/* GStreamer

 * Copyright (C) 2004 Benjamin Otte <otte@gnome.org>

 *               2005 Wim Taymans <wim@fluendo.com>

 *

 * 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:gstadapter

 * @short_description: adapts incoming data on a sink pad into chunks of N bytes

 *

 * This class is for elements that receive buffers in an undesired size.

 * While for example raw video contains one image per buffer, the same is not

 * true for a lot of other formats, especially those that come directly from

 * a file. So if you have undefined buffer sizes and require a specific size,

 * this object is for you.

 *

 * An adapter is created with gst_adapter_new(). It can be freed again with

 * g_object_unref().

 *

 * The theory of operation is like this: All buffers received are put

 * into the adapter using gst_adapter_push() and the data is then read back

 * in chunks of the desired size using gst_adapter_peek(). After the data is

 * processed, it is freed using gst_adapter_flush().

 *

 * For example, a sink pad's chain function that needs to pass data to a library

 * in 512-byte chunks could be implemented like this:

 * <programlisting>

 * static GstFlowReturn

 * sink_pad_chain (GstPad *pad, GstBuffer *buffer)

 * {

 *   MyElement *this;

 *   GstAdapter *adapter;

 *   GstFlowReturn ret = GST_FLOW_OK;

 *   

 *   // will give the element an extra ref; remember to drop it 

 *   this = MY_ELEMENT (gst_pad_get_parent (pad));

 *   adapter = this->adapter;

 *   

 *   // put buffer into adapter

 *   gst_adapter_push (adapter, buffer);

 *   // while we can read out 512 bytes, process them

 *   while (gst_adapter_available (adapter) >= 512 && ret == GST_FLOW_OK) {

 *     // use flowreturn as an error value

 *     ret = my_library_foo (gst_adapter_peek (adapter, 512));

 *     gst_adapter_flush (adapter, 512);

 *   }

 *   

 *   gst_object_unref (this);

 *   return ret;

 * }

 * </programlisting>

 * For another example, a simple element inside GStreamer that uses GstAdapter

 * is the libvisual element.

 *

 * An element using GstAdapter in its sink pad chain function should ensure that

 * when the FLUSH_STOP event is received, that any queued data is cleared using

 * gst_adapter_clear(). Data should also be cleared or processed on EOS and

 * when changing state from #GST_STATE_PAUSED to #GST_STATE_READY.

 *

 * Also check the GST_BUFFER_FLAG_DISCONT flag on the buffer. Some elements might

 * need to clear the adapter after a discontinuity.

 *

 * A last thing to note is that while GstAdapter is pretty optimized,

 *

 * GstAdapter is not MT safe. All operations on an adapter must be serialized by

 * the caller. This is not normally a problem, however, as the normal use case

 * of GstAdapter is inside one pad's chain function, in which case access is

 * serialized via the pad's STREAM_LOCK.

 *

 * Note that gst_adapter_push() takes ownership of the buffer passed. Use 

 * gst_buffer_ref() before pushing it into the adapter if you still want to

 * access the buffer later. The adapter will never modify the data in the

 * buffer pushed in it.

 *

 */

#ifdef __SYMBIAN32__

#include <gst_global.h>

#endif

#include "gstadapter.h"

#include <string.h>

/* default size for the assembled data buffer */

GST_DEBUG_CATEGORY_STATIC (gst_adapter_debug);

#define GST_CAT_DEFAULT gst_adapter_debug

#define _do_init(thing) \

  GST_DEBUG_CATEGORY_INIT (gst_adapter_debug, "adapter", 0, "object to splice and merge buffers to desired size")

GST_BOILERPLATE_FULL (GstAdapter, gst_adapter, GObject, G_TYPE_OBJECT,

    _do_init);

static void gst_adapter_dispose (GObject * object);

static void gst_adapter_finalize (GObject * object);

static void

gst_adapter_base_init (gpointer g_class)

{

  /* nop */

}

static void

gst_adapter_class_init (GstAdapterClass * klass)

{

  GObjectClass *object = G_OBJECT_CLASS (klass);

  object->dispose = gst_adapter_dispose;

  object->finalize = gst_adapter_finalize;

}

static void

gst_adapter_init (GstAdapter * adapter, GstAdapterClass * g_class)

{

  adapter->assembled_data = g_malloc (DEFAULT_SIZE);

  adapter->assembled_size = DEFAULT_SIZE;

