186 lines
6.0 KiB
Plaintext
186 lines
6.0 KiB
Plaintext
# log2l.m4
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# serial 9
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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_LOG2L],
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[
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AC_REQUIRE([gl_MATH_H_DEFAULTS])
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AC_REQUIRE([gl_LONG_DOUBLE_VS_DOUBLE])
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AC_REQUIRE([gl_FUNC_LOG2])
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dnl Persuade glibc <math.h> to declare log2l().
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AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
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dnl Test whether log2l() exists. Assume that log2l(), if it exists, is
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dnl defined in the same library as log2().
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saved_LIBS="$LIBS"
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LIBS="$LIBS $LOG2_LIBM"
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gl_CHECK_FUNCS_ANDROID([log2l], [[#include <math.h>]])
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LIBS="$saved_LIBS"
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if test $ac_cv_func_log2l = yes; then
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LOG2L_LIBM="$LOG2_LIBM"
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HAVE_LOG2L=1
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dnl Also check whether it's declared.
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dnl IRIX 6.5 has log2l() in libm but doesn't declare it in <math.h>.
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AC_CHECK_DECL([log2l], , [HAVE_DECL_LOG2L=0], [[#include <math.h>]])
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saved_LIBS="$LIBS"
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LIBS="$LIBS $LOG2L_LIBM"
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gl_FUNC_LOG2L_WORKS
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LIBS="$saved_LIBS"
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case "$gl_cv_func_log2l_works" in
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*yes) ;;
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*) REPLACE_LOG2L=1 ;;
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esac
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else
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HAVE_LOG2L=0
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HAVE_DECL_LOG2L=0
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case "$gl_cv_onwards_func_log2l" in
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future*) REPLACE_LOG2L=1 ;;
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esac
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fi
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if test $HAVE_LOG2L = 0 || test $REPLACE_LOG2L = 1; then
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dnl Find libraries needed to link lib/log2l.c.
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if test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 1; then
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LOG2L_LIBM="$LOG2_LIBM"
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else
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AC_REQUIRE([gl_FUNC_ISNANL])
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AC_REQUIRE([gl_FUNC_FREXPL])
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AC_REQUIRE([gl_FUNC_LOGL])
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LOG2L_LIBM=
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dnl Append $ISNANL_LIBM to LOG2L_LIBM, avoiding gratuitous duplicates.
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case " $LOG2L_LIBM " in
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*" $ISNANL_LIBM "*) ;;
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*) LOG2L_LIBM="$LOG2L_LIBM $ISNANL_LIBM" ;;
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esac
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dnl Append $FREXPL_LIBM to LOG2L_LIBM, avoiding gratuitous duplicates.
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case " $LOG2L_LIBM " in
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*" $FREXPL_LIBM "*) ;;
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*) LOG2L_LIBM="$LOG2L_LIBM $FREXPL_LIBM" ;;
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esac
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dnl Append $LOGL_LIBM to LOG2L_LIBM, avoiding gratuitous duplicates.
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case " $LOG2L_LIBM " in
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*" $LOGL_LIBM "*) ;;
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*) LOG2L_LIBM="$LOG2L_LIBM $LOGL_LIBM" ;;
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esac
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fi
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fi
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AC_SUBST([LOG2L_LIBM])
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])
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dnl Test whether log2l() works.
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dnl On OSF/1 5.1, log2l(-0.0) is NaN.
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dnl On musl 1.2.2/{arm64,s390x}, the result is accurate to only 16 digits.
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dnl On musl 1.2.2/{arm64,s390x} and NetBSD 10.0, the result is Infinity for
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dnl some large finite arguments.
