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Annotation of embedaddon/libiconv/srcm4/size_max.m4, revision 1.1.1.1

1.1       misho       1: # size_max.m4 serial 9
                      2: dnl Copyright (C) 2003, 2005-2006, 2008-2009 Free Software Foundation, Inc.
                      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: 
                      9: AC_DEFUN([gl_SIZE_MAX],
                     10: [
                     11:   AC_CHECK_HEADERS([stdint.h])
                     12:   dnl First test whether the system already has SIZE_MAX.
                     13:   AC_CACHE_CHECK([for SIZE_MAX], [gl_cv_size_max], [
                     14:     gl_cv_size_max=
                     15:     AC_EGREP_CPP([Found it], [
                     16: #include <limits.h>
                     17: #if HAVE_STDINT_H
                     18: #include <stdint.h>
                     19: #endif
                     20: #ifdef SIZE_MAX
                     21: Found it
                     22: #endif
                     23: ], [gl_cv_size_max=yes])
                     24:     if test -z "$gl_cv_size_max"; then
                     25:       dnl Define it ourselves. Here we assume that the type 'size_t' is not wider
                     26:       dnl than the type 'unsigned long'. Try hard to find a definition that can
                     27:       dnl be used in a preprocessor #if, i.e. doesn't contain a cast.
                     28:       AC_COMPUTE_INT([size_t_bits_minus_1], [sizeof (size_t) * CHAR_BIT - 1],
                     29:         [#include <stddef.h>
                     30: #include <limits.h>], [size_t_bits_minus_1=])
                     31:       AC_COMPUTE_INT([fits_in_uint], [sizeof (size_t) <= sizeof (unsigned int)],
                     32:         [#include <stddef.h>], [fits_in_uint=])
                     33:       if test -n "$size_t_bits_minus_1" && test -n "$fits_in_uint"; then
                     34:         if test $fits_in_uint = 1; then
                     35:           dnl Even though SIZE_MAX fits in an unsigned int, it must be of type
                     36:           dnl 'unsigned long' if the type 'size_t' is the same as 'unsigned long'.
                     37:           AC_TRY_COMPILE([#include <stddef.h>
                     38:             extern size_t foo;
                     39:             extern unsigned long foo;
                     40:             ], [], [fits_in_uint=0])
                     41:         fi
                     42:         dnl We cannot use 'expr' to simplify this expression, because 'expr'
                     43:         dnl works only with 'long' integers in the host environment, while we
                     44:         dnl might be cross-compiling from a 32-bit platform to a 64-bit platform.
                     45:         if test $fits_in_uint = 1; then
                     46:           gl_cv_size_max="(((1U << $size_t_bits_minus_1) - 1) * 2 + 1)"
                     47:         else
                     48:           gl_cv_size_max="(((1UL << $size_t_bits_minus_1) - 1) * 2 + 1)"
                     49:         fi
                     50:       else
                     51:         dnl Shouldn't happen, but who knows...
                     52:         gl_cv_size_max='((size_t)~(size_t)0)'
                     53:       fi
                     54:     fi
                     55:   ])
                     56:   if test "$gl_cv_size_max" != yes; then
                     57:     AC_DEFINE_UNQUOTED([SIZE_MAX], [$gl_cv_size_max],
                     58:       [Define as the maximum value of type 'size_t', if the system doesn't define it.])
                     59:   fi
                     60:   dnl Don't redefine SIZE_MAX in config.h if config.h is re-included after
                     61:   dnl <stdint.h>. Remember that the #undef in AH_VERBATIM gets replaced with
                     62:   dnl #define by AC_DEFINE_UNQUOTED.
                     63:   AH_VERBATIM([SIZE_MAX],
                     64: [/* Define as the maximum value of type 'size_t', if the system doesn't define
                     65:    it. */
                     66: #ifndef SIZE_MAX
                     67: # undef SIZE_MAX
                     68: #endif])
                     69: ])
                     70: 
                     71: dnl Autoconf >= 2.61 has AC_COMPUTE_INT built-in.
                     72: dnl Remove this when we can assume autoconf >= 2.61.
                     73: m4_ifdef([AC_COMPUTE_INT], [], [
                     74:   AC_DEFUN([AC_COMPUTE_INT], [_AC_COMPUTE_INT([$2],[$1],[$3],[$4])])
                     75: ])