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# exp2.m4 serial 3
dnl Copyright (C) 2010-2023 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_EXP2],
[
AC_REQUIRE([gl_MATH_H_DEFAULTS])
dnl Persuade glibc <math.h> to declare exp2().
AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
EXP2_LIBM=
AC_CACHE_CHECK([whether exp2() can be used without linking with libm],
[gl_cv_func_exp2_no_libm],
[
AC_LINK_IFELSE(
[AC_LANG_PROGRAM(
[[#ifndef __NO_MATH_INLINES
# define __NO_MATH_INLINES 1 /* for glibc */
#endif
#include <math.h>
extern
#ifdef __cplusplus
"C"
#endif
double exp2 (double);
double (* volatile funcptr) (double) = exp2;
double x;]],
[[return funcptr (x) > 1.5
|| exp2 (x) > 1.5;]])],
[gl_cv_func_exp2_no_libm=yes],
[gl_cv_func_exp2_no_libm=no])
])
if test $gl_cv_func_exp2_no_libm = no; then
AC_CACHE_CHECK([whether exp2() can be used with libm],
[gl_cv_func_exp2_in_libm],
[
save_LIBS="$LIBS"
LIBS="$LIBS -lm"
AC_LINK_IFELSE(
[AC_LANG_PROGRAM(
[[#ifndef __NO_MATH_INLINES
# define __NO_MATH_INLINES 1 /* for glibc */
#endif
#include <math.h>
extern
#ifdef __cplusplus
"C"
#endif
double exp2 (double);
double (* volatile funcptr) (double) = exp2;
double x;]],
[[return funcptr (x) > 1.5
|| exp2 (x) > 1.5;]])],
[gl_cv_func_exp2_in_libm=yes],
[gl_cv_func_exp2_in_libm=no])
LIBS="$save_LIBS"
])
if test $gl_cv_func_exp2_in_libm = yes; then
EXP2_LIBM=-lm
fi
fi
if test $gl_cv_func_exp2_no_libm = yes \
|| test $gl_cv_func_exp2_in_libm = yes; then
HAVE_EXP2=1
dnl Also check whether it's declared.
dnl IRIX 6.5 has exp2() in libm but doesn't declare it in <math.h>.
AC_CHECK_DECL([exp2], , [HAVE_DECL_EXP2=0], [[#include <math.h>]])
save_LIBS="$LIBS"
LIBS="$LIBS $EXP2_LIBM"
gl_FUNC_EXP2_WORKS
LIBS="$save_LIBS"
case "$gl_cv_func_exp2_works" in
*yes) ;;
*) REPLACE_EXP2=1 ;;
esac
else
HAVE_EXP2=0
HAVE_DECL_EXP2=0
fi
if test $HAVE_EXP2 = 0 || test $REPLACE_EXP2 = 1; then
dnl Find libraries needed to link lib/exp2.c.
AC_REQUIRE([gl_FUNC_ISNAND])
AC_REQUIRE([gl_FUNC_ROUND])
AC_REQUIRE([gl_FUNC_LDEXP])
EXP2_LIBM=
dnl Append $ISNAND_LIBM to EXP2_LIBM, avoiding gratuitous duplicates.
case " $EXP2_LIBM " in
*" $ISNAND_LIBM "*) ;;
*) EXP2_LIBM="$EXP2_LIBM $ISNAND_LIBM" ;;
esac
dnl Append $ROUND_LIBM to EXP2_LIBM, avoiding gratuitous duplicates.
case " $EXP2_LIBM " in
*" $ROUND_LIBM "*) ;;
*) EXP2_LIBM="$EXP2_LIBM $ROUND_LIBM" ;;
esac
dnl Append $LDEXP_LIBM to EXP2_LIBM, avoiding gratuitous duplicates.
case " $EXP2_LIBM " in
*" $LDEXP_LIBM "*) ;;
*) EXP2_LIBM="$EXP2_LIBM $LDEXP_LIBM" ;;
esac
fi
AC_SUBST([EXP2_LIBM])
])
dnl Test whether exp2() works.
dnl On OpenBSD 4.9, for the argument 0.6, it returns 1.517358639986284397,
dnl which has a relative error of 0.1%.
AC_DEFUN([gl_FUNC_EXP2_WORKS],
[
AC_REQUIRE([AC_PROG_CC])
AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
AC_CACHE_CHECK([whether exp2 works], [gl_cv_func_exp2_works],
[
AC_RUN_IFELSE(
[AC_LANG_SOURCE([[
#include <math.h>
extern
#ifdef __cplusplus
"C"
#endif
double exp2 (double);
volatile double x;
double y;
int main ()
{
x = 0.6;
y = exp2 (x);
if (y > 1.516)
return 1;
return 0;
}
]])],
[gl_cv_func_exp2_works=yes],
[gl_cv_func_exp2_works=no],
[case "$host_os" in
openbsd*) gl_cv_func_exp2_works="guessing no" ;;
# Guess yes on native Windows.
mingw*) gl_cv_func_exp2_works="guessing yes" ;;
*) gl_cv_func_exp2_works="guessing yes" ;;
esac
])
])
])
|
