SwfdecBuffer

SwfdecBuffer — memory region handling

Synopsis




                    SwfdecBuffer;
                    SwfdecBufferQueue;
SwfdecBuffer*       swfdec_buffer_new                   (void);
SwfdecBuffer*       swfdec_buffer_new_and_alloc         (unsigned int size);
SwfdecBuffer*       swfdec_buffer_new_and_alloc0        (unsigned int size);
SwfdecBuffer*       swfdec_buffer_new_subbuffer         (SwfdecBuffer *buffer,
                                                         unsigned int offset,
                                                         unsigned int length);
SwfdecBuffer*       swfdec_buffer_new_from_file         (const char *filename,
                                                         GError **error);
SwfdecBuffer*       swfdec_buffer_ref                   (SwfdecBuffer *buffer);
void                swfdec_buffer_unref                 (SwfdecBuffer *buffer);
SwfdecBufferQueue*  swfdec_buffer_queue_new             (void);
void                swfdec_buffer_queue_clear           (SwfdecBufferQueue *queue);
void                swfdec_buffer_queue_free            (SwfdecBufferQueue *queue);
int                 swfdec_buffer_queue_get_depth       (SwfdecBufferQueue *queue);
int                 swfdec_buffer_queue_get_offset      (SwfdecBufferQueue *queue);
void                swfdec_buffer_queue_push            (SwfdecBufferQueue *queue,
                                                         SwfdecBuffer *buffer);
SwfdecBuffer*       swfdec_buffer_queue_pull            (SwfdecBufferQueue *queue,
                                                         unsigned int length);
SwfdecBuffer*       swfdec_buffer_queue_pull_buffer     (SwfdecBufferQueue *queue);
SwfdecBuffer*       swfdec_buffer_queue_peek            (SwfdecBufferQueue *queue,
                                                         unsigned int length);

Description

To allow for easy sharing of memory regions, SwfdecBuffer was created. Every buffer refers to a memory region and its size and takes care of freeing that region when the buffer is no longer needed. They are reference countedto make it easy to refer to the same region from various independant parts of your code. Buffers also support some advanced functionalities like extracting parts of the buffer using swfdec_buffer_new_subbuffer() or using mmapped files with swfdec_buffer_new_from_file() without the need for a different API.

A SwfdecBufferQueue is a queue of continuous buffers that allows reading its data in chunks of pre-defined sizes. It is used to transform a data stream that was provided by buffers of random sizes to buffers of the right size.

Details

SwfdecBuffer

typedef struct {
  unsigned char *data;
  unsigned int length;

  int ref_count;

  SwfdecBuffer *parent;

  void (*free) (SwfdecBuffer *, void *);
  void *priv;
} SwfdecBuffer;


SwfdecBufferQueue

typedef struct {
  GList *buffers;
  unsigned int depth;
  unsigned int offset;
} SwfdecBufferQueue;


swfdec_buffer_new ()

SwfdecBuffer*       swfdec_buffer_new                   (void);

Creates a new SwfdecBuffer to be filled by the user. Use like this:

SwfdecBuffer *buffer = swfdec_buffer_new ();
buffer->data = mydata;
buffer->length = mydata_length;
buffer->free = mydata_freefunc;

Returns : a new SwfdecBuffer referencing nothing.

swfdec_buffer_new_and_alloc ()

SwfdecBuffer*       swfdec_buffer_new_and_alloc         (unsigned int size);

Creates a new buffer and allocates new memory of size bytes to be used with the buffer.

size : amount of bytes to allocate
Returns : a new SwfdecBuffer with buffer->data pointing to new data

swfdec_buffer_new_and_alloc0 ()

SwfdecBuffer*       swfdec_buffer_new_and_alloc0        (unsigned int size);

Createsa new buffer just like swfdec_buffer_new_and_alloc(), but ensures that the returned data gets initialized to be 0.

size : amount of bytes to allocate
Returns : a new SwfdecBuffer with buffer->data pointing to new data

swfdec_buffer_new_subbuffer ()

SwfdecBuffer*       swfdec_buffer_new_subbuffer         (SwfdecBuffer *buffer,
                                                         unsigned int offset,
                                                         unsigned int length);

Creates a SwfdecBuffer for managing a partial section of the memory pointed to by buffer.

buffer : SwfdecBuffer managing the region of memory
offset : starting offset into data
length : amount of bytes to manage
Returns : a new SwfdecBuffer managing the indicated region.

swfdec_buffer_new_from_file ()

SwfdecBuffer*       swfdec_buffer_new_from_file         (const char *filename,
                                                         GError **error);

Tries to create a buffer for the given filename using a GMappedFile. If the creation fails, NULL is returned and error is set. The error can be any of the errors that are valid from g_mapped_file_new().

filename : file to read
error : return location for a GError or NULL
Returns : a new SwfdecBuffer or NULL on failure

swfdec_buffer_ref ()

SwfdecBuffer*       swfdec_buffer_ref                   (SwfdecBuffer *buffer);

increases the reference count of buffer by one.

buffer : a SwfdecBuffer
Returns : The passed in buffer.

swfdec_buffer_unref ()

void                swfdec_buffer_unref                 (SwfdecBuffer *buffer);

Decreases the reference count of buffer by one. If no reference to this buffer exists anymore, the buffer and the memory it manages are freed.

buffer : a SwfdecBuffer

swfdec_buffer_queue_new ()

SwfdecBufferQueue*  swfdec_buffer_queue_new             (void);

Returns :

swfdec_buffer_queue_clear ()

void                swfdec_buffer_queue_clear           (SwfdecBufferQueue *queue);

queue :

swfdec_buffer_queue_free ()

void                swfdec_buffer_queue_free            (SwfdecBufferQueue *queue);

queue :

swfdec_buffer_queue_get_depth ()

int                 swfdec_buffer_queue_get_depth       (SwfdecBufferQueue *queue);

queue :
Returns :

swfdec_buffer_queue_get_offset ()

int                 swfdec_buffer_queue_get_offset      (SwfdecBufferQueue *queue);

queue :
Returns :

swfdec_buffer_queue_push ()

void                swfdec_buffer_queue_push            (SwfdecBufferQueue *queue,
                                                         SwfdecBuffer *buffer);

queue :
buffer :

swfdec_buffer_queue_pull ()

SwfdecBuffer*       swfdec_buffer_queue_pull            (SwfdecBufferQueue *queue,
                                                         unsigned int length);

queue :
length :
Returns :

swfdec_buffer_queue_pull_buffer ()

SwfdecBuffer*       swfdec_buffer_queue_pull_buffer     (SwfdecBufferQueue *queue);

queue :
Returns :

swfdec_buffer_queue_peek ()

SwfdecBuffer*       swfdec_buffer_queue_peek            (SwfdecBufferQueue *queue,
                                                         unsigned int length);

Creates a new buffer with the first length bytes from queue, but unlike swfdec_buffer_queue_pull(), does not remove them from queue.

queue : a SwfdecBufferQueue to read from
length : amount of bytes to peek
Returns : NULL if the requested amount of data wasn't available or a new readonly SwfdecBuffer. Use swfdec_buffer_unref() after use.