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aa706e13f4
With only two exceptions (sys/types.h and sys/param.h, both of which historically might have defined BYTE_ORDER) the public headers that include <endian.h> only want to be able to test __BYTE_ORDER against __*_ENDIAN. This patch creates a new bits/endian.h that can be included by any header that wants to be able to test __BYTE_ORDER and/or __FLOAT_WORD_ORDER against the __*_ENDIAN constants, or needs __LONG_LONG_PAIR. It only defines macros in the implementation namespace. The existing bits/endian.h (which could not be included independently of endian.h, and only defines __BYTE_ORDER and maybe __FLOAT_WORD_ORDER) is renamed to bits/endianness.h. I also took the opportunity to canonicalize the form of this header, which we are stuck with having one copy of per architecture. Since they are so short, this means git doesn’t understand that they were renamed from existing headers, sigh. endian.h itself is a nonstandard header and its only remaining use from a standard header is guarded by __USE_MISC, so I dropped the __USE_MISC conditionals from around all of the public-namespace things it defines. (This means, an application that requests strict library conformance but includes endian.h will still see the definition of BYTE_ORDER.) A few changes to specific bits/endian(ness).h variants deserve mention: - sysdeps/unix/sysv/linux/ia64/bits/endian.h is moved to sysdeps/ia64/bits/endianness.h. If I remember correctly, ia64 did have selectable endianness, but we have assembly code in sysdeps/ia64 that assumes it’s little-endian, so there is no reason to treat the ia64 endianness.h as linux-specific. - The C-SKY port does not fully support big-endian mode, the compile will error out if __CSKYBE__ is defined. - The PowerPC port had extra logic in its bits/endian.h to detect a broken compiler, which strikes me as unnecessary, so I removed it. - The only files that defined __FLOAT_WORD_ORDER always defined it to the same value as __BYTE_ORDER, so I removed those definitions. The SH bits/endian(ness).h had comments inconsistent with the actual setting of __FLOAT_WORD_ORDER, which I also removed. - I *removed* copyright boilerplate from the few bits/endian(ness).h headers that had it; these files record a single fact in a fashion dictated by an external spec, so I do not think they are copyrightable. As long as I was changing every copy of ieee754.h in the tree, I noticed that only the MIPS variant includes float.h, because it uses LDBL_MANT_DIG to decide among three different versions of ieee854_long_double. This patch makes it not include float.h when GCC’s intrinsic __LDBL_MANT_DIG__ is available. * string/endian.h: Unconditionally define LITTLE_ENDIAN, BIG_ENDIAN, PDP_ENDIAN, and BYTE_ORDER. Condition byteswapping macros only on !__ASSEMBLER__. Move the definitions of __BIG_ENDIAN, __LITTLE_ENDIAN, __PDP_ENDIAN, __FLOAT_WORD_ORDER, and __LONG_LONG_PAIR to... * string/bits/endian.h: ...this new file, which includes the renamed header bits/endianness.h for the definition of __BYTE_ORDER and possibly __FLOAT_WORD_ORDER. * string/Makefile: Install bits/endianness.h. * include/bits/endian.h: New wrapper. * bits/endian.h: Rename to bits/endianness.h. Add multiple-include guard. Rewrite the comment explaining what the machine-specific variants of this file should do. * sysdeps/unix/sysv/linux/ia64/bits/endian.h: Move to sysdeps/ia64. * sysdeps/aarch64/bits/endian.h * sysdeps/alpha/bits/endian.h * sysdeps/arm/bits/endian.h * sysdeps/csky/bits/endian.h * sysdeps/hppa/bits/endian.h * sysdeps/ia64/bits/endian.h * sysdeps/m68k/bits/endian.h * sysdeps/microblaze/bits/endian.h * sysdeps/mips/bits/endian.h * sysdeps/nios2/bits/endian.h * sysdeps/powerpc/bits/endian.h * sysdeps/riscv/bits/endian.h * sysdeps/s390/bits/endian.h * sysdeps/sh/bits/endian.h * sysdeps/sparc/bits/endian.h * sysdeps/x86/bits/endian.h: Rename to endianness.h; canonicalize form of file; remove redundant definitions of __FLOAT_WORD_ORDER. * sysdeps/powerpc/bits/endianness.h: Remove logic to check for broken compilers. * ctype/ctype.h * sysdeps/aarch64/nptl/bits/pthreadtypes-arch.h * sysdeps/arm/nptl/bits/pthreadtypes-arch.h * sysdeps/csky/nptl/bits/pthreadtypes-arch.h * sysdeps/ia64/ieee754.h * sysdeps/ieee754/ieee754.h * sysdeps/ieee754/ldbl-128/ieee754.h * sysdeps/ieee754/ldbl-128ibm/ieee754.h * sysdeps/m68k/nptl/bits/pthreadtypes-arch.h * sysdeps/microblaze/nptl/bits/pthreadtypes-arch.h * sysdeps/mips/ieee754/ieee754.h * sysdeps/mips/nptl/bits/pthreadtypes-arch.h * sysdeps/nios2/nptl/bits/pthreadtypes-arch.h * sysdeps/nptl/pthread.h * sysdeps/riscv/nptl/bits/pthreadtypes-arch.h * sysdeps/sh/nptl/bits/pthreadtypes-arch.h * sysdeps/sparc/sparc32/ieee754.h * sysdeps/unix/sysv/linux/generic/bits/stat.h * sysdeps/unix/sysv/linux/generic/bits/statfs.h * sysdeps/unix/sysv/linux/sys/acct.h * wctype/bits/wctype-wchar.h: Include bits/endian.h, not endian.h. * sysdeps/unix/sysv/linux/hppa/pthread.h: Don’t include endian.h. * sysdeps/mips/ieee754/ieee754.h: Use __LDBL_MANT_DIG__ in ifdefs, instead of LDBL_MANT_DIG. Only include float.h when __LDBL_MANT_DIG__ is not predefined, in which case define __LDBL_MANT_DIG__ to equal LDBL_MANT_DIG.
