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authorAlistair Francis <alistair.francis@wdc.com>2019-09-20 14:23:51 -0700
committerAlistair Francis <alistair.francis@wdc.com>2019-10-01 14:54:46 -0700
commitaa706e13f4bfdf32a27c498902edf4f6006e433e (patch)
treeb353543833401b629c2e085c3e7b0ac61d0e62d7 /string/endian.h
parent8e42fc6811ba94a01e194d46572c3cf803b3aae0 (diff)
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Split up endian.h to minimize exposure of BYTE_ORDER.
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.
Diffstat (limited to 'string/endian.h')
-rw-r--r--string/endian.h39
1 files changed, 6 insertions, 33 deletions
diff --git a/string/endian.h b/string/endian.h
index 17e4e89..0eb534e 100644
--- a/string/endian.h
+++ b/string/endian.h
@@ -20,42 +20,15 @@
#include <features.h>
-/* Definitions for byte order, according to significance of bytes,
- from low addresses to high addresses. The value is what you get by
- putting '4' in the most significant byte, '3' in the second most
- significant byte, '2' in the second least significant byte, and '1'
- in the least significant byte, and then writing down one digit for
- each byte, starting with the byte at the lowest address at the left,
- and proceeding to the byte with the highest address at the right. */
-
-#define __LITTLE_ENDIAN 1234
-#define __BIG_ENDIAN 4321
-#define __PDP_ENDIAN 3412
-
-/* This file defines `__BYTE_ORDER' for the particular machine. */
+/* Get the definitions of __*_ENDIAN, __BYTE_ORDER, and __FLOAT_WORD_ORDER. */
#include <bits/endian.h>
-/* Some machines may need to use a different endianness for floating point
- values. */
-#ifndef __FLOAT_WORD_ORDER
-# define __FLOAT_WORD_ORDER __BYTE_ORDER
-#endif
-
-#ifdef __USE_MISC
-# define LITTLE_ENDIAN __LITTLE_ENDIAN
-# define BIG_ENDIAN __BIG_ENDIAN
-# define PDP_ENDIAN __PDP_ENDIAN
-# define BYTE_ORDER __BYTE_ORDER
-#endif
-
-#if __BYTE_ORDER == __LITTLE_ENDIAN
-# define __LONG_LONG_PAIR(HI, LO) LO, HI
-#elif __BYTE_ORDER == __BIG_ENDIAN
-# define __LONG_LONG_PAIR(HI, LO) HI, LO
-#endif
-
+#define LITTLE_ENDIAN __LITTLE_ENDIAN
+#define BIG_ENDIAN __BIG_ENDIAN
+#define PDP_ENDIAN __PDP_ENDIAN
+#define BYTE_ORDER __BYTE_ORDER
-#if defined __USE_MISC && !defined __ASSEMBLER__
+#ifndef __ASSEMBLER__
/* Conversion interfaces. */
# include <bits/byteswap.h>
# include <bits/uintn-identity.h>