boost/detail/limits.hpp

   1 // Copyright 2001 John Maddock
   2 // Distributed under the Boost Software License, Version 1.0. (See accompany-
   3 // ing file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   4
   5 /*
   6  * Copyright (c) 1997
   7  * Silicon Graphics Computer Systems, Inc.
   8  *
   9  * Permission to use, copy, modify, distribute and sell this software
  10  * and its documentation for any purpose is hereby granted without fee,
  11  * provided that the above copyright notice appear in all copies and
  12  * that both that copyright notice and this permission notice appear
  13  * in supporting documentation.  Silicon Graphics makes no
  14  * representations about the suitability of this software for any
  15  * purpose.  It is provided "as is" without express or implied warranty.
  16  */
  17
  18 /* NOTE: This is not portable code.  Parts of numeric_limits<> are
  19  * inherently machine-dependent, and this file is written for the MIPS
  20  * architecture and the SGI MIPSpro C++ compiler.  Parts of it (in
  21  * particular, some of the characteristics of floating-point types)
  22  * are almost certainly incorrect for any other platform.
  23  */
  24
  25 /* The above comment is almost certainly out of date. This file works
  26  * on systems other than SGI MIPSpro C++ now.
  27  */
  28
  29 /*
  30  * Revision history:
  31  * 21 Sep 2001:
  32  *    Only include <cwchar> if BOOST_NO_CWCHAR is defined. (Darin Adler)
  33  * 10 Aug 2001:
  34  *    Added MIPS (big endian) to the big endian family. (Jens Maurer)
  35  * 13 Apr 2001:
  36  *    Added powerpc to the big endian family. (Jeremy Siek)
  37  * 5 Apr 2001:
  38  *    Added sparc (big endian) processor support (John Maddock).
  39  * Initial sub:
  40  *      Modified by Jens Maurer for gcc 2.95 on x86.
  41  */
  42
  43 #ifndef BOOST_SGI_CPP_LIMITS
  44 #define BOOST_SGI_CPP_LIMITS
  45
  46 #include <climits>
  47 #include <cfloat>
  48 #include <boost/config.hpp>
  49 #include <boost/detail/endian.hpp>
  50
  51 #ifndef BOOST_NO_CWCHAR
  52 #include <cwchar> // for WCHAR_MIN and WCHAR_MAX
  53 #endif
  54
  55 namespace std {
  56
  57 enum float_round_style {
  58   round_indeterminate       = -1,
  59   round_toward_zero         =  0,
  60   round_to_nearest          =  1,
  61   round_toward_infinity     =  2,
  62   round_toward_neg_infinity =  3
  63 };
  64
  65 enum float_denorm_style {
  66   denorm_indeterminate = -1,
  67   denorm_absent        =  0,
  68   denorm_present       =  1
  69 };
  70
  71 // The C++ standard (section 18.2.1) requires that some of the members of
  72 // numeric_limits be static const data members that are given constant-
  73 // initializers within the class declaration.  On compilers where the
  74 // BOOST_NO_INCLASS_MEMBER_INITIALIZATION macro is defined, it is impossible to write
  75 // a standard-conforming numeric_limits class.
  76 //
  77 // There are two possible workarounds: either initialize the data
  78 // members outside the class, or change them from data members to
  79 // enums.  Neither workaround is satisfactory: the former makes it
  80 // impossible to use the data members in constant-expressions, and the
  81 // latter means they have the wrong type and that it is impossible to
  82 // take their addresses.  We choose the former workaround.
  83
  84 #ifdef BOOST_NO_INCLASS_MEMBER_INITIALIZATION
  85 # define BOOST_STL_DECLARE_LIMITS_MEMBER(__mem_type, __mem_name, __mem_value) \
  86   enum { __mem_name = __mem_value }
  87 #else /* BOOST_NO_INCLASS_MEMBER_INITIALIZATION */
  88 # define BOOST_STL_DECLARE_LIMITS_MEMBER(__mem_type, __mem_name, __mem_value) \
  89   static const __mem_type __mem_name = __mem_value
  90 #endif /* BOOST_NO_INCLASS_MEMBER_INITIALIZATION */
  91
  92 // Base class for all specializations of numeric_limits.
