/* 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.

 */

/**

 * SECTION:gstbuffer

 * @short_description: Data-passing buffer type, supporting sub-buffers.

 * @see_also: #GstPad, #GstMiniObject

 *

 * Buffers are the basic unit of data transfer in GStreamer.  The #GstBuffer

 * type provides all the state necessary to define a region of memory as part

 * of a stream.  Sub-buffers are also supported, allowing a smaller region of a

 * buffer to become its own buffer, with mechanisms in place to ensure that

 * neither memory space goes away prematurely.

 *

 * Buffers are usually created with gst_buffer_new(). After a buffer has been

 * created one will typically allocate memory for it and set the size of the

 * buffer data.  The following example creates a buffer that can hold a given

 * video frame with a given width, height and bits per plane.

 * <example>

 * <title>Creating a buffer for a video frame</title>

 *   <programlisting>

 *   GstBuffer *buffer;

 *   gint size, width, height, bpp;

 *   ...

 *   size = width * height * bpp;

 *   buffer = gst_buffer_new ();

 *   GST_BUFFER_SIZE (buffer) = size;

 *   GST_BUFFER_MALLOCDATA (buffer) = g_malloc (size);

 *   GST_BUFFER_DATA (buffer) = GST_BUFFER_MALLOCDATA (buffer);

 *   ...

 *   </programlisting>

 * </example>

 *

 * Alternatively, use gst_buffer_new_and_alloc()

 * to create a buffer with preallocated data of a given size.

 *

 * The data pointed to by the buffer can be retrieved with the GST_BUFFER_DATA()

 * macro. The size of the data can be found with GST_BUFFER_SIZE(). For buffers

 * of size 0, the data pointer is undefined (usually NULL) and should never be used.

 *

 * If an element knows what pad you will push the buffer out on, it should use

 * gst_pad_alloc_buffer() instead to create a buffer.  This allows downstream

 * elements to provide special buffers to write in, like hardware buffers.

 *

 * A buffer has a pointer to a #GstCaps describing the media type of the data

 * in the buffer. Attach caps to the buffer with gst_buffer_set_caps(); this

 * is typically done before pushing out a buffer using gst_pad_push() so that

 * the downstream element knows the type of the buffer.

 *

 * A buffer will usually have a timestamp, and a duration, but neither of these

 * are guaranteed (they may be set to #GST_CLOCK_TIME_NONE). Whenever a

 * meaningful value can be given for these, they should be set. The timestamp

 * and duration are measured in nanoseconds (they are #GstClockTime values).

 *

 * A buffer can also have one or both of a start and an end offset. These are

 * media-type specific. For video buffers, the start offset will generally be

 * the frame number. For audio buffers, it will be the number of samples

 * produced so far. For compressed data, it could be the byte offset in a

 * source or destination file. Likewise, the end offset will be the offset of

 * the end of the buffer. These can only be meaningfully interpreted if you

 * know the media type of the buffer (the #GstCaps set on it). Either or both

 * can be set to #GST_BUFFER_OFFSET_NONE.

 *

 * gst_buffer_ref() is used to increase the refcount of a buffer. This must be

 * done when you want to keep a handle to the buffer after pushing it to the

 * next element.

 *

 * To efficiently create a smaller buffer out of an existing one, you can

 * use gst_buffer_create_sub().

 *

 * If a plug-in wants to modify the buffer data in-place, it should first obtain

 * a buffer that is safe to modify by using gst_buffer_make_writable().  This

 * function is optimized so that a copy will only be made when it is necessary.

 *

 * A plugin that only wishes to modify the metadata of a buffer, such as the

 * offset, timestamp or caps, should use gst_buffer_make_metadata_writable(),

 * which will create a subbuffer of the original buffer to ensure the caller

 * has sole ownership, and not copy the buffer data.

 *

 * Several flags of the buffer can be set and unset with the

 * GST_BUFFER_FLAG_SET() and GST_BUFFER_FLAG_UNSET() macros. Use

 * GST_BUFFER_FLAG_IS_SET() to test if a certain #GstBufferFlag is set.

