// Glaze Library

// For the license information refer to glaze.hpp

#pragma once

#include <bit>

#include <cstdint>

#include "glaze/util/inline.hpp"

namespace glz

{

   // std::countr_zero uses another branch check whether the input is zero,

   // we use this function when we know that x > 0

   GLZ_ALWAYS_INLINE auto countr_zero(const uint32_t x) noexcept

   {

#ifdef _MSC_VER

      return std::countr_zero(x);

#else

#if __has_builtin(__builtin_ctzl)

      return __builtin_ctzl(x);

#else

      return std::countr_zero(x);

#endif

#endif

   }

   GLZ_ALWAYS_INLINE auto countr_zero(const uint64_t x) noexcept

   {

#ifdef _MSC_VER

      return std::countr_zero(x);

#else

#if __has_builtin(__builtin_ctzll)

      return __builtin_ctzll(x);

#else

      return std::countr_zero(x);

#endif

#endif

   }

#if defined(__SIZEOF_INT128__)

   GLZ_ALWAYS_INLINE auto countr_zero(__uint128_t x) noexcept

   {

      uint64_t low = uint64_t(x);

      if (low != 0) {

         return countr_zero(low);

      }

      else {

         uint64_t high = uint64_t(x >> 64);

         return countr_zero(high) + 64;

      }

   }

#endif

   // std::countl_zero uses another branch check whether the input is zero,

   // we use this function when we know that x > 0

   GLZ_ALWAYS_INLINE constexpr auto countl_zero(const uint32_t x) noexcept

   {

#ifdef _MSC_VER

      return std::countl_zero(x);

#else

#if __has_builtin(__builtin_clz)

      return __builtin_clz(x);

#else

      return std::countl_zero(x);

#endif

#endif

   }

   constexpr int int_log2(uint32_t x) noexcept { return 31 - glz::countl_zero(x | 1); }

}