xn65/includes/xna/common/packedvalue.hpp

#ifndef CXNA_COMMON_PACKEDVECTOR_HPP
#define CXNA_COMMON_PACKEDVECTOR_HPP

#include "numerics.hpp"
#include <cmath>

namespace xna {
	class IPackedVector {
		virtual Vector4 ToVector4() const = 0;
		virtual void PackFromVector4(Vector4 const& vector) = 0;
	};

	template <typename T>
	class IPackedVectorT {
		virtual T PackedValue() const = 0;
		virtual void PackedValue(T const& value) = 0;
	};

	struct PackUtils {	

		static constexpr float UnpackUNorm(uint32_t bitmask, uint32_t value) {
			value &= bitmask;
			return static_cast<float>(value) / static_cast<float>(bitmask);
		}		

		static constexpr float UnpackSNorm(uint32_t bitmask, uint32_t value) {
			const auto num1 = (bitmask + 1U) >> 1;

			const auto ivalue = static_cast<int32_t>(value);
			const auto inum1 = static_cast<int32_t>(num1);
			const auto ibitmask = static_cast<int32_t>(bitmask);

			if ((ivalue & inum1) != 0) {
				if ((ivalue & ibitmask) == inum1)
					return -1.0f;

				value |= ~bitmask;
			}
			else
				value &= bitmask;

			const auto num2 = static_cast<float>(bitmask >> 1);

			return static_cast<int32_t>(value) / num2;
		}

		static uint32_t PackUnsigned(float bitmask, float value);
		static uint32_t PackSigned(uint32_t bitmask, float value);
		static uint32_t PackUNorm(float bitmask, float value);
		static uint32_t PackSNorm(uint32_t bitmask, float value);
		static double ClampAndRound(float value, float min, float max);
	};
}

#endif