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///////////////////////////////////////////////////////////////
// Copyright 2013 John Maddock. 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_
//
// Comparison operators for cpp_int_backend:
//
#ifndef BOOST_MP_DETAIL_BITSCAN_HPP
#define BOOST_MP_DETAIL_BITSCAN_HPP
#include <boost/detail/endian.hpp>
#if (defined(BOOST_MSVC) || (defined(__clang__) && defined(__c2__)) || (defined(BOOST_INTEL) && defined(_MSC_VER))) && (defined(_M_IX86) || defined(_M_X64))
#include <intrin.h>
#endif
namespace boost{ namespace multiprecision{ namespace detail{
template <class Unsigned>
inline unsigned find_lsb(Unsigned mask, const mpl::int_<0>&)
{
unsigned result = 0;
while(!(mask & 1u))
{
mask >>= 1;
++result;
}
return result;
}
template <class Unsigned>
inline unsigned find_msb(Unsigned mask, const mpl::int_<0>&)
{
unsigned index = 0;
while(mask)
{
++index;
mask >>= 1;
}
return --index;
}
#if (defined(BOOST_MSVC) || (defined(__clang__) && defined(__c2__)) || (defined(BOOST_INTEL) && defined(_MSC_VER))) && (defined(_M_IX86) || defined(_M_X64))
#pragma intrinsic(_BitScanForward,_BitScanReverse)
BOOST_FORCEINLINE unsigned find_lsb(unsigned long mask, const mpl::int_<1>&)
{
unsigned long result;
_BitScanForward(&result, mask);
return result;
}
BOOST_FORCEINLINE unsigned find_msb(unsigned long mask, const mpl::int_<1>&)
{
unsigned long result;
_BitScanReverse(&result, mask);
return result;
}
#ifdef _M_X64
#pragma intrinsic(_BitScanForward64,_BitScanReverse64)
BOOST_FORCEINLINE unsigned find_lsb(unsigned __int64 mask, const mpl::int_<2>&)
{
unsigned long result;
_BitScanForward64(&result, mask);
return result;
}
template <class Unsigned>
BOOST_FORCEINLINE unsigned find_msb(Unsigned mask, const mpl::int_<2>&)
{
unsigned long result;
_BitScanReverse64(&result, mask);
return result;
}
#endif
template <class Unsigned>
BOOST_FORCEINLINE unsigned find_lsb(Unsigned mask)
{
typedef typename make_unsigned<Unsigned>::type ui_type;
typedef typename mpl::if_c<
sizeof(Unsigned) <= sizeof(unsigned long),
mpl::int_<1>,
#ifdef _M_X64
typename mpl::if_c<
sizeof(Unsigned) <= sizeof(__int64),
mpl::int_<2>,
mpl::int_<0>
>::type
#else
mpl::int_<0>
#endif
>::type tag_type;
return find_lsb(static_cast<ui_type>(mask), tag_type());
}
template <class Unsigned>
BOOST_FORCEINLINE unsigned find_msb(Unsigned mask)
{
typedef typename make_unsigned<Unsigned>::type ui_type;
typedef typename mpl::if_c<
sizeof(Unsigned) <= sizeof(unsigned long),
mpl::int_<1>,
#ifdef _M_X64
typename mpl::if_c<
sizeof(Unsigned) <= sizeof(__int64),
mpl::int_<2>,
mpl::int_<0>
>::type
#else
mpl::int_<0>
#endif
>::type tag_type;
return find_msb(static_cast<ui_type>(mask), tag_type());
}
#elif defined(BOOST_GCC) || defined(__clang__) || (defined(BOOST_INTEL) && defined(__GNUC__))
BOOST_FORCEINLINE unsigned find_lsb(unsigned mask, mpl::int_<1> const&)
{
return __builtin_ctz(mask);
}
BOOST_FORCEINLINE unsigned find_lsb(unsigned long mask, mpl::int_<2> const&)
{
return __builtin_ctzl(mask);
}
BOOST_FORCEINLINE unsigned find_lsb(boost::ulong_long_type mask, mpl::int_<3> const&)
{
return __builtin_ctzll(mask);
}
BOOST_FORCEINLINE unsigned find_msb(unsigned mask, mpl::int_<1> const&)
{
return sizeof(unsigned) * CHAR_BIT - 1 - __builtin_clz(mask);
}
