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679 lines
18 KiB
C
679 lines
18 KiB
C
/* GStreamer
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* Copyright (C) 2011 Wim Taymans <wim.taymans@gmail.be>
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*
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* gstmemory.c: memory block handling
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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/**
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* SECTION:gstmemory
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* @short_description: refcounted wrapper for memory blocks
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* @see_also: #GstBuffer
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*
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* GstMemory is a lightweight refcounted object that wraps a region of memory.
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* They are typically used to manage the data of a #GstBuffer.
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*
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* Memory is usually created by allocators with a gst_allocator_alloc()
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* method call. When NULL is used as the allocator, the default allocator will
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* be used.
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*
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* New allocators can be registered with gst_allocator_register().
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* Allocators are identified by name and can be retrieved with
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* gst_allocator_find().
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*
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* New memory can be created with gst_memory_new_wrapped() that wraps the memory
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* allocated elsewhere.
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*
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* Refcounting of the memory block is performed with gst_memory_ref() and
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* gst_memory_unref().
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*
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* The size of the memory can be retrieved and changed with
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* gst_memory_get_sizes() and gst_memory_resize() respectively.
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*
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* Getting access to the data of the memory is performed with gst_memory_map().
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* After the memory access is completed, gst_memory_unmap() should be called.
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*
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* Memory can be copied with gst_memory_copy(), which will returnn a writable
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* copy. gst_memory_share() will create a new memory block that shares the
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* memory with an existing memory block at a custom offset and with a custom
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* size.
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*
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* Memory can be efficiently merged when gst_memory_is_span() returns TRUE.
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*
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* Last reviewed on 2011-06-08 (0.11.0)
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*/
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#include "config.h"
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#include "gst_private.h"
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#include "gstmemory.h"
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G_DEFINE_BOXED_TYPE (GstMemory, gst_memory, (GBoxedCopyFunc) gst_memory_ref,
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(GBoxedFreeFunc) gst_memory_unref);
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/* buffer alignment in bytes - 1
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* an alignment of 7 would be the same as malloc() guarantees
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*/
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#if defined(MEMORY_ALIGNMENT_MALLOC)
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size_t gst_memory_alignment = 7;
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#elif defined(MEMORY_ALIGNMENT_PAGESIZE)
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/* we fill this in in the _init method */
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size_t gst_memory_alignment = 0;
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#elif defined(MEMORY_ALIGNMENT)
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size_t gst_memory_alignment = MEMORY_ALIGNMENT - 1;
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#else
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#error "No memory alignment configured"
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size_t gst_memory_alignment = 0;
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#endif
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struct _GstAllocator
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{
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GQuark name;
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GstMemoryInfo info;
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};
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/* default memory implementation */
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typedef struct
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{
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GstMemory mem;
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gsize slice_size;
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guint8 *data;
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GFreeFunc free_func;
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gsize maxsize;
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gsize offset;
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gsize size;
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} GstMemoryDefault;
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/* the default allocator */
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static const GstAllocator *_default_allocator;
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/* our predefined allocators */
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static const GstAllocator *_default_mem_impl;
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/* initialize the fields */
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static void
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_default_mem_init (GstMemoryDefault * mem, GstMemoryFlags flags,
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GstMemory * parent, gsize slice_size, gpointer data,
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GFreeFunc free_func, gsize maxsize, gsize offset, gsize size)
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{
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mem->mem.allocator = _default_mem_impl;
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mem->mem.flags = flags;
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mem->mem.refcount = 1;
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mem->mem.parent = parent ? gst_memory_ref (parent) : NULL;
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mem->slice_size = slice_size;
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mem->data = data;
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mem->free_func = free_func;
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mem->maxsize = maxsize;
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mem->offset = offset;
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mem->size = size;
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}
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/* create a new memory block that manages the given memory */
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static GstMemoryDefault *
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_default_mem_new (GstMemoryFlags flags, GstMemory * parent, gpointer data,
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GFreeFunc free_func, gsize maxsize, gsize offset, gsize size)
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{
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GstMemoryDefault *mem;
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gsize slice_size;
