gstreamer/gst/gstbuffer.c

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/* GStreamer
* Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
* 2000 Wim Taymans <wtay@chello.be>
*
* gstbuffer.c: Buffer operations
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
Changes made to the DEBUG system. New header file gstdebug.h holds the stuff to keep it out of gst.h's hair. DEBUG ... Original commit message from CVS: Changes made to the DEBUG system. New header file gstdebug.h holds the stuff to keep it out of gst.h's hair. DEBUG prints out the process id, cothread id, source filename and line number. Two new macros DEBUG_ENTER and DEBUG_LEAVE are used to show the entry and exit of a given function. This eventually might be used to construct call trace graphs, even taking cothreads into account. This would be quite useful in visualizing the scheduling mechanism. Minor changes to various debug messages. Also sitting in gstdebug.h is a prototypical DEBUG_ENTER that's capable of performing DEBUG_LEAVE automatically. It does this by utilizing a little-known GCC extension that allows one to call a function with the same parameters as the current function. The macro uses this to basically call itself. A boolean is used to ensure that when it calls itself it actually runs the body of the function. In the meantime it prints stuff out before and after the real function, as well as constructing a debugging string. This can be used eventually to provide call-wide data on the DEBUG lines, instead of having to replicate data on each call to DEBUG. More research is needed into how this would most cleanly be fit into some other chunk of code, like GStreamer (I think of this DEBUG trick as a separate project, sorta). Unfortunately, the aforementioned DEBUG trick interacts quite poorly with cothreads. Almost any time it's used in a function that has anything remotely to do with a cothread context (as in, it runs in one), a segfault results from the __builtin_apply call, which is the heart of the whole thing. If someone who really knows assembly could analyze the resulting code to see what's really going on, we might find a way to fix either the macro or the cothreads (I'm thinking that there's something we missed in constructing the cothreads themselves) so this works in all cases. In the meantime, please insert both DEBUG_ENTER and DEBUG_LEAVE in your functions. Be sure to put DEBUG_ENTER after your variable declarations and before any functional code, not to put the function name in any DEBUG strings (it's already there, trust me), and put a DEBUG_LEAVE if you care enough. Changes are going to happen in the way DEBUGs and other printouts occur, so stay tuned.
2000-12-04 09:35:08 +00:00
/* this file makes too much noise for most debugging sessions */
#define GST_DEBUG_FORCE_DISABLE
#include "gst_private.h"
#include "gstbuffer.h"
GType _gst_buffer_type;
static GMemChunk *_gst_buffer_chunk;
static GMutex *_gst_buffer_chunk_lock;
void
_gst_buffer_initialize (void)
{
int buffersize = sizeof(GstBuffer);
static const GTypeInfo buffer_info = {
0, // sizeof(class),
NULL,
NULL,
NULL,
NULL,
NULL,
0, // sizeof(object),
0,
NULL,
};
// round up to the nearest 32 bytes for cache-line and other efficiencies
buffersize = (((buffersize-1) / 32) + 1) * 32;
_gst_buffer_chunk = g_mem_chunk_new ("GstBuffer", buffersize,
buffersize * 32, G_ALLOC_AND_FREE);
_gst_buffer_chunk_lock = g_mutex_new ();
_gst_buffer_type = g_type_register_static (G_TYPE_INT, "GstBuffer", &buffer_info, 0);
}
/**
* gst_buffer_new:
*
* Create a new buffer.
*
* Returns: new buffer
*/
GstBuffer*
gst_buffer_new (void)
{
GstBuffer *buffer;
g_mutex_lock (_gst_buffer_chunk_lock);
buffer = g_mem_chunk_alloc (_gst_buffer_chunk);
g_mutex_unlock (_gst_buffer_chunk_lock);
GST_INFO (GST_CAT_BUFFER,"creating new buffer %p",buffer);
GST_DATA_TYPE(buffer) = _gst_buffer_type;
buffer->lock = g_mutex_new ();
#ifdef HAVE_ATOMIC_H
atomic_set (&buffer->refcount, 1);
#else
buffer->refcount = 1;
#endif
buffer->flags = 0;
buffer->data = NULL;
buffer->size = 0;
buffer->maxsize = 0;
buffer->offset = -1;
buffer->timestamp = 0;
buffer->parent = NULL;
buffer->pool = NULL;
buffer->pool_private = NULL;
buffer->free = NULL;
buffer->copy = NULL;
return buffer;
}
/**
* gst_buffer_new_from_pool:
* @pool: the buffer pool to use
*
* Create a new buffer using the specified bufferpool.
