libstdc++-v3/testsuite/26_numerics/bit/bit.pow.two/ispow2.cc

   1 // Copyright (C) 2018 Free Software Foundation, Inc.
   2 //
   3 // This file is part of the GNU ISO C++ Library.  This library is free
   4 // software; you can redistribute it and/or modify it under the
   5 // terms of the GNU General Public License as published by the
   6 // Free Software Foundation; either version 3, or (at your option)
   7 // any later version.
   8
   9 // This library is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13
  14 // You should have received a copy of the GNU General Public License along
  15 // with this library; see the file COPYING3.  If not see
  16 // <http://www.gnu.org/licenses/>.
  17
  18 // { dg-options "-std=gnu++2a" }
  19 // { dg-do compile { target c++2a } }
  20
  21 #include <bit>
  22
  23 template<typename UInt>
  24 constexpr auto
  25 test(UInt x)
  26 -> decltype(std::ispow2(x))
  27 {
  28   static_assert( noexcept(std::ispow2(x)) );
  29
  30   static_assert( ! std::ispow2( (UInt)0 ) );
  31   static_assert( ! std::ispow2( (UInt)-1 ) );
  32   static_assert( ! std::ispow2( (UInt)3 ) );
  33   static_assert( ! std::ispow2( (UInt)0x0f ) );
  34   static_assert( ! std::ispow2( (UInt)0xff ) );
  35   static_assert( ! std::ispow2( (UInt)0x0a ) );
  36   static_assert( ! std::ispow2( (UInt)0xa0 ) );
  37
  38   constexpr UInt one = 1;
  39   static_assert( std::ispow2( (UInt)(one << 0) ) );
  40
  41   static_assert( std::ispow2( (UInt)(one << 1) ) );
  42   static_assert( std::ispow2( (UInt)(one << 2) ) );
  43   static_assert( std::ispow2( (UInt)(one << 3) ) );
  44   static_assert( std::ispow2( (UInt)(one << 4) ) );
  45   static_assert( std::ispow2( (UInt)(one << 5) ) );
  46   static_assert( std::ispow2( (UInt)(one << 6) ) );
  47   static_assert( std::ispow2( (UInt)(one << 7) ) );
  48
  49   if constexpr (std::numeric_limits<UInt>::digits > 8)
  50   {
  51     static_assert( std::ispow2( (UInt)(one << 8) ) );
  52     static_assert( std::ispow2( (UInt)(one << 9) ) );
  53     static_assert( std::ispow2( (UInt)(one << 10) ) );
  54     static_assert( std::ispow2( (UInt)(one << 11) ) );
  55     static_assert( std::ispow2( (UInt)(one << 12) ) );
  56     static_assert( std::ispow2( (UInt)(one << 13) ) );
  57     static_assert( std::ispow2( (UInt)(one << 14) ) );
  58     static_assert( std::ispow2( (UInt)(one << 15) ) );
  59
  60     static_assert( ! std::ispow2( (UInt)0xf000 ) );
  61     static_assert( ! std::ispow2( (UInt)0xff00 ) );
  62     static_assert( ! std::ispow2( (UInt)0xf0f0 ) );
  63     static_assert( ! std::ispow2( (UInt)0xf00f ) );
  64     static_assert( ! std::ispow2( (UInt)0x0f0f ) );
  65     static_assert( ! std::ispow2( (UInt)0x00ff ) );
  66   }
  67
  68   if constexpr (std::numeric_limits<UInt>::digits > 16)
  69   {
  70     static_assert( std::ispow2( (UInt)(one << 16) ) );
  71     static_assert( std::ispow2( (UInt)(one << 17) ) );
  72     static_assert( ! std::ispow2( (UInt)((one << 16) + 1) ) );
  73     static_assert( ! std::ispow2( (UInt)((one << 16) + 0x10) ) );
  74   }
  75
  76   // msp340 target has 20-bit __GLIBCXX_TYPE_INT_N_0 type
  77   if constexpr (std::numeric_limits<UInt>::digits > 20)
  78   {
  79     static_assert( std::ispow2( (UInt)(one << 20) ) );
  80     static_assert( std::ispow2( (UInt)(one << 21) ) );