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slice_size = sizeof (GstMemoryDefault);
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mem = g_slice_alloc (slice_size);
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_default_mem_init (mem, flags, parent, slice_size,
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data, free_func, maxsize, offset, size);
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return mem;
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}
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/* allocate the memory and structure in one block */
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static GstMemoryDefault *
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_default_mem_new_block (gsize maxsize, gsize align, gsize offset, gsize size)
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{
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GstMemoryDefault *mem;
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gsize aoffset, slice_size;
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guint8 *data;
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/* ensure configured alignment */
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align |= gst_memory_alignment;
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/* allocate more to compensate for alignment */
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maxsize += align;
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/* alloc header and data in one block */
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slice_size = sizeof (GstMemoryDefault) + maxsize;
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mem = g_slice_alloc (slice_size);
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if (mem == NULL)
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return NULL;
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data = (guint8 *) mem + sizeof (GstMemoryDefault);
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if ((aoffset = ((guintptr) data & align)))
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aoffset = (align + 1) - aoffset;
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_default_mem_init (mem, 0, NULL, slice_size, data, NULL, maxsize,
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aoffset + offset, size);
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return mem;
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}
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static GstMemory *
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_default_mem_alloc (const GstAllocator * allocator, gsize maxsize, gsize align)
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{
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return (GstMemory *) _default_mem_new_block (maxsize, align, 0, maxsize);
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}
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static gsize
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_default_mem_get_sizes (GstMemoryDefault * mem, gsize * offset, gsize * maxsize)
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{
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if (offset)
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*offset = mem->offset;
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if (maxsize)
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*maxsize = mem->maxsize;
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return mem->size;
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}
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static void
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_default_mem_resize (GstMemoryDefault * mem, gssize offset, gsize size)
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{
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g_return_if_fail (size + mem->offset + offset <= mem->maxsize);
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mem->offset += offset;
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mem->size = size;
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}
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static gpointer
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_default_mem_map (GstMemoryDefault * mem, gsize * size, gsize * maxsize,
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GstMapFlags flags)
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{
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if (size)
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*size = mem->size;
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if (maxsize)
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*maxsize = mem->maxsize;
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return mem->data + mem->offset;
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}
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static gboolean
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_default_mem_unmap (GstMemoryDefault * mem, gpointer data, gsize size)
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{
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if (size != -1)
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mem->size = size;
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return TRUE;
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}
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static void
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_default_mem_free (GstMemoryDefault * mem)
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{
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if (mem->mem.parent)
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gst_memory_unref (mem->mem.parent);
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if (mem->free_func)
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mem->free_func (mem->data);
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g_slice_free1 (mem->slice_size, mem);
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}
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static GstMemoryDefault *
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_default_mem_copy (GstMemoryDefault * mem, gssize offset, gsize size)
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{
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GstMemoryDefault *copy;
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if (size == -1)
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size = mem->size > offset ? mem->size - offset : 0;
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copy = _default_mem_new_block (mem->maxsize, 0, mem->offset + offset, size);
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memcpy (copy->data, mem->data, mem->maxsize);
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return copy;
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}
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static GstMemoryDefault *
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_default_mem_share (GstMemoryDefault * mem, gssize offset, gsize size)
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{
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GstMemoryDefault *sub;
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GstMemory *parent;
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/* find the real parent */
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if ((parent = mem->mem.parent) == NULL)
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parent = (GstMemory *) mem;
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if (size == -1)
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size = mem->size - offset;
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sub = _default_mem_new (parent->flags, parent, mem->data, NULL, mem->maxsize,
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mem->offset + offset, size);
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return sub;
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}
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static gboolean
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_default_mem_is_span (GstMemoryDefault * mem1, GstMemoryDefault * mem2,
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gsize * offset)
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{
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if (offset) {
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GstMemoryDefault *parent;
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parent = (GstMemoryDefault *) mem1->mem.parent;
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*offset = mem1->offset - parent->offset;
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}
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/* and memory is contiguous */
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return mem1->data + mem1->offset + mem1->size == mem2->data + mem2->offset;
