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().
43 * New memory can be created with gst_memory_new_wrapped() that wraps the memory
44 * allocated elsewhere.
46 * Refcounting of the memory block is performed with gst_memory_ref() and
49 * The size of the memory can be retrieved and changed with
50 * gst_memory_get_sizes() and gst_memory_resize() respectively.
52 * Getting access to the data of the memory is performed with gst_memory_map().
53 * The call will return a pointer to offset bytes into the region of memory.
54 * After the memory access is completed, gst_memory_unmap() should be called.
56 * Memory can be copied with gst_memory_copy(), which will return a writable
57 * copy. gst_memory_share() will create a new memory block that shares the
58 * memory with an existing memory block at a custom offset and with a custom
61 * Memory can be efficiently merged when gst_memory_is_span() returns TRUE.
63 * Last reviewed on 2011-06-08 (0.11.0)
70 #include "gst_private.h"
71 #include "gstmemory.h"
73 #ifndef GST_DISABLE_TRACE
75 static GstAllocTrace *_gst_memory_trace;
76 static GstAllocTrace *_gst_allocator_trace;
79 G_DEFINE_BOXED_TYPE (GstMemory, gst_memory, (GBoxedCopyFunc) gst_memory_ref,
80 (GBoxedFreeFunc) gst_memory_unref);
82 G_DEFINE_BOXED_TYPE (GstAllocator, gst_allocator,
83 (GBoxedCopyFunc) gst_allocator_ref, (GBoxedFreeFunc) gst_allocator_unref);
86 * gst_memory_alignment:
88 * The default memory alignment in bytes - 1
89 * an alignment of 7 would be the same as what malloc() guarantees.
91 #if defined(MEMORY_ALIGNMENT_MALLOC)
92 size_t gst_memory_alignment = 7;
93 #elif defined(MEMORY_ALIGNMENT_PAGESIZE)
94 /* we fill this in in the _init method */
95 size_t gst_memory_alignment = 0;
96 #elif defined(MEMORY_ALIGNMENT)
97 size_t gst_memory_alignment = MEMORY_ALIGNMENT - 1;
99 #error "No memory alignment configured"
100 size_t gst_memory_alignment = 0;
110 GDestroyNotify notify;
113 /* default memory implementation */
120 GDestroyNotify notify;
123 /* the default allocator */
124 static GstAllocator *_default_allocator;
126 /* our predefined allocators */
127 static GstAllocator *_default_mem_impl;
129 /* initialize the fields */
131 _default_mem_init (GstMemoryDefault * mem, GstMemoryFlags flags,
132 GstMemory * parent, gsize slice_size, gpointer data,
133 gsize maxsize, gsize offset, gsize size, gpointer user_data,
134 GDestroyNotify notify)
136 mem->mem.allocator = _default_mem_impl;
137 mem->mem.flags = flags;
138 mem->mem.refcount = 1;
139 mem->mem.parent = parent ? gst_memory_ref (parent) : NULL;
140 mem->mem.state = (flags & GST_MEMORY_FLAG_READONLY ? 0x1 : 0);
141 mem->mem.maxsize = maxsize;
142 mem->mem.offset = offset;
143 mem->mem.size = size;
144 mem->slice_size = slice_size;
146 mem->user_data = user_data;
147 mem->notify = notify;
149 GST_CAT_DEBUG (GST_CAT_MEMORY, "new memory %p, maxsize:%" G_GSIZE_FORMAT
150 " offset:%" G_GSIZE_FORMAT " size:%" G_GSIZE_FORMAT, mem, maxsize,
154 /* create a new memory block that manages the given memory */
155 static GstMemoryDefault *
156 _default_mem_new (GstMemoryFlags flags, GstMemory * parent, gpointer data,
157 gsize maxsize, gsize offset, gsize size, gpointer user_data,
158 GDestroyNotify notify)
