huge_vall.h 1.7 KB

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  1. /* `HUGE_VALL' constant for IEEE 754 machines (where it is infinity).
  2. Used by <stdlib.h> and <math.h> functions for overflow.
  3. Copyright (C) 1992, 1995, 1996, 1997, 1999, 2000, 2004
  4. Free Software Foundation, Inc.
  5. The GNU C Library is free software; you can redistribute it and/or
  6. modify it under the terms of the GNU Lesser General Public
  7. License as published by the Free Software Foundation; either
  8. version 2.1 of the License, or (at your option) any later version.
  9. The GNU C 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 GNU
  12. Lesser General Public License for more details.
  13. You should have received a copy of the GNU Lesser General Public
  14. License along with the GNU C Library; if not, see
  15. <http://www.gnu.org/licenses/>. */
  16. #ifndef _MATH_H
  17. # error "Never use <bits/huge_vall.h> directly; include <math.h> instead."
  18. #endif
  19. #if __GNUC_PREREQ(3,3)
  20. # define HUGE_VALL (__builtin_huge_vall())
  21. #else
  22. # include <bits/wordsize.h>
  23. # if __WORDSIZE == 32
  24. # define HUGE_VALL ((long double) HUGE_VAL)
  25. # elif __GNUC_PREREQ(2,96)
  26. # define HUGE_VALL (__extension__ 0x1.0p32767L)
  27. # elif defined __GNUC__
  28. # define HUGE_VALL \
  29. (__extension__ \
  30. ((union { struct { unsigned long __h, __l; } __i; long double __d; }) \
  31. { __i: { __h: 0x7fff000000000000UL, __l: 0 } }).__d)
  32. # else /* not GCC */
  33. typedef union { unsigned char __c[16]; long double __d; } __huge_vall_t;
  34. # define __HUGE_VALL_bytes { 0x7f, 0xff, 0,0,0,0,0,0,0,0,0,0,0,0,0,0 }
  35. static __huge_vall_t __huge_vall = { __HUGE_VALL_bytes };
  36. # define HUGE_VALL (__huge_vall.__d)
  37. # endif /* GCC. */
  38. #endif /* GCC 3.3. */