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| -rw-r--r-- | m4/ax_compile_check_sizeof.m4 | 115 |
1 files changed, 115 insertions, 0 deletions
diff --git a/m4/ax_compile_check_sizeof.m4 b/m4/ax_compile_check_sizeof.m4 new file mode 100644 index 000000000..5705508a3 --- /dev/null +++ b/m4/ax_compile_check_sizeof.m4 @@ -0,0 +1,115 @@ +# ============================================================================ +# https://www.gnu.org/software/autoconf-archive/ax_compile_check_sizeof.html +# ============================================================================ +# +# SYNOPSIS +# +# AX_COMPILE_CHECK_SIZEOF(TYPE [, HEADERS [, EXTRA_SIZES...]]) +# +# DESCRIPTION +# +# This macro checks for the size of TYPE using compile checks, not run +# checks. You can supply extra HEADERS to look into. the check will cycle +# through 1 2 4 8 16 and any EXTRA_SIZES the user supplies. If a match is +# found, it will #define SIZEOF_`TYPE' to that value. Otherwise it will +# emit a configure time error indicating the size of the type could not be +# determined. +# +# The trick is that C will not allow duplicate case labels. While this is +# valid C code: +# +# switch (0) case 0: case 1:; +# +# The following is not: +# +# switch (0) case 0: case 0:; +# +# Thus, the AC_TRY_COMPILE will fail if the currently tried size does not +# match. +# +# Here is an example skeleton configure.in script, demonstrating the +# macro's usage: +# +# AC_PROG_CC +# AC_CHECK_HEADERS(stddef.h unistd.h) +# AC_TYPE_SIZE_T +# AC_CHECK_TYPE(ssize_t, int) +# +# headers='#ifdef HAVE_STDDEF_H +# #include <stddef.h> +# #endif +# #ifdef HAVE_UNISTD_H +# #include <unistd.h> +# #endif +# ' +# +# AX_COMPILE_CHECK_SIZEOF(char) +# AX_COMPILE_CHECK_SIZEOF(short) +# AX_COMPILE_CHECK_SIZEOF(int) +# AX_COMPILE_CHECK_SIZEOF(long) +# AX_COMPILE_CHECK_SIZEOF(unsigned char *) +# AX_COMPILE_CHECK_SIZEOF(void *) +# AX_COMPILE_CHECK_SIZEOF(size_t, $headers) +# AX_COMPILE_CHECK_SIZEOF(ssize_t, $headers) +# AX_COMPILE_CHECK_SIZEOF(ptrdiff_t, $headers) +# AX_COMPILE_CHECK_SIZEOF(off_t, $headers) +# +# LICENSE +# +# Copyright (c) 2008 Kaveh Ghazi <ghazi@caip.rutgers.edu> +# Copyright (c) 2017 Reini Urban <rurban@cpan.org> +# +# This program is free software: you can redistribute it and/or modify it +# under the terms of the GNU General Public License as published by the +# Free Software Foundation, either version 3 of the License, or (at your +# option) any later version. +# +# This program is distributed in the hope that it will be useful, but +# WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General +# Public License for more details. +# +# You should have received a copy of the GNU General Public License along +# with this program. If not, see <https://www.gnu.org/licenses/>. +# +# As a special exception, the respective Autoconf Macro's copyright owner +# gives unlimited permission to copy, distribute and modify the configure +# scripts that are the output of Autoconf when processing the Macro. You +# need not follow the terms of the GNU General Public License when using +# or distributing such scripts, even though portions of the text of the +# Macro appear in them. The GNU General Public License (GPL) does govern +# all other use of the material that constitutes the Autoconf Macro. +# +# This special exception to the GPL applies to versions of the Autoconf +# Macro released by the Autoconf Archive. When you make and distribute a +# modified version of the Autoconf Macro, you may extend this special +# exception to the GPL to apply to your modified version as well. + +#serial 7 + +AU_ALIAS([AC_COMPILE_CHECK_SIZEOF], [AX_COMPILE_CHECK_SIZEOF]) +AC_DEFUN([AX_COMPILE_CHECK_SIZEOF], +[changequote(<<, >>)dnl +dnl The name to #define. +define(<<AC_TYPE_NAME>>, translit(sizeof_$1, [a-z *], [A-Z_P]))dnl +dnl The cache variable name. +define(<<AC_CV_NAME>>, translit(ac_cv_sizeof_$1, [ *], [_p]))dnl +changequote([, ])dnl +AC_MSG_CHECKING(size of $1) +AC_CACHE_VAL(AC_CV_NAME, +[for ac_size in 4 8 1 2 16 $3 ; do # List sizes in rough order of prevalence. + AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[ +#include <sys/types.h> +$2 +]], [[switch (0) case 0: case (sizeof ($1) == $ac_size):;]])], [AC_CV_NAME=$ac_size]) + if test x$AC_CV_NAME != x ; then break; fi +done +]) +if test x$AC_CV_NAME = x ; then + AC_MSG_ERROR([cannot determine a size for $1]) +fi +AC_MSG_RESULT($AC_CV_NAME) +AC_DEFINE_UNQUOTED(AC_TYPE_NAME, $AC_CV_NAME, [The number of bytes in type $1]) +undefine([AC_TYPE_NAME])dnl +undefine([AC_CV_NAME])dnl +]) |