mirror of
https://gitlab.freedesktop.org/gstreamer/gstreamer.git
synced 2024-12-22 16:26:39 +00:00
446e8cb5e6
Original commit message from CVS: * libs/gst/base/gstbitreader.c: * libs/gst/base/gstbytereader.c: Fix the names of 2 functions in the docs strings.
400 lines
9.3 KiB
C
400 lines
9.3 KiB
C
/* GStreamer
|
|
*
|
|
* Copyright (C) 2008 Sebastian Dröge <sebastian.droege@collabora.co.uk>.
|
|
*
|
|
* 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.
|
|
*/
|
|
|
|
#ifdef HAVE_CONFIG_H
|
|
#include "config.h"
|
|
#endif
|
|
|
|
#include "gstbitreader.h"
|
|
|
|
#include <string.h>
|
|
|
|
/**
|
|
* SECTION:gstbitreader
|
|
* @short_description: Reads any number of bits from a memory buffer
|
|
*
|
|
* #GstBitReader provides a bit reader that can read any number of bits
|
|
* from a memory buffer. It provides functions for reading any number of bits
|
|
* into 8, 16, 32 and 64 bit variables.
|
|
*/
|
|
|
|
/**
|
|
* gst_bit_reader_new:
|
|
* @data: Data from which the #GstBitReader should read
|
|
* @size: Size of @data in bytes
|
|
*
|
|
* Create a new #GstBitReader instance, which will read from @data.
|
|
*
|
|
* Returns: a new #GstBitReader instance
|
|
*
|
|
* Since: 0.10.22
|
|
*/
|
|
GstBitReader *
|
|
gst_bit_reader_new (const guint8 * data, guint size)
|
|
{
|
|
GstBitReader *ret = g_slice_new0 (GstBitReader);
|
|
|
|
ret->data = data;
|
|
ret->size = size;
|
|
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* gst_bit_reader_new_from_buffer:
|
|
* @buffer: Buffer from which the #GstBitReader should read
|
|
*
|
|
* Create a new #GstBitReader instance, which will read from the
|
|
* #GstBuffer @buffer.
|
|
*
|
|
* Returns: a new #GstBitReader instance
|
|
*
|
|
* Since: 0.10.22
|
|
*/
|
|
GstBitReader *
|
|
gst_bit_reader_new_from_buffer (const GstBuffer * buffer)
|
|
{
|
|
g_return_val_if_fail (GST_IS_BUFFER (buffer), NULL);
|
|
|
|
return gst_bit_reader_new (GST_BUFFER_DATA (buffer),
|
|
GST_BUFFER_SIZE (buffer));
|
|
}
|
|
|
|
/**
|
|
* gst_bit_reader_free:
|
|
* @reader: a #GstBitReader instance
|
|
*
|
|
* Frees a #GstBitReader instance, which was previously allocated by
|
|
* gst_bit_reader_new() or gst_bit_reader_new_from_buffer().
|
|
*
|
|
* Since: 0.10.22
|
|
*/
|
|
void
|
|
gst_bit_reader_free (GstBitReader * reader)
|
|
{
|
|
g_return_if_fail (reader != NULL);
|
|
|
|
g_slice_free (GstBitReader, reader);
|
|
}
|
|
|
|
/**
|
|
* gst_bit_reader_init:
|
|
* @reader: a #GstBitReader instance
|
|
* @data: Data from which the #GstBitReader should read
|
|
* @size: Size of @data in bytes
|
|
*
|
|
* Initializes a #GstBitReader instance to read from @data. This function
|
|
* can be called on already initialized instances.
|
|
*
|
|
* Since: 0.10.22
|
|
*/
|
|
void
|
|
gst_bit_reader_init (GstBitReader * reader, const guint8 * data, guint size)
|
|
{
|
|
g_return_if_fail (reader != NULL);
|
|
|
|
reader->data = data;
|
|
reader->size = size;
|
|
reader->byte = reader->bit = 0;
|
|
}
|
|
|
|
/**
|
|
* gst_bit_reader_init_from_buffer:
|
|
* @reader: a #GstBitReader instance
|
|
* @buffer: Buffer from which the #GstBitReader should read
|
|
*
|
|
* Initializes a #GstBitReader instance to read from @buffer. This function
|
|
* can be called on already initialized instances.
|
|
*
|
|
* Since: 0.10.22
|
|
*/
|
|
void
|
|
gst_bit_reader_init_from_buffer (GstBitReader * reader,
|
|
const GstBuffer * buffer)
|
|
{
|
|
g_return_if_fail (GST_IS_BUFFER (buffer));
|
|
|
|
gst_bit_reader_init (reader, GST_BUFFER_DATA (buffer),
|
|
GST_BUFFER_SIZE (buffer));
|
|
}
|
|
|
|
/**
|
|
* gst_bit_reader_set_pos:
|
|
* @reader: a #GstBitReader instance
|
|
* @pos: The new position in bits
|
|
*
|
|
* Sets the new position of a #GstBitReader instance to @pos in bits.