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}
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static GstMemory *
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_fallback_copy (GstMemory * mem, gssize offset, gssize size)
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{
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GstMemory *copy;
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guint8 *data, *dest;
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gsize msize;
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data = gst_memory_map (mem, &msize, NULL, GST_MAP_READ);
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if (size == -1)
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size = msize > offset ? msize - offset : 0;
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/* use the same allocator as the memory we copy, FIXME, alignment? */
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copy = gst_allocator_alloc (mem->allocator, size, 0);
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dest = gst_memory_map (copy, NULL, NULL, GST_MAP_WRITE);
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memcpy (dest, data + offset, size);
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gst_memory_unmap (copy, dest, size);
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gst_memory_unmap (mem, data, msize);
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return (GstMemory *) copy;
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}
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static gboolean
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_fallback_is_span (GstMemory * mem1, GstMemory * mem2, gsize * offset)
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{
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return FALSE;
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}
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static GStaticRWLock lock = G_STATIC_RW_LOCK_INIT;
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static GHashTable *allocators;
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void
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_priv_gst_memory_initialize (void)
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{
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static const GstMemoryInfo _mem_info = {
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(GstMemoryAllocFunction) _default_mem_alloc,
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(GstMemoryGetSizesFunction) _default_mem_get_sizes,
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(GstMemoryResizeFunction) _default_mem_resize,
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(GstMemoryMapFunction) _default_mem_map,
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(GstMemoryUnmapFunction) _default_mem_unmap,
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(GstMemoryFreeFunction) _default_mem_free,
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(GstMemoryCopyFunction) _default_mem_copy,
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(GstMemoryShareFunction) _default_mem_share,
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(GstMemoryIsSpanFunction) _default_mem_is_span,
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NULL
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};
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allocators = g_hash_table_new (g_str_hash, g_str_equal);
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#ifdef HAVE_GETPAGESIZE
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#ifdef MEMORY_ALIGNMENT_PAGESIZE
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gst_memory_alignment = getpagesize () - 1;
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#endif
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#endif
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GST_DEBUG ("memory alignment: %" G_GSIZE_FORMAT, gst_memory_alignment);
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_default_mem_impl = gst_allocator_register (GST_ALLOCATOR_SYSMEM, &_mem_info);
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_default_allocator = _default_mem_impl;
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}
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/**
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* gst_memory_new_wrapped:
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* @flags: #GstMemoryFlags
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* @data: data to wrap
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* @free_func: function to free @data
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* @maxsize: allocated size of @data
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* @offset: offset in @data
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* @size: size of valid data
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*
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* Allocate a new memory block that wraps the given @data.
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*
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* Returns: a new #GstMemory.
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*/
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GstMemory *
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gst_memory_new_wrapped (GstMemoryFlags flags, gpointer data,
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GFreeFunc free_func, gsize maxsize, gsize offset, gsize size)
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{
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GstMemoryDefault *mem;
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g_return_val_if_fail (data != NULL, NULL);
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g_return_val_if_fail (offset + size <= maxsize, NULL);
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mem = _default_mem_new (flags, NULL, data, free_func, maxsize, offset, size);
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return (GstMemory *) mem;
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}
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/**
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* gst_memory_ref:
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* @mem: a #GstMemory
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*
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* Increases the refcount of @mem.
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*
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* Returns: @mem with increased refcount
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*/
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GstMemory *
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gst_memory_ref (GstMemory * mem)
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{
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g_return_val_if_fail (mem != NULL, NULL);
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g_atomic_int_inc (&mem->refcount);
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return mem;
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}
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/**
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* gst_memory_unref:
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* @mem: a #GstMemory
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*
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* Decreases the refcount of @mem. When the refcount reaches 0, the free
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* function of @mem will be called.
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*/
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void
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gst_memory_unref (GstMemory * mem)
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{
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g_return_if_fail (mem != NULL);
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g_return_if_fail (mem->allocator != NULL);
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if (g_atomic_int_dec_and_test (&mem->refcount))
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mem->allocator->info.free (mem);
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}
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/**
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* gst_memory_get_sizes:
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* @mem: a #GstMemory
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* @offset: pointer to offset
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* @maxsize: pointer to maxsize
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*
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* Get the current @size, @offset and @maxsize of @mem.