  81     static_assert( std::ispow2( (UInt)(one << 24) ) );
  82     static_assert( std::ispow2( (UInt)(one << 28) ) );
  83     static_assert( std::ispow2( (UInt)(one << 31) ) );
  84   }
  85
  86   if constexpr (std::numeric_limits<UInt>::digits > 32)
  87   {
  88     static_assert( std::ispow2( (UInt)(one << 32) ) );
  89     static_assert( std::ispow2( (UInt)(one << 33) ) );
  90     static_assert( std::ispow2( (UInt)(one << 41) ) );
  91
  92     static_assert( ! std::ispow2( (UInt)((one << 32) + 1) ) );
  93     static_assert( ! std::ispow2( (UInt)((one << 32) + (one << 31)) ) );
  94     static_assert( ! std::ispow2( (UInt)((one << 33) + 1) ) );
  95     static_assert( ! std::ispow2( (UInt)((one << 33) + (one << 32)) ) );
  96   }
  97
  98   if constexpr (std::numeric_limits<UInt>::digits == 64)
  99   {
 100     static_assert( std::ispow2( (UInt)(one << 63) ) );
 101
 102     static_assert( ! std::ispow2( (UInt)((one << 63) + 1) ) );
 103     static_assert( ! std::ispow2( (UInt)((one << 63) + (one << 8)) ) );
 104     static_assert( ! std::ispow2( (UInt)((one << 63) + (one << 32)) ) );
 105   }
 106   return true;
 107 }
 108
 109 static_assert( test( (unsigned char)0 ) );
 110 static_assert( test( (unsigned short)0 ) );
 111 static_assert( test( (unsigned int)0 ) );
 112 static_assert( test( (unsigned long)0 ) );
 113 static_assert( test( (unsigned long long)0 ) );
 114
 115 // std::ispow2(T) shall not participate in overload resolution
 116 // unless T is an unsigned integer type.
 117 struct X { constexpr bool did_not_match() { return true; } };
 118 constexpr X test(...) { return X{}; }
 119 static_assert( test( (bool)0 ).did_not_match() );
 120 static_assert( test( (char)0 ).did_not_match() );
 121 static_assert( test( (int)0 ).did_not_match() );
 122 static_assert( test( (char16_t)0 ).did_not_match() );
 123 static_assert( test( (float)0 ).did_not_match() );
 124 static_assert( test( (void*)0 ).did_not_match() );
 125 static_assert( test( X{} ).did_not_match() );
 126 enum E : unsigned { e };
 127 static_assert( test( e ).did_not_match() );
 128
 129 #ifndef __STRICT_ANSI__
 130 #include <cstddef>
 131 static_assert( std::ispow2(std::byte{0}) == false );
 132 static_assert( std::ispow2(std::byte{1}) == true );
 133 static_assert( std::ispow2(std::byte{2}) == true );
 134 static_assert( std::ispow2(std::byte{3}) == false );
 135 static_assert( std::ispow2(std::byte{100}) == false );
 136 static_assert( std::ispow2(std::byte{128}) == true );
 137 static_assert( std::ispow2(std::byte{255}) == false );
 138 #else
 139 static_assert( test( (std::byte)0 ).did_not_match() );
 140 #endif
 141
 142 #if !defined(__STRICT_ANSI__) && defined _GLIBCXX_USE_INT128
 143 static_assert( test( (unsigned __int128)0 ) );
 144 static_assert( test( (__int128)0 ).did_not_match() );
 145 #endif
 146 #if defined(__GLIBCXX_TYPE_INT_N_0)
 147 static_assert( test( (unsigned __GLIBCXX_TYPE_INT_N_0)0 ) );
 148 static_assert( test( (__GLIBCXX_TYPE_INT_N_0)0 ).did_not_match() );
 149 #endif
 150 #if defined(__GLIBCXX_TYPE_INT_N_1)
 151 static_assert( test( (unsigned __GLIBCXX_TYPE_INT_N_1)0 ) );
 152 static_assert( test( (__GLIBCXX_TYPE_INT_N_1)0 ).did_not_match() );
 153 #endif
 154 #if defined(__GLIBCXX_TYPE_INT_N_2)
 155 static_assert( test( (unsigned __GLIBCXX_TYPE_INT_N_2)0 ) );
 156 static_assert( test( (__GLIBCXX_TYPE_INT_N_2)0 ).did_not_match() );
 157 #endif