZERO_PREFIXED and #GST_MEMORY_FLAG_ZERO_PADDED will be
479 * cleared when offset or padding is increased respectively.
482 gst_memory_resize (GstMemory * mem, gssize offset, gsize size)
484 g_return_if_fail (mem != NULL);
485 g_return_if_fail (offset >= 0 || mem->offset >= -offset);
486 g_return_if_fail (size + mem->offset + offset <= mem->maxsize);
488 /* if we increase the prefix, we can't guarantee it is still 0 filled */
489 if ((offset > 0) && GST_MEMORY_IS_ZERO_PREFIXED (mem))
490 GST_MEMORY_FLAG_UNSET (mem, GST_MEMORY_FLAG_ZERO_PREFIXED);
492 /* if we increase the padding, we can't guarantee it is still 0 filled */
493 if ((offset + size < mem->size) && GST_MEMORY_IS_ZERO_PADDED (mem))
494 GST_MEMORY_FLAG_UNSET (mem, GST_MEMORY_FLAG_ZERO_PADDED);
496 mem->offset += offset;
501 gst_memory_lock (GstMemory * mem, GstMapFlags flags)
503 gint access_mode, state, newstate;
505 access_mode = flags & 3;
508 state = g_atomic_int_get (&mem->state);
510 /* nothing mapped, set access_mode and refcount */
511 newstate = 4 | access_mode;
513 /* access_mode must match */
514 if ((state & access_mode) != access_mode)
516 /* increase refcount */
517 newstate = state + 4;
519 } while (!g_atomic_int_compare_and_exchange (&mem->state, state, newstate));
525 GST_CAT_DEBUG (GST_CAT_MEMORY, "lock failed %p: state %d, access_mode %d",
526 mem, state, access_mode);
532 gst_memory_unlock (GstMemory * mem)
534 gint state, newstate;
537 state = g_atomic_int_get (&mem->state);
538 /* decrease the refcount */
539 newstate = state - 4;
540 /* last refcount, unset access_mode */
543 } while (!g_atomic_int_compare_and_exchange (&mem->state, state, newstate));
548 * gst_memory_make_mapped:
549 * @mem: (transfer full): a #GstMemory
550 * @info: (out): pointer for info
551 * @flags: mapping flags
553 * Create a #GstMemory object that is mapped with @flags. If @mem is mappable
554 * with @flags, this function returns the mapped @mem directly. Otherwise a
555 * mapped copy of @mem is returned.
557 * This function takes ownership of old @mem and returns a reference to a new
560 * Returns: (transfer full): a #GstMemory object mapped with @flags or NULL when
561 * a mapping is not possible.
564 gst_memory_make_mapped (GstMemory * mem, GstMapInfo * info, GstMapFlags flags)
568 if (gst_memory_map (mem, info, flags)) {
571 result = gst_memory_copy (mem, 0, -1);
572 gst_memory_unref (mem);
577 if (!gst_memory_map (result, info, flags))
585 GST_CAT_DEBUG (GST_CAT_MEMORY, "cannot copy memory %p", mem);
590 GST_CAT_DEBUG (GST_CAT_MEMORY, "cannot map memory %p with flags %d", mem,
592 gst_memory_unref (result);
600 * @info: (out): pointer for info
601 * @flags: mapping flags
603 * Fill @info with the pointer and sizes of the memory in @mem that can be
604 * accessed according to @flags.
606 * This function can return %FALSE for various reasons:
607 * - the memory backed by @mem is not accessible with the given @flags.
608 * - the memory was already mapped with a different mapping.
610 * @info and its contents remain valid for as long as @mem is valid and
611 * until gst_memory_unmap() is called.
613 * For each gst_memory_map() call, a corresponding gst_memory_unmap() call
616 * Returns: %TRUE if the map operation was successful.
619 gst_memory_map (GstMemory * mem, GstMapInfo * info, GstMapFlags flags)
621 g_return_val_if_fail (mem != NULL, FALSE);
622 g_return_val_if_fail (info != NULL, FALSE);
624 if (!gst_memory_lock (mem, flags))
627 info->data = mem->allocator->info.mem_map (mem, mem->maxsize, flags);
629 if (G_UNLIKELY (info->data == NULL))
634 info->size = mem->size;
635 info->maxsize = mem->maxsize - mem->offset;
636 info->data = info->data + mem->offset;
643 GST_CAT_DEBUG (GST_CAT_MEMORY, "mem %p: lock %d failed", mem, flags);
648 /* something went wrong, restore the orginal state again */
649 GST_CAT_ERROR (GST_CAT_MEMORY, "mem %p: map failed", mem);
650 gst_memory_unlock (mem);
658 * @info: a #GstMapInfo
660 * Release the memory obtained with gst_memory_map()
663 gst_memory_unmap (GstMemory * mem, GstMapInfo * info)
665 g_return_if_fail (mem != NULL);
666 g_return_if_fail (info != NULL);
667 g_return_if_fail (info->memory == mem);
668 /* there must be a ref */
669 g_return_if_fail (g_atomic_int_get (&mem->state) >= 4);
671 mem->allocator->info.mem_unmap (mem);
672 gst_memory_unlock (mem);
678 * @offset: an offset to copy
679 * @size: size to copy or -1 to copy all bytes from offset
681 * Return a copy of @size bytes from @mem starting from @offset. This copy is
682 * guaranteed to be writable. @size can be set to -1 to return a copy all bytes
685 * Returns: a new #GstMemory.
