ceph/src/boost/libs/core/test/bit_width_test.cpp

   1 // Test for boost/core/bit.hpp (bit_width)
   2 //
   3 // Copyright 2020 Peter Dimov
   4 // Distributed under the Boost Software License, Version 1.0.
   5 // https://www.boost.org/LICENSE_1_0.txt
   6
   7 #include <boost/core/bit.hpp>
   8 #include <boost/core/lightweight_test.hpp>
   9 #include <boost/core/detail/splitmix64.hpp>
  10 #include <boost/cstdint.hpp>
  11 #include <limits>
  12
  13 template<class T> void test_width( T x )
  14 {
  15     BOOST_TEST_EQ( boost::core::bit_width( x ), std::numeric_limits<T>::digits - boost::core::countl_zero( x ) );
  16 }
  17
  18 int main()
  19 {
  20     {
  21         boost::uint8_t x = 0;
  22
  23         BOOST_TEST_EQ( boost::core::bit_width( x ), 0 );
  24
  25         x = 1;
  26
  27         for( int i = 0; i < 8; ++i, x <<= 1 )
  28         {
  29             BOOST_TEST_EQ( boost::core::bit_width( x ), i+1 );
  30             BOOST_TEST_EQ( boost::core::bit_width( static_cast<boost::uint8_t>( x | ( x >> 1 ) ) ), i+1 );
  31             BOOST_TEST_EQ( boost::core::bit_width( static_cast<boost::uint8_t>( x | ( x >> 2 ) ) ), i+1 );
  32         }
  33     }
  34
  35     {
  36         boost::uint16_t x = 0;
  37
  38         BOOST_TEST_EQ( boost::core::bit_width( x ), 0 );
  39
  40         x = 1;
  41
  42         for( int i = 0; i < 16; ++i, x <<= 1 )
  43         {
  44             BOOST_TEST_EQ( boost::core::bit_width( x ), i+1 );
  45             BOOST_TEST_EQ( boost::core::bit_width( static_cast<boost::uint16_t>( x | ( x >> 1 ) ) ), i+1 );
  46             BOOST_TEST_EQ( boost::core::bit_width( static_cast<boost::uint16_t>( x | ( x >> 2 ) ) ), i+1 );
  47         }
  48     }
  49
  50     {
  51         boost::uint32_t x = 0;
  52
  53         BOOST_TEST_EQ( boost::core::bit_width( x ), 0 );
  54
  55         x = 1;
  56
  57         for( int i = 0; i < 32; ++i, x <<= 1 )
  58         {
  59             BOOST_TEST_EQ( boost::core::bit_width( x ), i+1 );
  60             BOOST_TEST_EQ( boost::core::bit_width( static_cast<boost::uint32_t>( x | ( x >> 1 ) ) ), i+1 );
  61             BOOST_TEST_EQ( boost::core::bit_width( static_cast<boost::uint32_t>( x | ( x >> 2 ) ) ), i+1 );
  62         }
  63     }
  64
  65     {
  66         boost::uint64_t x = 0;
  67
  68         BOOST_TEST_EQ( boost::core::bit_width( x ), 0 );
  69
  70         x = 1;
  71
  72         for( int i = 0; i < 64; ++i, x <<= 1 )
  73         {
  74             BOOST_TEST_EQ( boost::core::bit_width( x ), i+1 );
  75             BOOST_TEST_EQ( boost::core::bit_width( static_cast<boost::uint64_t>( x | ( x >> 1 ) ) ), i+1 );
  76             BOOST_TEST_EQ( boost::core::bit_width( static_cast<boost::uint64_t>( x | ( x >> 2 ) ) ), i+1 );
  77         }
  78     }
  79
  80     boost::detail::splitmix64 rng;
  81
  82     for( int i = 0; i < 1000; ++i )
  83     {
  84         boost::uint64_t x = rng();
  85
  86         test_width( static_cast<unsigned char>( x ) );
  87         test_width( static_cast<unsigned short>( x ) );
  88         test_width( static_cast<unsigned int>( x ) );
  89         test_width( static_cast<unsigned long>( x ) );
  90         test_width( static_cast<boost::ulong_long_type>( x ) );
  91     }
  92
  93     return boost::report_errors();
  94 }