|
|
*
|
|
* Returns: %TRUE if the position could be set successfully, %FALSE
|
|
* otherwise.
|
|
*
|
|
* Since: 0.10.22
|
|
*/
|
|
gboolean
|
|
gst_bit_reader_set_pos (GstBitReader * reader, guint pos)
|
|
{
|
|
g_return_val_if_fail (reader != NULL, FALSE);
|
|
|
|
if (pos > reader->size * 8)
|
|
return FALSE;
|
|
|
|
reader->byte = pos / 8;
|
|
reader->bit = pos % 8;
|
|
|
|
return TRUE;
|
|
}
|
|
|
|
/**
|
|
* gst_bit_reader_get_pos:
|
|
* @reader: a #GstBitReader instance
|
|
*
|
|
* Returns the current position of a #GstBitReader instance in bits.
|
|
*
|
|
* Returns: The current position of @reader in bits.
|
|
*
|
|
* Since: 0.10.22
|
|
*/
|
|
guint
|
|
gst_bit_reader_get_pos (const GstBitReader * reader)
|
|
{
|
|
g_return_val_if_fail (reader != NULL, 0);
|
|
|
|
return reader->byte * 8 + reader->bit;
|
|
}
|
|
|
|
/**
|
|
* gst_bit_reader_get_remaining:
|
|
* @reader: a #GstBitReader instance
|
|
*
|
|
* Returns the remaining number of bits of a #GstBitReader instance.
|
|
*
|
|
* Returns: The remaining number of bits of @reader instance.
|
|
*
|
|
* Since: 0.10.22
|
|
*/
|
|
guint
|
|
gst_bit_reader_get_remaining (const GstBitReader * reader)
|
|
{
|
|
g_return_val_if_fail (reader != NULL, 0);
|
|
|
|
return reader->size * 8 - (reader->byte * 8 + reader->bit);
|
|
}
|
|
|
|
/**
|
|
* gst_bit_reader_skip:
|
|
* @reader: a #GstBitReader instance
|
|
* @nbits: the number of bits to skip
|
|
*
|
|
* Skips @nbits bits of the #GstBitReader instance.
|
|
*
|
|
* Returns: %TRUE if @nbits bits could be skipped, %FALSE otherwise.
|
|
*
|
|
* Since: 0.10.22
|
|
*/
|
|
gboolean
|
|
gst_bit_reader_skip (GstBitReader * reader, guint nbits)
|
|
{
|
|
g_return_val_if_fail (reader != NULL, FALSE);
|
|
|
|
if (gst_bit_reader_get_remaining (reader) < nbits)
|
|
return FALSE;
|
|
|
|
reader->bit += nbits;
|
|
reader->byte += reader->bit / 8;
|
|
reader->bit = reader->bit % 8;
|
|
|
|
return TRUE;
|
|
}
|
|
|
|
/**
|
|
* gst_bit_reader_skip_to_byte:
|
|
* @reader: a #GstBitReader instance
|
|
*
|
|
* Skips until the next byte.
|
|
*
|
|
* Returns: %TRUE if successful, %FALSE otherwise.
|
|
*
|
|
* Since: 0.10.22
|
|
*/
|
|
gboolean
|
|
gst_bit_reader_skip_to_byte (GstBitReader * reader)
|
|
{
|
|
g_return_val_if_fail (reader != NULL, FALSE);
|
|
|
|
if (reader->byte > reader->size)
|
|
return FALSE;
|
|
|
|
if (reader->bit) {
|
|
reader->bit = 0;
|
|
reader->byte++;
|
|
}
|
|
|
|
return TRUE;
|
|
}
|
|
|
|
/**
|
|
* gst_bit_reader_get_bits_uint8:
|
|
* @reader: a #GstBitReader instance
|
|
* @val: Pointer to a #guint8 to store the result
|
|
* @nbits: number of bits to read
|
|
*
|
|
* Read @nbits bits into @val and update the current position.
|
|
*
|
|
* Returns: %TRUE if successful, %FALSE otherwise.
|
|
*
|
|
* Since: 0.10.22
|
|
*/
|
|
|
|
/**
|
|
* gst_bit_reader_get_bits_uint16:
|
|
* @reader: a #GstBitReader instance
|
|
* @val: Pointer to a #guint16 to store the result
|
|
* @nbits: number of bits to read
|
|
*
|
|
* Read @nbits bits into @val and update the current position.
|
|
*
|
|
* Returns: %TRUE if successful, %FALSE otherwise.
