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/*
* This file is part of AtracDEnc.
*
* AtracDEnc 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.
*
* AtracDEnc 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 AtracDEnc; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <cstdint>
#include "bitstream.h"
#ifndef BIGENDIAN_ORDER
#define NBITSTREAM__LITTLE_ENDIAN_CPU
#endif
namespace NBitStream {
union UBytes {
uint32_t ui = 0;
uint8_t bytes[4];
};
TBitStream::TBitStream(const char* buf, int size)
: Buf(buf, buf+size)
{}
TBitStream::TBitStream()
{}
void TBitStream::Write(uint32_t val, int n) {
if (n > 23 || n < 0)
abort();
const int bitsLeft = Buf.size() * 8 - BitsUsed;
const int bitsReq = n - bitsLeft;
const int bytesPos = BitsUsed / 8;
const int overlap = BitsUsed % 8;
if (overlap || bitsReq >= 0) {
Buf.resize(Buf.size() + (bitsReq / 8 + (overlap ? 2 : 1 )), 0);
}
UBytes t;
t.ui = (val << (32 - n) >> overlap);
for (int i = 0; i < n/8 + (overlap ? 2 : 1); ++i) {
#ifdef NBITSTREAM__LITTLE_ENDIAN_CPU
Buf[bytesPos+i] |= t.bytes[3-i];
#else
Buf[bytesPos + i] |= t.bytes[i];
#endif
}
BitsUsed += n;
}
uint32_t TBitStream::Read(int n) {
if (n >23 || n < 0)
abort();
const int bytesPos = ReadPos / 8;
const int overlap = ReadPos % 8;
UBytes t;
for (int i = 0; i < n/8 + (overlap ? 2 : 1); ++i) {
#ifdef NBITSTREAM__LITTLE_ENDIAN_CPU
t.bytes[3-i] = (uint8_t)Buf[bytesPos+i];
#else
t.bytes[i] = (uint8_t)Buf[bytesPos+i];
#endif
}
t.ui = (t.ui << overlap >> (32 - n));
ReadPos += n;
return t.ui;
}
unsigned long long TBitStream::GetSizeInBits() const {
return BitsUsed;
}
}
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