160 GstMemoryDefault *mem;
163 slice_size = sizeof (GstMemoryDefault);
165 mem = g_slice_alloc (slice_size);
166 _default_mem_init (mem, flags, parent, slice_size,
167 data, maxsize, offset, size, user_data, notify);
172 /* allocate the memory and structure in one block */
173 static GstMemoryDefault *
174 _default_mem_new_block (GstMemoryFlags flags, gsize maxsize, gsize align,
175 gsize offset, gsize size)
177 GstMemoryDefault *mem;
178 gsize aoffset, slice_size, padding;
181 /* ensure configured alignment */
182 align |= gst_memory_alignment;
183 /* allocate more to compensate for alignment */
185 /* alloc header and data in one block */
186 slice_size = sizeof (GstMemoryDefault) + maxsize;
188 mem = g_slice_alloc (slice_size);
192 data = (guint8 *) mem + sizeof (GstMemoryDefault);
194 if ((aoffset = ((guintptr) data & align))) {
195 aoffset = (align + 1) - aoffset;
200 if (offset && (flags & GST_MEMORY_FLAG_ZERO_PREFIXED))
201 memset (data, 0, offset);
203 padding = maxsize - (offset + size);
204 if (padding && (flags & GST_MEMORY_FLAG_ZERO_PADDED))
205 memset (data + offset + size, 0, padding);
207 _default_mem_init (mem, flags, NULL, slice_size, data, maxsize,
208 offset, size, NULL, NULL);
214 _default_alloc_alloc (GstAllocator * allocator, GstMemoryFlags flags,
215 gsize maxsize, gsize offset, gsize size, gsize align, gpointer user_data)
217 return (GstMemory *) _default_mem_new_block (flags, maxsize, align, offset,
222 _default_mem_map (GstMemoryDefault * mem, GstMapFlags flags)
228 _default_mem_unmap (GstMemoryDefault * mem)
234 _default_mem_free (GstMemoryDefault * mem)
236 GST_CAT_DEBUG (GST_CAT_MEMORY, "free memory %p", mem);
239 gst_memory_unref (mem->mem.parent);
242 mem->notify (mem->user_data);
244 g_slice_free1 (mem->slice_size, mem);
247 static GstMemoryDefault *
248 _default_mem_copy (GstMemoryDefault * mem, gssize offset, gsize size)
250 GstMemoryDefault *copy;
253 size = mem->mem.size > offset ? mem->mem.size - offset : 0;
256 _default_mem_new_block (0, mem->mem.maxsize, 0, mem->mem.offset + offset,
258 memcpy (copy->data, mem->data, mem->mem.maxsize);
259 GST_CAT_DEBUG (GST_CAT_PERFORMANCE, "copy memory %p -> %p", mem, copy);
264 static GstMemoryDefault *
265 _default_mem_share (GstMemoryDefault * mem, gssize offset, gsize size)
267 GstMemoryDefault *sub;
270 /* find the real parent */
271 if ((parent = mem->mem.parent) == NULL)
272 parent = (GstMemory *) mem;
275 size = mem->mem.size - offset;
278 _default_mem_new (parent->flags, parent, mem->data,
279 mem->mem.maxsize, mem->mem.offset + offset, size, NULL, NULL);
285 _default_mem_is_span (GstMemoryDefault * mem1, GstMemoryDefault * mem2,
290 GstMemoryDefault *parent;
292 parent = (GstMemoryDefault *) mem1->mem.parent;
294 *offset = mem1->mem.offset - parent->mem.offset;
297 /* and memory is contiguous */
298 return mem1->data + mem1->mem.offset + mem1->mem.size ==
299 mem2->data + mem2->mem.offset;
303 _fallback_mem_copy (GstMemory * mem, gssize offset, gssize size)
306 GstMapInfo sinfo, dinfo;
308 if (!gst_memory_map (mem, &sinfo, GST_MAP_READ))
312 size = sinfo.size > offset ? sinfo.size - offset : 0;
314 /* use the same allocator as the memory we copy */
