ceph/src/boost/libs/math/example/inspect_fp.cpp

   1 // inspect.cpp
   2
   3 // Copyright (c) 2006 Johan Rade
   4
   5 // Distributed under the Boost Software License, Version 1.0.
   6 // (See accompanying file LICENSE_1_0.txt
   7 // or copy at http://www.boost.org/LICENSE_1_0.txt)
   8
   9 //-------------------------------------
  10
  11 #include <cstring>
  12
  13 #include <iomanip>
  14 #include <iostream>
  15 #include <limits>
  16 #include <boost/detail/endian.hpp>
  17
  18 //------------------------------------------------------------------------------
  19
  20 bool is_big_endian()
  21 {
  22     float x = 1.0f;
  23     unsigned char first_byte;
  24   memcpy(&first_byte, &x, 1);
  25     return first_byte != 0;
  26 }
  27
  28 //------------------------------------------------------------------------------
  29
  30 void print_processor();
  31 void print_endianness();
  32 template<class T> void print_table();
  33 template<class T> void print_row(const char* name, T val, bool ok = true);
  34
  35 //------------------------------------------------------------------------------
  36
  37 int main()
  38 {
  39     std::cout << '\n';
  40
  41   print_processor();
  42
  43   print_endianness();
  44
  45     std::cout << "---------- float --------------------\n\n";
  46     print_table<float>();
  47
  48     std::cout << "---------- double -------------------\n\n";
  49     print_table<double>();
  50
  51     std::cout << "---------- long double --------------\n\n";
  52     print_table<long double>();
  53
  54     return 0;
  55 }
  56
  57 //------------------------------------------------------------------------------
  58
  59 void print_processor()
  60 {
  61 #if defined(__i386) || defined(__i386__) || defined(_M_IX86) \
  62     || defined(__amd64) || defined(__amd64__)  || defined(_M_AMD64) \
  63     || defined(__x86_64) || defined(__x86_64__) || defined(_M_X64)
  64
  65   std::cout << "Processor: x86 or x64\n\n";
  66
  67 #elif defined(__ia64) || defined(__ia64__) || defined(_M_IA64)
  68
  69   std::cout << "Processor: ia64\n\n";
  70
  71 #elif defined(__powerpc) || defined(__powerpc__) || defined(__POWERPC__) \
  72     || defined(__ppc) || defined(__ppc__) || defined(__PPC__)
  73
  74   std::cout << "Processor: PowerPC\n\n";
  75
  76 #elif defined(__m68k) || defined(__m68k__) \
  77     || defined(__mc68000) || defined(__mc68000__) \
  78
  79   std::cout << "Processor: Motorola 68K\n\n";
  80
  81 #else
  82
  83   std::cout << "Processor: Unknown\n\n";
  84
  85 #endif
  86 }
  87
  88 void print_endianness()
  89 {
  90     if(is_big_endian())
  91         std::cout << "This platform is big-endian.\n";
  92     else
  93         std::cout << "This platform is little-endian.\n";
  94
  95 #ifdef BOOST_BIG_ENDIAN
  96     std::cout << "BOOST_BIG_ENDIAN is defined.\n\n";
  97 #endif
  98 #if defined BOOST_LITTLE_ENDIAN
  99     std::cout << "BOOST_LITTTLE_ENDIAN is defined.\n\n";
 100 #endif
 101 }
 102
 103 //..............................................................................
