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e2239af353
Improve the commentary to aid future developers who will stumble upon this novel, yet not always perfect, mechanism to support alternative formats for long double. Likewise, rename __LONG_DOUBLE_USES_FLOAT128 to __LDOUBLE_REDIRECTS_TO_FLOAT128_ABI now that development work has settled down. The command used was git grep -l __LONG_DOUBLE_USES_FLOAT128 ':!./ChangeLog*' | \ xargs sed -i 's/__LONG_DOUBLE_USES_FLOAT128/__LDOUBLE_REDIRECTS_TO_FLOAT128_ABI/g' Reviewed-by: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>
54 lines
2.3 KiB
C
54 lines
2.3 KiB
C
/* Properties of long double type.
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Copyright (C) 2016-2020 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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/* This header is included by <sys/cdefs.h>.
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If long double is ABI-compatible with double, it should define
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__NO_LONG_DOUBLE_MATH to 1; otherwise, it should leave
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__NO_LONG_DOUBLE_MATH undefined.
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If this build of the GNU C Library supports both long double
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ABI-compatible with double and some other long double format not
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ABI-compatible with double, it should define
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__LONG_DOUBLE_MATH_OPTIONAL to 1; otherwise, it should leave
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__LONG_DOUBLE_MATH_OPTIONAL undefined.
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If __NO_LONG_DOUBLE_MATH is already defined, this header must not
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define anything; this is needed to work with the definition of
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__NO_LONG_DOUBLE_MATH in nldbl-compat.h. */
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/* In the default version of this header, long double is
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ABI-compatible with double. */
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#ifndef __NO_LONG_DOUBLE_MATH
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# define __NO_LONG_DOUBLE_MATH 1
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#endif
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/* The macro __LDOUBLE_REDIRECTS_TO_FLOAT128_ABI is used to determine the
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choice of the underlying ABI of long double. It will always assume
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a constant value for each translation unit.
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If the value is non-zero, any API which is parameterized by the long
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double type (i.e the scanf/printf family of functions or the explicitly
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parameterized math.h functions) will be redirected to a compatible
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implementation using _Float128 ABI via symbols suffixed with ieee128.
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The mechanism this macro uses to acquire may be a function
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of architecture, or target specific options used to invoke the
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compiler. */
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#define __LDOUBLE_REDIRECTS_TO_FLOAT128_ABI 0
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