315 copy = gst_allocator_alloc (mem->allocator, 0, size, 0, size, mem->align);
316 if (!gst_memory_map (copy, &dinfo, GST_MAP_WRITE)) {
317 GST_CAT_WARNING (GST_CAT_MEMORY, "could not write map memory %p", copy);
318 gst_memory_unmap (mem, &sinfo);
322 memcpy (dinfo.data, sinfo.data + offset, size);
323 GST_CAT_DEBUG (GST_CAT_PERFORMANCE, "copy memory %p -> %p", mem, copy);
324 gst_memory_unmap (copy, &dinfo);
325 gst_memory_unmap (mem, &sinfo);
331 _fallback_mem_is_span (GstMemory * mem1, GstMemory * mem2, gsize * offset)
337 static GHashTable *allocators;
340 _priv_sysmem_notify (gpointer user_data)
342 g_warning ("The default memory allocator was freed!");
346 _priv_gst_memory_initialize (void)
348 static const GstMemoryInfo _mem_info = {
349 GST_ALLOCATOR_SYSMEM,
350 (GstAllocatorAllocFunction) _default_alloc_alloc,
351 (GstMemoryMapFunction) _default_mem_map,
352 (GstMemoryUnmapFunction) _default_mem_unmap,
353 (GstMemoryFreeFunction) _default_mem_free,
354 (GstMemoryCopyFunction) _default_mem_copy,
355 (GstMemoryShareFunction) _default_mem_share,
356 (GstMemoryIsSpanFunction) _default_mem_is_span,
359 #ifndef GST_DISABLE_TRACE
360 _gst_memory_trace = _gst_alloc_trace_register ("GstMemory", -1);
361 _gst_allocator_trace = _gst_alloc_trace_register ("GstAllocator", -1);
364 g_rw_lock_init (&lock);
365 allocators = g_hash_table_new (g_str_hash, g_str_equal);
367 #ifdef HAVE_GETPAGESIZE
368 #ifdef MEMORY_ALIGNMENT_PAGESIZE
369 gst_memory_alignment = getpagesize () - 1;
373 GST_CAT_DEBUG (GST_CAT_MEMORY, "memory alignment: %" G_GSIZE_FORMAT,
374 gst_memory_alignment);
376 _default_mem_impl = gst_allocator_new (&_mem_info, NULL, _priv_sysmem_notify);
378 _default_allocator = gst_allocator_ref (_default_mem_impl);
379 gst_allocator_register (GST_ALLOCATOR_SYSMEM,
380 gst_allocator_ref (_default_mem_impl));
384 * gst_memory_new_wrapped:
385 * @flags: #GstMemoryFlags
386 * @data: data to wrap
387 * @maxsize: allocated size of @data
388 * @offset: offset in @data
389 * @size: size of valid data
390 * @user_data: user_data
391 * @notify: called with @user_data when the memory is freed
393 * Allocate a new memory block that wraps the given @data.
395 * The prefix/padding must be filled with 0 if @flags contains
396 * #GST_MEMORY_FLAG_ZERO_PREFIXED and #GST_MEMORY_FLAG_ZERO_PADDED respectively.
398 * Returns: a new #GstMemory.
401 gst_memory_new_wrapped (GstMemoryFlags flags, gpointer data,
402 gsize maxsize, gsize offset, gsize size, gpointer user_data,
403 GDestroyNotify notify)
405 GstMemoryDefault *mem;
407 g_return_val_if_fail (data != NULL, NULL);
408 g_return_val_if_fail (offset + size <= maxsize, NULL);
411 _default_mem_new (flags, NULL, data, maxsize, offset, size, user_data,
414 #ifndef GST_DISABLE_TRACE
415 _gst_alloc_trace_new (_gst_memory_trace, mem);
418 return (GstMemory *) mem;
425 * Increases the refcount of @mem.
427 * Returns: @mem with increased refcount
430 gst_memory_ref (GstMemory * mem)
432 g_return_val_if_fail (mem != NULL, NULL);
434 GST_CAT_TRACE (GST_CAT_MEMORY, "memory %p, %d->%d", mem, mem->refcount,
437 g_atomic_int_inc (&mem->refcount);
446 * Decreases the refcount of @mem. When the refcount reaches 0, the free
447 * function of @mem will be called.