|
|
*
|
|
* Since: 0.10.22
|
|
*/
|
|
|
|
/**
|
|
* gst_bit_reader_get_bits_uint32:
|
|
* @reader: a #GstBitReader instance
|
|
* @val: Pointer to a #guint32 to store the result
|
|
* @nbits: number of bits to read
|
|
*
|
|
* Read @nbits bits into @val and update the current position.
|
|
*
|
|
* Returns: %TRUE if successful, %FALSE otherwise.
|
|
*
|
|
* Since: 0.10.22
|
|
*/
|
|
|
|
/**
|
|
* gst_bit_reader_get_bits_uint64:
|
|
* @reader: a #GstBitReader instance
|
|
* @val: Pointer to a #guint64 to store the result
|
|
* @nbits: number of bits to read
|
|
*
|
|
* Read @nbits bits into @val and update the current position.
|
|
*
|
|
* Returns: %TRUE if successful, %FALSE otherwise.
|
|
*
|
|
* Since: 0.10.22
|
|
*/
|
|
|
|
/**
|
|
* gst_bit_reader_peek_bits_uint8:
|
|
* @reader: a #GstBitReader instance
|
|
* @val: Pointer to a #guint8 to store the result
|
|
* @nbits: number of bits to read
|
|
*
|
|
* Read @nbits bits into @val but keep the current position.
|
|
*
|
|
* Returns: %TRUE if successful, %FALSE otherwise.
|
|
*
|
|
* Since: 0.10.22
|
|
*/
|
|
|
|
/**
|
|
* gst_bit_reader_peek_bits_uint16:
|
|
* @reader: a #GstBitReader instance
|
|
* @val: Pointer to a #guint16 to store the result
|
|
* @nbits: number of bits to read
|
|
*
|
|
* Read @nbits bits into @val but keep the current position.
|
|
*
|
|
* Returns: %TRUE if successful, %FALSE otherwise.
|
|
*
|
|
* Since: 0.10.22
|
|
*/
|
|
|
|
/**
|
|
* gst_bit_reader_peek_bits_uint32:
|
|
* @reader: a #GstBitReader instance
|
|
* @val: Pointer to a #guint32 to store the result
|
|
* @nbits: number of bits to read
|
|
*
|
|
* Read @nbits bits into @val but keep the current position.
|
|
*
|
|
* Returns: %TRUE if successful, %FALSE otherwise.
|
|
*
|
|
* Since: 0.10.22
|
|
*/
|
|
|
|
/**
|
|
* gst_bit_reader_peek_bits_uint64:
|
|
* @reader: a #GstBitReader instance
|
|
* @val: Pointer to a #guint64 to store the result
|
|
* @nbits: number of bits to read
|
|
*
|
|
* Read @nbits bits into @val but keep the current position.
|
|
*
|
|
* Returns: %TRUE if successful, %FALSE otherwise.
|
|
*
|
|
* Since: 0.10.22
|
|
*/
|
|
|
|
#define GST_BIT_READER_READ_BITS(bits) \
|
|
gboolean \
|
|
gst_bit_reader_get_bits_uint##bits (GstBitReader *reader, guint##bits *val, guint nbits) \
|
|
{ \
|
|
guint##bits ret = 0; \
|
|
\
|
|
g_return_val_if_fail (reader != NULL, FALSE); \
|
|
g_return_val_if_fail (val != NULL, FALSE); \
|
|
g_return_val_if_fail (nbits <= bits, FALSE); \
|
|
\
|
|
if (reader->byte * 8 + reader->bit + nbits > reader->size * 8) \
|
|
return FALSE; \
|
|
\
|
|
while (nbits > 0) { \
|
|
guint toread = MIN (nbits, 8 - reader->bit); \
|
|
\
|
|
ret <<= toread; \
|
|
ret |= (reader->data[reader->byte] & (0xff >> reader->bit)) >> (8 - toread - reader->bit); \
|
|
\
|
|
reader->bit += toread; \
|
|
if (reader->bit >= 8) { \
|
|
reader->byte++; \
|
|
reader->bit = 0; \
|
|
} \
|
|
nbits -= toread; \
|
|
} \
|
|
\
|
|
*val = ret; \
|
|
return TRUE; \
|
|
} \
|
|
\
|
|
gboolean \
|
|
gst_bit_reader_peek_bits_uint##bits (const GstBitReader *reader, guint##bits *val, guint nbits) \
|
|
{ \
|
|
GstBitReader tmp; \
|
|
\
|
|
g_return_val_if_fail (reader != NULL, FALSE); \
|
|
tmp = *reader; \
|
|
return gst_bit_reader_get_bits_uint##bits (&tmp, val, nbits); \
|
|
}
|
|
|
|
GST_BIT_READER_READ_BITS (8);
|
|
GST_BIT_READER_READ_BITS (16);
|
|
GST_BIT_READER_READ_BITS (32);
|
|
GST_BIT_READER_READ_BITS (64);
|