82 lines
2.2 KiB
C++
82 lines
2.2 KiB
C++
#ifndef __CXXMPH_MPH_BITS_H__
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#define __CXXMPH_MPH_BITS_H__
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#include <stdint.h> // for uint32_t and friends
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#include <array>
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#include <cassert>
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#include <climits>
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#include <cmath>
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#include <cstdio>
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#include <cstring>
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#include <limits>
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#include <vector>
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#include <utility>
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namespace cxxmph {
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class dynamic_2bitset {
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public:
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dynamic_2bitset() : size_(0), fill_(false) {}
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dynamic_2bitset(uint32_t size, bool fill = false)
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: size_(size), fill_(fill), data_(ceil(size / 4.0), ones()*fill) {
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}
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const uint8_t operator[](uint32_t i) const { return get(i); }
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const uint8_t get(uint32_t i) const {
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assert(i < size());
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assert((i >> 2) < data_.size());
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return (data_[(i >> 2)] >> (((i & 3) << 1)) & 3);
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}
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uint8_t set(uint32_t i, uint8_t v) {
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assert((i >> 2) < data_.size());
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data_[(i >> 2)] |= ones() ^ dynamic_2bitset::vmask[i & 3];
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data_[(i >> 2)] &= ((v << ((i & 3) << 1)) | dynamic_2bitset::vmask[i & 3]);
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assert(v <= 3);
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assert(get(i) == v);
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}
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void resize(uint32_t size) {
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size_ = size;
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data_.resize(size >> 2, fill_*ones());
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}
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void swap(dynamic_2bitset& other) {
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std::swap(other.size_, size_);
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std::swap(other.fill_, fill_);
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other.data_.swap(data_);
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}
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void clear() { data_.clear(); size_ = 0; }
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uint32_t size() const { return size_; }
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static const uint8_t vmask[];
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const std::vector<uint8_t>& data() const { return data_; }
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private:
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uint32_t size_;
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bool fill_;
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std::vector<uint8_t> data_;
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const uint8_t ones() { return std::numeric_limits<uint8_t>::max(); }
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};
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static uint32_t nextpoweroftwo(uint32_t k) {
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if (k == 0) return 1;
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k--;
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for (int i=1; i<sizeof(uint32_t)*CHAR_BIT; i<<=1) k = k | k >> i;
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return k+1;
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}
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// Interesting bit tricks that might end up here:
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// http://graphics.stanford.edu/~seander/bithacks.html#ZeroInWord
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// Fast a % (k*2^t)
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// http://www.azillionmonkeys.com/qed/adiv.html
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// rank and select:
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// http://vigna.dsi.unimi.it/ftp/papers/Broadword.pdf
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struct Ranktable { static uint8_t get(uint8_t); };
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static uint8_t rank64(uint64_t bits) {
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auto bytes = reinterpret_cast<const uint8_t*>(&bits);
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return Ranktable::get(bytes[0]) + Ranktable::get(bytes[1]) +
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Ranktable::get(bytes[2]) + Ranktable::get(bytes[3]);
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};
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} // namespace cxxmph
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#endif
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