}

static void

gst_adapter_dispose (GObject * object)

{

  GstAdapter *adapter = GST_ADAPTER (object);

  gst_adapter_clear (adapter);

  GST_CALL_PARENT (G_OBJECT_CLASS, dispose, (object));

}

static void

gst_adapter_finalize (GObject * object)

{

  GstAdapter *adapter = GST_ADAPTER (object);

  g_free (adapter->assembled_data);

  GST_CALL_PARENT (G_OBJECT_CLASS, finalize, (object));

}

/**

 * gst_adapter_new:

 *

 * Creates a new #GstAdapter. Free with g_object_unref().

 *

 * Returns: a new #GstAdapter

 */

#ifdef __SYMBIAN32__

EXPORT_C

#endif

GstAdapter *

gst_adapter_new (void)

{

  return g_object_new (GST_TYPE_ADAPTER, NULL);

}

/**

 * gst_adapter_clear:

 * @adapter: a #GstAdapter

 *

 * Removes all buffers from @adapter.

 */

#ifdef __SYMBIAN32__

EXPORT_C

#endif

void

gst_adapter_clear (GstAdapter * adapter)

{

  g_return_if_fail (GST_IS_ADAPTER (adapter));

  g_slist_foreach (adapter->buflist, (GFunc) gst_mini_object_unref, NULL);

  g_slist_free (adapter->buflist);

  adapter->buflist = NULL;

  adapter->buflist_end = NULL;

  adapter->size = 0;

  adapter->skip = 0;

  adapter->assembled_len = 0;

}

/**

 * gst_adapter_push:

 * @adapter: a #GstAdapter

 * @buf: a #GstBuffer to add to queue in the adapter

 *

 * Adds the data from @buf to the data stored inside @adapter and takes

 * ownership of the buffer.

 */

#ifdef __SYMBIAN32__

EXPORT_C

#endif

void

gst_adapter_push (GstAdapter * adapter, GstBuffer * buf)

{

  g_return_if_fail (GST_IS_ADAPTER (adapter));

  g_return_if_fail (GST_IS_BUFFER (buf));

  } else {

  }

}

/* Internal method only. Tries to merge buffers at the head of the queue

 * to form a single larger buffer of size 'size'. Only merges buffers that

 * where 'gst_buffer_is_span_fast' returns TRUE.

 *

 * Returns TRUE if it managed to merge anything.

 */

static gboolean

gst_adapter_try_to_merge_up (GstAdapter * adapter, guint size)

{

  GstBuffer *cur, *head;

  GSList *g;

  g = adapter->buflist;

  if (g == NULL)

    return FALSE;

  head = g->data;

  g = g_slist_next (g);

  /* How large do we want our head buffer? The requested size, plus whatever's

   * been skipped already */

  size += adapter->skip;

  while (g != NULL && GST_BUFFER_SIZE (head) < size) {

    cur = g->data;

    if (!gst_buffer_is_span_fast (head, cur))

      return TRUE;

    /* Merge the head buffer and the next in line */

    GST_LOG_OBJECT (adapter,

        "Merging buffers of size %u & %u in search of target %u",

        GST_BUFFER_SIZE (head), GST_BUFFER_SIZE (cur), size);

    head = gst_buffer_join (head, cur);

    /* Delete the front list item, and store our new buffer in the 2nd list 

     * item */

    adapter->buflist = g_slist_delete_link (adapter->buflist, adapter->buflist);

    g->data = head;

  }

  return FALSE;

}

/**

 * gst_adapter_peek:

 * @adapter: a #GstAdapter

 * @size: the number of bytes to peek

 *

 * Gets the first @size bytes stored in the @adapter. The returned pointer is

 * valid until the next function is called on the adapter.

 *

 * Note that setting the returned pointer as the data of a #GstBuffer is

 * incorrect for general-purpose plugins. The reason is that if a downstream

 * element stores the buffer so that it has access to it outside of the bounds

 * of its chain function, the buffer will have an invalid data pointer after

 * your element flushes the bytes. In that case you should use

 * gst_adapter_take(), which returns a freshly-allocated buffer that you can set

 * as #GstBuffer malloc_data or the potentially more performant 

 * gst_adapter_take_buffer().

 *

 * Returns #NULL if @size bytes are not available.

