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Annotation of embedaddon/libiconv/srcm4/size_max.m4, revision 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: ])