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/*
* Copyright (C) 2014 - 2020 René Rebe, ExactCODE GmbH Germany.
*
* 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; version 2. A copy of the GNU General
* Public License can be found in the file LICENSE.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANT-
* ABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
* Public License for more details.
*
* Alternatively, commercial licensing options are available from the
* copyright holder ExactCODE GmbH Germany.
*/
#ifndef LOWLEVEL__BITS_HH__
#define LOWLEVEL__BITS_HH__
#include <stdint.h>
#include <istream>
#include <algorithm>
#include <cstdio>
namespace Exact {
static const unsigned char reverse4table[] = {
0, 8, 4, 12, 2, 10, 6, 14,
1, 9, 5, 13, 3, 11, 7, 15,
};
static inline
uint8_t reversebits(uint8_t v) {
return (reverse4table[v & 0xf] << 4) | reverse4table[(v & 0xf0) >> 4];
}
static const unsigned char popcount[] = {
0,1,1,2,1,2,2,3,
1,2,2,3,2,3,3,4,
1,2,2,3,2,3,3,4,
2,3,3,4,3,4,4,5,
1,2,2,3,2,3,3,4,
2,3,3,4,3,4,4,5,
2,3,3,4,3,4,4,5,
3,4,4,5,4,5,5,6,
1,2,2,3,2,3,3,4,
2,3,3,4,3,4,4,5,
2,3,3,4,3,4,4,5,
3,4,4,5,4,5,5,6,
2,3,3,4,3,4,4,5,
3,4,4,5,4,5,5,6,
3,4,4,5,4,5,5,6,
4,5,5,6,5,6,6,7,
1,2,2,3,2,3,3,4,
2,3,3,4,3,4,4,5,
2,3,3,4,3,4,4,5,
3,4,4,5,4,5,5,6,
2,3,3,4,3,4,4,5,
3,4,4,5,4,5,5,6,
3,4,4,5,4,5,5,6,
4,5,5,6,5,6,6,7,
2,3,3,4,3,4,4,5,
3,4,4,5,4,5,5,6,
3,4,4,5,4,5,5,6,
4,5,5,6,5,6,6,7,
3,4,4,5,4,5,5,6,
4,5,5,6,5,6,6,7,
4,5,5,6,5,6,6,7,
5,6,6,7,6,7,7,8,
};
static inline
int popcountf(uint32_t v) {
return
popcount[(v >> 24) & 0xff] +
popcount[(v >> 16) & 0xff] +
popcount[(v >> 8) & 0xff] +
popcount[(v >> 0) & 0xff];
}
template<typename T>
static inline int ms_bit_set (const T& v) {
for (int i = sizeof(v) * 8 - 1; i > 0; --i) {
if (v & (1L << i))
return i;
}
return 0;
}
template<typename T>
static inline T rotleft(const T a, unsigned b)
{
const unsigned bits = sizeof(T) * 8;
return (a << b) | (a >> (bits - b));
}
template<typename T>
static inline T rotright(const T a, unsigned b)
{
const unsigned bits = sizeof(T) * 8;
return (a >> b) | (a << (bits - b));
}
static inline std::ostream& debugbits(std::ostream& s, unsigned code, int bits) {
for (int i = bits - 1; i >= 0; --i)
s << (code >> i & 1);
s << "(#" << bits << ")";
return s;
}
struct Bitstream {
Bitstream(std::istream& stream, bool lsbFirst = false)
: stream(stream), bit(0), z(0), lsbFirst(lsbFirst)
{
}
uint32_t operator() (uint32_t v, uint8_t bits) {
for (uint8_t i = 0; i < bits;) {
if (bit <= 0) {
int _z = stream.get();
if (_z == EOF) {
// TODO: maybe throw exception, too?
return _z;
}
z = _z;
bit = 8;
//std::cerr << "bitstream: load: " << lsbFirst << " "; debugbits(std::cerr, z, 8) << std::endl;
}
const unsigned thisbits = std::min((uint8_t)(bits - i), (uint8_t)bit);
if (!lsbFirst) {
v <<= thisbits;
v |= z >> (8 - thisbits);
z <<= thisbits;
} else {
v |= (z & ((1 << thisbits) - 1)) << i;
z >>= thisbits;
}
i += thisbits;
bit -= thisbits;
}
//std::cerr << "ret: "; debugbits(std::cerr, v, bits) << std::endl;
return v;
}
void align() {
bit = 0;
}
protected:
std::istream& stream;
int8_t bit;
uint8_t z;
bool lsbFirst;
};
}
#endif // LOWLEVEL__BITS_HH__
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