 *

 * Buffers can be efficiently merged into a larger buffer with

 * gst_buffer_merge() and gst_buffer_span() if the gst_buffer_is_span_fast()

 * function returns TRUE.

 *

 * An element should either unref the buffer or push it out on a src pad

 * using gst_pad_push() (see #GstPad).

 *

 * Buffers are usually freed by unreffing them with gst_buffer_unref(). When

 * the refcount drops to 0, any data pointed to by GST_BUFFER_MALLOCDATA() will

 * also be freed.

 *

 * Last reviewed on August 11th, 2006 (0.10.10)

 */

#include "gst_private.h"

#include "gstbuffer.h"

#include "gstinfo.h"

#include "gstutils.h"

#include "gstminiobject.h"

static void gst_buffer_finalize (GstBuffer * buffer);

static GstBuffer *_gst_buffer_copy (GstBuffer * buffer);

static GType gst_subbuffer_get_type (void);

static GType _gst_subbuffer_type = 0;

static GType _gst_buffer_type = 0;

#ifdef __SYMBIAN32__

EXPORT_C

#endif

void

_gst_buffer_initialize (void)

{

  /* the GstMiniObject types need to be class_ref'd once before it can be

   * done from multiple threads;

   * see http://bugzilla.gnome.org/show_bug.cgi?id=304551 */

  g_type_class_ref (gst_buffer_get_type ());

  g_type_class_ref (gst_subbuffer_get_type ());

}

}

      (GstMiniObjectFinalizeFunction) gst_buffer_finalize;

}

static void

gst_buffer_finalize (GstBuffer * buffer)

{

  g_return_if_fail (buffer != NULL);

  GST_CAT_LOG (GST_CAT_BUFFER, "finalize %p", buffer);

  /* free our data */

  gst_caps_replace (&GST_BUFFER_CAPS (buffer), NULL);

}

/**

 * gst_buffer_copy_metadata:

 * @dest: a destination #GstBuffer

 * @src: a source #GstBuffer

 * @flags: flags indicating what metadata fields should be copied.

 *

 * Copies the metadata from @src into @dest. The data, size and mallocdata

 * fields are not copied.

 *

 * @flags indicate which fields will be copied. Use #GST_BUFFER_COPY_ALL to copy

 * all the metadata fields.

 *

 * This function is typically called from a custom buffer copy function after

 * creating @dest and setting the data, size, mallocdata.

 *

 * Since: 0.10.13

 */

#ifdef __SYMBIAN32__

EXPORT_C

#endif

void

gst_buffer_copy_metadata (GstBuffer * dest, const GstBuffer * src,

    GstBufferCopyFlags flags)

{

  g_return_if_fail (dest != NULL);

  g_return_if_fail (src != NULL);

  GST_CAT_LOG (GST_CAT_BUFFER, "copy %p to %p", src, dest);

  if (flags & GST_BUFFER_COPY_FLAGS) {

    guint mask;

    /* copy relevant flags */

    mask = GST_BUFFER_FLAG_PREROLL | GST_BUFFER_FLAG_IN_CAPS |

        GST_BUFFER_FLAG_DELTA_UNIT | GST_BUFFER_FLAG_DISCONT |

    GST_MINI_OBJECT_FLAGS (dest) |= GST_MINI_OBJECT_FLAGS (src) & mask;

  }

  if (flags & GST_BUFFER_COPY_TIMESTAMPS) {

    GST_BUFFER_TIMESTAMP (dest) = GST_BUFFER_TIMESTAMP (src);

    GST_BUFFER_DURATION (dest) = GST_BUFFER_DURATION (src);

    GST_BUFFER_OFFSET (dest) = GST_BUFFER_OFFSET (src);

    GST_BUFFER_OFFSET_END (dest) = GST_BUFFER_OFFSET_END (src);

  }

  if (flags & GST_BUFFER_COPY_CAPS) {

  }

}

static GstBuffer *

_gst_buffer_copy (GstBuffer * buffer)

