s_trunc.c 1.6 KB

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  1. /* Truncate argument to nearest integral value not larger than the argument.
  2. Copyright (C) 1997, 1998 Free Software Foundation, Inc.
  3. This file is part of the GNU C Library.
  4. Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
  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, write to the Free
  15. Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  16. 02111-1307 USA. */
  17. #include <math.h>
  18. #include "math_private.h"
  19. libm_hidden_proto(trunc)
  20. double
  21. trunc (double x)
  22. {
  23. int32_t i0, j0;
  24. u_int32_t i1;
  25. int sx;
  26. EXTRACT_WORDS (i0, i1, x);
  27. sx = i0 & 0x80000000;
  28. j0 = ((i0 >> 20) & 0x7ff) - 0x3ff;
  29. if (j0 < 20)
  30. {
  31. if (j0 < 0)
  32. /* The magnitude of the number is < 1 so the result is +-0. */
  33. INSERT_WORDS (x, sx, 0);
  34. else
  35. INSERT_WORDS (x, sx | (i0 & ~(0x000fffff >> j0)), 0);
  36. }
  37. else if (j0 > 51)
  38. {
  39. if (j0 == 0x400)
  40. /* x is inf or NaN. */
  41. return x + x;
  42. }
  43. else
  44. {
  45. INSERT_WORDS (x, i0, i1 & ~(0xffffffffu >> (j0 - 20)));
  46. }
  47. return x;
  48. }
  49. libm_hidden_def(trunc)