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| author | Remko Tronçon <git@el-tramo.be> | 2012-12-23 13:16:26 (GMT) |
|---|---|---|
| committer | Remko Tronçon <git@el-tramo.be> | 2012-12-23 14:43:26 (GMT) |
| commit | 491ddd570a752cf9bda85933bed0c6942e39b1f9 (patch) | |
| tree | 10c25c1be8cc08d0497df1dccd56a10fbb30beee /3rdParty/Boost/src/boost/pending | |
| parent | da7d7a0ca71b80281aa9ff2526290b61ccb0cc60 (diff) | |
| download | swift-491ddd570a752cf9bda85933bed0c6942e39b1f9.zip swift-491ddd570a752cf9bda85933bed0c6942e39b1f9.tar.bz2 | |
Update Boost to 1.52.0.
Change-Id: I1e56bea2600bf2ed9c5b3aba8c4f9d2a0f350e77
Diffstat (limited to '3rdParty/Boost/src/boost/pending')
| -rw-r--r-- | 3rdParty/Boost/src/boost/pending/integer_log2.hpp | 112 |
1 files changed, 112 insertions, 0 deletions
diff --git a/3rdParty/Boost/src/boost/pending/integer_log2.hpp b/3rdParty/Boost/src/boost/pending/integer_log2.hpp new file mode 100644 index 0000000..f4bc846 --- /dev/null +++ b/3rdParty/Boost/src/boost/pending/integer_log2.hpp @@ -0,0 +1,112 @@ +// ----------------------------------------------------------- +// integer_log2.hpp +// +// Gives the integer part of the logarithm, in base 2, of a +// given number. Behavior is undefined if the argument is <= 0. +// +// Copyright (c) 2003-2004, 2008 Gennaro Prota +// +// Distributed under the Boost Software License, Version 1.0. +// (See accompanying file LICENSE_1_0.txt or copy at +// http://www.boost.org/LICENSE_1_0.txt) +// +// ----------------------------------------------------------- + +#ifndef BOOST_INTEGER_LOG2_HPP_GP_20030301 +#define BOOST_INTEGER_LOG2_HPP_GP_20030301 + +#include <assert.h> +#ifdef __BORLANDC__ +#include <climits> +#endif +#include "boost/limits.hpp" +#include "boost/config.hpp" + + +namespace boost { + namespace detail { + + template <typename T> + int integer_log2_impl(T x, int n) { + + int result = 0; + + while (x != 1) { + + const T t = static_cast<T>(x >> n); + if (t) { + result += n; + x = t; + } + n /= 2; + + } + + return result; + } + + + + // helper to find the maximum power of two + // less than p (more involved than necessary, + // to avoid PTS) + // + template <int p, int n> + struct max_pow2_less { + + enum { c = 2*n < p }; + + BOOST_STATIC_CONSTANT(int, value = + c ? (max_pow2_less< c*p, 2*c*n>::value) : n); + + }; + + template <> + struct max_pow2_less<0, 0> { + + BOOST_STATIC_CONSTANT(int, value = 0); + }; + + // this template is here just for Borland :( + // we could simply rely on numeric_limits but sometimes + // Borland tries to use numeric_limits<const T>, because + // of its usual const-related problems in argument deduction + // - gps + template <typename T> + struct width { + +#ifdef __BORLANDC__ + BOOST_STATIC_CONSTANT(int, value = sizeof(T) * CHAR_BIT); +#else + BOOST_STATIC_CONSTANT(int, value = (std::numeric_limits<T>::digits)); +#endif + + }; + + } // detail + + + // --------- + // integer_log2 + // --------------- + // + template <typename T> + int integer_log2(T x) { + + assert(x > 0); + + const int n = detail::max_pow2_less< + detail::width<T> :: value, 4 + > :: value; + + return detail::integer_log2_impl(x, n); + + } + + + +} + + + +#endif // include guard |