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Edit File: sysmacros.h
/* Definitions of macros to access `dev_t' values. Copyright (C) 1996-2021 Free Software Foundation, Inc. This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. The GNU C Library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with the GNU C Library; if not, see <https://www.gnu.org/licenses/>. */ #ifndef _BITS_SYSMACROS_H #define _BITS_SYSMACROS_H 1 #ifndef _SYS_SYSMACROS_H # error "Never include <bits/sysmacros.h> directly; use <sys/sysmacros.h> instead." #endif /* dev_t in glibc is a 64-bit quantity, with 32-bit major and minor numbers. Our default encoding is MMMM Mmmm mmmM MMmm, where M is a hex digit of the major number and m is a hex digit of the minor number. This is downward compatible with legacy systems where dev_t is 16 bits wide, encoded as MMmm. It is also downward compatible with the Linux kernel, which (as of 2016) uses 32-bit dev_t, encoded as mmmM MMmm. Systems that use an incompatible encoding for dev_t should override this file in the appropriate sysdeps subdirectory. */ #define __SYSMACROS_DECLARE_MAJOR(DECL_TEMPL) \ DECL_TEMPL(unsigned int, major, (__dev_t __dev)) #define __SYSMACROS_DEFINE_MAJOR(DECL_TEMPL) \ __SYSMACROS_DECLARE_MAJOR (DECL_TEMPL) \ { \ unsigned int __major; \ __major = ((__dev & (__dev_t) 0x00000000000fff00u) >> 8); \ __major |= ((__dev & (__dev_t) 0xfffff00000000000u) >> 32); \ return __major; \ } #define __SYSMACROS_DECLARE_MINOR(DECL_TEMPL) \ DECL_TEMPL(unsigned int, minor, (__dev_t __dev)) #define __SYSMACROS_DEFINE_MINOR(DECL_TEMPL) \ __SYSMACROS_DECLARE_MINOR (DECL_TEMPL) \ { \ unsigned int __minor; \ __minor = ((__dev & (__dev_t) 0x00000000000000ffu) >> 0); \ __minor |= ((__dev & (__dev_t) 0x00000ffffff00000u) >> 12); \ return __minor; \ } #define __SYSMACROS_DECLARE_MAKEDEV(DECL_TEMPL) \ DECL_TEMPL(__dev_t, makedev, (unsigned int __major, unsigned int __minor)) #define __SYSMACROS_DEFINE_MAKEDEV(DECL_TEMPL) \ __SYSMACROS_DECLARE_MAKEDEV (DECL_TEMPL) \ { \ __dev_t __dev; \ __dev = (((__dev_t) (__major & 0x00000fffu)) << 8); \ __dev |= (((__dev_t) (__major & 0xfffff000u)) << 32); \ __dev |= (((__dev_t) (__minor & 0x000000ffu)) << 0); \ __dev |= (((__dev_t) (__minor & 0xffffff00u)) << 12); \ return __dev; \ } #endif /* bits/sysmacros.h */