intprops.h 3.0 KB

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  1. /* intprops.h -- properties of integer types
  2. Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
  3. This program is free software: you can redistribute it and/or modify
  4. it under the terms of the GNU General Public License as published by
  5. the Free Software Foundation; either version 3 of the License, or
  6. (at your option) any later version.
  7. This program is distributed in the hope that it will be useful,
  8. but WITHOUT ANY WARRANTY; without even the implied warranty of
  9. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  10. GNU General Public License for more details.
  11. You should have received a copy of the GNU General Public License
  12. along with this program. If not, see <http://www.gnu.org/licenses/>. */
  13. /* Written by Paul Eggert. */
  14. #include <limits.h>
  15. /* The extra casts in the following macros work around compiler bugs,
  16. e.g., in Cray C 5.0.3.0. */
  17. /* True if the arithmetic type T is an integer type. bool counts as
  18. an integer. */
  19. #define TYPE_IS_INTEGER(t) ((t) 1.5 == 1)
  20. /* True if negative values of the signed integer type T use two's
  21. complement, ones' complement, or signed magnitude representation,
  22. respectively. Much GNU code assumes two's complement, but some
  23. people like to be portable to all possible C hosts. */
  24. #define TYPE_TWOS_COMPLEMENT(t) ((t) ~ (t) 0 == (t) -1)
  25. #define TYPE_ONES_COMPLEMENT(t) ((t) ~ (t) 0 == 0)
  26. #define TYPE_SIGNED_MAGNITUDE(t) ((t) ~ (t) 0 < (t) -1)
  27. /* True if the arithmetic type T is signed. */
  28. #define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
  29. /* The maximum and minimum values for the integer type T. These
  30. macros have undefined behavior if T is signed and has padding bits.
  31. If this is a problem for you, please let us know how to fix it for
  32. your host. */
  33. #define TYPE_MINIMUM(t) \
  34. ((t) (! TYPE_SIGNED (t) \
  35. ? (t) 0 \
  36. : TYPE_SIGNED_MAGNITUDE (t) \
  37. ? ~ (t) 0 \
  38. : ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1)))
  39. #define TYPE_MAXIMUM(t) \
  40. ((t) (! TYPE_SIGNED (t) \
  41. ? (t) -1 \
  42. : ~ (~ (t) 0 << (sizeof (t) * CHAR_BIT - 1))))
  43. /* Return zero if T can be determined to be an unsigned type.
  44. Otherwise, return 1.
  45. When compiling with GCC, INT_STRLEN_BOUND uses this macro to obtain a
  46. tighter bound. Otherwise, it overestimates the true bound by one byte
  47. when applied to unsigned types of size 2, 4, 16, ... bytes.
  48. The symbol signed_type_or_expr__ is private to this header file. */
  49. #if __GNUC__ >= 2
  50. # define signed_type_or_expr__(t) TYPE_SIGNED (__typeof__ (t))
  51. #else
  52. # define signed_type_or_expr__(t) 1
  53. #endif
  54. /* Bound on length of the string representing an integer type or expression T.
  55. Subtract 1 for the sign bit if T is signed; log10 (2.0) < 146/485;
  56. add 1 for integer division truncation; add 1 more for a minus sign
  57. if needed. */
  58. #define INT_STRLEN_BOUND(t) \
  59. ((sizeof (t) * CHAR_BIT - signed_type_or_expr__ (t)) * 146 / 485 \
  60. + signed_type_or_expr__ (t) + 1)
  61. /* Bound on buffer size needed to represent an integer type or expression T,
  62. including the terminating null. */
  63. #define INT_BUFSIZE_BOUND(t) (INT_STRLEN_BOUND (t) + 1)