  93 template <class __number>
  94 class _Numeric_limits_base {
  95 public:
  96   BOOST_STL_DECLARE_LIMITS_MEMBER(bool, is_specialized, false);
  97
  98   static __number min BOOST_PREVENT_MACRO_SUBSTITUTION () throw() { return __number(); }
  99   static __number max BOOST_PREVENT_MACRO_SUBSTITUTION () throw() { return __number(); }
 100
 101   BOOST_STL_DECLARE_LIMITS_MEMBER(int, digits,   0);
 102   BOOST_STL_DECLARE_LIMITS_MEMBER(int, digits10, 0);
 103
 104   BOOST_STL_DECLARE_LIMITS_MEMBER(bool, is_signed,  false);
 105   BOOST_STL_DECLARE_LIMITS_MEMBER(bool, is_integer, false);
 106   BOOST_STL_DECLARE_LIMITS_MEMBER(bool, is_exact,   false);
 107
 108   BOOST_STL_DECLARE_LIMITS_MEMBER(int, radix, 0);
 109
 110   static __number epsilon() throw()     { return __number(); }
 111   static __number round_error() throw() { return __number(); }
 112
 113   BOOST_STL_DECLARE_LIMITS_MEMBER(int, min_exponent,   0);
 114   BOOST_STL_DECLARE_LIMITS_MEMBER(int, min_exponent10, 0);
 115   BOOST_STL_DECLARE_LIMITS_MEMBER(int, max_exponent,   0);
 116   BOOST_STL_DECLARE_LIMITS_MEMBER(int, max_exponent10, 0);
 117
 118   BOOST_STL_DECLARE_LIMITS_MEMBER(bool, has_infinity,      false);
 119   BOOST_STL_DECLARE_LIMITS_MEMBER(bool, has_quiet_NaN,     false);
 120   BOOST_STL_DECLARE_LIMITS_MEMBER(bool, has_signaling_NaN, false);
 121   BOOST_STL_DECLARE_LIMITS_MEMBER(float_denorm_style,
 122                               has_denorm,
 123                               denorm_absent);
 124   BOOST_STL_DECLARE_LIMITS_MEMBER(bool, has_denorm_loss,   false);
 125
 126   static __number infinity() throw()      { return __number(); }
 127   static __number quiet_NaN() throw()     { return __number(); }
 128   static __number signaling_NaN() throw() { return __number(); }
 129   static __number denorm_min() throw()    { return __number(); }
 130
 131   BOOST_STL_DECLARE_LIMITS_MEMBER(bool, is_iec559,  false);
 132   BOOST_STL_DECLARE_LIMITS_MEMBER(bool, is_bounded, false);
 133   BOOST_STL_DECLARE_LIMITS_MEMBER(bool, is_modulo,  false);
 134
 135   BOOST_STL_DECLARE_LIMITS_MEMBER(bool, traps,            false);
 136   BOOST_STL_DECLARE_LIMITS_MEMBER(bool, tinyness_before,  false);
 137   BOOST_STL_DECLARE_LIMITS_MEMBER(float_round_style,
 138                               round_style,
 139                               round_toward_zero);
 140 };
 141
 142 // Base class for integers.
 143
 144 template <class _Int,
 145           _Int __imin,
 146           _Int __imax,
 147           int __idigits = -1>
 148 class _Integer_limits : public _Numeric_limits_base<_Int>
 149 {
 150 public:
 151   BOOST_STL_DECLARE_LIMITS_MEMBER(bool, is_specialized, true);
 152
 153   static _Int min BOOST_PREVENT_MACRO_SUBSTITUTION () throw() { return __imin; }
 154   static _Int max BOOST_PREVENT_MACRO_SUBSTITUTION () throw() { return __imax; }
 155
 156   BOOST_STL_DECLARE_LIMITS_MEMBER(int,
 157                               digits,
 158                               (__idigits < 0) ? (int)(sizeof(_Int) * CHAR_BIT)
 159                                                    - (__imin == 0 ? 0 : 1)
 160                                               : __idigits);
 161   BOOST_STL_DECLARE_LIMITS_MEMBER(int, digits10, (digits * 301) / 1000);
 162                                 // log 2 = 0.301029995664...
