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# trunc.m4 serial 16
dnl Copyright (C) 2007, 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_TRUNC],
[
m4_divert_text([DEFAULTS], [gl_trunc_required=plain])
AC_REQUIRE([gl_MATH_H_DEFAULTS])
dnl Persuade glibc <math.h> to declare trunc().
AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
dnl Test whether trunc() is declared.
AC_CHECK_DECLS([trunc], , , [[#include <math.h>]])
if test "$ac_cv_have_decl_trunc" = yes; then
dnl Test whether trunc() can be used without libm.
TRUNC_LIBM=?
AC_LINK_IFELSE(
[AC_LANG_PROGRAM(
[[#ifndef __NO_MATH_INLINES
# define __NO_MATH_INLINES 1 /* for glibc */
#endif
#include <math.h>
double (*funcptr) (double) = trunc;
double x;]],
[[x = funcptr(x) + trunc(x);]])],
[TRUNC_LIBM=])
if test "$TRUNC_LIBM" = "?"; then
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>
double (*funcptr) (double) = trunc;
double x;]],
[[x = funcptr(x) + trunc(x);]])],
[TRUNC_LIBM="-lm"])
LIBS="$save_LIBS"
fi
if test "$TRUNC_LIBM" = "?"; then
TRUNC_LIBM=
fi
m4_ifdef([gl_FUNC_TRUNC_IEEE], [
if test $gl_trunc_required = ieee && test $REPLACE_TRUNC = 0; then
AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
AC_CACHE_CHECK([whether trunc works according to ISO C 99 with IEC 60559],
[gl_cv_func_trunc_ieee],
[
save_LIBS="$LIBS"
LIBS="$LIBS $TRUNC_LIBM"
AC_RUN_IFELSE(
[AC_LANG_SOURCE([[
#ifndef __NO_MATH_INLINES
# define __NO_MATH_INLINES 1 /* for glibc */
#endif
#include <math.h>
]gl_DOUBLE_MINUS_ZERO_CODE[
]gl_DOUBLE_SIGNBIT_CODE[
static double dummy (double f) { return 0; }
int main (int argc, char *argv[])
{
double (* volatile my_trunc) (double) = argc ? trunc : dummy;
/* Test whether trunc (-0.0) is -0.0. */
if (signbitd (minus_zerod) && !signbitd (my_trunc (minus_zerod)))
return 1;
return 0;
}
]])],
[gl_cv_func_trunc_ieee=yes],
[gl_cv_func_trunc_ieee=no],
[case "$host_os" in
# Guess yes on glibc systems.
*-gnu* | gnu*) gl_cv_func_trunc_ieee="guessing yes" ;;
# Guess yes on musl systems.
*-musl* | midipix*) gl_cv_func_trunc_ieee="guessing yes" ;;
# Guess yes on native Windows.
mingw*) gl_cv_func_trunc_ieee="guessing yes" ;;
# If we don't know, obey --enable-cross-guesses.
*) gl_cv_func_trunc_ieee="$gl_cross_guess_normal" ;;
esac
])
LIBS="$save_LIBS"
])
case "$gl_cv_func_trunc_ieee" in
*yes) ;;
*) REPLACE_TRUNC=1 ;;
esac
fi
])
else
HAVE_DECL_TRUNC=0
fi
if test $HAVE_DECL_TRUNC = 0 || test $REPLACE_TRUNC = 1; then
dnl No libraries are needed to link lib/trunc.c.
TRUNC_LIBM=
fi
AC_SUBST([TRUNC_LIBM])
])
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