688 gst_memory_copy (GstMemory * mem, gssize offset, gssize size)
692 g_return_val_if_fail (mem != NULL, NULL);
694 copy = mem->allocator->info.mem_copy (mem, offset, size);
702 * @offset: an offset to share
703 * @size: size to share or -1 to share bytes from offset
705 * Return a shared copy of @size bytes from @mem starting from @offset. No
706 * memory copy is performed and the memory region is simply shared. The result
707 * is guaranteed to be not-writable. @size can be set to -1 to return a share
708 * all bytes from @offset.
710 * Returns: a new #GstMemory.
713 gst_memory_share (GstMemory * mem, gssize offset, gssize size)
717 g_return_val_if_fail (mem != NULL, NULL);
718 g_return_val_if_fail (!GST_MEMORY_FLAG_IS_SET (mem, GST_MEMORY_FLAG_NO_SHARE),
721 shared = mem->allocator->info.mem_share (mem, offset, size);
727 * gst_memory_is_span:
728 * @mem1: a #GstMemory
729 * @mem2: a #GstMemory
730 * @offset: a pointer to a result offset
732 * Check if @mem1 and mem2 share the memory with a common parent memory object
733 * and that the memory is contiguous.
735 * If this is the case, the memory of @mem1 and @mem2 can be merged
736 * efficiently by performing gst_memory_share() on the parent object from
737 * the returned @offset.
739 * Returns: %TRUE if the memory is contiguous and of a common parent.
742 gst_memory_is_span (GstMemory * mem1, GstMemory * mem2, gsize * offset)
744 g_return_val_if_fail (mem1 != NULL, FALSE);
745 g_return_val_if_fail (mem2 != NULL, FALSE);
747 /* need to have the same allocators */
748 if (mem1->allocator != mem2->allocator)
751 /* need to have the same parent */
752 if (mem1->parent == NULL || mem1->parent != mem2->parent)
755 /* and memory is contiguous */
756 if (!mem1->allocator->info.mem_is_span (mem1, mem2, offset))
763 _gst_allocator_free (GstAllocator * allocator)
765 if (allocator->notify)
766 allocator->notify (allocator->user_data);
768 g_slice_free1 (sizeof (GstAllocator), allocator);
771 static GstAllocator *
772 _gst_allocator_copy (GstAllocator * allocator)
774 return gst_allocator_ref (allocator);
779 * @info: a #GstMemoryInfo
780 * @user_data: user data
781 * @notify: a #GDestroyNotify for @user_data
783 * Create a new memory allocator with @info and @user_data.
785 * All functions in @info are mandatory exept the copy and is_span
786 * functions, which will have a default implementation when left NULL.
788 * The @user_data will be passed to all calls of the alloc function. @notify
789 * will be called with @user_data when the allocator is freed.
791 * Returns: a new #GstAllocator.