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AC_DEFUN([gl_FUNC_LOG2L_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 log2l works], [gl_cv_func_log2l_works],
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[
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AC_RUN_IFELSE(
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[AC_LANG_SOURCE([[
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#ifndef __NO_MATH_INLINES
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# define __NO_MATH_INLINES 1 /* for glibc */
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#endif
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#include <float.h>
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#include <math.h>
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/* Override the values of <float.h>, like done in float.in.h. */
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#if defined __i386__ && (defined __BEOS__ || defined __OpenBSD__)
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# undef LDBL_MANT_DIG
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# define LDBL_MANT_DIG 64
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# undef LDBL_MIN_EXP
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# define LDBL_MIN_EXP (-16381)
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# undef LDBL_MAX_EXP
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# define LDBL_MAX_EXP 16384
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#endif
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#if defined __i386__ && (defined __FreeBSD__ || defined __DragonFly__)
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# undef LDBL_MANT_DIG
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# define LDBL_MANT_DIG 64
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# undef LDBL_MIN_EXP
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# define LDBL_MIN_EXP (-16381)
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# undef LDBL_MAX_EXP
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# define LDBL_MAX_EXP 16384
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#endif
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#if (defined _ARCH_PPC || defined _POWER) && defined _AIX && (LDBL_MANT_DIG == 106) && defined __GNUC__
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# undef LDBL_MIN_EXP
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# define LDBL_MIN_EXP DBL_MIN_EXP
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#endif
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#if defined __sgi && (LDBL_MANT_DIG >= 106)
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# undef LDBL_MANT_DIG
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# define LDBL_MANT_DIG 106
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# if defined __GNUC__
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# undef LDBL_MIN_EXP
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# define LDBL_MIN_EXP DBL_MIN_EXP
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# endif
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#endif
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#ifndef log2l /* for AIX */
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extern
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#ifdef __cplusplus
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"C"
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#endif
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long double log2l (long double);
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#endif
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static long double dummy (long double x) { return 0; }
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volatile long double gx;
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volatile long double gy;
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int main (int argc, char *argv[])
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{
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long double (* volatile my_log2l) (long double) = argc ? log2l : dummy;
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int result = 0;
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/* This test fails on OSF/1 5.1. */
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{
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gx = -0.0L;
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gy = my_log2l (gx);
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if (!(gy + gy == gy))
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result |= 1;
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}
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/* This test fails on musl 1.2.2/arm64, musl 1.2.2/s390x. */
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{
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const long double TWO_LDBL_MANT_DIG = /* 2^LDBL_MANT_DIG */
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(long double) (1U << ((LDBL_MANT_DIG - 1) / 5))
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* (long double) (1U << ((LDBL_MANT_DIG - 1 + 1) / 5))
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* (long double) (1U << ((LDBL_MANT_DIG - 1 + 2) / 5))
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* (long double) (1U << ((LDBL_MANT_DIG - 1 + 3) / 5))
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* (long double) (1U << ((LDBL_MANT_DIG - 1 + 4) / 5));
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long double x = 11.358L;
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long double y = my_log2l (x);
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long double z = my_log2l (1.0L / x);
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long double err = (y + z) * TWO_LDBL_MANT_DIG;
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if (!(err >= -10000.0L && err <= 10000.0L))
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result |= 2;
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}
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/* This test fails on musl 1.2.2/arm64, musl 1.2.2/s390x, NetBSD 10.0. */
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if (DBL_MAX_EXP < LDBL_MAX_EXP)
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{
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long double x = ldexpl (1.0L, DBL_MAX_EXP); /* finite! */
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long double y = my_log2l (x);
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if (y > 0 && y + y == y) /* infinite? */
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result |= 4;
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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_log2l_works=yes],
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[gl_cv_func_log2l_works=no],
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[case "$host_os" in
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# Guess yes on glibc systems.
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*-gnu* | gnu*) gl_cv_func_log2l_works="guessing yes" ;;
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# Guess no on musl systems.
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*-musl* | midipix*) gl_cv_func_log2l_works="guessing no" ;;
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# Guess no on NetBSD and OSF/1.
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netbsd* | osf*) gl_cv_func_log2l_works="guessing no" ;;
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# Guess yes on native Windows.
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mingw* | windows*) gl_cv_func_log2l_works="guessing yes" ;;
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# If we don't know, obey --enable-cross-guesses.
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*) gl_cv_func_log2l_works="$gl_cross_guess_normal" ;;
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esac
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])
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])
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])
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