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Annotation of embedaddon/libiconv/srcm4/size_max.m4, revision 1.1.1.3

1.1.1.3 ! misho       1: # size_max.m4 serial 11
        !             2: dnl Copyright (C) 2003, 2005-2006, 2008-2019 Free Software Foundation, Inc.
1.1       misho       3: dnl This file is free software; the Free Software Foundation
                      4: dnl gives unlimited permission to copy and/or distribute it,
                      5: dnl with or without modifications, as long as this notice is preserved.
                      6: 
                      7: dnl From Bruno Haible.
                      8: 
1.1.1.3 ! misho       9: AC_PREREQ([2.61])
        !            10: 
1.1       misho      11: AC_DEFUN([gl_SIZE_MAX],
                     12: [
                     13:   AC_CHECK_HEADERS([stdint.h])
                     14:   dnl First test whether the system already has SIZE_MAX.
                     15:   AC_CACHE_CHECK([for SIZE_MAX], [gl_cv_size_max], [
                     16:     gl_cv_size_max=
                     17:     AC_EGREP_CPP([Found it], [
                     18: #include <limits.h>
                     19: #if HAVE_STDINT_H
                     20: #include <stdint.h>
                     21: #endif
                     22: #ifdef SIZE_MAX
                     23: Found it
                     24: #endif
                     25: ], [gl_cv_size_max=yes])
                     26:     if test -z "$gl_cv_size_max"; then
                     27:       dnl Define it ourselves. Here we assume that the type 'size_t' is not wider
                     28:       dnl than the type 'unsigned long'. Try hard to find a definition that can
                     29:       dnl be used in a preprocessor #if, i.e. doesn't contain a cast.
                     30:       AC_COMPUTE_INT([size_t_bits_minus_1], [sizeof (size_t) * CHAR_BIT - 1],
                     31:         [#include <stddef.h>
                     32: #include <limits.h>], [size_t_bits_minus_1=])
                     33:       AC_COMPUTE_INT([fits_in_uint], [sizeof (size_t) <= sizeof (unsigned int)],
                     34:         [#include <stddef.h>], [fits_in_uint=])
                     35:       if test -n "$size_t_bits_minus_1" && test -n "$fits_in_uint"; then
                     36:         if test $fits_in_uint = 1; then
                     37:           dnl Even though SIZE_MAX fits in an unsigned int, it must be of type
                     38:           dnl 'unsigned long' if the type 'size_t' is the same as 'unsigned long'.
1.1.1.2   misho      39:           AC_COMPILE_IFELSE(
                     40:             [AC_LANG_PROGRAM(
                     41:                [[#include <stddef.h>
                     42:                  extern size_t foo;
                     43:                  extern unsigned long foo;
                     44:                ]],
                     45:                [[]])],
                     46:             [fits_in_uint=0])
1.1       misho      47:         fi
                     48:         dnl We cannot use 'expr' to simplify this expression, because 'expr'
                     49:         dnl works only with 'long' integers in the host environment, while we
                     50:         dnl might be cross-compiling from a 32-bit platform to a 64-bit platform.
                     51:         if test $fits_in_uint = 1; then
                     52:           gl_cv_size_max="(((1U << $size_t_bits_minus_1) - 1) * 2 + 1)"
                     53:         else
                     54:           gl_cv_size_max="(((1UL << $size_t_bits_minus_1) - 1) * 2 + 1)"
                     55:         fi
                     56:       else
                     57:         dnl Shouldn't happen, but who knows...
                     58:         gl_cv_size_max='((size_t)~(size_t)0)'
                     59:       fi
                     60:     fi
                     61:   ])
                     62:   if test "$gl_cv_size_max" != yes; then
                     63:     AC_DEFINE_UNQUOTED([SIZE_MAX], [$gl_cv_size_max],
                     64:       [Define as the maximum value of type 'size_t', if the system doesn't define it.])
                     65:   fi
                     66:   dnl Don't redefine SIZE_MAX in config.h if config.h is re-included after
                     67:   dnl <stdint.h>. Remember that the #undef in AH_VERBATIM gets replaced with
                     68:   dnl #define by AC_DEFINE_UNQUOTED.
                     69:   AH_VERBATIM([SIZE_MAX],
                     70: [/* Define as the maximum value of type 'size_t', if the system doesn't define
                     71:    it. */
                     72: #ifndef SIZE_MAX
                     73: # undef SIZE_MAX
                     74: #endif])
                     75: ])