 163
 164   BOOST_STL_DECLARE_LIMITS_MEMBER(bool, is_signed,  __imin != 0);
 165   BOOST_STL_DECLARE_LIMITS_MEMBER(bool, is_integer, true);
 166   BOOST_STL_DECLARE_LIMITS_MEMBER(bool, is_exact,   true);
 167   BOOST_STL_DECLARE_LIMITS_MEMBER(int,  radix,      2);
 168
 169   BOOST_STL_DECLARE_LIMITS_MEMBER(bool, is_bounded, true);
 170   BOOST_STL_DECLARE_LIMITS_MEMBER(bool, is_modulo, true);
 171 };
 172
 173 #if defined(BOOST_BIG_ENDIAN)
 174
 175  template<class Number, unsigned int Word>
 176  struct float_helper{
 177   static Number get_word() throw() {
 178     // sizeof(long double) == 16
 179     const unsigned int _S_word[4] = { Word, 0, 0, 0 };
 180     return *reinterpret_cast<const Number*>(&_S_word);
 181   }
 182 };
 183
 184 #else
 185
 186  template<class Number, unsigned int Word>
 187  struct float_helper{
 188   static Number get_word() throw() {
 189     // sizeof(long double) == 12, but only 10 bytes significant
 190     const unsigned int _S_word[4] = { 0, 0, 0, Word };
 191     return *reinterpret_cast<const Number*>(
 192         reinterpret_cast<const char *>(&_S_word)+16-
 193                 (sizeof(Number) == 12 ? 10 : sizeof(Number)));
 194   }
 195 };
 196
 197 #endif
 198
 199 // Base class for floating-point numbers.
 200 template <class __number,
 201          int __Digits, int __Digits10,
 202          int __MinExp, int __MaxExp,
 203          int __MinExp10, int __MaxExp10,
 204          unsigned int __InfinityWord,
 205          unsigned int __QNaNWord, unsigned int __SNaNWord,
 206          bool __IsIEC559,
 207          float_round_style __RoundStyle>
 208 class _Floating_limits : public _Numeric_limits_base<__number>
 209 {
 210 public:
 211   BOOST_STL_DECLARE_LIMITS_MEMBER(bool, is_specialized, true);
 212
 213   BOOST_STL_DECLARE_LIMITS_MEMBER(int, digits,   __Digits);
 214   BOOST_STL_DECLARE_LIMITS_MEMBER(int, digits10, __Digits10);
 215
 216   BOOST_STL_DECLARE_LIMITS_MEMBER(bool, is_signed, true);
 217
 218   BOOST_STL_DECLARE_LIMITS_MEMBER(int, radix, 2);
 219
 220   BOOST_STL_DECLARE_LIMITS_MEMBER(int, min_exponent,   __MinExp);
 221   BOOST_STL_DECLARE_LIMITS_MEMBER(int, max_exponent,   __MaxExp);
 222   BOOST_STL_DECLARE_LIMITS_MEMBER(int, min_exponent10, __MinExp10);
 223   BOOST_STL_DECLARE_LIMITS_MEMBER(int, max_exponent10, __MaxExp10);
 224
 225   BOOST_STL_DECLARE_LIMITS_MEMBER(bool, has_infinity,      true);
 226   BOOST_STL_DECLARE_LIMITS_MEMBER(bool, has_quiet_NaN,     true);
 227   BOOST_STL_DECLARE_LIMITS_MEMBER(bool, has_signaling_NaN, true);
 228   BOOST_STL_DECLARE_LIMITS_MEMBER(float_denorm_style,
 229                               has_denorm,
 230                               denorm_indeterminate);
 231   BOOST_STL_DECLARE_LIMITS_MEMBER(bool, has_denorm_loss,   false);
 232
 233
 234   static __number infinity() throw() {
 235     return float_helper<__number, __InfinityWord>::get_word();
 236   }
 237   static __number quiet_NaN() throw() {
 238     return float_helper<__number,__QNaNWord>::get_word();
 239   }
 240   static __number signaling_NaN() throw() {
 241     return float_helper<__number,__SNaNWord>::get_word();
 242   }
 243
 244   BOOST_STL_DECLARE_LIMITS_MEMBER(bool, is_iec559,       __IsIEC559);
 245   BOOST_STL_DECLARE_LIMITS_MEMBER(bool, is_bounded,      true);
 246   BOOST_STL_DECLARE_LIMITS_MEMBER(bool, traps,           false /* was: true */ );
 247   BOOST_STL_DECLARE_LIMITS_MEMBER(bool, tinyness_before, false);
 248
 249   BOOST_STL_DECLARE_LIMITS_MEMBER(float_round_style, round_style, __RoundStyle);
 250 };
 251
 252 // Class numeric_limits
 253
 254 // The unspecialized class.
 255
 256 template<class T>
 257 class numeric_limits : public _Numeric_limits_base<T> {};
 258
 259 // Specializations for all built-in integral types.