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*
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* Returns: the current sizes of @mem
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*/
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gsize
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gst_memory_get_sizes (GstMemory * mem, gsize * offset, gsize * maxsize)
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{
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g_return_val_if_fail (mem != NULL, 0);
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return mem->allocator->info.get_sizes (mem, offset, maxsize);
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}
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/**
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* gst_memory_resize:
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* @mem: a #GstMemory
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* @offset: a new offset
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* @size: a new size
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*
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* Resize the memory region. @mem should be writable and offset + size should be
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* less than the maxsize of @mem.
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*/
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void
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gst_memory_resize (GstMemory * mem, gssize offset, gsize size)
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{
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g_return_if_fail (mem != NULL);
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g_return_if_fail (GST_MEMORY_IS_WRITABLE (mem));
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mem->allocator->info.resize (mem, offset, size);
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}
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/**
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* gst_memory_map:
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* @mem: a #GstMemory
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* @size: (out) (allow-none): pointer for size
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* @maxsize: (out) (allow-none): pointer for maxsize
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* @flags: mapping flags
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*
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* Get a pointer to the memory of @mem that can be accessed according to @flags.
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*
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* @size and @maxsize will contain the size of the memory and the maximum
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* allocated memory of @mem respectively. They can be set to NULL.
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*
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* Returns: (transfer none): a pointer to the memory of @mem.
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*/
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gpointer
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gst_memory_map (GstMemory * mem, gsize * size, gsize * maxsize,
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GstMapFlags flags)
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{
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g_return_val_if_fail (mem != NULL, NULL);
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g_return_val_if_fail (!(flags & GST_MAP_WRITE) ||
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GST_MEMORY_IS_WRITABLE (mem), NULL);
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return mem->allocator->info.map (mem, size, maxsize, flags);
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}
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/**
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* gst_memory_unmap:
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* @mem: a #GstMemory
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* @data: data to unmap
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* @size: new size of @mem, or -1
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*
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* Release the memory pointer obtained with gst_memory_map() and set the size of
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* the memory to @size. @size can be set to -1 when the size should not be
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* updated.
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*
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* Returns: TRUE when the memory was release successfully.
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*/
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gboolean
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gst_memory_unmap (GstMemory * mem, gpointer data, gssize size)
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{
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g_return_val_if_fail (mem != NULL, FALSE);
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return mem->allocator->info.unmap (mem, data, size);
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}
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/**
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* gst_memory_copy:
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* @mem: a #GstMemory
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* @offset: an offset to copy
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* @size: size to copy or -1 to copy all bytes from offset
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*
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* Return a copy of @size bytes from @mem starting from @offset. This copy is
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* guaranteed to be writable. @size can be set to -1 to return a copy all bytes
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* from @offset.
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*
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* Returns: a new #GstMemory.
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*/
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GstMemory *
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gst_memory_copy (GstMemory * mem, gssize offset, gssize size)
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{
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g_return_val_if_fail (mem != NULL, NULL);
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return mem->allocator->info.copy (mem, offset, size);
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}
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/**
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* gst_memory_share:
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* @mem: a #GstMemory
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* @offset: an offset to share
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* @size: size to share or -1 to share bytes from offset
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*
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* Return a shared copy of @size bytes from @mem starting from @offset. No
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* memory copy is performed and the memory region is simply shared. The result
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* is guaranteed to be not-writable. @size can be set to -1 to return a share
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* all bytes from @offset.
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*
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* Returns: a new #GstMemory.
