src/libpspp/float-range.h

   1 /* PSPP - a program for statistical analysis.
   2    Copyright (C) 2023 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation, either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program 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
  15    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
  16
  17 #ifndef LIBPSPP_FLOAT_RANGE_H
  18 #define LIBPSPP_FLOAT_RANGE_H 1
  19
  20 #include <float.h>
  21 #include <limits.h>
  22
  23 #ifndef LONG_WIDTH
  24 #error                          /* Defined in C2x <limits.h> */
  25 #endif
  26
  27 /* Maximum positive integer 'double' represented with no loss of precision
  28    (that is, with unit precision).
  29
  30    The maximum negative integer with this property is -DBL_UNIT_MAX. */
  31 #if DBL_MANT_DIG == 53          /* 64-bit double */
  32 #define DBL_UNIT_MAX 9007199254740992.0
  33 #elif DBL_MANT_DIG == 64        /* 80-bit double */
  34 #define DBL_UNIT_MAX 18446744073709551616.0
  35 #elif DBL_MANT_DIG == 113       /* 128-bit double */
  36 #define DBL_UNIT_MAX 10384593717069655257060992658440192.0
  37 #else
  38 #error "Please define DBL_UNIT_MAX for your system (as 2**DBL_MANT_DIG)."
  39 #endif
  40
  41 /* Intersection of ranges [LONG_MIN,LONG_MAX] and [-DBL_UNIT_MAX,DBL_UNIT_MAX],
  42    as a range of 'long's.  This range is the (largest contiguous) set of
  43    integer values that can be safely converted between 'long' and 'double'
  44    without loss of precision. */
  45 #if DBL_MANT_DIG < LONG_WIDTH - 1
  46 #define DBL_UNIT_LONG_MIN ((long) -DBL_UNIT_MAX)
  47 #define DBL_UNIT_LONG_MAX ((long) DBL_UNIT_MAX)
  48 #else
  49 #define DBL_UNIT_LONG_MIN LONG_MIN
  50 #define DBL_UNIT_LONG_MAX LONG_MAX
  51 #endif
  52
  53 #endif /* float-range.h */