1 //  Boost integer/integer_mask.hpp header file  ------------------------------//

     2 

     3 //  (C) Copyright Daryle Walker 2001.

     4 //  Distributed under the Boost Software License, Version 1.0. (See

     5 //  accompanying file LICENSE_1_0.txt or copy at

     6 //  http://www.boost.org/LICENSE_1_0.txt)

     7 

     8 //  See http://www.boost.org for updates, documentation, and revision history. 

     9 

    10 #ifndef BOOST_INTEGER_INTEGER_MASK_HPP

    11 #define BOOST_INTEGER_INTEGER_MASK_HPP

    12 

    13 #include <boost/integer_fwd.hpp>  // self include

    14 

    15 #include <boost/config.hpp>   // for BOOST_STATIC_CONSTANT

    16 #include <boost/integer.hpp>  // for boost::uint_t

    17 

    18 #include <climits>  // for UCHAR_MAX, etc.

    19 #include <cstddef>  // for std::size_t

    20 

    21 #include <boost/limits.hpp>  // for std::numeric_limits

    22 

    23 

    24 namespace boost

    25 {

    26 

    27 

    28 //  Specified single-bit mask class declaration  -----------------------------//

    29 //  (Lowest bit starts counting at 0.)

    30 

    31 template < std::size_t Bit >

    32 struct high_bit_mask_t

    33 {

    34     typedef typename uint_t<(Bit + 1)>::least  least;

    35     typedef typename uint_t<(Bit + 1)>::fast   fast;

    36 

    37     BOOST_STATIC_CONSTANT( least, high_bit = (least( 1u ) << Bit) );

    38     BOOST_STATIC_CONSTANT( fast, high_bit_fast = (fast( 1u ) << Bit) );

    39 

    40     BOOST_STATIC_CONSTANT( std::size_t, bit_position = Bit );

    41 

    42 };  // boost::high_bit_mask_t

    43 

    44 

    45 //  Specified bit-block mask class declaration  ------------------------------//

    46 //  Makes masks for the lowest N bits

    47 //  (Specializations are needed when N fills up a type.)

    48 

    49 template < std::size_t Bits >

    50 struct low_bits_mask_t

    51 {

    52     typedef typename uint_t<Bits>::least  least;

    53     typedef typename uint_t<Bits>::fast   fast;

    54 

    55     BOOST_STATIC_CONSTANT( least, sig_bits = (~( ~(least( 0u )) << Bits )) );

    56     BOOST_STATIC_CONSTANT( fast, sig_bits_fast = fast(sig_bits) );

    57 

    58     BOOST_STATIC_CONSTANT( std::size_t, bit_count = Bits );

    59 

    60 };  // boost::low_bits_mask_t

    61 

    62 

    63 #define BOOST_LOW_BITS_MASK_SPECIALIZE( Type )                                  \

    64   template <  >  struct low_bits_mask_t< std::numeric_limits<Type>::digits >  { \

    65       typedef std::numeric_limits<Type>           limits_type;                  \

    66       typedef uint_t<limits_type::digits>::least  least;                        \

    67       typedef uint_t<limits_type::digits>::fast   fast;                         \

    68       BOOST_STATIC_CONSTANT( least, sig_bits = (~( least(0u) )) );              \

    69       BOOST_STATIC_CONSTANT( fast, sig_bits_fast = fast(sig_bits) );            \

    70       BOOST_STATIC_CONSTANT( std::size_t, bit_count = limits_type::digits );    \

    71   }

    72 

    73 BOOST_LOW_BITS_MASK_SPECIALIZE( unsigned char );

    74 

    75 #if USHRT_MAX > UCHAR_MAX

    76 BOOST_LOW_BITS_MASK_SPECIALIZE( unsigned short );

    77 #endif

    78 

    79 #if UINT_MAX > USHRT_MAX

    80 BOOST_LOW_BITS_MASK_SPECIALIZE( unsigned int );

    81 #endif

    82 

    83 #if ULONG_MAX > UINT_MAX

    84 BOOST_LOW_BITS_MASK_SPECIALIZE( unsigned long );

    85 #endif

    86 

    87 #undef BOOST_LOW_BITS_MASK_SPECIALIZE

    88 

    89 

    90 }  // namespace boost

    91 

    92 

    93 #endif  // BOOST_INTEGER_INTEGER_MASK_HPP