*
* Returns: new buffer
*/
GstBuffer*
gst_buffer_new_from_pool (GstBufferPool *pool, guint32 offset, guint32 size)
{
GstBuffer *buffer;
g_return_val_if_fail (pool != NULL, NULL);
g_return_val_if_fail (pool->buffer_new != NULL, NULL);
buffer = pool->buffer_new (pool, offset, size, pool->user_data);
buffer->pool = pool;
buffer->free = pool->buffer_free;
buffer->copy = pool->buffer_copy;
GST_INFO (GST_CAT_BUFFER,"creating new buffer %p from pool %p (size %x, offset %x)",
buffer, pool, size, offset);
return buffer;
}
/**
* gst_buffer_create_sub:
* @parent: parent buffer
* @offset: offset into parent buffer
* @size: size of new subbuffer
*
* Creates a sub-buffer from the parent at a given offset.
*
* Returns: new buffer
*/
GstBuffer*
gst_buffer_create_sub (GstBuffer *parent,
guint32 offset,
guint32 size)
{
GstBuffer *buffer;
g_return_val_if_fail (parent != NULL, NULL);
g_return_val_if_fail (GST_BUFFER_REFCOUNT(parent) > 0, NULL);
g_return_val_if_fail (size > 0, NULL);
g_return_val_if_fail ((offset+size) <= parent->size, NULL);
g_mutex_lock (_gst_buffer_chunk_lock);
buffer = g_mem_chunk_alloc (_gst_buffer_chunk);
GST_DATA_TYPE(buffer) = _gst_buffer_type;
g_mutex_unlock (_gst_buffer_chunk_lock);
GST_INFO (GST_CAT_BUFFER,"creating new subbuffer %p from parent %p (size %u, offset %u)",
buffer, parent, size, offset);
buffer->lock = g_mutex_new ();
#ifdef HAVE_ATOMIC_H
atomic_set (&buffer->refcount, 1);
#else
buffer->refcount = 1;
#endif
// copy flags and type from parent, for lack of better
buffer->flags = parent->flags;
// set the data pointer, size, offset, and maxsize
buffer->data = parent->data + offset;
buffer->size = size;
buffer->maxsize = parent->size - offset;
// deal with bogus/unknown offsets
if (parent->offset != -1)
buffer->offset = parent->offset + offset;
else
buffer->offset = -1;
// again, for lack of better, copy parent's timestamp
buffer->timestamp = parent->timestamp;
buffer->maxage = parent->maxage;
// if the parent buffer is a subbuffer itself, use its parent, a real buffer
if (parent->parent != NULL)
parent = parent->parent;
// set parentage and reference the parent
buffer->parent = parent;
gst_buffer_ref (parent);
buffer->pool = NULL;
return buffer;
}
// FIXME FIXME: how does this overlap with the newly-added gst_buffer_span() ???
/**
* gst_buffer_append:
* @buffer: a buffer
* @append: the buffer to append
*
* Creates a new buffer by appending the data of append to the
* existing data of buffer.
