From 63ef07d124c1c703dfd764c408a2fe20587d9d4d Mon Sep 17 00:00:00 2001
From: bolero-MURAKAMI <bolero.murakami@gmail.com>
Date: Thu, 7 Feb 2013 19:26:24 +0900
Subject: [PATCH] add floating point functions: float_pair, float_exponent,
 float_mantissa

---
 sprout/math/float_exponent.hpp | 38 +++++++++++++++++++++++++++
 sprout/math/float_mantissa.hpp | 40 +++++++++++++++++++++++++++++
 sprout/math/float_pair.hpp     | 47 ++++++++++++++++++++++++++++++++++
 sprout/math/floating_point.hpp |  3 +++
 4 files changed, 128 insertions(+)
 create mode 100644 sprout/math/float_exponent.hpp
 create mode 100644 sprout/math/float_mantissa.hpp
 create mode 100644 sprout/math/float_pair.hpp

diff --git a/sprout/math/float_exponent.hpp b/sprout/math/float_exponent.hpp
new file mode 100644
index 00000000..5dbe9455
--- /dev/null
+++ b/sprout/math/float_exponent.hpp
@@ -0,0 +1,38 @@
+#ifndef SPROUT_MATH_FLOAT_EXPONENT_HPP
+#define SPROUT_MATH_FLOAT_EXPONENT_HPP
+
+#include <type_traits>
+#include <sprout/config.hpp>
+#include <sprout/math/detail/config.hpp>
+#include <sprout/math/ilogb.hpp>
+#include <sprout/type_traits/enabler_if.hpp>
+
+namespace sprout {
+	namespace math {
+		namespace detail {
+			template<
+				typename FloatType,
+				typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
+			>
+			inline SPROUT_CONSTEXPR int
+			float_exponent(FloatType x) {
+				return sprout::math::ilogb(x) + 1;
+			}
+
+			template<
+				typename IntType,
+				typename sprout::enabler_if<std::is_integral<IntType>::value>::type = sprout::enabler
+			>
+			inline SPROUT_CONSTEXPR int
+			float_exponent(IntType x) {
+				return sprout::math::detail::float_exponent(static_cast<double>(x));
+			}
+		}	// namespace detail
+
+		using sprout::math::detail::float_exponent;
+	}	// namespace math
+
+	using sprout::math::float_exponent;
+}	// namespace sprout
+
+#endif	// #ifndef SPROUT_MATH_FLOAT_EXPONENT_HPP
diff --git a/sprout/math/float_mantissa.hpp b/sprout/math/float_mantissa.hpp
new file mode 100644
index 00000000..d4f692ff
--- /dev/null
+++ b/sprout/math/float_mantissa.hpp
@@ -0,0 +1,40 @@
+#ifndef SPROUT_MATH_FLOAT_MANTISSA_HPP
+#define SPROUT_MATH_FLOAT_MANTISSA_HPP
+
+#include <cfloat>
+#include <type_traits>
+#include <sprout/config.hpp>
+#include <sprout/math/detail/config.hpp>
+#include <sprout/detail/pow.hpp>
+#include <sprout/math/float_exponent.hpp>
+#include <sprout/type_traits/enabler_if.hpp>
+
+namespace sprout {
+	namespace math {
+		namespace detail {
+			template<
+				typename FloatType,
+				typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
+			>
+			inline SPROUT_CONSTEXPR FloatType
+			float_mantissa(FloatType x) {
+				return x / sprout::detail::pow_n(FloatType(FLT_RADIX), sprout::math::float_exponent(x));
+			}
+
+			template<
+				typename IntType,
+				typename sprout::enabler_if<std::is_integral<IntType>::value>::type = sprout::enabler
+			>
+			inline SPROUT_CONSTEXPR double
+			float_mantissa(IntType x) {
+				return sprout::math::detail::float_mantissa(static_cast<double>(x));
+			}
+		}	// namespace detail
+
+		using sprout::math::detail::float_mantissa;
+	}	// namespace math
+
+	using sprout::math::float_mantissa;
+}	// namespace sprout
+
+#endif	// #ifndef SPROUT_MATH_FLOAT_MANTISSA_HPP
diff --git a/sprout/math/float_pair.hpp b/sprout/math/float_pair.hpp
new file mode 100644
index 00000000..cb57cb1e
--- /dev/null
+++ b/sprout/math/float_pair.hpp
@@ -0,0 +1,47 @@
+#ifndef SPROUT_MATH_FLOAT_PAIR_HPP
+#define SPROUT_MATH_FLOAT_PAIR_HPP
+
+#include <cfloat>
+#include <type_traits>
+#include <sprout/config.hpp>
+#include <sprout/math/detail/config.hpp>
+#include <sprout/detail/pow.hpp>
+#include <sprout/math/float_exponent.hpp>
+#include <sprout/type_traits/enabler_if.hpp>
+#include <sprout/utility/pair.hpp>
+
+namespace sprout {
+	namespace math {
+		namespace detail {
+			template<typename T>
+			inline SPROUT_CONSTEXPR sprout::pair<T, int>
+			float_pair_impl(T x, int exp) {
+				return sprout::pair<T, int>(x / sprout::detail::pow_n(T(FLT_RADIX), exp), exp);
+			}
+
+			template<
+				typename FloatType,
+				typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
+			>
+			inline SPROUT_CONSTEXPR sprout::pair<FloatType, int>
+			float_pair(FloatType x) {
+				return sprout::math::detail::float_pair_impl(x, sprout::math::float_exponent(x));
+			}
+
+			template<
+				typename IntType,
+				typename sprout::enabler_if<std::is_integral<IntType>::value>::type = sprout::enabler
+			>
+			inline SPROUT_CONSTEXPR sprout::pair<double, int>
+			float_pair(IntType x) {
+				return sprout::math::detail::float_pair(static_cast<double>(x));
+			}
+		}	// namespace detail
+
+		using sprout::math::detail::float_pair;
+	}	// namespace math
+
+	using sprout::math::float_pair;
+}	// namespace sprout
+
+#endif	// #ifndef SPROUT_MATH_FLOAT_PAIR_HPP
diff --git a/sprout/math/floating_point.hpp b/sprout/math/floating_point.hpp
index 72e97d35..524e7552 100644
--- a/sprout/math/floating_point.hpp
+++ b/sprout/math/floating_point.hpp
@@ -7,5 +7,8 @@
 #include <sprout/math/scalbln.hpp>
 #include <sprout/math/ilogb.hpp>
 #include <sprout/math/logb.hpp>
+#include <sprout/math/float_exponent.hpp>
+#include <sprout/math/float_mantissa.hpp>
+#include <sprout/math/float_pair.hpp>
 
 #endif	// #ifndef SPROUT_MATH_FLOATING_POINT_HPP