 260
 261 template<>
 262 class numeric_limits<bool>
 263   : public _Integer_limits<bool, false, true, 0>
 264 {};
 265
 266 template<>
 267 class numeric_limits<char>
 268   : public _Integer_limits<char, CHAR_MIN, CHAR_MAX>
 269 {};
 270
 271 template<>
 272 class numeric_limits<signed char>
 273   : public _Integer_limits<signed char, SCHAR_MIN, SCHAR_MAX>
 274 {};
 275
 276 template<>
 277 class numeric_limits<unsigned char>
 278   : public _Integer_limits<unsigned char, 0, UCHAR_MAX>
 279 {};
 280
 281 #ifndef BOOST_NO_INTRINSIC_WCHAR_T
 282 template<>
 283 class numeric_limits<wchar_t>
 284 #if !defined(WCHAR_MAX) || !defined(WCHAR_MIN)
 285 #if defined(_WIN32) || defined(__CYGWIN__)
 286   : public _Integer_limits<wchar_t, 0, USHRT_MAX>
 287 #elif defined(__hppa)
 288 // wchar_t has "unsigned int" as the underlying type
 289   : public _Integer_limits<wchar_t, 0, UINT_MAX>
 290 #else
 291 // assume that wchar_t has "int" as the underlying type
 292   : public _Integer_limits<wchar_t, INT_MIN, INT_MAX>
 293 #endif
 294 #else
 295 // we have WCHAR_MIN and WCHAR_MAX defined, so use it
 296   : public _Integer_limits<wchar_t, WCHAR_MIN, WCHAR_MAX>
 297 #endif
 298 {};
 299 #endif
 300
 301 template<>
 302 class numeric_limits<short>
 303   : public _Integer_limits<short, SHRT_MIN, SHRT_MAX>
 304 {};
 305
 306 template<>
 307 class numeric_limits<unsigned short>
 308   : public _Integer_limits<unsigned short, 0, USHRT_MAX>
 309 {};
 310
 311 template<>
 312 class numeric_limits<int>
 313   : public _Integer_limits<int, INT_MIN, INT_MAX>
 314 {};
 315
 316 template<>
 317 class numeric_limits<unsigned int>
 318   : public _Integer_limits<unsigned int, 0, UINT_MAX>
 319 {};
 320
 321 template<>
 322 class numeric_limits<long>
 323   : public _Integer_limits<long, LONG_MIN, LONG_MAX>
 324 {};
 325
 326 template<>
 327 class numeric_limits<unsigned long>
 328   : public _Integer_limits<unsigned long, 0, ULONG_MAX>
 329 {};
 330
 331 #ifdef __GNUC__
 332
 333 // Some compilers have long long, but don't define the
 334 // LONGLONG_MIN and LONGLONG_MAX macros in limits.h.  This
 335 // assumes that long long is 64 bits.
 336 #if !defined(LONGLONG_MAX) && !defined(ULONGLONG_MAX)
 337
 338 # define ULONGLONG_MAX 0xffffffffffffffffLLU
 339 # define LONGLONG_MAX 0x7fffffffffffffffLL
 340
 341 #endif
 342
 343 #if !defined(LONGLONG_MIN)
 344 # define LONGLONG_MIN (-LONGLONG_MAX - 1)
 345 #endif
 346
 347
 348 #if !defined(ULONGLONG_MIN)
 349 # define ULONGLONG_MIN 0
 350 #endif
 351
 352 #endif /* __GNUC__ */
 353
 354 // Specializations for all built-in floating-point type.
 355
 356 template<> class numeric_limits<float>
 357   : public _Floating_limits<float,
 358                             FLT_MANT_DIG,   // Binary digits of precision
 359                             FLT_DIG,        // Decimal digits of precision
 360                             FLT_MIN_EXP,    // Minimum exponent
 361                             FLT_MAX_EXP,    // Maximum exponent
 362                             FLT_MIN_10_EXP, // Minimum base 10 exponent
 363                             FLT_MAX_10_EXP, // Maximum base 10 exponent
 364 #if defined(BOOST_BIG_ENDIAN)
 365                             0x7f80 << (sizeof(int)*CHAR_BIT-16),    // Last word of +infinity
 366                             0x7f81 << (sizeof(int)*CHAR_BIT-16),    // Last word of quiet NaN
 367                             0x7fc1 << (sizeof(int)*CHAR_BIT-16),    // Last word of signaling NaN
 368 #else
 369                             0x7f800000u,    // Last word of +infinity
 370                             0x7f810000u,    // Last word of quiet NaN
 371                             0x7fc10000u,    // Last word of signaling NaN
 372 #endif
 373                             true,           // conforms to iec559
 374                             round_to_nearest>
 375 {
 376 public:
 377   static float min BOOST_PREVENT_MACRO_SUBSTITUTION () throw() { return FLT_MIN; }
 378   static float denorm_min() throw() { return FLT_MIN; }
 379   static float max BOOST_PREVENT_MACRO_SUBSTITUTION () throw() { return FLT_MAX; }
 380   static float epsilon() throw() { return FLT_EPSILON; }
 381   static float round_error() throw() { return 0.5f; } // Units: ulps.
