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https://gitlab.freedesktop.org/gstreamer/gstreamer.git
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418 lines
9.6 KiB
C
418 lines
9.6 KiB
C
/* GStreamer
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*
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* Copyright (C) 2008 Sebastian Dröge <sebastian.droege@collabora.co.uk>.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include "gstbitreader.h"
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#include <string.h>
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/**
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* SECTION:gstbitreader
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* @short_description: Reads any number of bits from a memory buffer
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*
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* #GstBitReader provides a bit reader that can read any number of bits
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* from a memory buffer. It provides functions for reading any number of bits
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* into 8, 16, 32 and 64 bit variables.
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*/
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/**
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* gst_bit_reader_new:
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* @data: Data from which the #GstBitReader should read
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* @size: Size of @data in bytes
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*
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* Create a new #GstBitReader instance, which will read from @data.
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*
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* Returns: a new #GstBitReader instance
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*
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* Since: 0.10.22
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*/
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GstBitReader *
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gst_bit_reader_new (const guint8 * data, guint size)
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{
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GstBitReader *ret = g_slice_new0 (GstBitReader);
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ret->data = data;
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ret->size = size;
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return ret;
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}
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/**
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* gst_bit_reader_new_from_buffer:
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* @buffer: Buffer from which the #GstBitReader should read
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*
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* Create a new #GstBitReader instance, which will read from the
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* #GstBuffer @buffer.
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*
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* Returns: a new #GstBitReader instance
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*
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* Since: 0.10.22
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*/
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GstBitReader *
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gst_bit_reader_new_from_buffer (const GstBuffer * buffer)
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{
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g_return_val_if_fail (GST_IS_BUFFER (buffer), NULL);
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return gst_bit_reader_new (GST_BUFFER_DATA (buffer),
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GST_BUFFER_SIZE (buffer));
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}
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/**
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* gst_bit_reader_free:
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* @reader: a #GstBitReader instance
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*
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* Frees a #GstBitReader instance, which was previously allocated by
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* gst_bit_reader_new() or gst_bit_reader_new_from_buffer().
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*
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* Since: 0.10.22
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*/
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void
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gst_bit_reader_free (GstBitReader * reader)
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{
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g_return_if_fail (reader != NULL);
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g_slice_free (GstBitReader, reader);
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}
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/**
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* gst_bit_reader_init:
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* @reader: a #GstBitReader instance
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* @data: Data from which the #GstBitReader should read
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* @size: Size of @data in bytes
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*
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* Initializes a #GstBitReader instance to read from @data. This function
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* can be called on already initialized instances.
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*
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* Since: 0.10.22
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*/
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void
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gst_bit_reader_init (GstBitReader * reader, const guint8 * data, guint size)
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{
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g_return_if_fail (reader != NULL);
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reader->data = data;
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reader->size = size;
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reader->byte = reader->bit = 0;
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}
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/**
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* gst_bit_reader_init_from_buffer:
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* @reader: a #GstBitReader instance
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* @buffer: Buffer from which the #GstBitReader should read
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*
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* Initializes a #GstBitReader instance to read from @buffer. This function
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* can be called on already initialized instances.
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*
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* Since: 0.10.22
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*/
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void
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gst_bit_reader_init_from_buffer (GstBitReader * reader,
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const GstBuffer * buffer)
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{
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g_return_if_fail (GST_IS_BUFFER (buffer));
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gst_bit_reader_init (reader, GST_BUFFER_DATA (buffer),
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GST_BUFFER_SIZE (buffer));
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}
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/**
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* gst_bit_reader_set_pos:
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* @reader: a #GstBitReader instance
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* @pos: The new position in bits
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*
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* Sets the new position of a #GstBitReader instance to @pos in bits.
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*
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* Returns: %TRUE if the position could be set successfully, %FALSE
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* otherwise.
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*
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* Since: 0.10.22
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*/
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gboolean
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gst_bit_reader_set_pos (GstBitReader * reader, guint pos)
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{
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g_return_val_if_fail (reader != NULL, FALSE);
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if (pos > reader->size * 8)
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return FALSE;
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reader->byte = pos / 8;
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reader->bit = pos % 8;
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return TRUE;
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}
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/**
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* gst_bit_reader_get_pos:
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* @reader: a #GstBitReader instance
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*
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* Returns the current position of a #GstBitReader instance in bits.
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*
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* Returns: The current position of @reader in bits.
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*
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* Since: 0.10.22
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*/
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guint
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gst_bit_reader_get_pos (const GstBitReader * reader)
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{
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g_return_val_if_fail (reader != NULL, 0);
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return reader->byte * 8 + reader->bit;
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}
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/**
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* gst_bit_reader_get_remaining:
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* @reader: a #GstBitReader instance
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*
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* Returns the remaining number of bits of a #GstBitReader instance.
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*
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* Returns: The remaining number of bits of @reader instance.
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*
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* Since: 0.10.22
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*/
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guint
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gst_bit_reader_get_remaining (const GstBitReader * reader)
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{
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g_return_val_if_fail (reader != NULL, 0);
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return reader->size * 8 - (reader->byte * 8 + reader->bit);
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}
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/**
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* gst_bit_reader_get_size:
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* @reader: a #GstBitReader instance
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*
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* Returns the total number of bits of a #GstBitReader instance.
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*
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* Returns: The total number of bits of @reader instance.
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*
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* Since: 0.10.26
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*/
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guint
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gst_bit_reader_get_size (const GstBitReader * reader)
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{
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g_return_val_if_fail (reader != NULL, 0);
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return reader->size * 8;
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}
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/**
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* gst_bit_reader_skip:
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* @reader: a #GstBitReader instance
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* @nbits: the number of bits to skip
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*
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* Skips @nbits bits of the #GstBitReader instance.
