glm/glm/core/func_exponential.inl

///////////////////////////////////////////////////////////////////////////////////
/// OpenGL Mathematics (glm.g-truc.net)
///
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/// all copies or substantial portions of the Software.
/// 
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/// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
/// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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/// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
/// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
/// THE SOFTWARE.
///
/// @ref core
/// @file glm/core/func_exponential.inl
/// @date 2008-08-03 / 2011-06-15
/// @author Christophe Riccio
///////////////////////////////////////////////////////////////////////////////////

#include "func_vector_relational.hpp"
#include "_vectorize.hpp"
#include <limits>
#include <cassert>

namespace glm
{
	// pow
	template <typename genType>
	GLM_FUNC_QUALIFIER genType pow
	(
		genType const & x, 
		genType const & y
	)
	{
		GLM_STATIC_ASSERT(
			std::numeric_limits<genType>::is_iec559,
			"'pow' only accept floating-point inputs");

		return std::pow(x, y);
	}

	VECTORIZE_VEC_VEC(pow)

	// exp
	template <typename genType>
	GLM_FUNC_QUALIFIER genType exp
	(
		genType const & x
	)
	{
		GLM_STATIC_ASSERT(
			std::numeric_limits<genType>::is_iec559,
			"'exp' only accept floating-point inputs");

		return std::exp(x);
	}

	VECTORIZE_VEC(exp)

	// log
	template <typename genType>
	GLM_FUNC_QUALIFIER genType log
	(
		genType const & x
	)
	{
		GLM_STATIC_ASSERT(
			std::numeric_limits<genType>::is_iec559,
			"'log' only accept floating-point inputs");

		return std::log(x);
	}

	VECTORIZE_VEC(log)

	//exp2, ln2 = 0.69314718055994530941723212145818f
	template <typename genType>
	GLM_FUNC_QUALIFIER genType exp2
	(
		genType const & x
	)
	{
		GLM_STATIC_ASSERT(
			std::numeric_limits<genType>::is_iec559,
			"'exp2' only accept floating-point inputs");

		return std::exp(static_cast<genType>(0.69314718055994530941723212145818) * x);
	}

	VECTORIZE_VEC(exp2)

namespace detail
{
	template <bool isFloat>
	struct compute_log2
	{
		template <typename T>
		T operator() (T const & Value) const;
	};

	template <>
	struct compute_log2<true>
	{
		template <typename T>
		T operator() (T const & Value) const
		{
			return static_cast<T>(::std::log(Value)) * static_cast<T>(1.4426950408889634073599246810019);
		}
	};

}//namespace detail

	// log2, ln2 = 0.69314718055994530941723212145818f
	template <typename genType>
	GLM_FUNC_QUALIFIER genType log2
	(
		genType const & x
	)
	{
		GLM_STATIC_ASSERT(std::numeric_limits<genType>::is_iec559 || std::numeric_limits<genType>::is_integer,
			"GLM core 'log2' only accept floating-point inputs. Include <glm/gtx/integer.hpp> for additional integer support.");

		assert(x > genType(0)); // log2 is only defined on the range (0, inf]
		return detail::compute_log2<std::numeric_limits<genType>::is_iec559>()(x);
	}

	VECTORIZE_VEC(log2)

	// sqrt
	template <typename genType>
	GLM_FUNC_QUALIFIER genType sqrt
	(
		genType const & x
	)
	{
		GLM_STATIC_ASSERT(
			std::numeric_limits<genType>::is_iec559,
			"'sqrt' only accept floating-point inputs");

		assert(x >= genType(0));

		return std::sqrt(x);
	}

	VECTORIZE_VEC(sqrt)

	template <typename genType>
	GLM_FUNC_QUALIFIER genType inversesqrt
	(
		genType const & x
	)
	{
		GLM_STATIC_ASSERT(
			std::numeric_limits<genType>::is_iec559,
			"'inversesqrt' only accept floating-point inputs");

		assert(x > genType(0));

		return genType(1) / std::sqrt(x);
	}

	VECTORIZE_VEC(inversesqrt)
	
	namespace detail
	{
		template <typename genType, typename genUType>
		genType fastInversesqrt(genType const & v)
		{
			genType tmp(v);
			genType xhalf(tmp * genType(0.5f));
			genUType i = *reinterpret_cast<genUType*>(const_cast<genType*>(&v));
			i = genUType(0x5f375a86) - (i >> genUType(1));
      // tmp = *reinterpret_cast<genType*>(&i);
      {
        genType* ptr(reinterpret_cast<genType*>(&i));
        tmp = *ptr;
      }
			tmp = tmp * (genType(1.5f) - xhalf * tmp * tmp);
			return tmp;
		}
	}
	
	template <>
	GLM_FUNC_QUALIFIER lowp_vec1 inversesqrt(lowp_vec1 const & v)
	{
		assert(glm::all(glm::greaterThan(v, lowp_vec1(0))));

		return detail::fastInversesqrt<lowp_vec1, uint>(v);
	}

	template <>
	GLM_FUNC_QUALIFIER lowp_vec2 inversesqrt(lowp_vec2 const & v)
	{
		assert(glm::all(glm::greaterThan(v, lowp_vec2(0))));

		return detail::fastInversesqrt<lowp_vec2, lowp_uvec2>(v);
	}

	template <>
	GLM_FUNC_QUALIFIER lowp_vec3 inversesqrt(lowp_vec3 const & v)
	{
		assert(glm::all(glm::greaterThan(v, lowp_vec3(0))));

		return detail::fastInversesqrt<lowp_vec3, lowp_uvec3>(v);
	}

	template <>
	GLM_FUNC_QUALIFIER lowp_vec4 inversesqrt(lowp_vec4 const & v)
	{
		assert(glm::all(glm::greaterThan(v, lowp_vec4(0))));

		return detail::fastInversesqrt<lowp_vec4, lowp_uvec4>(v);
	}
	
}//namespace glm