 104
 105 template<class T> void print_table()
 106 {
 107     print_row("0", (T)0);
 108     print_row("sn.min", std::numeric_limits<T>::denorm_min(),
 109           std::numeric_limits<T>::has_denorm);
 110     print_row("-sn.min", -std::numeric_limits<T>::denorm_min(),
 111           std::numeric_limits<T>::has_denorm);
 112     print_row("n.min/256", (std::numeric_limits<T>::min)()/256);
 113     print_row("n.min/2", (std::numeric_limits<T>::min)()/2);
 114     print_row("-n.min/2", -(std::numeric_limits<T>::min)()/2);
 115     print_row("n.min", (std::numeric_limits<T>::min)());
 116     print_row("1", (T)1);
 117     print_row("3/4", (T)3/(T)4);
 118     print_row("4/3", (T)4/(T)3);
 119     print_row("max", (std::numeric_limits<T>::max)());
 120     print_row("inf", std::numeric_limits<T>::infinity(),
 121           std::numeric_limits<T>::has_infinity);
 122     print_row("q.nan", std::numeric_limits<T>::quiet_NaN(),
 123           std::numeric_limits<T>::has_quiet_NaN);
 124     print_row("s.nan", std::numeric_limits<T>::signaling_NaN(),
 125           std::numeric_limits<T>::has_signaling_NaN);
 126
 127     std::cout << "\n\n";
 128 }
 129
 130 template<class T>
 131 void print_row(const char* name, T val, bool ok)
 132 {
 133     std::cout << std::left << std::setw(10) << name << std::right;
 134
 135     std::cout << std::hex << std::setfill('0');
 136
 137     if(ok) {
 138         if(is_big_endian()) {
 139       for(size_t i = 0; i < sizeof(T); ++i) {
 140         unsigned char c = *(reinterpret_cast<unsigned char*>(&val) + i);
 141                 std::cout << std::setw(2)
 142                     << static_cast<unsigned int>(c) << ' ';
 143       }
 144         }
 145         else {
 146       for(size_t i = sizeof(T) - 1; i < sizeof(T); --i) {
 147         unsigned char c = *(reinterpret_cast<unsigned char*>(&val) + i);
 148                 std::cout << std::setw(2)
 149                     << static_cast<unsigned int>(c) << ' ';
 150       }
 151         }
 152     }
 153     else {
 154         for(size_t i = 0; i < sizeof(T); ++i)
 155             std::cout << "-- ";
 156     }
 157
 158     std::cout << '\n';
 159     std::cout << std::dec << std::setfill(' ');
 160 }
 161
 162 /*
 163
 164 Sample output on an AMD Quadcore running MSVC 10
 165
 166   Processor: x86 or x64
 167
 168   This platform is little-endian.
 169   BOOST_LITTTLE_ENDIAN is defined.
 170
 171   ---------- float --------------------
 172
 173   0         00 00 00 00
 174   sn.min    00 00 00 01
 175   -sn.min   80 00 00 01
 176   n.min/256 00 00 80 00
 177   n.min/2   00 40 00 00
 178   -n.min/2  80 40 00 00
 179   n.min     00 80 00 00
 180   1         3f 80 00 00
 181   3/4       3f 40 00 00
 182   4/3       3f aa aa ab
 183   max       7f 7f ff ff
 184   inf       7f 80 00 00
 185   q.nan     7f c0 00 00
 186   s.nan     7f c0 00 01
 187
 188
 189   ---------- double -------------------
 190
 191   0         00 00 00 00 00 00 00 00
 192   sn.min    00 00 00 00 00 00 00 01
 193   -sn.min   80 00 00 00 00 00 00 01
 194   n.min/256 00 00 10 00 00 00 00 00
 195   n.min/2   00 08 00 00 00 00 00 00
 196   -n.min/2  80 08 00 00 00 00 00 00
 197   n.min     00 10 00 00 00 00 00 00
 198   1         3f f0 00 00 00 00 00 00
 199   3/4       3f e8 00 00 00 00 00 00
 200   4/3       3f f5 55 55 55 55 55 55
 201   max       7f ef ff ff ff ff ff ff
 202   inf       7f f0 00 00 00 00 00 00
 203   q.nan     7f f8 00 00 00 00 00 00
 204   s.nan     7f f8 00 00 00 00 00 01
 205
 206
 207   ---------- long double --------------
 208
 209   0         00 00 00 00 00 00 00 00
 210   sn.min    00 00 00 00 00 00 00 01
 211   -sn.min   80 00 00 00 00 00 00 01
 212   n.min/256 00 00 10 00 00 00 00 00
 213   n.min/2   00 08 00 00 00 00 00 00
 214   -n.min/2  80 08 00 00 00 00 00 00
 215   n.min     00 10 00 00 00 00 00 00
 216   1         3f f0 00 00 00 00 00 00
 217   3/4       3f e8 00 00 00 00 00 00
 218   4/3       3f f5 55 55 55 55 55 55
 219   max       7f ef ff ff ff ff ff ff
 220   inf       7f f0 00 00 00 00 00 00
 221   q.nan     7f f8 00 00 00 00 00 00
 222   s.nan     7f f8 00 00 00 00 00 01
 223
 224   */