src/openvic-simulation/utility/NumberUtils.hpp


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#include <cstdint>

namespace OpenVic::NumberUtils {
   constexpr int64_t round_to_int64(float num) {
      return (num > 0.0f) ? (num + 0.5f) : (num - 0.5f);
   }

   constexpr int64_t round_to_int64(double num) {
      return (num > 0.0) ? (num + 0.5) : (num - 0.5);
   }

   constexpr uint64_t pow(uint64_t base, std::size_t exponent) {
      uint64_t ret = 1;
      while (exponent-- > 0) {
         ret *= base;
      }
      return ret;
   }

   constexpr int64_t pow(int64_t base, std::size_t exponent) {
      int64_t ret = 1;
      while (exponent-- > 0) {
         ret *= base;
      }
      return ret;
   }

   constexpr uint64_t sqrt(uint64_t n) {
      uint64_t x = n;
      uint64_t c = 0;
      uint64_t d = 1ull << 62;

      while (d > n)
         d >>= 2;

      for (; d != 0; d >>= 2) {
         if (x >= c + d) {
            x -= c + d;
            c = (c >> 1) + d;
         } else {
            c >>= 1;
         }
      }

      //round up
      if (x > 0) {
         c += 1;
      }

      return c;
   }
}