*
* Returns: new buffer
*/
GstBuffer*
gst_buffer_append (GstBuffer *buffer,
GstBuffer *append)
{
guint size;
GstBuffer *newbuf;
g_return_val_if_fail (buffer != NULL, NULL);
g_return_val_if_fail (append != NULL, NULL);
g_return_val_if_fail (buffer->pool == NULL, NULL);
g_return_val_if_fail (GST_BUFFER_REFCOUNT(buffer) > 0, NULL);
g_return_val_if_fail (GST_BUFFER_REFCOUNT(append) > 0, NULL);
GST_INFO (GST_CAT_BUFFER,"appending buffers %p and %p",buffer,append);
GST_BUFFER_LOCK (buffer);
// the buffer is not used by anyone else
if (GST_BUFFER_REFCOUNT (buffer) == 1 && buffer->parent == NULL
&& !GST_BUFFER_FLAG_IS_SET (buffer, GST_BUFFER_DONTFREE)) {
// save the old size
size = buffer->size;
buffer->size += append->size;
buffer->data = g_realloc (buffer->data, buffer->size);
memcpy(buffer->data + size, append->data, append->size);
GST_BUFFER_UNLOCK (buffer);
}
// the buffer is used, create a new one
else {
newbuf = gst_buffer_new ();
newbuf->size = buffer->size+append->size;
newbuf->data = g_malloc (newbuf->size);
memcpy (newbuf->data, buffer->data, buffer->size);
memcpy (newbuf->data+buffer->size, append->data, append->size);
GST_BUFFER_UNLOCK (buffer);
gst_buffer_unref (buffer);
buffer = newbuf;
}
return buffer;
}
/**
* gst_buffer_destroy:
* @buffer: the GstBuffer to destroy
*
* destroy the buffer
*/
void
gst_buffer_destroy (GstBuffer *buffer)
{
g_return_if_fail (buffer != NULL);
GST_INFO (GST_CAT_BUFFER, "freeing %sbuffer %p",
(buffer->parent?"sub":""),
buffer);
// free the data only if there is some, DONTFREE isn't set, and not sub
if (GST_BUFFER_DATA (buffer) &&
!GST_BUFFER_FLAG_IS_SET (buffer, GST_BUFFER_DONTFREE) &&
(buffer->parent == NULL)) {
// if there's a free function, use it
if (buffer->free != NULL) {
(buffer->free)(buffer);
} else {
g_free (GST_BUFFER_DATA (buffer));
}
}
// unreference the parent if there is one
if (buffer->parent != NULL)
gst_buffer_unref (buffer->parent);
g_mutex_free (buffer->lock);
//g_print("freed mutex\n");
#ifdef GST_DEBUG_ENABLED
// make it hard to reuse by mistake
memset (buffer, 0, sizeof (GstBuffer));
#endif
// remove it entirely from memory
g_mutex_lock (_gst_buffer_chunk_lock);
g_mem_chunk_free (_gst_buffer_chunk,buffer);
g_mutex_unlock (_gst_buffer_chunk_lock);
}
/**
* gst_buffer_ref:
* @buffer: the GstBuffer to reference
*
* Increment the refcount of this buffer.
*/
void
gst_buffer_ref (GstBuffer *buffer)
{
g_return_if_fail (buffer != NULL);
g_return_if_fail (GST_BUFFER_REFCOUNT(buffer) > 0);
GST_INFO (GST_CAT_BUFFER, "ref buffer %p\n", buffer);
#ifdef HAVE_ATOMIC_H
atomic_inc (&(buffer->refcount));
#else
GST_BUFFER_LOCK (buffer);
buffer->refcount++;
GST_BUFFER_UNLOCK (buffer);
#endif
}
/**
* gst_buffer_unref:
* @buffer: the GstBuffer to unref
*
* Decrement the refcount of this buffer. If the refcount is
* zero, the buffer will be destroyed.
*/
void
gst_buffer_unref (GstBuffer *buffer)
{
gint zero;
g_return_if_fail (buffer != NULL);
g_return_if_fail (GST_BUFFER_REFCOUNT(buffer) > 0);
GST_INFO (GST_CAT_BUFFER, "unref buffer %p\n", buffer);
#ifdef HAVE_ATOMIC_H
zero = atomic_dec_and_test (&(buffer->refcount));
#else
GST_BUFFER_LOCK (buffer);
buffer->refcount--;
zero = (buffer->refcount == 0);
GST_BUFFER_UNLOCK (buffer);
#endif
/* if we ended up with the refcount at zero, destroy the buffer */
if (zero) {
gst_buffer_destroy (buffer);
}
}
/**
* gst_buffer_copy:
* @buffer: the orignal GstBuffer to make a copy of
*
* Make a full copy of the give buffer, data and all.