450 gst_memory_unref (GstMemory * mem)
452 g_return_if_fail (mem != NULL);
453 g_return_if_fail (mem->allocator != NULL);
455 GST_CAT_TRACE (GST_CAT_MEMORY, "memory %p, %d->%d", mem, mem->refcount,
458 if (g_atomic_int_dec_and_test (&mem->refcount)) {
459 /* there should be no outstanding mappings */
460 g_return_if_fail (g_atomic_int_get (&mem->state) < 4);
461 #ifndef GST_DISABLE_TRACE
462 _gst_alloc_trace_free (_gst_memory_trace, mem);
464 mem->allocator->info.mem_free (mem);
469 * gst_memory_is_exclusive:
472 * Check if the current ref to @mem is exclusive, this means that no other
473 * references exist other than @mem.
476 gst_memory_is_exclusive (GstMemory * mem)
478 g_return_val_if_fail (mem != NULL, FALSE);
480 return (g_atomic_int_get (&mem->refcount) == 1);
484 * gst_memory_get_sizes:
486 * @offset: pointer to offset
487 * @maxsize: pointer to maxsize
489 * Get the current @size, @offset and @maxsize of @mem.
491 * Returns: the current sizes of @mem
494 gst_memory_get_sizes (GstMemory * mem, gsize * offset, gsize * maxsize)
496 g_return_val_if_fail (mem != NULL, 0);
499 *offset = mem->offset;
501 *maxsize = mem->maxsize;
509 * @offset: a new offset
512 * Resize the memory region. @mem should be writable and offset + size should be
513 * less than the maxsize of @mem.
515 * #GST_MEMORY_FLAG_ZERO_PREFIXED and #GST_MEMORY_FLAG_ZERO_PADDED will be
516 * cleared when offset or padding is increased respectively.
519 gst_memory_resize (GstMemory * mem, gssize offset, gsize size)
521 g_return_if_fail (mem != NULL);
522 g_return_if_fail (offset >= 0 || mem->offset >= -offset);
523 g_return_if_fail (size + mem->offset + offset <= mem->maxsize);
525 /* if we increase the prefix, we can't guarantee it is still 0 filled */
526 if ((offset > 0) && GST_MEMORY_IS_ZERO_PREFIXED (mem))
527 GST_MEMORY_FLAG_UNSET (mem, GST_MEMORY_FLAG_ZERO_PREFIXED);
529 /* if we increase the padding, we can't guarantee it is still 0 filled */
530 if ((offset + size < mem->size) && GST_MEMORY_IS_ZERO_PADDED (mem))
531 GST_MEMORY_FLAG_UNSET (mem, GST_MEMORY_FLAG_ZERO_PADDED);
533 mem->offset += offset;
538 gst_memory_lock (GstMemory * mem, GstMapFlags flags)
540 gint access_mode, state, newstate;
542 access_mode = flags & 3;
545 state = g_atomic_int_get (&mem->state);
547 /* nothing mapped, set access_mode and refcount */
548 newstate = 4 | access_mode;
550 /* access_mode must match */
551 if ((state & access_mode) != access_mode)
553 /* increase refcount */
554 newstate = state + 4;
556 } while (!g_atomic_int_compare_and_exchange (&mem->state, state, newstate));
562 GST_CAT_DEBUG (GST_CAT_MEMORY, "lock failed %p: state %d, access_mode %d",
563 mem, state, access_mode);
569 gst_memory_unlock (GstMemory * mem)
571 gint state, newstate;
574 state = g_atomic_int_get (&mem->state);
575 /* decrease the refcount */
576 newstate = state - 4;
577 /* last refcount, unset access_mode */
580 } while (!g_atomic_int_compare_and_exchange (&mem->state, state, newstate));
585 * gst_memory_make_mapped:
586 * @mem: (transfer full): a #GstMemory
587 * @info: (out): pointer for info
588 * @flags: mapping flags
590 * Create a #GstMemory object that is mapped with @flags. If @mem is mappable
591 * with @flags, this function returns the mapped @mem directly. Otherwise a
592 * mapped copy of @mem is returned.
