gstreamer/gst/gstdata.c

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/* GStreamer
* Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
* 2000 Wim Taymans <wim@fluendo.com>
*
* gstdata.c: Data 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.
*/
#include "gst_private.h"
#include "gstdata.h"
#include "gstdata_private.h"
#include "gstinfo.h"
#include "gstutils.h"
GType
gst_data_get_type (void)
{
static GType type = 0;
if (!type)
type = g_boxed_type_register_static ("GstData",
(GBoxedCopyFunc) gst_data_copy, (GBoxedFreeFunc) gst_data_unref);
return type;
}
/**
* gst_data_init:
* @data: a #GstData to initialize
* @type: the type of this data
* @flags: flags for this data
* @free: a free function
* @copy: a copy function
*
* Initialize the given data structure with the given parameters.
* The free and copy function will be called when this data is freed
* or copied, respectively.
*/
void
gst_data_init (GstData * data, GType type, guint16 flags,
GstDataFreeFunction free, GstDataCopyFunction copy)
{
g_return_if_fail (data != NULL);
_GST_DATA_INIT (data, type, flags, free, copy);
}
/**
* gst_data_copy_into:
* @data: a #GstData to copy
* @target: the target #GstData to copy into
*
* Copy the GstData into the specified target GstData structure.
* This method is mainly used by subclasses when they want to copy
* the relevant GstData info.
*/
void
gst_data_copy_into (const GstData * data, GstData * target)
{
g_return_if_fail (data != NULL);
}
/**
* gst_data_dispose:
* @data: a #GstData to dispose
*
* Free all the resources allocated in the gst_data_init() function,
* mainly used by subclass implementors.
*/
void
gst_data_dispose (GstData * data)
{
g_return_if_fail (data != NULL);
_GST_DATA_DISPOSE (data);
}
/**
* gst_data_copy:
* @data: a #GstData to copy
*
* Copies the given #GstData. This function will call the custom subclass
* copy function or return NULL if no function was provided by the subclass.
*
* Returns: a copy of the data or NULL if the data cannot be copied.
* The refcount of the original buffer is not changed so you should unref it
* when you don't need it anymore.
*
* MT safe.
*/
GstData *
gst_data_copy (const GstData * data)
{
g_return_val_if_fail (data != NULL, NULL);
if (data->copy)
return data->copy (data);
return NULL;
}
/**
* gst_data_is_writable:
* @data: a #GstData to check
*
* Query if the data needs to be copied before it can safely be modified.
*
* Returns: FALSE if the given #GstData is potentially shared and needs to
* be copied before it can be modified safely.
*
* MT safe.
*/
gboolean
gst_data_is_writable (GstData * data)
{
gint refcount;
g_return_val_if_fail (data != NULL, FALSE);
refcount = g_atomic_int_get (&data->refcount);
/* if we have the only ref and the data is not readonly, we can
* safely write */
if (refcount == 1 && !GST_DATA_FLAG_IS_SET (data, GST_DATA_READONLY))
return TRUE;
return FALSE;
}
/**
* gst_data_copy_on_write:
* @data: a #GstData to copy
*
* Copies the given #GstData if the refcount is greater than 1 so that the
* #GstData object can be written to safely.
*
* Returns: a copy of the data if the refcount is > 1 or the buffer is
* marked READONLY, data if the refcount == 1,
* or NULL if the data could not be copied.
*
* The refcount of the passed @data is decreased when a copy is made, so
* you are not supposed to use it anymore after a call to this function.
*
* MT safe.
*/
GstData *
gst_data_copy_on_write (GstData * data)
{
gint refcount;
g_return_val_if_fail (data != NULL, NULL);
refcount = g_atomic_int_get (&data->refcount);
/* if we have the only ref and the data is not readonly, we can
* safely write, so we return the input data */
if (refcount == 1 && !GST_DATA_FLAG_IS_SET (data, GST_DATA_READONLY))
return GST_DATA (data);
if (data->copy) {
GstData *copy = data->copy (data);
gst_data_unref (data);
return copy;
}
return NULL;
}
/**
* gst_data_ref:
* @data: a #GstData to reference
*
* Increments the reference count of this data.
*
* Returns: the data
*
* MT safe.
*/
GstData *
gst_data_ref (GstData * data)
{
g_return_val_if_fail (data != NULL, NULL);
g_return_val_if_fail (GST_DATA_REFCOUNT_VALUE (data) > 0, NULL);
GST_CAT_LOG (GST_CAT_BUFFER, "%p %d->%d", data,
GST_DATA_REFCOUNT_VALUE (data), GST_DATA_REFCOUNT_VALUE (data) + 1);
g_atomic_int_inc (&data->refcount);
return data;
}
/**
* gst_data_ref_by_count:
* @data: a #GstData to reference
* @count: the number to increment the reference count by
*
* Increments the reference count of this data by the given number.
*
* Returns: the data
*
* MT safe.
*/
GstData *
gst_data_ref_by_count (GstData * data, gint count)
{
g_return_val_if_fail (data != NULL, NULL);
g_return_val_if_fail (count >= 0, NULL);
g_return_val_if_fail (GST_DATA_REFCOUNT_VALUE (data) > 0, NULL);
GST_CAT_LOG (GST_CAT_BUFFER, "%p %d->%d", data,
GST_DATA_REFCOUNT_VALUE (data), GST_DATA_REFCOUNT_VALUE (data) + count);
g_atomic_int_add (&data->refcount, count);
return data;
}
/**
* gst_data_unref:
* @data: a #GstData to unreference
*
* Decrements the refcount of this data. If the refcount is
* zero, the data will be freed.
*
* When you move data out of your element into the pipeline,
* the pipeline takes ownership of the
* data. When the data has been consumed by some element, it must unref() it.
* Applications usually don't need to unref() @data.
*
* MT safe.
*/
void
gst_data_unref (GstData * data)
{
gint zero;
g_return_if_fail (data != NULL);
GST_CAT_LOG (GST_CAT_BUFFER, "%p %d->%d", data,
GST_DATA_REFCOUNT_VALUE (data), GST_DATA_REFCOUNT_VALUE (data) - 1);
g_return_if_fail (GST_DATA_REFCOUNT_VALUE (data) > 0);
zero = g_atomic_int_dec_and_test (&data->refcount);
/* if we ended up with the refcount at zero, free the data */
if (zero) {
if (data->free)
data->free (data);
}
}
/**
* gst_data_replace:
* @olddata: pointer to place of old GstData
* @newdata: new GstData
*
* Unrefs the data pointer to by olddata, refs the newdata and
* puts the newdata in *olddata. Be carefull when calling this
* function, it does not take any locks. You might want to lock
* the object owning the olddata pointer before calling this
* function.
*
* MT safe.
*/
void
gst_data_replace (GstData ** olddata, GstData * newdata)
{
if (G_LIKELY (*olddata != newdata)) {
if (newdata)
gst_data_ref (newdata);
if (*olddata)
gst_data_unref (*olddata);
*olddata = newdata;
}
}