{

  GstBuffer *copy;

  g_return_val_if_fail (buffer != NULL, NULL);

  /* create a fresh new buffer */

  copy = gst_buffer_new ();

  /* we simply copy everything from our parent */

  copy->data = g_memdup (buffer->data, buffer->size);

  /* make sure it gets freed (even if the parent is subclassed, we return a

     normal buffer) */

  copy->malloc_data = copy->data;

  copy->size = buffer->size;

  gst_buffer_copy_metadata (copy, buffer, GST_BUFFER_COPY_ALL);

  return copy;

}

static void

{

  GST_CAT_LOG (GST_CAT_BUFFER, "init %p", buffer);

  GST_BUFFER_TIMESTAMP (buffer) = GST_CLOCK_TIME_NONE;

  GST_BUFFER_DURATION (buffer) = GST_CLOCK_TIME_NONE;

  GST_BUFFER_OFFSET (buffer) = GST_BUFFER_OFFSET_NONE;

  GST_BUFFER_OFFSET_END (buffer) = GST_BUFFER_OFFSET_NONE;

}

/**

 * gst_buffer_new:

 *

 * Creates a newly allocated buffer without any data.

 *

 * MT safe.

 * Returns: the new #GstBuffer.

 */

#ifdef __SYMBIAN32__

EXPORT_C

#endif

GstBuffer *

gst_buffer_new (void)

{

  GstBuffer *newbuf;

  newbuf = (GstBuffer *) gst_mini_object_new (_gst_buffer_type);

  GST_CAT_LOG (GST_CAT_BUFFER, "new %p", newbuf);

  return newbuf;

}

/**

 * gst_buffer_new_and_alloc:

 * @size: the size of the new buffer's data.

 *

 * Creates a newly allocated buffer with data of the given size.

 * The buffer memory is not cleared. If the requested amount of

 * memory can't be allocated, the program will abort. Use

 * gst_buffer_try_new_and_alloc() if you want to handle this case

 * gracefully or have gotten the size to allocate from an untrusted

 * source such as a media stream.

 * 

 *

 * Note that when @size == 0, the buffer data pointer will be NULL.

 *

 * MT safe.

 * Returns: the new #GstBuffer.

 */

#ifdef __SYMBIAN32__

EXPORT_C

#endif

GstBuffer *

gst_buffer_new_and_alloc (guint size)

{

  GstBuffer *newbuf;

  newbuf = gst_buffer_new ();

  newbuf->malloc_data = g_malloc (size);

  GST_BUFFER_DATA (newbuf) = newbuf->malloc_data;

  GST_BUFFER_SIZE (newbuf) = size;

  GST_CAT_LOG (GST_CAT_BUFFER, "new %p of size %d", newbuf, size);

  return newbuf;

}

/**

 * gst_buffer_try_new_and_alloc:

 * @size: the size of the new buffer's data.

 *

 * Tries to create a newly allocated buffer with data of the given size. If

 * the requested amount of memory can't be allocated, NULL will be returned.

 * The buffer memory is not cleared.

 *

 * Note that when @size == 0, the buffer data pointer will be NULL.

 *

 * MT safe.

 *

 * Returns: a new #GstBuffer, or NULL if the memory couldn't be allocated.

 *

 * Since: 0.10.13

 */

#ifdef __SYMBIAN32__

EXPORT_C

#endif

GstBuffer *

gst_buffer_try_new_and_alloc (guint size)

{

  GstBuffer *newbuf;

  guint8 *malloc_data;

  malloc_data = g_try_malloc (size);

  if (G_UNLIKELY (malloc_data == NULL && size != 0)) {

    GST_CAT_WARNING (GST_CAT_BUFFER, "failed to allocate %d bytes", size);

    return NULL;

  }

  /* FIXME: there's no g_type_try_create_instance() in GObject yet, so this

   * will still abort if a new GstBuffer structure can't be allocated */

  newbuf = gst_buffer_new ();

  GST_BUFFER_MALLOCDATA (newbuf) = malloc_data;

  GST_BUFFER_DATA (newbuf) = malloc_data;

  GST_BUFFER_SIZE (newbuf) = size;

  GST_CAT_LOG (GST_CAT_BUFFER, "new %p of size %d", newbuf, size);

  return newbuf;

}

/**

 * gst_buffer_get_caps:

 * @buffer: a #GstBuffer.

