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/*
* Copyright (C) 2010-2014 Hendrik Leppkes
* http://www.1f0.de
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Initial design and concept by Gabest and the MPC-HC Team, copyright under GPLv2
*/
#include "stdafx.h"
#include "ByteParser.h"
#pragma warning( push )
#pragma warning( disable : 4018 )
#pragma warning( disable : 4244 )
extern "C" {
#define AVCODEC_X86_MATHOPS_H
#define __STDC_CONSTANT_MACROS
#include "libavcodec/get_bits.h"
};
#pragma warning( pop )
CByteParser::CByteParser(const BYTE *pData, size_t length)
: m_pData(pData), m_pEnd(pData+length)
{
m_gbCtx = (GetBitContext *)av_mallocz(sizeof(GetBitContext));
init_get_bits(m_gbCtx, pData, (int)(length << 3));
}
CByteParser::~CByteParser()
{
av_freep(&m_gbCtx);
}
unsigned int CByteParser::BitRead(unsigned int numBits, bool peek)
{
if (numBits == 0)
return 0;
if (peek)
return show_bits_long(m_gbCtx, numBits);
else
return get_bits_long(m_gbCtx, numBits);
}
size_t CByteParser::RemainingBits() const
{
int bits = get_bits_left(m_gbCtx);
if (bits < 0)
return 0;
return (size_t)bits;
}
size_t CByteParser::Pos() const
{
return (size_t)(m_pEnd - m_pData - Remaining());
}
// Exponential Golomb Coding (with k = 0)
// As used in H.264/MPEG-4 AVC
// http://en.wikipedia.org/wiki/Exponential-Golomb_coding
unsigned CByteParser::UExpGolombRead()
{
int n = -1;
for(BYTE b = 0; !b && RemainingBits(); n++) {
b = get_bits1(m_gbCtx);
}
if (!RemainingBits())
return 0;
return ((1 << n) | BitRead(n)) - 1;
}
int CByteParser::SExpGolombRead()
{
int k = UExpGolombRead() + 1;
// Negative numbers are interleaved in the series
// unsigned: 0, 1, 2, 3, 4, 5, 6, ...
// signed: 0, 1, -1, 2, -2, 3, -3, ....
// So all even numbers are negative (last bit = 0)
// Note that we added 1 to the unsigned value already, so the check is inverted
if (k&1)
return -(k>>1);
else
return (k>>1);
}
void CByteParser::BitByteAlign()
{
align_get_bits(m_gbCtx);
}
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