view m4/wctob.m4 @ 16869:38e6d30d7e4d

poll/select: prevent busy-waiting 2012-05-21 Paolo Bonzini <bonzini@gnu.org> poll/select: prevent busy-waiting. SwitchToThread() only gives away the rest of the current time slice to another thread in the current process. So if the thread that feeds the file decscriptor we're polling is not in the current process, we get busy-waiting. * lib/poll.c: Use SleepEx(1, TRUE) instead of SwitchToThread(). Patch from Theodore Leblond. * lib/select.c: Split polling out of the loop that sets the output fd_sets. Check for zero result and loop if the wait timeout is infinite.
author Paolo Bonzini <bonzini@gnu.org>
date Mon, 21 May 2012 09:52:42 +0200
parents 8250f2777afc
children e542fd46ad6f
line wrap: on
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# wctob.m4 serial 10
dnl Copyright (C) 2008-2012 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_WCTOB],
[
  AC_REQUIRE([gl_WCHAR_H_DEFAULTS])

  AC_CHECK_FUNCS_ONCE([wctob])
  if test $ac_cv_func_wctob = no; then
    HAVE_WCTOB=0
    HAVE_DECL_WCTOB=0
  else
    HAVE_WCTOB=1

    dnl Solaris 9 has the wctob() function but it does not work.
    dnl Cygwin 1.7.2 has the wctob() function but it clobbers caller-owned
    dnl registers, see <http://cygwin.com/ml/cygwin/2010-05/msg00015.html>.
    AC_REQUIRE([AC_PROG_CC])
    AC_REQUIRE([gt_LOCALE_FR])
    AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
    AC_CACHE_CHECK([whether wctob works],
      [gl_cv_func_wctob_works],
      [
        dnl Initial guess, used when cross-compiling or when no suitable locale
        dnl is present.
changequote(,)dnl
        case "$host_os" in
            # Guess no on Solaris <= 9 and Cygwin.
          solaris2.[1-9] | solaris2.[1-9].* | cygwin*)
            gl_cv_func_wctob_works="guessing no" ;;
            # Guess yes otherwise.
          *) gl_cv_func_wctob_works="guessing yes" ;;
        esac
changequote([,])dnl
        case "$host_os" in
          cygwin*)
            AC_RUN_IFELSE(
              [AC_LANG_SOURCE([[
#include <locale.h>
/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
   <wchar.h>.
   BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be
   included before <wchar.h>.  */
#include <stddef.h>
#include <stdio.h>
#include <time.h>
#include <wchar.h>

register long global __asm__ ("%ebx");

int main ()
{
  setlocale (LC_ALL, "en_US.UTF-8");

  global = 0x12345678;
  if (wctob (0x00FC) != -1)
    return 1;
  if (global != 0x12345678)
    return 2;
  return 0;
}]])],
              [:],
              [gl_cv_func_wctob_works=no],
              [:])
            ;;
        esac
        if test "$gl_cv_func_wctob_works" != no && test $LOCALE_FR != none; then
          AC_RUN_IFELSE(
            [AC_LANG_SOURCE([[
#include <locale.h>
#include <string.h>
/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
   <wchar.h>.
   BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be
   included before <wchar.h>.  */
#include <stddef.h>
#include <stdio.h>
#include <time.h>
#include <wchar.h>
int main ()
{
  if (setlocale (LC_ALL, "$LOCALE_FR") != NULL)
    {
      wchar_t wc;

      if (mbtowc (&wc, "\374", 1) == 1)
        if (wctob (wc) != (unsigned char) '\374')
          return 1;
    }
  return 0;
}]])],
            [gl_cv_func_wctob_works=yes],
            [gl_cv_func_wctob_works=no],
            [:])
        fi
      ])
    case "$gl_cv_func_wctob_works" in
      *yes) ;;
      *) REPLACE_WCTOB=1 ;;
    esac
    if test $REPLACE_WCTOB = 0; then

      dnl IRIX 6.5 has the wctob() function but does not declare it.
      AC_CHECK_DECLS([wctob], [], [], [[
/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
   <wchar.h>.
   BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be included
   before <wchar.h>.  */
#include <stddef.h>
#include <stdio.h>
#include <time.h>
#include <wchar.h>
]])
      if test $ac_cv_have_decl_wctob != yes; then
        HAVE_DECL_WCTOB=0
      fi
    fi
  fi
])

# Prerequisites of lib/wctob.c.
AC_DEFUN([gl_PREREQ_WCTOB], [
  :
])