181 lines
5.1 KiB
Text
181 lines
5.1 KiB
Text
# frexp.m4 serial 16
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dnl Copyright (C) 2007-2021 Free Software Foundation, Inc.
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dnl This file is free software; the Free Software Foundation
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dnl gives unlimited permission to copy and/or distribute it,
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dnl with or without modifications, as long as this notice is preserved.
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AC_DEFUN([gl_FUNC_FREXP],
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[
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AC_REQUIRE([gl_MATH_H_DEFAULTS])
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AC_REQUIRE([gl_CHECK_FREXP_NO_LIBM])
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FREXP_LIBM=
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if test $gl_cv_func_frexp_no_libm = no; then
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AC_CACHE_CHECK([whether frexp() can be used with libm],
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[gl_cv_func_frexp_in_libm],
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[
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save_LIBS="$LIBS"
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LIBS="$LIBS -lm"
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AC_LINK_IFELSE(
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[AC_LANG_PROGRAM(
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[[#include <math.h>
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double x;]],
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[[int e; return frexp (x, &e) > 0;]])],
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[gl_cv_func_frexp_in_libm=yes],
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[gl_cv_func_frexp_in_libm=no])
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LIBS="$save_LIBS"
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])
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if test $gl_cv_func_frexp_in_libm = yes; then
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FREXP_LIBM=-lm
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fi
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fi
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if test $gl_cv_func_frexp_no_libm = yes \
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|| test $gl_cv_func_frexp_in_libm = yes; then
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save_LIBS="$LIBS"
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LIBS="$LIBS $FREXP_LIBM"
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gl_FUNC_FREXP_WORKS
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LIBS="$save_LIBS"
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case "$gl_cv_func_frexp_works" in
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*yes) gl_func_frexp=yes ;;
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*) gl_func_frexp=no; REPLACE_FREXP=1; FREXP_LIBM= ;;
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esac
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else
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gl_func_frexp=no
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fi
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if test $gl_func_frexp = yes; then
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AC_DEFINE([HAVE_FREXP], [1],
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[Define if the frexp() function is available and works.])
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fi
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AC_SUBST([FREXP_LIBM])
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])
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AC_DEFUN([gl_FUNC_FREXP_NO_LIBM],
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[
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AC_REQUIRE([gl_MATH_H_DEFAULTS])
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AC_REQUIRE([gl_CHECK_FREXP_NO_LIBM])
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if test $gl_cv_func_frexp_no_libm = yes; then
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gl_FUNC_FREXP_WORKS
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case "$gl_cv_func_frexp_works" in
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*yes) gl_func_frexp_no_libm=yes ;;
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*) gl_func_frexp_no_libm=no; REPLACE_FREXP=1 ;;
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esac
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else
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gl_func_frexp_no_libm=no
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dnl Set REPLACE_FREXP here because the system may have frexp in libm.
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REPLACE_FREXP=1
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fi
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if test $gl_func_frexp_no_libm = yes; then
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AC_DEFINE([HAVE_FREXP_IN_LIBC], [1],
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[Define if the frexp() function is available in libc.])
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fi
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])
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dnl Test whether frexp() can be used without linking with libm.
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dnl Set gl_cv_func_frexp_no_libm to 'yes' or 'no' accordingly.
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AC_DEFUN([gl_CHECK_FREXP_NO_LIBM],
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[
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AC_CACHE_CHECK([whether frexp() can be used without linking with libm],
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[gl_cv_func_frexp_no_libm],
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[
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AC_LINK_IFELSE(
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[AC_LANG_PROGRAM(
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[[#include <math.h>
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double x;]],
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[[int e; return frexp (x, &e) > 0;]])],
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[gl_cv_func_frexp_no_libm=yes],
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[gl_cv_func_frexp_no_libm=no])
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])
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])
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dnl Test whether frexp() works also on denormalized numbers (this fails e.g. on
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dnl NetBSD 3.0), on infinite numbers (this fails e.g. on IRIX 6.5 and mingw),
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dnl and on negative zero (this fails e.g. on NetBSD 4.99 and mingw).
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AC_DEFUN([gl_FUNC_FREXP_WORKS],
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[
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AC_REQUIRE([AC_PROG_CC])
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AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
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AC_CHECK_DECLS_ONCE([alarm])
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AC_CACHE_CHECK([whether frexp works], [gl_cv_func_frexp_works],
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[
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AC_RUN_IFELSE(
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[AC_LANG_SOURCE([[
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#include <float.h>
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#include <math.h>
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#include <string.h>
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#if HAVE_DECL_ALARM
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# include <signal.h>
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# include <unistd.h>
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#endif
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/* HP cc on HP-UX 10.20 has a bug with the constant expression -0.0.
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ICC 10.0 has a bug when optimizing the expression -zero.
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The expression -DBL_MIN * DBL_MIN does not work when cross-compiling
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to PowerPC on Mac OS X 10.5. */
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#if defined __hpux || defined __sgi || defined __ICC
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static double
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compute_minus_zero (void)
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{
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return -DBL_MIN * DBL_MIN;
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}
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# define minus_zero compute_minus_zero ()
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#else
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double minus_zero = -0.0;
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#endif
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int main()
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{
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int result = 0;
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int i;
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volatile double x;
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double zero = 0.0;
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#if HAVE_DECL_ALARM
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/* NeXTstep 3.3 frexp() runs into an endless loop when called on an infinite
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number. Let the test fail in this case. */
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signal (SIGALRM, SIG_DFL);
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alarm (5);
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#endif
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/* Test on denormalized numbers. */
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for (i = 1, x = 1.0; i >= DBL_MIN_EXP; i--, x *= 0.5)
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;
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if (x > 0.0)
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{
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int exp;
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double y = frexp (x, &exp);
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/* On machines with IEEE754 arithmetic: x = 1.11254e-308, exp = -1022.
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On NetBSD: y = 0.75. Correct: y = 0.5. */
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if (y != 0.5)
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result |= 1;
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}
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/* Test on infinite numbers. */
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x = 1.0 / zero;
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{
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int exp;
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double y = frexp (x, &exp);
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if (y != x)
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result |= 2;
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}
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/* Test on negative zero. */
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x = minus_zero;
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{
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int exp;
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double y = frexp (x, &exp);
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if (memcmp (&y, &x, sizeof x))
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result |= 4;
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}
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return result;
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}]])],
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[gl_cv_func_frexp_works=yes],
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[gl_cv_func_frexp_works=no],
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[case "$host_os" in
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netbsd* | irix*) gl_cv_func_frexp_works="guessing no" ;;
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mingw*) # Guess yes with MSVC, no with mingw.
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AC_EGREP_CPP([Good], [
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#ifdef _MSC_VER
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Good
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#endif
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],
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[gl_cv_func_frexp_works="guessing yes"],
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[gl_cv_func_frexp_works="guessing no"])
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;;
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*) gl_cv_func_frexp_works="guessing yes" ;;
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esac
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])
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])
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])
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