fibbonaci_counter.cppm

export module fibbonaci_counter;

import <algorithm>;
import <cstddef>;
import <cstdint>;
import <functional>;
import <vector>;

import counter;

export class Fibbonaci_counter : public Counter {
private:
  static constexpr std::vector<std::uint64_t> fibb_gen() {
    std::uint64_t a = 1, b = 1;
    std::vector<std::uint64_t> res = {b};

    while (true) {
      // check if a+b<=UINT64_MAX
      if (UINT64_MAX - b >= a) {
        a = a + b;
        std::swap(a, b);
        res.push_back(b);

      } else {
        return res;
      }
    }
  }

  const inline static std::vector<std::uint64_t> fibbonaci{fibb_gen()};
  std::size_t next_fib = 0; // next fibbonaci index.

  virtual void perform_inner_ticks(std::uint64_t ticks,
                                   const std::function<void(std::uint64_t)>
                                       &report_ov) noexcept override final {

    std::uint64_t initial_ticks = ticks;

    while (next_fib != fibbonaci.size() && ticks != 0) {

      // add ticks up to next fibbonaci number.
      std::uint64_t how_many =
          std::min(ticks, fibbonaci[next_fib] - inner_value);
      ticks -= how_many;
      inner_value += how_many;

      if (inner_value == fibbonaci[next_fib]) {
        ++next_fib;
        report_ov(initial_ticks - ticks);
      }
    }
    inner_value+=std::min(ticks,UINT64_MAX-inner_value);
  }

public:
  Fibbonaci_counter(std::uint64_t ignored2) noexcept : Counter(ignored2) {}
};