/**
* 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
*/
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;
/* we have enough assembled data, take from there */
if (adapter->assembled_len >= nbytes) {
GST_LOG_OBJECT (adapter, "taking %u bytes already assembled", nbytes);
data = adapter->assembled_data;
/* allocate new data, assembled_len will be set to 0 in the flush below */
adapter->assembled_data = g_malloc (adapter->assembled_size);
} else {
/* we need to allocate and copy. We could potentially copy bytes from the
* assembled data before doing the copy_into */
GST_LOG_OBJECT (adapter, "taking %u bytes by collection", nbytes);
data = g_malloc (nbytes);
copy_into_unchecked (adapter, data, adapter->skip, nbytes);
}
gst_adapter_flush_unchecked (adapter, nbytes);
return 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
*/
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);
g_return_if_fail (offset + size <= adapter->size);
copy_into_unchecked (adapter, dest, offset + adapter->skip, size);
}
/**
* 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.
*/
const guint8 *
gst_adapter_peek (GstAdapter * adapter, guint size)
{
GstBuffer *cur;
guint skip;
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;
skip = adapter->skip;
if (GST_BUFFER_SIZE (cur) >= size + skip)
return GST_BUFFER_DATA (cur) + skip;
/* 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;
if (GST_BUFFER_SIZE (cur) >= size + skip)
return GST_BUFFER_DATA (cur) + skip;
}
/* Gonna need to copy stuff out */
if (G_UNLIKELY (adapter->assembled_size < size)) {
adapter->assembled_size = (size / DEFAULT_SIZE + 1) * DEFAULT_SIZE;
GST_DEBUG_OBJECT (adapter, "resizing internal buffer to %u",
adapter->assembled_size);
/* no g_realloc to avoid a memcpy that is not desired here since we are
* going to copy new data into the area below */
g_free (adapter->assembled_data);
adapter->assembled_data = g_malloc (adapter->assembled_size);
}
adapter->assembled_len = size;
GST_CAT_DEBUG (GST_CAT_PERFORMANCE, "copy data from adapter");
copy_into_unchecked (adapter, adapter->assembled_data, skip, size);
return adapter->assembled_data;
}
/* internal function, nbytes should be flushed after calling this function */
static guint8 *
gst_adapter_take_internal (GstAdapter * adapter, gsize nbytes)
{
guint8 *data;
gsize toreuse, tocopy;
/* see how much data we can reuse from the assembled memory and how much
* we need to copy */
toreuse = MIN (nbytes, adapter->assembled_len);
tocopy = nbytes - toreuse;
/* find memory to return */
if (adapter->assembled_size >= nbytes && toreuse > 0) {
/* we reuse already allocated memory but only when we're going to reuse
* something from it because else we are worse than the malloc and copy
* case below */
GST_LOG_OBJECT (adapter, "reusing %" G_GSIZE_FORMAT " bytes of assembled"
" data", toreuse);
/* we have enough free space in the assembled array */
data = adapter->assembled_data;
/* flush after this function should set the assembled_size to 0 */
adapter->assembled_data = g_malloc (adapter->assembled_size);
} else {
GST_LOG_OBJECT (adapter, "allocating %" G_GSIZE_FORMAT " bytes", nbytes);
/* not enough bytes in the assembled array, just allocate new space */
data = g_malloc (nbytes);
/* reuse what we can from the already assembled data */
if (toreuse) {
GST_LOG_OBJECT (adapter, "reusing %" G_GSIZE_FORMAT " bytes", toreuse);
GST_CAT_LOG_OBJECT (GST_CAT_PERFORMANCE, adapter,
"memcpy %" G_GSIZE_FORMAT " bytes", toreuse);
memcpy (data, adapter->assembled_data, toreuse);
}
}
if (tocopy) {
/* copy the remaining data */
copy_into_unchecked (adapter, toreuse + data, toreuse + adapter->skip,
tocopy);
}
return data;
}
/**
* gst_adapter_take_buffer:
* @adapter: a #GstAdapter
* @nbytes: the number of bytes to take
*
* Returns a #GstBuffer containing the first @nbytes bytes of the
* @adapter. The returned bytes will be flushed from the adapter.
* This function is potentially more performant than gst_adapter_take()
* since it can reuse the memory in pushed buffers by subbuffering
* or merging.
*
* Caller owns returned value. gst_buffer_unref() after usage.
