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75 lines
2.9 KiB
C
75 lines
2.9 KiB
C
/* Definitions of macros to access `dev_t' values.
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Copyright (C) 1996-2017 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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<http://www.gnu.org/licenses/>. */
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#ifndef _BITS_SYSMACROS_H
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#define _BITS_SYSMACROS_H 1
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#ifndef _SYS_SYSMACROS_H
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# error "Never include <bits/sysmacros.h> directly; use <sys/sysmacros.h> instead."
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#endif
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/* dev_t in glibc is a 64-bit quantity, with 32-bit major and minor numbers.
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Our default encoding is MMMM Mmmm mmmM MMmm, where M is a hex digit of
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the major number and m is a hex digit of the minor number. This is
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downward compatible with legacy systems where dev_t is 16 bits wide,
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encoded as MMmm. It is also downward compatible with the Linux kernel,
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which (as of 2016) uses 32-bit dev_t, encoded as mmmM MMmm.
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Systems that use an incompatible encoding for dev_t should override this
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file in the appropriate sysdeps subdirectory. */
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#define __SYSMACROS_DECLARE_MAJOR(DECL_TEMPL) \
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DECL_TEMPL(unsigned int, major, (__dev_t __dev))
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#define __SYSMACROS_DEFINE_MAJOR(DECL_TEMPL) \
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__SYSMACROS_DECLARE_MAJOR (DECL_TEMPL) \
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{ \
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unsigned int __major; \
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__major = ((__dev & (__dev_t) 0x00000000000fff00u) >> 8); \
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__major |= ((__dev & (__dev_t) 0xfffff00000000000u) >> 32); \
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return __major; \
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}
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#define __SYSMACROS_DECLARE_MINOR(DECL_TEMPL) \
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DECL_TEMPL(unsigned int, minor, (__dev_t __dev))
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#define __SYSMACROS_DEFINE_MINOR(DECL_TEMPL) \
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__SYSMACROS_DECLARE_MINOR (DECL_TEMPL) \
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{ \
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unsigned int __minor; \
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__minor = ((__dev & (__dev_t) 0x00000000000000ffu) >> 0); \
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__minor |= ((__dev & (__dev_t) 0x00000ffffff00000u) >> 12); \
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return __minor; \
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}
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#define __SYSMACROS_DECLARE_MAKEDEV(DECL_TEMPL) \
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DECL_TEMPL(__dev_t, makedev, (unsigned int __major, unsigned int __minor))
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#define __SYSMACROS_DEFINE_MAKEDEV(DECL_TEMPL) \
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__SYSMACROS_DECLARE_MAKEDEV (DECL_TEMPL) \
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{ \
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__dev_t __dev; \
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__dev = (((__dev_t) (__major & 0x00000fffu)) << 8); \
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__dev |= (((__dev_t) (__major & 0xfffff000u)) << 32); \
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__dev |= (((__dev_t) (__minor & 0x000000ffu)) << 0); \
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__dev |= (((__dev_t) (__minor & 0xffffff00u)) << 12); \
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return __dev; \
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}
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#endif /* bits/sysmacros.h */
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