139 lines
3.9 KiB
Plaintext
139 lines
3.9 KiB
Plaintext
# ilogb.m4
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# serial 10
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dnl Copyright (C) 2010-2024 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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dnl This file is offered as-is, without any warranty.
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AC_DEFUN([gl_FUNC_ILOGB],
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[
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AC_REQUIRE([gl_MATH_H_DEFAULTS])
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dnl Determine ILOGB_LIBM.
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gl_MATHFUNC([ilogb], [int], [(double)])
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if test $gl_cv_func_ilogb_no_libm = yes \
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|| test $gl_cv_func_ilogb_in_libm = yes; then
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saved_LIBS="$LIBS"
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LIBS="$LIBS $ILOGB_LIBM"
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gl_FUNC_ILOGB_WORKS
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LIBS="$saved_LIBS"
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case "$gl_cv_func_ilogb_works" in
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*yes) ;;
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*) REPLACE_ILOGB=1 ;;
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esac
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else
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HAVE_ILOGB=0
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fi
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if test $HAVE_ILOGB = 0 || test $REPLACE_ILOGB = 1; then
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dnl Find libraries needed to link lib/ilogb.c.
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AC_REQUIRE([gl_FUNC_FREXP])
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AC_REQUIRE([gl_FUNC_ISNAND])
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ILOGB_LIBM=
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dnl Append $FREXP_LIBM to ILOGB_LIBM, avoiding gratuitous duplicates.
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case " $ILOGB_LIBM " in
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*" $FREXP_LIBM "*) ;;
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*) ILOGB_LIBM="$ILOGB_LIBM $FREXP_LIBM" ;;
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esac
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dnl Append $ISNAND_LIBM to ILOGB_LIBM, avoiding gratuitous duplicates.
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case " $ILOGB_LIBM " in
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*" $ISNAND_LIBM "*) ;;
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*) ILOGB_LIBM="$ILOGB_LIBM $ISNAND_LIBM" ;;
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esac
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fi
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AC_SUBST([ILOGB_LIBM])
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])
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dnl Test whether ilogb() works.
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dnl On OpenBSD 6.7, AIX 5.1, ilogb(0.0) is wrong.
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dnl On Mac OS X 10.5 in 64-bit mode and on AIX 7.1 in 64-bit mode,
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dnl ilogb(2^(DBL_MIN_EXP-1)) is wrong.
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dnl On NetBSD 7.1, OpenBSD 6.7, ilogb(Infinity) is wrong.
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dnl On NetBSD 7.1, OpenBSD 6.7, ilogb(NaN) is wrong.
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AC_DEFUN([gl_FUNC_ILOGB_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_CACHE_CHECK([whether ilogb works], [gl_cv_func_ilogb_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 <limits.h>
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#include <math.h>
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/* Provide FP_ILOGB0, FP_ILOGBNAN, like in math.in.h. */
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#if defined FP_ILOGB0 && defined FP_ILOGBNAN
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# if defined __HAIKU__
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/* Haiku: match what ilogb() does */
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# undef FP_ILOGB0
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# undef FP_ILOGBNAN
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# define FP_ILOGB0 (- 2147483647 - 1) /* INT_MIN */
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# define FP_ILOGBNAN (- 2147483647 - 1) /* INT_MIN */
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# endif
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#else
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# if defined __NetBSD__ || defined __sgi
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/* NetBSD, IRIX 6.5: match what ilogb() does */
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# define FP_ILOGB0 INT_MIN
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# define FP_ILOGBNAN INT_MIN
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# elif defined _AIX
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/* AIX 5.1: match what ilogb() does in AIX >= 5.2 */
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# define FP_ILOGB0 INT_MIN
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# define FP_ILOGBNAN INT_MAX
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# elif defined __sun
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/* Solaris 9: match what ilogb() does */
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# define FP_ILOGB0 (- INT_MAX)
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# define FP_ILOGBNAN INT_MAX
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# endif
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#endif
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volatile double x;
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static double zero;
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static int dummy (double x) { return 0; }
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int main (int argc, char *argv[])
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{
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int (* volatile my_ilogb) (double) = argc ? ilogb : dummy;
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int result = 0;
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/* This test fails on OpenBSD 6.7, AIX 5.1. */
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{
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x = 0.0;
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if (my_ilogb (x) != FP_ILOGB0)
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result |= 1;
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}
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/* This test fails on Mac OS X 10.5 in 64-bit mode and on
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AIX 7.1 in 64-bit mode. */
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{
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int i;
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x = 0.5;
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for (i = DBL_MIN_EXP - 1; i < 0; i++)
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x = x * 0.5;
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if (x > 0.0 && my_ilogb (x) != DBL_MIN_EXP - 2)
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result |= 2;
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}
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/* This test fails on NetBSD 7.1, OpenBSD 6.7. */
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{
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x = 1.0 / zero;
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if (my_ilogb (x) != INT_MAX)
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result |= 4;
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}
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/* This test fails on NetBSD 7.1, OpenBSD 6.7. */
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{
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x = zero / zero;
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if (my_ilogb (x) != FP_ILOGBNAN)
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result |= 8;
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}
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return result;
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}
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]])],
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[gl_cv_func_ilogb_works=yes],
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[gl_cv_func_ilogb_works=no],
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[case "$host_os" in
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aix* | openbsd* | netbsd* | solaris*)
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gl_cv_func_ilogb_works="guessing no" ;;
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# Guess yes on native Windows.
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mingw* | windows*)
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gl_cv_func_ilogb_works="guessing yes" ;;
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*) gl_cv_func_ilogb_works="guessing yes" ;;
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esac
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])
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])
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])
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