594 * This function takes ownership of old @mem and returns a reference to a new
597 * Returns: (transfer full): a #GstMemory object mapped with @flags or NULL when
598 * a mapping is not possible.
601 gst_memory_make_mapped (GstMemory * mem, GstMapInfo * info, GstMapFlags flags)
605 if (gst_memory_map (mem, info, flags)) {
608 result = gst_memory_copy (mem, 0, -1);
609 gst_memory_unref (mem);
614 if (!gst_memory_map (result, info, flags))
622 GST_CAT_DEBUG (GST_CAT_MEMORY, "cannot copy memory %p", mem);
627 GST_CAT_DEBUG (GST_CAT_MEMORY, "cannot map memory %p with flags %d", mem,
629 gst_memory_unref (result);
637 * @info: (out): pointer for info
638 * @flags: mapping flags
640 * Fill @info with the pointer and sizes of the memory in @mem that can be
641 * accessed according to @flags.
643 * This function can return %FALSE for various reasons:
644 * - the memory backed by @mem is not accessible with the given @flags.
645 * - the memory was already mapped with a different mapping.
647 * @info and its contents remain valid for as long as @mem is valid and
648 * until gst_memory_unmap() is called.
650 * For each gst_memory_map() call, a corresponding gst_memory_unmap() call
653 * Returns: %TRUE if the map operation was successful.
656 gst_memory_map (GstMemory * mem, GstMapInfo * info, GstMapFlags flags)
658 g_return_val_if_fail (mem != NULL, FALSE);
659 g_return_val_if_fail (info != NULL, FALSE);
661 if (!gst_memory_lock (mem, flags))
664 info->data = mem->allocator->info.mem_map (mem, mem->maxsize, flags);
666 if (G_UNLIKELY (info->data == NULL))
671 info->size = mem->size;
672 info->maxsize = mem->maxsize - mem->offset;
673 info->data = info->data + mem->offset;
680 GST_CAT_DEBUG (GST_CAT_MEMORY, "mem %p: lock %d failed", mem, flags);
685 /* something went wrong, restore the orginal state again */
686 GST_CAT_ERROR (GST_CAT_MEMORY, "mem %p: map failed", mem);
687 gst_memory_unlock (mem);
695 * @info: a #GstMapInfo
697 * Release the memory obtained with gst_memory_map()
700 gst_memory_unmap (GstMemory * mem, GstMapInfo * info)
702 g_return_if_fail (mem != NULL);
703 g_return_if_fail (info != NULL);
704 g_return_if_fail (info->memory == mem);
705 /* there must be a ref */
706 g_return_if_fail (g_atomic_int_get (&mem->state) >= 4);
708 mem->allocator->info.mem_unmap (mem);
709 gst_memory_unlock (mem);
715 * @offset: an offset to copy
716 * @size: size to copy or -1 to copy all bytes from offset
718 * Return a copy of @size bytes from @mem starting from @offset. This copy is
719 * guaranteed to be writable. @size can be set to -1 to return a copy all bytes
722 * Returns: a new #GstMemory.
725 gst_memory_copy (GstMemory * mem, gssize offset, gssize size)
729 g_return_val_if_fail (mem != NULL, NULL);
731 copy = mem->allocator->info.mem_copy (mem, offset, size);
733 #ifndef GST_DISABLE_TRACE
734 _gst_alloc_trace_new (_gst_memory_trace, copy);
743 * @offset: an offset to share
744 * @size: size to share or -1 to share bytes from offset
746 * Return a shared copy of @size bytes from @mem starting from @offset. No
747 * memory copy is performed and the memory region is simply shared. The result
748 * is guaranteed to be not-writable. @size can be set to -1 to return a share
749 * all bytes from @offset.
751 * Returns: a new #GstMemory.
