#pragma once

#include "tl/detail/prologue.h"
#include "tl/functional.h"

namespace tl
{
namespace algorithm
{

//////////////////////////////////////////////////////////////////////////

/**
 * @brief Count the number of bit set for the given value.
 */
inline uint8_t bits_count(uint32_t i_value) noexcept
{
#if defined(_MSC_VER)
	return uint8_t(__popcnt(i_value));
#elif defined(__clang__) || defined(__GNUC__)
	return uint8_t(__builtin_popcount(i_value));
#else
	static_assert(!std::is_same_v<T, T>, "no-builtin function found for this compiler");
#endif
}

//////////////////////////////////////////////////////////////////////////

/**
 * @brief Count the number of bit set for the given value.
 */
inline uint64_t bits_count(uint64_t i_value) noexcept
{
#if defined(_MSC_VER)
#if defined(TL_PLATFORM_64)
	return uint8_t(__popcnt64(i_value));
#elif defined(TL_PLATFORM_32)
	return bits_count(uint32_t(i_value >> 32)) + bits_count(uint32_t(i_value & 0xffffffff));
#else 
	static_assert(!std::is_same_v<T, T>, "no-builtin function found for this compiler);");
#endif // TL_PLATFORM_XX
#elif defined(__clang__) || defined(__GNUC__)
	return uint8_t(__builtin_popcountl(i_value));
#else
	static_assert(!std::is_same_v<T, T>, "no-builtin function found for this compiler");
#endif
}

//////////////////////////////////////////////////////////////////////////

/**
 * @brief Position of the top bit set to 1.
 * @param the given value
 * @return  -1 in case value is 0 otherwise the position.
 */
inline int8_t top_bit(uint32_t i_value) noexcept
{
#if defined(_MSC_VER)
	unsigned long index = 0;
	return _BitScanReverse(&index, (unsigned long)i_value) ? uint8_t(index) : -1;
#elif defined(__clang__) || defined(__GNUC__)
	return i_value ? 31u - __builtin_clzl(i_value) : -1;
#else
	static_assert(!std::is_same_v<T, T>, "no-builtin function found for this compiler);");
#endif
}

//////////////////////////////////////////////////////////////////////////

/**
 * @brief Position of the top bit set to 1.
 * @param the given value
 * @return  -1 in case value is 0 otherwise the position.
 */
inline int8_t top_bit(uint64_t i_value) noexcept
{
#if defined(_MSC_VER)
	unsigned long index = 0;
#if defined(TL_PLATFORM_64)
	return _BitScanReverse64(&index, (unsigned long long)i_value) ? uint8_t(index) : -1;
#elif defined(TL_PLATFORM_32)
	const int8_t position = top_bit(uint32_t(i_value >> 32));
	if (position > -1)
	{
		return position + 32;
	}
	
	return top_bit(uint32_t(i_value & 0xffffffff));
#else 
	static_assert(!std::is_same_v<T, T>, "no-builtin function found for this compiler);");
#endif // TL_PLATFORM_XX
#elif defined(__clang__) || defined(__GNUC__)
	return i_value ? 63u - __builtin_clzll(i_value) : -1;
#else
	static_assert(!std::is_same_v<T, T>, "no-builtin function found for this compiler);");
#endif
}

//////////////////////////////////////////////////////////////////////////

} // namespace algorithm
} // namespace tl