116 lines
4.2 KiB
Plaintext
116 lines
4.2 KiB
Plaintext
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# ============================================================================
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# https://www.gnu.org/software/autoconf-archive/ax_compile_check_sizeof.html
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# ============================================================================
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#
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# SYNOPSIS
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#
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# AX_COMPILE_CHECK_SIZEOF(TYPE [, HEADERS [, EXTRA_SIZES...]])
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#
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# DESCRIPTION
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#
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# This macro checks for the size of TYPE using compile checks, not run
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# checks. You can supply extra HEADERS to look into. the check will cycle
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# through 1 2 4 8 16 and any EXTRA_SIZES the user supplies. If a match is
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# found, it will #define SIZEOF_`TYPE' to that value. Otherwise it will
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# emit a configure time error indicating the size of the type could not be
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# determined.
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#
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# The trick is that C will not allow duplicate case labels. While this is
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# valid C code:
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#
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# switch (0) case 0: case 1:;
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#
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# The following is not:
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#
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# switch (0) case 0: case 0:;
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#
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# Thus, the AC_TRY_COMPILE will fail if the currently tried size does not
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# match.
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#
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# Here is an example skeleton configure.in script, demonstrating the
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# macro's usage:
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#
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# AC_PROG_CC
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# AC_CHECK_HEADERS(stddef.h unistd.h)
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# AC_TYPE_SIZE_T
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# AC_CHECK_TYPE(ssize_t, int)
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#
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# headers='#ifdef HAVE_STDDEF_H
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# #include <stddef.h>
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# #endif
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# #ifdef HAVE_UNISTD_H
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# #include <unistd.h>
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# #endif
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# '
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#
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# AX_COMPILE_CHECK_SIZEOF(char)
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# AX_COMPILE_CHECK_SIZEOF(short)
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# AX_COMPILE_CHECK_SIZEOF(int)
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# AX_COMPILE_CHECK_SIZEOF(long)
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# AX_COMPILE_CHECK_SIZEOF(unsigned char *)
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# AX_COMPILE_CHECK_SIZEOF(void *)
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# AX_COMPILE_CHECK_SIZEOF(size_t, $headers)
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# AX_COMPILE_CHECK_SIZEOF(ssize_t, $headers)
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# AX_COMPILE_CHECK_SIZEOF(ptrdiff_t, $headers)
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# AX_COMPILE_CHECK_SIZEOF(off_t, $headers)
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#
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# LICENSE
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#
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# Copyright (c) 2008 Kaveh Ghazi <ghazi@caip.rutgers.edu>
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# Copyright (c) 2017 Reini Urban <rurban@cpan.org>
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#
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# This program is free software: you can redistribute it and/or modify it
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# under the terms of the GNU General Public License as published by the
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# Free Software Foundation, either version 3 of the License, or (at your
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# option) any later version.
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#
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# This program is distributed in the hope that it will be useful, but
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# WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
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# Public License for more details.
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#
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# You should have received a copy of the GNU General Public License along
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# with this program. If not, see <https://www.gnu.org/licenses/>.
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#
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# As a special exception, the respective Autoconf Macro's copyright owner
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# gives unlimited permission to copy, distribute and modify the configure
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# scripts that are the output of Autoconf when processing the Macro. You
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# need not follow the terms of the GNU General Public License when using
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# or distributing such scripts, even though portions of the text of the
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# Macro appear in them. The GNU General Public License (GPL) does govern
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# all other use of the material that constitutes the Autoconf Macro.
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#
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# This special exception to the GPL applies to versions of the Autoconf
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# Macro released by the Autoconf Archive. When you make and distribute a
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# modified version of the Autoconf Macro, you may extend this special
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# exception to the GPL to apply to your modified version as well.
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#serial 7
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AU_ALIAS([AC_COMPILE_CHECK_SIZEOF], [AX_COMPILE_CHECK_SIZEOF])
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AC_DEFUN([AX_COMPILE_CHECK_SIZEOF],
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[changequote(<<, >>)dnl
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dnl The name to #define.
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define(<<AC_TYPE_NAME>>, translit(sizeof_$1, [a-z *], [A-Z_P]))dnl
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dnl The cache variable name.
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define(<<AC_CV_NAME>>, translit(ac_cv_sizeof_$1, [ *], [_p]))dnl
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changequote([, ])dnl
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AC_MSG_CHECKING(size of $1)
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AC_CACHE_VAL(AC_CV_NAME,
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[for ac_size in 4 8 1 2 16 $3 ; do # List sizes in rough order of prevalence.
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AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
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#include <sys/types.h>
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$2
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]], [[switch (0) case 0: case (sizeof ($1) == $ac_size):;]])], [AC_CV_NAME=$ac_size])
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if test x$AC_CV_NAME != x ; then break; fi
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done
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])
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if test x$AC_CV_NAME = x ; then
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AC_MSG_ERROR([cannot determine a size for $1])
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fi
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AC_MSG_RESULT($AC_CV_NAME)
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AC_DEFINE_UNQUOTED(AC_TYPE_NAME, $AC_CV_NAME, [The number of bytes in type $1])
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undefine([AC_TYPE_NAME])dnl
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undefine([AC_CV_NAME])dnl
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])
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