 *

 * Returns: a pointer to the first @size bytes of data, or NULL.

 */

#ifdef __SYMBIAN32__

EXPORT_C

#endif

const guint8 *

gst_adapter_peek (GstAdapter * adapter, guint size)

{

  GstBuffer *cur;

  g_return_val_if_fail (GST_IS_ADAPTER (adapter), NULL);

  g_return_val_if_fail (size > 0, NULL);

  /* we don't have enough data, return NULL. This is unlikely

   * as one usually does an _available() first instead of peeking a

   * random size. */

  if (G_UNLIKELY (size > adapter->size))

    return NULL;

  /* we have enough assembled data, return it */

  if (adapter->assembled_len >= size)

    return adapter->assembled_data;

  /* our head buffer has enough data left, return it */

  cur = adapter->buflist->data;

  /* We may be able to efficiently merge buffers in our pool to 

   * gather a big enough chunk to return it from the head buffer directly */

  if (gst_adapter_try_to_merge_up (adapter, size)) {

    /* Merged something! Check if there's enough avail now */

    cur = adapter->buflist->data;

  }

  /* Gonna need to copy stuff out */

    adapter->assembled_size = (size / DEFAULT_SIZE + 1) * DEFAULT_SIZE;

        adapter->assembled_size);

    g_free (adapter->assembled_data);

    adapter->assembled_data = g_malloc (adapter->assembled_size);

  }

  adapter->assembled_len = size;

  return adapter->assembled_data;

}

/**

 * gst_adapter_copy:

 * @adapter: a #GstAdapter

 * @dest: the memory where to copy to

 * @offset: the bytes offset in the adapter to start from

 * @size: the number of bytes to copy

 *

 * Copies @size bytes of data starting at @offset out of the buffers

 * contained in @GstAdapter into an array @dest provided by the caller.

 *

 * The array @dest should be large enough to contain @size bytes.

 * The user should check that the adapter has (@offset + @size) bytes

 * available before calling this function.

 *

 * Since: 0.10.12

 */

#ifdef __SYMBIAN32__

EXPORT_C

#endif

void

gst_adapter_copy (GstAdapter * adapter, guint8 * dest, guint offset, guint size)

{

  g_return_if_fail (GST_IS_ADAPTER (adapter));

  g_return_if_fail (size > 0);

}

/**

 * gst_adapter_flush:

 * @adapter: a #GstAdapter

 * @flush: the number of bytes to flush

 *

 * Flushes the first @flush bytes in the @adapter. The caller must ensure that

 * at least this many bytes are available.

 *

 * See also: gst_adapter_peek().

 */

#ifdef __SYMBIAN32__

EXPORT_C

#endif

void

gst_adapter_flush (GstAdapter * adapter, guint flush)

{

  GstBuffer *cur;

  g_return_if_fail (GST_IS_ADAPTER (adapter));

  g_return_if_fail (flush <= adapter->size);

  GST_LOG_OBJECT (adapter, "flushing %u bytes", flush);

  adapter->size -= flush;

  adapter->assembled_len = 0;

      break;

    }

  }

}

/**

 * gst_adapter_take:

 * @adapter: a #GstAdapter

 * @nbytes: the number of bytes to take

 *

 * Returns a freshly allocated buffer containing the first @nbytes bytes of the

 * @adapter. The returned bytes will be flushed from the adapter.

 *

 * Caller owns returned value. g_free after usage.

 *

 * Returns: oven-fresh hot data, or #NULL if @nbytes bytes are not available

 */

#ifdef __SYMBIAN32__

EXPORT_C

#endif

guint8 *

gst_adapter_take (GstAdapter * adapter, guint nbytes)

{

  guint8 *data;

  g_return_val_if_fail (GST_IS_ADAPTER (adapter), NULL);

  g_return_val_if_fail (nbytes > 0, NULL);

  /* we don't have enough data, return NULL. This is unlikely

   * as one usually does an _available() first instead of peeking a

   * random size. */

  if (G_UNLIKELY (nbytes > adapter->size))

    return NULL;

  if (adapter->assembled_len >= nbytes) {

    GST_LOG_OBJECT (adapter, "taking %u bytes already assembled", nbytes);

  } else {

    GST_LOG_OBJECT (adapter, "taking %u bytes by collection", nbytes);

  }

  gst_adapter_flush (adapter, nbytes);

  return data;

}

/**