754 gst_memory_share (GstMemory * mem, gssize offset, gssize size)
758 g_return_val_if_fail (mem != NULL, NULL);
759 g_return_val_if_fail (!GST_MEMORY_FLAG_IS_SET (mem, GST_MEMORY_FLAG_NO_SHARE),
762 shared = mem->allocator->info.mem_share (mem, offset, size);
764 #ifndef GST_DISABLE_TRACE
765 _gst_alloc_trace_new (_gst_memory_trace, shared);
772 * gst_memory_is_span:
773 * @mem1: a #GstMemory
774 * @mem2: a #GstMemory
775 * @offset: a pointer to a result offset
777 * Check if @mem1 and mem2 share the memory with a common parent memory object
778 * and that the memory is contiguous.
780 * If this is the case, the memory of @mem1 and @mem2 can be merged
781 * efficiently by performing gst_memory_share() on the parent object from
782 * the returned @offset.
784 * Returns: %TRUE if the memory is contiguous and of a common parent.
787 gst_memory_is_span (GstMemory * mem1, GstMemory * mem2, gsize * offset)
789 g_return_val_if_fail (mem1 != NULL, FALSE);
790 g_return_val_if_fail (mem2 != NULL, FALSE);
792 /* need to have the same allocators */
793 if (mem1->allocator != mem2->allocator)
796 /* need to have the same parent */
797 if (mem1->parent == NULL || mem1->parent != mem2->parent)
800 /* and memory is contiguous */
801 if (!mem1->allocator->info.mem_is_span (mem1, mem2, offset))
808 * gst_allocator_register:
809 * @info: a #GstMemoryInfo
810 * @user_data: user data
811 * @notify: a #GDestroyNotify for @user_data
813 * Create a new memory allocator with @info and @user_data.
815 * All functions in @info are mandatory exept the copy and is_span
816 * functions, which will have a default implementation when left NULL.
818 * The @user_data will be passed to all calls of the alloc function. @notify
819 * will be called with @user_data when the allocator is freed.
821 * Returns: a new #GstAllocator.
824 gst_allocator_new (const GstMemoryInfo * info, gpointer user_data,
825 GDestroyNotify notify)
827 GstAllocator *allocator;
829 #define INSTALL_FALLBACK(_t) \
830 if (allocator->info._t == NULL) allocator->info._t = _fallback_ ##_t;
832 g_return_val_if_fail (info != NULL, NULL);
833 g_return_val_if_fail (info->alloc != NULL, NULL);
834 g_return_val_if_fail (info->mem_map != NULL, NULL);
835 g_return_val_if_fail (info->mem_unmap != NULL, NULL);
836 g_return_val_if_fail (info->mem_free != NULL, NULL);
837 g_return_val_if_fail (info->mem_share != NULL, NULL);
839 allocator = g_slice_new (GstAllocator);
840 allocator->refcount = 1;
841 allocator->info = *info;
842 allocator->user_data = user_data;
843 allocator->notify = notify;
844 INSTALL_FALLBACK (mem_copy);
845 INSTALL_FALLBACK (mem_is_span);
846 #undef INSTALL_FALLBACK
848 GST_CAT_DEBUG (GST_CAT_MEMORY, "new allocator %p", allocator);
850 #ifndef GST_DISABLE_TRACE
851 _gst_alloc_trace_new (_gst_allocator_trace, allocator);
858 * gst_alocator_get_memory_type:
859 * @allocator: a #GstAllocator
861 * Get the memory type allocated by this allocator
863 * Returns: the memory type provided by @allocator
866 gst_allocator_get_memory_type (GstAllocator * allocator)
868 g_return_val_if_fail (allocator != NULL, NULL);
870 return allocator->info.mem_type;
875 * @allocator: a #GstAllocator
877 * Increases the refcount of @allocator.
879 * Returns: @allocator with increased refcount
882 gst_allocator_ref (GstAllocator * allocator)
884 g_return_val_if_fail (allocator != NULL, NULL);
886 GST_CAT_TRACE (GST_CAT_MEMORY, "alocator %p, %d->%d", allocator,
887 allocator->refcount, allocator->refcount + 1);
889 g_atomic_int_inc (&allocator->refcount);
895 * gst_allocator_unref:
896 * @allocator: a #GstAllocator
898 * Decreases the refcount of @allocator. When the refcount reaches 0, the notify
899 * function of @allocator will be called and the allocator will be freed.
