1# ldexp.m4 serial 1 2dnl Copyright (C) 2010-2012 Free Software Foundation, Inc. 3dnl This file is free software; the Free Software Foundation 4dnl gives unlimited permission to copy and/or distribute it, 5dnl with or without modifications, as long as this notice is preserved. 6 7AC_DEFUN([gl_FUNC_LDEXP], 8[ 9 AC_REQUIRE([gl_CHECK_LDEXP_NO_LIBM]) 10 LDEXP_LIBM= 11 if test $gl_cv_func_ldexp_no_libm = no; then 12 AC_CACHE_CHECK([whether ldexp() can be used with libm], 13 [gl_cv_func_ldexp_in_libm], 14 [ 15 save_LIBS="$LIBS" 16 LIBS="$LIBS -lm" 17 AC_LINK_IFELSE( 18 [AC_LANG_PROGRAM([[#ifndef __NO_MATH_INLINES 19 # define __NO_MATH_INLINES 1 /* for glibc */ 20 #endif 21 #include <math.h> 22 double (*funcptr) (double, int) = ldexp; 23 double x;]], 24 [[return ldexp (x, -1) > 0;]])], 25 [gl_cv_func_ldexp_in_libm=yes], 26 [gl_cv_func_ldexp_in_libm=no]) 27 LIBS="$save_LIBS" 28 ]) 29 if test $gl_cv_func_ldexp_in_libm = yes; then 30 LDEXP_LIBM=-lm 31 fi 32 fi 33 AC_SUBST([LDEXP_LIBM]) 34]) 35 36dnl Test whether ldexp() can be used without linking with libm. 37dnl Set gl_cv_func_ldexp_no_libm to 'yes' or 'no' accordingly. 38AC_DEFUN([gl_CHECK_LDEXP_NO_LIBM], 39[ 40 AC_CACHE_CHECK([whether ldexp() can be used without linking with libm], 41 [gl_cv_func_ldexp_no_libm], 42 [ 43 AC_LINK_IFELSE( 44 [AC_LANG_PROGRAM([[#ifndef __NO_MATH_INLINES 45 # define __NO_MATH_INLINES 1 /* for glibc */ 46 #endif 47 #include <math.h> 48 double (*funcptr) (double, int) = ldexp; 49 double x;]], 50 [[return ldexp (x, -1) > 0;]])], 51 [gl_cv_func_ldexp_no_libm=yes], 52 [gl_cv_func_ldexp_no_libm=no]) 53 ]) 54]) 55