BOOST_FORCEINLINE unsigned find_msb(unsigned long mask, mpl::int_<2> const&)
{
return sizeof(unsigned long) * CHAR_BIT - 1 - __builtin_clzl(mask);
}
BOOST_FORCEINLINE unsigned find_msb(boost::ulong_long_type mask, mpl::int_<3> const&)
{
return sizeof(boost::ulong_long_type) * CHAR_BIT - 1 - __builtin_clzll(mask);
}
#ifdef BOOST_HAS_INT128
__extension__ typedef unsigned __int128 uint128_type;
BOOST_FORCEINLINE unsigned find_msb(uint128_type mask, mpl::int_<0> const&)
{
union { uint128_type v; boost::uint64_t sv[2]; } val;
val.v = mask;
#ifdef BOOST_LITTLE_ENDIAN
if(val.sv[1])
return find_msb(val.sv[1], mpl::int_<3>()) + 64;
return find_msb(val.sv[0], mpl::int_<3>());
#else
if(val.sv[0])
return find_msb(val.sv[0], mpl::int_<3>()) + 64;
return find_msb(val.sv[1], mpl::int_<3>());
#endif
}
BOOST_FORCEINLINE unsigned find_lsb(uint128_type mask, mpl::int_<0> const&)
{
union { uint128_type v; boost::uint64_t sv[2]; } val;
val.v = mask;
#ifdef BOOST_LITTLE_ENDIAN
if(val.sv[0] == 0)
return find_lsb(val.sv[1], mpl::int_<3>()) + 64;
return find_lsb(val.sv[0], mpl::int_<3>());
#else
if(val.sv[1] == 0)
return find_lsb(val.sv[0], mpl::int_<3>()) + 64;
return find_lsb(val.sv[1], mpl::int_<3>());
#endif
}
#endif
template <class Unsigned>
BOOST_FORCEINLINE unsigned find_lsb(Unsigned mask)
{
typedef typename make_unsigned<Unsigned>::type ui_type;
typedef typename mpl::if_c<
sizeof(Unsigned) <= sizeof(unsigned),
mpl::int_<1>,
typename mpl::if_c<
sizeof(Unsigned) <= sizeof(unsigned long),
mpl::int_<2>,
typename mpl::if_c<
sizeof(Unsigned) <= sizeof(boost::ulong_long_type),
mpl::int_<3>,
mpl::int_<0>
>::type
>::type
>::type tag_type;
return find_lsb(static_cast<ui_type>(mask), tag_type());
}
template <class Unsigned>
BOOST_FORCEINLINE unsigned find_msb(Unsigned mask)
{
typedef typename make_unsigned<Unsigned>::type ui_type;
typedef typename mpl::if_c<
sizeof(Unsigned) <= sizeof(unsigned),
mpl::int_<1>,
typename mpl::if_c<
sizeof(Unsigned) <= sizeof(unsigned long),
mpl::int_<2>,
typename mpl::if_c<
sizeof(Unsigned) <= sizeof(boost::ulong_long_type),
mpl::int_<3>,
mpl::int_<0>
>::type
>::type
>::type tag_type;
return find_msb(static_cast<ui_type>(mask), tag_type());
}
#elif defined(BOOST_INTEL)
BOOST_FORCEINLINE unsigned find_lsb(unsigned mask, mpl::int_<1> const&)
{
return _bit_scan_forward(mask);
}
BOOST_FORCEINLINE unsigned find_msb(unsigned mask, mpl::int_<1> const&)
{
return _bit_scan_reverse(mask);
}
template <class Unsigned>
BOOST_FORCEINLINE unsigned find_lsb(Unsigned mask)
{
typedef typename make_unsigned<Unsigned>::type ui_type;
typedef typename mpl::if_c<
sizeof(Unsigned) <= sizeof(unsigned),
mpl::int_<1>,
mpl::int_<0>
>::type tag_type;
return find_lsb(static_cast<ui_type>(mask), tag_type());
}
template <class Unsigned>
BOOST_FORCEINLINE unsigned find_msb(Unsigned mask)
{
typedef typename make_unsigned<Unsigned>::type ui_type;
typedef typename mpl::if_c<
sizeof(Unsigned) <= sizeof(unsigned),
mpl::int_<1>,
mpl::int_<0>
>::type tag_type;
return find_msb(static_cast<ui_type>(mask), tag_type());
}
#else
template <class Unsigned>
BOOST_FORCEINLINE unsigned find_lsb(Unsigned mask)
{
return find_lsb(mask, mpl::int_<0>());
}
template <class Unsigned>
BOOST_FORCEINLINE unsigned find_msb(Unsigned mask)
{
return find_msb(mask, mpl::int_<0>());
}
#endif
}}}
#endif
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