902 gst_allocator_unref (GstAllocator * allocator)
904 g_return_if_fail (allocator != NULL);
906 GST_CAT_TRACE (GST_CAT_MEMORY, "allocator %p, %d->%d", allocator,
907 allocator->refcount, allocator->refcount - 1);
909 if (g_atomic_int_dec_and_test (&allocator->refcount)) {
910 if (allocator->notify)
911 allocator->notify (allocator->user_data);
912 #ifndef GST_DISABLE_TRACE
913 _gst_alloc_trace_free (_gst_allocator_trace, allocator);
915 g_slice_free1 (sizeof (GstAllocator), allocator);
920 * gst_allocator_register:
921 * @name: the name of the allocator
922 * @allocator: (transfer full): #GstAllocator
924 * Registers the memory @allocator with @name. This function takes ownership of
928 gst_allocator_register (const gchar * name, GstAllocator * allocator)
930 g_return_if_fail (name != NULL);
931 g_return_if_fail (allocator != NULL);
933 GST_CAT_DEBUG (GST_CAT_MEMORY, "registering allocator %p with name \"%s\"",
936 g_rw_lock_writer_lock (&lock);
937 g_hash_table_insert (allocators, (gpointer) name, (gpointer) allocator);
938 g_rw_lock_writer_unlock (&lock);
942 * gst_allocator_find:
943 * @name: the name of the allocator
945 * Find a previously registered allocator with @name. When @name is NULL, the
946 * default allocator will be returned.
948 * Returns: (transfer full): a #GstAllocator or NULL when the allocator with @name was not
949 * registered. Use gst_allocator_unref() to release the allocator after usage.
952 gst_allocator_find (const gchar * name)
954 GstAllocator *allocator;
956 g_rw_lock_reader_lock (&lock);
958 allocator = g_hash_table_lookup (allocators, (gconstpointer) name);
960 allocator = _default_allocator;
963 gst_allocator_ref (allocator);
964 g_rw_lock_reader_unlock (&lock);
970 * gst_allocator_set_default:
971 * @allocator: (transfer full): a #GstAllocator
973 * Set the default allocator. This function takes ownership of @allocator.
976 gst_allocator_set_default (GstAllocator * allocator)
979 g_return_if_fail (allocator != NULL);
981 g_rw_lock_writer_lock (&lock);
982 old = _default_allocator;
983 _default_allocator = allocator;
984 g_rw_lock_writer_unlock (&lock);
987 gst_allocator_unref (old);
991 * gst_allocator_alloc:
992 * @allocator: (transfer none) (allow-none): a #GstAllocator to use
994 * @maxsize: allocated size of @data
995 * @offset: offset in allocated memory
996 * @size: size of visible
997 * @align: alignment for the data
999 * Use @allocator to allocate a new memory block with memory that is at least
1000 * @maxsize big and has the given alignment.
1002 * @offset and @size describe the start and size of the accessible memory.
1004 * The prefix/padding will be filled with 0 if @flags contains
1005 * #GST_MEMORY_FLAG_ZERO_PREFIXED and #GST_MEMORY_FLAG_ZERO_PADDED respectively.
1007 * When @allocator is NULL, the default allocator will be used.
1009 * @align is given as a bitmask so that @align + 1 equals the amount of bytes to
1010 * align to. For example, to align to 8 bytes, use an alignment of 7.
1012 * Returns: (transfer full): a new #GstMemory.
1015 gst_allocator_alloc (GstAllocator * allocator, GstMemoryFlags flags,
1016 gsize maxsize, gsize offset, gsize size, gsize align)
1020 g_return_val_if_fail (((align + 1) & align) == 0, NULL);
1022 if (allocator == NULL)
1023 allocator = _default_allocator;
1025 mem = allocator->info.alloc (allocator, flags, maxsize, offset, size,
1026 align, allocator->user_data);
1027 #ifndef GST_DISABLE_TRACE
1028 _gst_alloc_trace_new (_gst_memory_trace, mem);