 382 };
 383
 384 template<> class numeric_limits<double>
 385   : public _Floating_limits<double,
 386                             DBL_MANT_DIG,   // Binary digits of precision
 387                             DBL_DIG,        // Decimal digits of precision
 388                             DBL_MIN_EXP,    // Minimum exponent
 389                             DBL_MAX_EXP,    // Maximum exponent
 390                             DBL_MIN_10_EXP, // Minimum base 10 exponent
 391                             DBL_MAX_10_EXP, // Maximum base 10 exponent
 392 #if defined(BOOST_BIG_ENDIAN)
 393                             0x7ff0 << (sizeof(int)*CHAR_BIT-16),    // Last word of +infinity
 394                             0x7ff1 << (sizeof(int)*CHAR_BIT-16),    // Last word of quiet NaN
 395                             0x7ff9 << (sizeof(int)*CHAR_BIT-16),    // Last word of signaling NaN
 396 #else
 397                             0x7ff00000u,    // Last word of +infinity
 398                             0x7ff10000u,    // Last word of quiet NaN
 399                             0x7ff90000u,    // Last word of signaling NaN
 400 #endif
 401                             true,           // conforms to iec559
 402                             round_to_nearest>
 403 {
 404 public:
 405   static double min BOOST_PREVENT_MACRO_SUBSTITUTION () throw() { return DBL_MIN; }
 406   static double denorm_min() throw() { return DBL_MIN; }
 407   static double max BOOST_PREVENT_MACRO_SUBSTITUTION () throw() { return DBL_MAX; }
 408   static double epsilon() throw() { return DBL_EPSILON; }
 409   static double round_error() throw() { return 0.5; } // Units: ulps.
 410 };
 411
 412 template<> class numeric_limits<long double>
 413   : public _Floating_limits<long double,
 414                             LDBL_MANT_DIG,  // Binary digits of precision
 415                             LDBL_DIG,       // Decimal digits of precision
 416                             LDBL_MIN_EXP,   // Minimum exponent
 417                             LDBL_MAX_EXP,   // Maximum exponent
 418                             LDBL_MIN_10_EXP,// Minimum base 10 exponent
 419                             LDBL_MAX_10_EXP,// Maximum base 10 exponent
 420 #if defined(BOOST_BIG_ENDIAN)
 421                             0x7ff0 << (sizeof(int)*CHAR_BIT-16),    // Last word of +infinity
 422                             0x7ff1 << (sizeof(int)*CHAR_BIT-16),    // Last word of quiet NaN
 423                             0x7ff9 << (sizeof(int)*CHAR_BIT-16),    // Last word of signaling NaN
 424 #else
 425                             0x7fff8000u,    // Last word of +infinity
 426                             0x7fffc000u,    // Last word of quiet NaN
 427                             0x7fff9000u,    // Last word of signaling NaN
 428 #endif
 429                             false,          // Doesn't conform to iec559
 430                             round_to_nearest>
 431 {
 432 public:
 433   static long double min BOOST_PREVENT_MACRO_SUBSTITUTION () throw() { return LDBL_MIN; }
 434   static long double denorm_min() throw() { return LDBL_MIN; }
 435   static long double max BOOST_PREVENT_MACRO_SUBSTITUTION () throw() { return LDBL_MAX; }
 436   static long double epsilon() throw() { return LDBL_EPSILON; }
 437   static long double round_error() throw() { return 4; } // Units: ulps.
 438 };
 439
 440 } // namespace std
 441
 442 #endif /* BOOST_SGI_CPP_LIMITS */
 443
 444 // Local Variables:
 445 // mode:C++
 446 // End:
 447
 448
 449