 *

 * Gets the media type of the buffer. This can be NULL if there

 * is no media type attached to this buffer.

 *

 * Returns: a reference to the #GstCaps. unref after usage.

 * Returns NULL if there were no caps on this buffer.

 */

/* this is not made atomic because if the buffer were reffed from multiple

 * threads, it would have a refcount > 2 and thus be immutable.

 */

#ifdef __SYMBIAN32__

EXPORT_C

#endif

GstCaps *

gst_buffer_get_caps (GstBuffer * buffer)

{

  GstCaps *ret;

  g_return_val_if_fail (buffer != NULL, NULL);

  ret = GST_BUFFER_CAPS (buffer);

  if (ret)

    gst_caps_ref (ret);

  return ret;

}

/**

 * gst_buffer_set_caps:

 * @buffer: a #GstBuffer.

 * @caps: a #GstCaps.

 *

 * Sets the media type on the buffer. The refcount of the caps will

 * be increased and any previous caps on the buffer will be

 * unreffed.

 */

/* this is not made atomic because if the buffer were reffed from multiple

 * threads, it would have a refcount > 2 and thus be immutable.

 */

#ifdef __SYMBIAN32__

EXPORT_C

#endif

void

gst_buffer_set_caps (GstBuffer * buffer, GstCaps * caps)

{

  g_return_if_fail (buffer != NULL);

  gst_caps_replace (&GST_BUFFER_CAPS (buffer), caps);

}

/**

 * gst_buffer_is_metadata_writable:

 * @buf: a #GstBuffer

 *

 * Similar to gst_buffer_is_writable, but this only ensures that the

 * refcount of the buffer is 1, indicating that the caller is the sole

 * owner and can change the buffer metadata, such as caps and timestamps.

 *

 * Returns: TRUE if the metadata is writable.

 */

#ifdef __SYMBIAN32__

EXPORT_C

#endif

gboolean

gst_buffer_is_metadata_writable (GstBuffer * buf)

{

  return (GST_MINI_OBJECT_REFCOUNT_VALUE (GST_MINI_OBJECT_CAST (buf)) == 1);

}

/**

 * gst_buffer_make_metadata_writable:

 * @buf: a #GstBuffer

 *

 * Similar to gst_buffer_make_writable, but does not ensure that the buffer

 * data array is writable. Instead, this just ensures that the returned buffer

 * is solely owned by the caller, by creating a subbuffer of the original

 * buffer if necessary.

 * 

 * After calling this function, @buf should not be referenced anymore. The

 * result of this function has guaranteed writable metadata.

 *

 * Returns: A new #GstBuffer with writable metadata.

 */

#ifdef __SYMBIAN32__

EXPORT_C

#endif

GstBuffer *

gst_buffer_make_metadata_writable (GstBuffer * buf)

{

  GstBuffer *ret;

  if (gst_buffer_is_metadata_writable (buf)) {

    ret = buf;

  } else {

    ret = gst_buffer_create_sub (buf, 0, GST_BUFFER_SIZE (buf));

    gst_buffer_unref (buf);

  }

  return ret;

}

typedef struct _GstSubBuffer GstSubBuffer;

typedef struct _GstSubBufferClass GstSubBufferClass;

#define GST_IS_SUBBUFFER(obj)   (G_TYPE_CHECK_INSTANCE_TYPE ((obj), _gst_subbuffer_type))

#define GST_SUBBUFFER_CAST(obj) ((GstSubBuffer *)(obj))

struct _GstSubBuffer

{

  GstBuffer buffer;

  GstBuffer *parent;

};

struct _GstSubBufferClass

{

  GstBufferClass buffer_class;

};

static void gst_subbuffer_finalize (GstSubBuffer * buffer);

}