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*/
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GstMemory *
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gst_memory_share (GstMemory * mem, gssize offset, gssize size)
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{
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g_return_val_if_fail (mem != NULL, NULL);
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return mem->allocator->info.share (mem, offset, size);
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}
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/**
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* 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.
|
|
*/
|
|
gboolean
|
|
gst_memory_is_span (GstMemory * mem1, GstMemory * mem2, gsize * offset)
|
|
{
|
|
g_return_val_if_fail (mem1 != NULL, FALSE);
|
|
g_return_val_if_fail (mem2 != NULL, FALSE);
|
|
|
|
/* need to have the same allocators */
|
|
if (mem1->allocator != mem2->allocator)
|
|
return FALSE;
|
|
|
|
/* need to have the same parent */
|
|
if (mem1->parent == NULL || mem1->parent != mem2->parent)
|
|
return FALSE;
|
|
|
|
/* and memory is contiguous */
|
|
if (!mem1->allocator->info.is_span (mem1, mem2, offset))
|
|
return FALSE;
|
|
|
|
return TRUE;
|
|
}
|
|
|
|
/**
|
|
* gst_allocator_register:
|
|
* @name: the name of the allocator
|
|
* @info: #GstMemoryInfo
|
|
*
|
|
* Registers the memory allocator with @name and implementation functions
|
|
* @info.
|
|
*
|
|
* All functions in @info are mandatory exept the copy 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.
|
|
*
|
|
* Returns: a new #GstAllocator.
|
|
*/
|
|
const GstAllocator *
|
|
gst_allocator_register (const gchar * name, const GstMemoryInfo * info)
|
|
{
|
|
GstAllocator *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);
|
|
g_return_val_if_fail (info->alloc != NULL, NULL);
|
|
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);
|
|
g_return_val_if_fail (info->share != NULL, NULL);
|
|
|
|
allocator = g_slice_new (GstAllocator);
|
|
allocator->name = g_quark_from_string (name);
|
|
allocator->info = *info;
|
|
INSTALL_FALLBACK (copy);
|
|
INSTALL_FALLBACK (is_span);
|
|
#undef INSTALL_FALLBACK
|
|
|
|
GST_DEBUG ("registering allocator \"%s\"", name);
|
|
|
|
g_static_rw_lock_writer_lock (&lock);
|
|
g_hash_table_insert (allocators, (gpointer) name, (gpointer) allocator);
|
|
g_static_rw_lock_writer_unlock (&lock);
|
|
|
|
return allocator;
|
|
}
|
|
|
|
/**
|
|
* gst_allocator_find:
|
|
* @name: the name of the allocator
|
|
*
|
|
* Find a previously registered allocator with @name. When @name is NULL, the
|
|
* default allocator will be returned.
|
|
*
|
|
* Returns: a #GstAllocator or NULL when the allocator with @name was not
|
|
* registered.
|
|
*/
|
|
const GstAllocator *
|
|
gst_allocator_find (const gchar * name)
|
|
{
|
|
const GstAllocator *allocator;
|
|
|
|
g_static_rw_lock_reader_lock (&lock);
|
|
if (name) {
|
|
allocator = g_hash_table_lookup (allocators, (gconstpointer) name);
|
|
} else {
|
|
allocator = _default_allocator;
|
|
}
|
|
g_static_rw_lock_reader_unlock (&lock);
|
|
|
|
return allocator;
|
|
}
|
|
|
|
/**
|
|
* gst_allocator_set_default:
|
|
* @allocator: a #GstAllocator
|
|
*
|
|
* Set the default allocator.
|
|
*/
|
|
void
|
|
gst_allocator_set_default (const GstAllocator * allocator)
|
|
{
|
|
g_return_if_fail (allocator != NULL);
|
|
|
|
g_static_rw_lock_writer_lock (&lock);
|
|
_default_allocator = allocator;
|
|
g_static_rw_lock_writer_unlock (&lock);
|
|
}
|
|
|
|
/**
|
|
* gst_allocator_alloc:
|
|
* @allocator: (transfer none) (allow-none): a #GstAllocator 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.
|
|
*
|
|
* When @allocator is NULL, the default allocator will be used.
|
|
*
|
|
* @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: (transfer full): a new #GstMemory.
|
|
*/
|
|
GstMemory *
|
|
gst_allocator_alloc (const GstAllocator * allocator, gsize maxsize, gsize align)
|
|
{
|
|
g_return_val_if_fail (((align + 1) & align) == 0, NULL);
|
|
|
|
if (allocator == NULL)
|
|
allocator = _default_allocator;
|
|
|
|
return allocator->info.alloc (allocator, maxsize, align,
|
|
allocator->info.user_data);
|
|
}
|