*
* Since: 0.10.6
*
* Returns: a #GstBuffer containing the first @nbytes of the adapter,
* or #NULL if @nbytes bytes are not available
*/
GstBuffer *
gst_adapter_take_buffer (GstAdapter * adapter, guint nbytes)
{
GstBuffer *buffer;
GstBuffer *cur;
guint hsize, skip;
g_return_val_if_fail (GST_IS_ADAPTER (adapter), NULL);
g_return_val_if_fail (nbytes > 0, NULL);
GST_LOG_OBJECT (adapter, "taking buffer of %u bytes", nbytes);
/* we don't have enough data, return NULL. This is unlikely
* as one usually does an _available() first instead of grabbing a
* random size. */
if (G_UNLIKELY (nbytes > adapter->size))
return NULL;
cur = adapter->buflist->data;
skip = adapter->skip;
hsize = GST_BUFFER_SIZE (cur);
/* our head buffer has enough data left, return it */
if (skip == 0 && hsize == nbytes) {
GST_LOG_OBJECT (adapter, "providing buffer of %d bytes as head buffer",
nbytes);
buffer = gst_buffer_ref (cur);
goto done;
} else if (hsize >= nbytes + skip) {
GST_LOG_OBJECT (adapter, "providing buffer of %d bytes via sub-buffer",
nbytes);
buffer = gst_buffer_create_sub (cur, skip, nbytes);
goto done;
}
if (gst_adapter_try_to_merge_up (adapter, nbytes)) {
/* Merged something, let's try again for sub-buffering */
cur = adapter->buflist->data;
if (GST_BUFFER_SIZE (cur) >= nbytes + skip) {
GST_LOG_OBJECT (adapter, "providing buffer of %d bytes via sub-buffer",
nbytes);
buffer = gst_buffer_create_sub (cur, skip, nbytes);
goto done;
}
}
/* we have enough assembled data, copy from there */
if (adapter->assembled_len >= nbytes) {
GST_LOG_OBJECT (adapter, "taking %u bytes already assembled", nbytes);
buffer = gst_buffer_new ();
GST_BUFFER_SIZE (buffer) = nbytes;
GST_BUFFER_DATA (buffer) = adapter->assembled_data;
GST_BUFFER_MALLOCDATA (buffer) = adapter->assembled_data;
/* flush will set the assembled_len to 0 */
adapter->assembled_data = g_malloc (adapter->assembled_size);
} else {
/* we need to allocate and copy. We could potentially copy bytes from the
* assembled data before doing the copy_into */
buffer = gst_buffer_new_and_alloc (nbytes);
GST_LOG_OBJECT (adapter, "taking %u bytes by collection", nbytes);
copy_into_unchecked (adapter, GST_BUFFER_DATA (buffer), skip, nbytes);
}
done:
gst_adapter_flush_unchecked (adapter, nbytes);
return buffer;
}
/**
* gst_adapter_map:
* @adapter: a #GstAdapter
* @size: the number of bytes to map/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 memory or the potentially more performant
* gst_adapter_take_buffer().
*
* Returns #NULL if @size bytes are not available.
*
* Returns: (transfer none) (array length=size) (element-type guint8):
* a pointer to the first @size bytes of data, or NULL
*/
gconstpointer
gst_adapter_map (GstAdapter * adapter, gsize size)
{
GstBuffer *cur;
gsize skip, csize;
gsize toreuse, tocopy;
guint8 *data;
g_return_val_if_fail (GST_IS_ADAPTER (adapter), NULL);
g_return_val_if_fail (size > 0, NULL);
if (adapter->info.memory)
gst_adapter_unmap (adapter);
/* 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;
#if 0
do {
#endif
cur = adapter->buflist->data;
skip = adapter->skip;
csize = gst_buffer_get_size (cur);
if (csize >= size + skip) {
if (!gst_buffer_map (cur, &adapter->info, GST_MAP_READ))
return FALSE;
return (guint8 *) adapter->info.data + skip;
}
/* 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 0
} while (gst_adapter_try_to_merge_up (adapter, size));
#endif
/* see how much data we can reuse from the assembled memory and how much
* we need to copy */
toreuse = adapter->assembled_len;
tocopy = size - toreuse;
/* Gonna need to copy stuff out */
if (G_UNLIKELY (adapter->assembled_size < size)) {
adapter->assembled_size = (size / DEFAULT_SIZE + 1) * DEFAULT_SIZE;
GST_DEBUG_OBJECT (adapter, "resizing internal buffer to %" G_GSIZE_FORMAT,
adapter->assembled_size);
if (toreuse == 0) {
GST_CAT_DEBUG (GST_CAT_PERFORMANCE, "alloc new buffer");
/* no g_realloc to avoid a memcpy that is not desired here since we are
* not going to reuse any data here */
g_free (adapter->assembled_data);
adapter->assembled_data = g_malloc (adapter->assembled_size);
} else {
/* we are going to reuse all data, realloc then */
GST_CAT_DEBUG (GST_CAT_PERFORMANCE, "reusing %" G_GSIZE_FORMAT " bytes",
toreuse);
adapter->assembled_data =
g_realloc (adapter->assembled_data, adapter->assembled_size);
}
}
GST_CAT_DEBUG (GST_CAT_PERFORMANCE, "copy remaining %" G_GSIZE_FORMAT
" bytes from adapter", tocopy);
data = adapter->assembled_data;
copy_into_unchecked (adapter, data + toreuse, skip + toreuse, tocopy);
adapter->assembled_len = size;
return adapter->assembled_data;
}
