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ax_compile_check_sizeof.m4 4.2 KB

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  1. # ============================================================================
  2. # https://www.gnu.org/software/autoconf-archive/ax_compile_check_sizeof.html
  3. # ============================================================================
  4. #
  5. # SYNOPSIS
  6. #
  7. # AX_COMPILE_CHECK_SIZEOF(TYPE [, HEADERS [, EXTRA_SIZES...]])
  8. #
  9. # DESCRIPTION
  10. #
  11. # This macro checks for the size of TYPE using compile checks, not run
  12. # checks. You can supply extra HEADERS to look into. the check will cycle
  13. # through 1 2 4 8 16 and any EXTRA_SIZES the user supplies. If a match is
  14. # found, it will #define SIZEOF_`TYPE' to that value. Otherwise it will
  15. # emit a configure time error indicating the size of the type could not be
  16. # determined.
  17. #
  18. # The trick is that C will not allow duplicate case labels. While this is
  19. # valid C code:
  20. #
  21. # switch (0) case 0: case 1:;
  22. #
  23. # The following is not:
  24. #
  25. # switch (0) case 0: case 0:;
  26. #
  27. # Thus, the AC_TRY_COMPILE will fail if the currently tried size does not
  28. # match.
  29. #
  30. # Here is an example skeleton configure.in script, demonstrating the
  31. # macro's usage:
  32. #
  33. # AC_PROG_CC
  34. # AC_CHECK_HEADERS(stddef.h unistd.h)
  35. # AC_TYPE_SIZE_T
  36. # AC_CHECK_TYPE(ssize_t, int)
  37. #
  38. # headers='#ifdef HAVE_STDDEF_H
  39. # #include <stddef.h>
  40. # #endif
  41. # #ifdef HAVE_UNISTD_H
  42. # #include <unistd.h>
  43. # #endif
  44. # '
  45. #
  46. # AX_COMPILE_CHECK_SIZEOF(char)
  47. # AX_COMPILE_CHECK_SIZEOF(short)
  48. # AX_COMPILE_CHECK_SIZEOF(int)
  49. # AX_COMPILE_CHECK_SIZEOF(long)
  50. # AX_COMPILE_CHECK_SIZEOF(unsigned char *)
  51. # AX_COMPILE_CHECK_SIZEOF(void *)
  52. # AX_COMPILE_CHECK_SIZEOF(size_t, $headers)
  53. # AX_COMPILE_CHECK_SIZEOF(ssize_t, $headers)
  54. # AX_COMPILE_CHECK_SIZEOF(ptrdiff_t, $headers)
  55. # AX_COMPILE_CHECK_SIZEOF(off_t, $headers)
  56. #
  57. # LICENSE
  58. #
  59. # Copyright (c) 2008 Kaveh Ghazi <ghazi@caip.rutgers.edu>
  60. # Copyright (c) 2017 Reini Urban <rurban@cpan.org>
  61. #
  62. # This program is free software: you can redistribute it and/or modify it
  63. # under the terms of the GNU General Public License as published by the
  64. # Free Software Foundation, either version 3 of the License, or (at your
  65. # option) any later version.
  66. #
  67. # This program is distributed in the hope that it will be useful, but
  68. # WITHOUT ANY WARRANTY; without even the implied warranty of
  69. # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
  70. # Public License for more details.
  71. #
  72. # You should have received a copy of the GNU General Public License along
  73. # with this program. If not, see <https://www.gnu.org/licenses/>.
  74. #
  75. # As a special exception, the respective Autoconf Macro's copyright owner
  76. # gives unlimited permission to copy, distribute and modify the configure
  77. # scripts that are the output of Autoconf when processing the Macro. You
  78. # need not follow the terms of the GNU General Public License when using
  79. # or distributing such scripts, even though portions of the text of the
  80. # Macro appear in them. The GNU General Public License (GPL) does govern
  81. # all other use of the material that constitutes the Autoconf Macro.
  82. #
  83. # This special exception to the GPL applies to versions of the Autoconf
  84. # Macro released by the Autoconf Archive. When you make and distribute a
  85. # modified version of the Autoconf Macro, you may extend this special
  86. # exception to the GPL to apply to your modified version as well.
  87. #serial 7
  88. AU_ALIAS([AC_COMPILE_CHECK_SIZEOF], [AX_COMPILE_CHECK_SIZEOF])
  89. AC_DEFUN([AX_COMPILE_CHECK_SIZEOF],
  90. [changequote(<<, >>)dnl
  91. dnl The name to #define.
  92. define(<<AC_TYPE_NAME>>, translit(sizeof_$1, [a-z *], [A-Z_P]))dnl
  93. dnl The cache variable name.
  94. define(<<AC_CV_NAME>>, translit(ac_cv_sizeof_$1, [ *], [_p]))dnl
  95. changequote([, ])dnl
  96. AC_MSG_CHECKING(size of $1)
  97. AC_CACHE_VAL(AC_CV_NAME,
  98. [for ac_size in 4 8 1 2 16 $3 ; do # List sizes in rough order of prevalence.
  99. AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
  100. #include <sys/types.h>
  101. $2
  102. ]], [[switch (0) case 0: case (sizeof ($1) == $ac_size):;]])], [AC_CV_NAME=$ac_size])
  103. if test x$AC_CV_NAME != x ; then break; fi
  104. done
  105. ])
  106. if test x$AC_CV_NAME = x ; then
  107. AC_MSG_ERROR([cannot determine a size for $1])
  108. fi
  109. AC_MSG_RESULT($AC_CV_NAME)
  110. AC_DEFINE_UNQUOTED(AC_TYPE_NAME, $AC_CV_NAME, [The number of bytes in type $1])
  111. undefine([AC_TYPE_NAME])dnl
  112. undefine([AC_CV_NAME])dnl
  113. ])