794 gst_allocator_new (const GstMemoryInfo * info, gpointer user_data,
795 GDestroyNotify notify)
797 GstAllocator *allocator;
799 g_return_val_if_fail (info != NULL, NULL);
800 g_return_val_if_fail (info->alloc != NULL, NULL);
801 g_return_val_if_fail (info->mem_map != NULL, NULL);
802 g_return_val_if_fail (info->mem_unmap != NULL, NULL);
803 g_return_val_if_fail (info->mem_free != NULL, NULL);
804 g_return_val_if_fail (info->mem_share != NULL, NULL);
806 allocator = g_slice_new0 (GstAllocator);
808 gst_mini_object_init (GST_MINI_OBJECT_CAST (allocator), GST_TYPE_ALLOCATOR);
810 allocator->mini_object.copy = (GstMiniObjectCopyFunction) _gst_allocator_copy;
811 allocator->mini_object.free = (GstMiniObjectFreeFunction) _gst_allocator_free;
813 allocator->info = *info;
814 allocator->user_data = user_data;
815 allocator->notify = notify;
817 #define INSTALL_FALLBACK(_t) \
818 if (allocator->info._t == NULL) allocator->info._t = _fallback_ ##_t;
819 INSTALL_FALLBACK (mem_copy);
820 INSTALL_FALLBACK (mem_is_span);
821 #undef INSTALL_FALLBACK
823 GST_CAT_DEBUG (GST_CAT_MEMORY, "new allocator %p", allocator);
829 * gst_allocator_get_memory_type:
830 * @allocator: a #GstAllocator
832 * Get the memory type allocated by this allocator
834 * Returns: the memory type provided by @allocator
837 gst_allocator_get_memory_type (GstAllocator * allocator)
839 g_return_val_if_fail (allocator != NULL, NULL);
841 return allocator->info.mem_type;
845 * gst_allocator_register:
846 * @name: the name of the allocator
847 * @allocator: (transfer full): #GstAllocator
849 * Registers the memory @allocator with @name. This function takes ownership of
853 gst_allocator_register (const gchar * name, GstAllocator * allocator)
855 g_return_if_fail (name != NULL);
856 g_return_if_fail (allocator != NULL);
858 GST_CAT_DEBUG (GST_CAT_MEMORY, "registering allocator %p with name \"%s\"",
861 g_rw_lock_writer_lock (&lock);
862 g_hash_table_insert (allocators, (gpointer) name, (gpointer) allocator);
863 g_rw_lock_writer_unlock (&lock);
867 * gst_allocator_find:
868 * @name: the name of the allocator
870 * Find a previously registered allocator with @name. When @name is NULL, the
871 * default allocator will be returned.
873 * Returns: (transfer full): a #GstAllocator or NULL when the allocator with @name was not
874 * registered. Use gst_allocator_unref() to release the allocator after usage.
877 gst_allocator_find (const gchar * name)
879 GstAllocator *allocator;
881 g_rw_lock_reader_lock (&lock);
883 allocator = g_hash_table_lookup (allocators, (gconstpointer) name);
885 allocator = _default_allocator;
888 gst_allocator_ref (allocator);
889 g_rw_lock_reader_unlock (&lock);
895 * gst_allocator_set_default:
896 * @allocator: (transfer full): a #GstAllocator
898 * Set the default allocator. This function takes ownership of @allocator.
901 gst_allocator_set_default (GstAllocator * allocator)
904 g_return_if_fail (allocator != NULL);
906 g_rw_lock_writer_lock (&lock);
907 old = _default_allocator;
908 _default_allocator = allocator;
909 g_rw_lock_writer_unlock (&lock);
912 gst_allocator_unref (old);
916 * gst_allocation_params_init:
917 * @params: a #GstAllocationParams
919 * Initialize @params to its default values
922 gst_allocation_params_init (GstAllocationParams * params)
924 g_return_if_fail (params != NULL);
926 memset (params, 0, sizeof (GstAllocationParams));
930 * gst_allocation_params_copy:
931 * @params: (transfer none): a #GstAllocationParams
933 * Create a copy of @params.
935 * Free-function: gst_allocation_params_free
937 * Returns: (transfer full): a new ##GstAllocationParams, free with
938 * gst_allocation_params_free().
940 GstAllocationParams *
941 gst_allocation_params_copy (const GstAllocationParams * params)
943 GstAllocationParams *result = NULL;
947 (GstAllocationParams *) g_slice_copy (sizeof (GstAllocationParams),
954 * gst_allocation_params_free:
955 * @params: (in) (transfer full): a #GstAllocationParams
960 gst_allocation_params_free (GstAllocationParams * params)
962 g_slice_free (GstAllocationParams, params);
966 * gst_allocator_alloc:
967 * @allocator: (transfer none) (allow-none): a #GstAllocator to use
968 * @size: size of the visible memory area
969 * @params: (transfer none) (allow-none): optional parameters
971 * Use @allocator to allocate a new memory block with memory that is at least
974 * The optional @params can specify the prefix and padding for the memory. If
975 * NULL is passed, no flags, no extra prefix/padding and a default alignment is
978 * The prefix/padding will be filled with 0 if flags contains
979 * #GST_MEMORY_FLAG_ZERO_PREFIXED and #GST_MEMORY_FLAG_ZERO_PADDED respectively.
981 * When @allocator is NULL, the default allocator will be used.
983 * The alignment in @params is given as a bitmask so that @align + 1 equals
984 * the amount of bytes to align to. For example, to align to 8 bytes,
985 * use an alignment of 7.
987 * Returns: (transfer full): a new #GstMemory.
990 gst_allocator_alloc (GstAllocator * allocator, gsize size,
991 GstAllocationParams * params)
994 static GstAllocationParams defparams = { 0, 0, 0, 0, };
997 g_return_val_if_fail (((params->align + 1) & params->align) == 0, NULL);
1002 if (allocator == NULL)
1003 allocator = _default_allocator;
1005 mem = allocator->info.alloc (allocator, size, params, allocator->user_data);