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glbasememory: don't unconditionally add the alignment bytes to the size

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e.g when wrapping a data pointer we don't want to map/unmap off the end of
pointer with the alignment bytes.

Instead track that information separately as maxsize is used for mapping by
GstMemory and thus represents a size without any alignment padding bytes.
This commit is contained in:
Matthew Waters 2015-12-15 14:14:36 +11:00
parent 98784aa72c
commit d8dacd50bf
2 changed files with 29 additions and 4 deletions
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32
gst-libs/gst/gl/gstglbasememory.c
View file

@ -109,15 +109,39 @@ gst_gl_base_memory_init (GstGLBaseMemory * mem, GstAllocator * allocator,
GstMemory * parent, GstGLContext * context, GstAllocationParams * params,
gsize size, gpointer user_data, GDestroyNotify notify)
{
gsize align = gst_memory_alignment, offset = 0, maxsize = size;
gsize align = gst_memory_alignment, offset = 0, maxsize;
GstMemoryFlags flags = 0;
struct create_data data;
/* A note on sizes.
* gl_mem->alloc_size: the size to allocate when we control the allocation.
* Size of the unaligned allocation.
* mem->maxsize: the size that is used by GstMemory for mapping, to map the
* entire memory. The size of the aligned allocation
* mem->size: represents the size of the valid data. Can be reduced with
* gst_memory_resize()
*
* It holds that:
* mem->size + mem->offset <= mem->maxsize
* and
* mem->maxsize + alignment offset <= gl_mem->alloc_size
*
* We need to add the alignment mask to the allocated size in order to have
* the freedom to align the gl_mem->data pointer correctly which may be offset
* by at most align bytes in the alloc_data pointer.
*
* maxsize is not suitable for this as it is used by GstMemory as the size
* to map with.
*/
mem->alloc_size = maxsize = size;
if (params) {
flags = params->flags;
align |= params->align;
offset = params->prefix;
maxsize += params->prefix + params->padding + align;
maxsize += params->prefix + params->padding;
/* deals with any alignment */
mem->alloc_size = maxsize + align;
}
gst_memory_init (GST_MEMORY_CAST (mem), flags, allocator, parent, maxsize,
@ -168,8 +192,8 @@ gst_gl_base_memory_alloc_data (GstGLBaseMemory * gl_mem)
return TRUE;
GST_CAT_LOG (GST_CAT_GL_BASE_MEMORY, "%p attempting allocation of data "
"pointer of size %" G_GSIZE_FORMAT, gl_mem, mem->maxsize);
gl_mem->alloc_data = g_try_malloc (mem->maxsize);
"pointer of size %" G_GSIZE_FORMAT, gl_mem, gl_mem->alloc_size);
gl_mem->alloc_data = g_try_malloc (gl_mem->alloc_size);
if (gl_mem->alloc_data == NULL)
return FALSE;

1
gst-libs/gst/gl/gstglbasememory.h
View file

@ -91,6 +91,7 @@ struct _GstGLBaseMemory
gpointer data;
/* <private> */
gsize alloc_size; /* because maxsize is used for mapping */
gpointer alloc_data;
GDestroyNotify notify;