raze-gles/source/libsmackerdec/src/BitReader.cpp
2019-09-20 00:42:45 +02:00

91 lines
1.8 KiB
C++

/*
* libsmackerdec - Smacker video decoder
* Copyright (C) 2011 Barry Duncan
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "BitReader.h"
#include <assert.h>
namespace SmackerCommon {
BitReader::BitReader(SmackerCommon::FileStream &file, uint32_t size)
{
this->file = &file;
this->totalSize = size;
this->currentOffset = 0;
this->bytesRead = 0;
this->cache = (uint8_t*)Xmalloc(size);
file.ReadBytes(this->cache, size);
}
BitReader::~BitReader()
{
Bfree(this->cache);
}
void BitReader::FillCache()
{
}
uint32_t BitReader::GetSize()
{
return totalSize * 8;
}
uint32_t BitReader::GetPosition()
{
return currentOffset;
}
uint32_t BitReader::GetBit()
{
uint32_t ret = (cache[currentOffset>>3]>>(currentOffset&7))&1;
currentOffset++;
return ret;
}
uint32_t BitReader::GetBits(uint32_t n)
{
uint32_t ret = 0;
int bitsTodo = n;
uint32_t theShift = 0;
while (bitsTodo)
{
uint32_t bit = GetBit();
bit <<= theShift;
theShift++;
ret |= bit;
bitsTodo--;
}
return ret;
}
void BitReader::SkipBits(uint32_t n)
{
GetBits(n);
}
} // close namespace SmackerCommon