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DEFINITIONS
This source file includes following definitions.
- gst_bit_reader_new
- gst_bit_reader_new_from_buffer
- gst_bit_reader_free
- gst_bit_reader_init
- gst_bit_reader_init_from_buffer
- gst_bit_reader_set_pos
- gst_bit_reader_get_pos
- gst_bit_reader_get_remaining
- gst_bit_reader_get_size
- gst_bit_reader_skip
- gst_bit_reader_skip_to_byte
/* 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_get_size:
* @reader: a #GstBitReader instance
*
* Returns the total number of bits of a #GstBitReader instance.
*
* Returns: The total number of bits of @reader instance.
*
* Since: 0.10.26
*/
guint
gst_bit_reader_get_size (const GstBitReader * reader)
{
g_return_val_if_fail (reader != NULL, 0);
return reader->size * 8;
}
/**
* 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);