*
* Returns: new buffer
*/
GstBuffer *
gst_buffer_copy (GstBuffer *buffer)
{
GstBuffer *newbuf;
g_return_val_if_fail (GST_BUFFER_REFCOUNT(buffer) > 0, NULL);
// if a copy function exists, use it, else copy the bytes
if (buffer->copy != NULL) {
newbuf = (buffer->copy)(buffer);
} else {
// allocate a new buffer
newbuf = gst_buffer_new();
// copy the absolute size
newbuf->size = buffer->size;
// allocate space for the copy
newbuf->data = (guchar *)g_malloc (buffer->size);
// copy the data straight across
memcpy(newbuf->data,buffer->data,buffer->size);
// the new maxsize is the same as the size, since we just malloc'd it
newbuf->maxsize = newbuf->size;
}
newbuf->offset = buffer->offset;
newbuf->timestamp = buffer->timestamp;
newbuf->maxage = buffer->maxage;
// since we just created a new buffer, so we have no ties to old stuff
newbuf->parent = NULL;
newbuf->pool = NULL;
return newbuf;
}
/*
* gst_buffer_is_span_fast
* @buf1: first source buffer
* @buf2: second source buffer
*
* Determines whether a gst_buffer_span is free, or requires a memcpy.
*
* Returns: TRUE if the buffers are contiguous, FALSE if a copy would be required.
*/
gboolean
gst_buffer_is_span_fast (GstBuffer *buf1, GstBuffer *buf2)
{
g_return_val_if_fail (GST_BUFFER_REFCOUNT(buf1) > 0, FALSE);
g_return_val_if_fail (GST_BUFFER_REFCOUNT(buf2) > 0, FALSE);
return (buf1->parent && buf2->parent &&
(buf1->parent == buf2->parent) &&
((buf1->data + buf1->size) == buf2->data));
}
/**
* gst_buffer_span:
* @buf1: first source buffer to merge
* @offset: offset in first buffer to start new buffer
* @buf2: second source buffer to merge
* @len: length of new buffer
*
* Create a new buffer that consists of part of buf1 and buf2.
* Logically, buf1 and buf2 are concatenated into a single larger
* buffer, and a new buffer is created at the given offset inside
* this space, with a given length.
*
* If the two source buffers are children of the same larger buffer,
* and are contiguous, the new buffer will be a child of the shared
* parent, and thus no copying is necessary.
*
* Returns: new buffer that spans the two source buffers
*/
// FIXME need to think about CoW and such...
GstBuffer *
gst_buffer_span (GstBuffer *buf1, guint32 offset, GstBuffer *buf2, guint32 len)
{
GstBuffer *newbuf;
g_return_val_if_fail (GST_BUFFER_REFCOUNT(buf1) > 0, NULL);
g_return_val_if_fail (GST_BUFFER_REFCOUNT(buf2) > 0, NULL);
// make sure buf1 has a lower address than buf2
if (buf1->data > buf2->data) {
GstBuffer *tmp = buf1;
g_print ("swapping buffers\n");
buf1 = buf2;
buf2 = tmp;
}
// if the two buffers have the same parent and are adjacent
if (gst_buffer_is_span_fast(buf1,buf2)) {
// we simply create a subbuffer of the common parent
newbuf = gst_buffer_create_sub (buf1->parent, buf1->data - (buf1->parent->data) + offset, len);
}
else {
g_print ("slow path taken in buffer_span\n");
// otherwise we simply have to brute-force copy the buffers
newbuf = gst_buffer_new ();
// put in new size
newbuf->size = len;
// allocate space for the copy
newbuf->data = (guchar *)g_malloc(len);
// copy the first buffer's data across
memcpy(newbuf->data, buf1->data + offset, buf1->size - offset);
// copy the second buffer's data across
memcpy(newbuf->data + (buf1->size - offset), buf2->data, len - (buf1->size - offset));
if (newbuf->offset != -1)
newbuf->offset = buf1->offset + offset;
newbuf->timestamp = buf1->timestamp;
if (buf2->maxage > buf1->maxage) newbuf->maxage = buf2->maxage;
else newbuf->maxage = buf1->maxage;
}
return newbuf;
}
/**
* gst_buffer_merge:
* @buf1: first source buffer to merge
* @buf2: second source buffer to merge
*
* Create a new buffer that is the concatenation of the two source
* buffers. The original source buffers will not be modified or
* unref'd.
*
* Internally is nothing more than a specialized gst_buffer_span,
* so the same optimizations can occur.
*
* Returns: new buffer that's the concatenation of the source buffers
*/
GstBuffer *
gst_buffer_merge (GstBuffer *buf1, GstBuffer *buf2)
{
// we're just a specific case of the more general gst_buffer_span()
return gst_buffer_span (buf1, 0, buf2, buf1->size + buf2->size);
}