134 lines
3.6 KiB
C
134 lines
3.6 KiB
C
/* Copyright (C) 1992-2019 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 as 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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#ifndef _IEEE754_H
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#define _IEEE754_H 1
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#include <features.h>
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#include <bits/endian.h>
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__BEGIN_DECLS
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union ieee754_float
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{
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float f;
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/* This is the IEEE 754 single-precision format. */
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struct
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{
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#if __BYTE_ORDER == __BIG_ENDIAN
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unsigned int negative:1;
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unsigned int exponent:8;
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unsigned int mantissa:23;
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#endif /* Big endian. */
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#if __BYTE_ORDER == __LITTLE_ENDIAN
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unsigned int mantissa:23;
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unsigned int exponent:8;
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unsigned int negative:1;
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#endif /* Little endian. */
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} ieee;
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/* This format makes it easier to see if a NaN is a signalling NaN. */
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struct
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{
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#if __BYTE_ORDER == __BIG_ENDIAN
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unsigned int negative:1;
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unsigned int exponent:8;
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unsigned int quiet_nan:1;
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unsigned int mantissa:22;
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#endif /* Big endian. */
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#if __BYTE_ORDER == __LITTLE_ENDIAN
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unsigned int mantissa:22;
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unsigned int quiet_nan:1;
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unsigned int exponent:8;
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unsigned int negative:1;
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#endif /* Little endian. */
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} ieee_nan;
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};
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#define IEEE754_FLOAT_BIAS 0x7f /* Added to exponent. */
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union ieee754_double
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{
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double d;
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/* This is the IEEE 754 double-precision format. */
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struct
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{
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#if __BYTE_ORDER == __BIG_ENDIAN
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unsigned int negative:1;
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unsigned int exponent:11;
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/* Together these comprise the mantissa. */
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unsigned int mantissa0:20;
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unsigned int mantissa1:32;
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#endif /* Big endian. */
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#if __BYTE_ORDER == __LITTLE_ENDIAN
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/* Together these comprise the mantissa. */
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unsigned int mantissa1:32;
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unsigned int mantissa0:20;
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unsigned int exponent:11;
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unsigned int negative:1;
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#endif /* Little endian. */
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} ieee;
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/* This format makes it easier to see if a NaN is a signalling NaN. */
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struct
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{
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#if __BYTE_ORDER == __BIG_ENDIAN
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unsigned int negative:1;
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unsigned int exponent:11;
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unsigned int quiet_nan:1;
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/* Together these comprise the mantissa. */
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unsigned int mantissa0:19;
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unsigned int mantissa1:32;
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#else
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/* Together these comprise the mantissa. */
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unsigned int mantissa1:32;
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unsigned int mantissa0:19;
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unsigned int quiet_nan:1;
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unsigned int exponent:11;
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unsigned int negative:1;
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#endif
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} ieee_nan;
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};
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#define IEEE754_DOUBLE_BIAS 0x3ff /* Added to exponent. */
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/* IBM extended format for long double.
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Each long double is made up of two IEEE doubles. The value of the
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long double is the sum of the values of the two parts. The most
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significant part is required to be the value of the long double
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rounded to the nearest double, as specified by IEEE. For Inf
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values, the least significant part is required to be one of +0.0 or
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-0.0. No other requirements are made; so, for example, 1.0 may be
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represented as (1.0, +0.0) or (1.0, -0.0), and the low part of a
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NaN is don't-care. */
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union ibm_extended_long_double
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{
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long double ld;
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union ieee754_double d[2];
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};
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__END_DECLS
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#endif /* ieee754.h */
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