turbonss/cxxmph/mph_bits.h
2012-03-21 10:20:30 -03:00

93 lines
2.5 KiB
C++

#ifndef __CXXMPH_MPH_BITS_H__
#define __CXXMPH_MPH_BITS_H__
#include <stdint.h> // for uint32_t and friends
#include <array>
#include <cassert>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <limits>
#include <vector>
#include <utility>
namespace cxxmph {
class dynamic_2bitset {
public:
dynamic_2bitset() : size_(0), fill_(false) {}
dynamic_2bitset(uint32_t size, bool fill = false)
: size_(size), fill_(fill), data_(ceil(size / 4.0), ones()*fill) {
}
const uint8_t operator[](uint32_t i) const { return get(i); }
const uint8_t get(uint32_t i) const {
assert(i < size());
assert((i >> 2) < data_.size());
return (data_[(i >> 2)] >> (((i & 3) << 1)) & 3);
}
uint8_t set(uint32_t i, uint8_t v) {
assert((i >> 2) < data_.size());
data_[(i >> 2)] |= ones() ^ dynamic_2bitset::vmask[i & 3];
data_[(i >> 2)] &= ((v << ((i & 3) << 1)) | dynamic_2bitset::vmask[i & 3]);
assert(v <= 3);
assert(get(i) == v);
}
void resize(uint32_t size) {
size_ = size;
data_.resize(size >> 2, fill_*ones());
}
void swap(dynamic_2bitset& other) {
std::swap(other.size_, size_);
std::swap(other.fill_, fill_);
other.data_.swap(data_);
}
void clear() { data_.clear(); size_ = 0; }
uint32_t size() const { return size_; }
static const uint8_t vmask[];
const std::vector<uint8_t>& data() const { return data_; }
private:
uint32_t size_;
bool fill_;
std::vector<uint8_t> data_;
const uint8_t ones() { return std::numeric_limits<uint8_t>::max(); }
};
static uint32_t nextpoweroftwo(uint32_t k) {
if (k == 0) return 1;
k--;
for (int i=1; i<sizeof(uint32_t)*CHAR_BIT; i<<=1) k = k | k >> i;
return k+1;
}
template <int n, int mask = (1 << 7)> struct bitcount {
enum { value = (n & mask ? 1:0) + bitcount<n, (mask >> 1)>::value };
};
template <int n> struct bitcount<n, 0> { enum { value = 0 }; };
template <int size, int index = size>
class CompileTimeRankTable {
public:
CompileTimeRankTable() : current(bitcount<index - 1>::value) { }
int operator[] (int i) { return *(&current + size - i - 1); }
private:
unsigned char current;
CompileTimeRankTable<index -1> next;
};
template <int size> class CompileTimeRankTable<size, 0> { };
typedef CompileTimeRankTable<256> Ranktable;
// Interesting bit tricks that might end up here:
// http://graphics.stanford.edu/~seander/bithacks.html#ZeroInWord
// Fast a % (k*2^t)
// http://www.azillionmonkeys.com/qed/adiv.html
// rank and select:
// http://vigna.dsi.unimi.it/ftp/papers/Broadword.pdf
} // namespace cxxmph
#endif