# memcmp.m4 serial 16
dnl Copyright (C) 2002-2004, 2007-2023 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.

AC_DEFUN([gl_FUNC_MEMCMP],
[
  dnl We don't use AC_FUNC_MEMCMP any more, because it is no longer maintained
  dnl in Autoconf and because it invokes AC_LIBOBJ.
  AC_CACHE_CHECK([for working memcmp], [gl_cv_func_memcmp_working],
    [AC_RUN_IFELSE(
       [AC_LANG_PROGRAM(
          [AC_INCLUDES_DEFAULT],
          [[/* Some versions of memcmp are not 8-bit clean.  */
            char c0 = '\100', c1 = '\200', c2 = '\201';
            if (memcmp(&c0, &c2, 1) >= 0 || memcmp(&c1, &c2, 1) >= 0)
              return 1;
            /* The Next x86 OpenStep bug shows up only when comparing 16 bytes
               or more and with at least one buffer not starting on a 4-byte
               boundary.  William Lewis provided this test program.   */
            {
              char foo[21];
              char bar[21];
              int i;
              for (i = 0; i < 4; i++)
                {
                  char *a = foo + i;
                  char *b = bar + i;
                  strcpy (a, "--------01111111");
                  strcpy (b, "--------10000000");
                  if (memcmp (a, b, 16) >= 0)
                    return 1;
                }
              return 0;
            }
          ]])],
       [gl_cv_func_memcmp_working=yes],
       [gl_cv_func_memcmp_working=no],
       [dnl When cross-compiling, guess memcmp works when it exists.
        dnl This is useful for mingw.
        AC_LINK_IFELSE(
          [AC_LANG_PROGRAM(
             [[#include <string.h>]],
             [[int ret = memcmp ("foo", "bar", 0);]])],
          [gl_cv_func_memcmp_working="guessing yes"],
          [gl_cv_func_memcmp_working="guessing no"])
       ])
    ])
  case "$gl_cv_func_memcmp_working" in
    *yes) gl_func_memcmp=yes ;;
    *)    gl_func_memcmp=no ;;
  esac
  if test $gl_func_memcmp = no; then
    AC_DEFINE([memcmp], [rpl_memcmp],
      [Define to rpl_memcmp if the replacement function should be used.])
  fi
])

# Prerequisites of lib/memcmp.c.
AC_DEFUN([gl_PREREQ_MEMCMP], [:])