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*
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* Returns: %TRUE if @nbits bits could be skipped, %FALSE otherwise.
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*
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* Since: 0.10.22
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*/
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gboolean
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gst_bit_reader_skip (GstBitReader * reader, guint nbits)
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{
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g_return_val_if_fail (reader != NULL, FALSE);
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if (gst_bit_reader_get_remaining (reader) < nbits)
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return FALSE;
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reader->bit += nbits;
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reader->byte += reader->bit / 8;
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reader->bit = reader->bit % 8;
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return TRUE;
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}
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/**
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* gst_bit_reader_skip_to_byte:
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* @reader: a #GstBitReader instance
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*
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* Skips until the next byte.
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*
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* Returns: %TRUE if successful, %FALSE otherwise.
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*
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* Since: 0.10.22
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*/
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gboolean
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gst_bit_reader_skip_to_byte (GstBitReader * reader)
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{
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g_return_val_if_fail (reader != NULL, FALSE);
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if (reader->byte > reader->size)
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return FALSE;
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if (reader->bit) {
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reader->bit = 0;
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reader->byte++;
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}
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return TRUE;
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}
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/**
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* gst_bit_reader_get_bits_uint8:
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* @reader: a #GstBitReader instance
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* @val: Pointer to a #guint8 to store the result
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* @nbits: number of bits to read
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*
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* Read @nbits bits into @val and update the current position.
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*
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* Returns: %TRUE if successful, %FALSE otherwise.
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*
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* Since: 0.10.22
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*/
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/**
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* gst_bit_reader_get_bits_uint16:
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* @reader: a #GstBitReader instance
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* @val: Pointer to a #guint16 to store the result
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* @nbits: number of bits to read
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*
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* Read @nbits bits into @val and update the current position.
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*
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* Returns: %TRUE if successful, %FALSE otherwise.
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*
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* Since: 0.10.22
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*/
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/**
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* gst_bit_reader_get_bits_uint32:
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* @reader: a #GstBitReader instance
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* @val: Pointer to a #guint32 to store the result
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* @nbits: number of bits to read
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*
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* Read @nbits bits into @val and update the current position.
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*
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* Returns: %TRUE if successful, %FALSE otherwise.
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*
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* Since: 0.10.22
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*/
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/**
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* gst_bit_reader_get_bits_uint64:
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* @reader: a #GstBitReader instance
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* @val: Pointer to a #guint64 to store the result
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* @nbits: number of bits to read
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*
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* Read @nbits bits into @val and update the current position.
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*
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* Returns: %TRUE if successful, %FALSE otherwise.
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*
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* Since: 0.10.22
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*/
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/**
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* gst_bit_reader_peek_bits_uint8:
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* @reader: a #GstBitReader instance
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* @val: Pointer to a #guint8 to store the result
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* @nbits: number of bits to read
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*
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* Read @nbits bits into @val but keep the current position.
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*
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* Returns: %TRUE if successful, %FALSE otherwise.
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*
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* Since: 0.10.22
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*/
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/**
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* gst_bit_reader_peek_bits_uint16:
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* @reader: a #GstBitReader instance
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* @val: Pointer to a #guint16 to store the result
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* @nbits: number of bits to read
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*
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* Read @nbits bits into @val but keep the current position.
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*
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* Returns: %TRUE if successful, %FALSE otherwise.
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*
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* Since: 0.10.22
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*/
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/**
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* gst_bit_reader_peek_bits_uint32:
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* @reader: a #GstBitReader instance
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* @val: Pointer to a #guint32 to store the result
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* @nbits: number of bits to read
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*
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* Read @nbits bits into @val but keep the current position.
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*
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* Returns: %TRUE if successful, %FALSE otherwise.
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*
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* Since: 0.10.22
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*/
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/**
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* gst_bit_reader_peek_bits_uint64:
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* @reader: a #GstBitReader instance
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* @val: Pointer to a #guint64 to store the result
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* @nbits: number of bits to read
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*
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* Read @nbits bits into @val but keep the current position.
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*
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* Returns: %TRUE if successful, %FALSE otherwise.
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*
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* Since: 0.10.22
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*/
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#define GST_BIT_READER_READ_BITS(bits) \
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gboolean \
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gst_bit_reader_get_bits_uint##bits (GstBitReader *reader, guint##bits *val, guint nbits) \
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{ \
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guint##bits ret = 0; \
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\
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g_return_val_if_fail (reader != NULL, FALSE); \
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g_return_val_if_fail (val != NULL, FALSE); \
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g_return_val_if_fail (nbits <= bits, FALSE); \
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\
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if (reader->byte * 8 + reader->bit + nbits > reader->size * 8) \
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return FALSE; \
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\
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while (nbits > 0) { \
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guint toread = MIN (nbits, 8 - reader->bit); \
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\
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ret <<= toread; \
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ret |= (reader->data[reader->byte] & (0xff >> reader->bit)) >> (8 - toread - reader->bit); \
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\
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reader->bit += toread; \
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if (reader->bit >= 8) { \
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reader->byte++; \
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reader->bit = 0; \
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} \
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nbits -= toread; \
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} \
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\
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*val = ret; \
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return TRUE; \
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} \
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\
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gboolean \
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gst_bit_reader_peek_bits_uint##bits (const GstBitReader *reader, guint##bits *val, guint nbits) \
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{ \
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GstBitReader tmp; \
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\
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g_return_val_if_fail (reader != NULL, FALSE); \
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tmp = *reader; \
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return gst_bit_reader_get_bits_uint##bits (&tmp, val, nbits); \
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}
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GST_BIT_READER_READ_BITS (8);
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GST_BIT_READER_READ_BITS (16);
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GST_BIT_READER_READ_BITS (32);
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GST_BIT_READER_READ_BITS (64);
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