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/*
* Copyright (C) 2005-2012 Team XBMC
* http://www.xbmc.org
*
* 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, 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 XBMC; see the file COPYING. If not, see
* <http://www.gnu.org/licenses/>.
*
*/
#include "bitstream.h"
using namespace TSDemux;
void CBitstream::skipBits(unsigned int num)
{
if (m_doEP3)
{
while (num)
{
unsigned int tmp = m_offset >> 3;
if (!(m_offset & 7) && (m_data[tmp--] == 3) && (m_data[tmp--] == 0) && (m_data[tmp] == 0))
m_offset += 8; // skip EP3 byte
if (!(m_offset & 7) && (num >= 8)) // byte boundary, speed up things a little bit
{
m_offset += 8;
num -= 8;
}
else if ((tmp = 8-(m_offset & 7)) <= num) // jump to byte boundary
{
m_offset += tmp;
num -= tmp;
}
else
{
m_offset += num;
num = 0;
}
if (m_offset >= m_len)
{
m_error = true;
break;
}
}
return;
}
m_offset += num;
}
unsigned int CBitstream::readBits(int num)
{
unsigned int r = 0;
while(num > 0)
{
if (m_doEP3)
{
size_t tmp = m_offset >> 3;
if (!(m_offset & 7) && (m_data[tmp--] == 3) && (m_data[tmp--] == 0) && (m_data[tmp] == 0))
m_offset += 8; // skip EP3 byte
}
if(m_offset >= m_len)
{
m_error = true;
return 0;
}
num--;
if(m_data[m_offset / 8] & (1 << (7 - (m_offset & 7))))
r |= 1 << num;
m_offset++;
}
return r;
}
unsigned int CBitstream::showBits(int num)
{
unsigned int r = 0;
size_t offs = m_offset;
while(num > 0)
{
if(offs >= m_len)
{
m_error = true;
return 0;
}
num--;
if(m_data[offs / 8] & (1 << (7 - (offs & 7))))
r |= 1 << num;
offs++;
}
return r;
}
unsigned int CBitstream::readGolombUE(int maxbits)
{
int lzb = -1;
int bits = 0;
for(int b = 0; !b; lzb++, bits++)
{
if (bits > maxbits)
return 0;
b = readBits1();
}
return (1 << lzb) - 1 + readBits(lzb);
}
signed int CBitstream::readGolombSE()
{
int v, pos;
v = readGolombUE();
if(v == 0)
return 0;
pos = (v & 1);
v = (v + 1) >> 1;
return pos ? v : -v;
}
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