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/*
* Infrastructure to handle byte data as bit data, and particularly to read
* Exp-Golomb encoded data.
*
* See H.264 clause 10.
*
* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is the MPEG TS, PS and ES tools.
*
* The Initial Developer of the Original Code is Amino Communications Ltd.
* Portions created by the Initial Developer are Copyright (C) 2008
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Amino Communications Ltd, Swavesey, Cambridge UK
*
* ***** END LICENSE BLOCK *****
*/
#ifndef _bitdata_fns
#define _bitdata_fns
#include "bitdata_defns.h"
/*
* Build a new bitdata datastructure.
*
* - `data` is the byte array we're extracting bits from.
* - `data_len` is its length (in bytes).
*
* Returns 0 if it succeeds, 1 if some error occurs.
*/
extern int build_bitdata(bitdata_p *bitdata,
byte data[],
int data_len);
/*
* Tidy up and free a bitdata datastructure after we've finished with it.
*
* Clears the bitdata datastructure, frees it, and sets `bitdata` to NULL.
*/
extern void free_bitdata(bitdata_p *bitdata);
/*
* Return the next bit from the data.
*
* Returns 0 if it reads the bit correctly, 1 if there are no more
* bits to be read.
*/
extern int read_bit(bitdata_p bitdata,
byte *bit);
/*
* Reads `count` bits from the data.
*
* Note it is asserted that `count` must be in the range 0..32.
*
* Returns 0 if all went well, 1 if there were not enough bits in the data.
*/
extern int read_bits(bitdata_p bitdata,
int count,
uint32_t *bits);
/*
* Reads `count` bits from the data, into a byte.
*
* Note it is asserted that `count` must be in the range 0..8.
*
* Returns 0 if all went well, 1 if there were not enough bits in the data.
*/
extern int read_bits_into_byte(bitdata_p bitdata,
int count,
byte *bits);
/*
* Read zero bits, counting them. Stop at the first non-zero bit.
*
* Returns the number of zero bits. Note that the non-zero bit is not
* "unread" in any way, so reading another bit will retrieve the first bit
* thereafter.
*/
extern int count_zero_bits(bitdata_p bitdata);
/*
* Read and decode an Exp-Golomb code.
*
* Reference H.264 10.1 for an explanation.
*
* Returns 0 if all went well, 1 if there were not enough bits in the data.
*/
extern int read_exp_golomb(bitdata_p bitdata,
uint32_t *result);
/*
* Read and decode a signed Exp-Golomb code.
*
* Reference H.264 10.1 sqq for an explanation.
*
* Returns 0 if all went well, 1 if there were not enough bits in the data.
*/
extern int read_signed_exp_golomb(bitdata_p bitdata,
int32_t *result);
#endif // _bitdata_fns
// Local Variables:
// tab-width: 8
// indent-tabs-mode: nil
// c-basic-offset: 2
// End:
// vim: set tabstop=8 shiftwidth=2 expandtab:
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