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/*
* Copyright (C) 2004-2012 Geometer Plus <[email protected]>
*
* 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.
*/
#include <cstring>
#include <string>
#include "BitReader.h"
BitReader::BitReader(const unsigned char* data, std::size_t size) : myOffset(0), myLength(size * 8) {
myData = new unsigned char[size + 4];
std::memcpy(myData, data, size);
std::memset(myData + size, 0x00, 4);
}
BitReader::~BitReader() {
delete[] myData;
}
unsigned long long BitReader::peek(std::size_t n) {
if (n > 32) {
return 0;
}
unsigned long long r = 0;
std::size_t g = 0;
while (g < n) {
r = (r << 8) | myData[(myOffset + g) >> 3];
g = g + 8 - ((myOffset+g) & 7);
}
unsigned long long mask = 1;
mask = (mask << n) - 1;
return (r >> (g - n)) & mask;
}
bool BitReader::eat(std::size_t n) {
myOffset += n;
return myOffset <= myLength;
}
std::size_t BitReader::left() const {
return myLength - myOffset;
}
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