1 /* Definitions of macros to access `dev_t' values. 2 Copyright (C) 1996-2022 Free Software Foundation, Inc. 3 This file is part of the GNU C Library. 4 5 The GNU C Library is free software; you can redistribute it and/or 6 modify it under the terms of the GNU Lesser General Public 7 License as published by the Free Software Foundation; either 8 version 2.1 of the License, or (at your option) any later version. 9 10 The GNU C Library is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 13 Lesser General Public License for more details. 14 15 You should have received a copy of the GNU Lesser General Public 16 License along with the GNU C Library; if not, see 17 <https://www.gnu.org/licenses/>. */ 18 19 #ifndef _BITS_SYSMACROS_H 20 #define _BITS_SYSMACROS_H 1 21 22 #ifndef _SYS_SYSMACROS_H 23 # error "Never include <bits/sysmacros.h> directly; use <sys/sysmacros.h> instead." 24 #endif 25 26 /* dev_t in glibc is a 64-bit quantity, with 32-bit major and minor numbers. 27 Our default encoding is MMMM Mmmm mmmM MMmm, where M is a hex digit of 28 the major number and m is a hex digit of the minor number. This is 29 downward compatible with legacy systems where dev_t is 16 bits wide, 30 encoded as MMmm. It is also downward compatible with the Linux kernel, 31 which (as of 2016) uses 32-bit dev_t, encoded as mmmM MMmm. 32 33 Systems that use an incompatible encoding for dev_t should override this 34 file in the appropriate sysdeps subdirectory. */ 35 36 #define __SYSMACROS_DECLARE_MAJOR(DECL_TEMPL) \ 37 DECL_TEMPL(unsigned int, major, (__dev_t __dev)) 38 39 #define __SYSMACROS_DEFINE_MAJOR(DECL_TEMPL) \ 40 __SYSMACROS_DECLARE_MAJOR (DECL_TEMPL) \ 41 { \ 42 unsigned int __major; \ 43 __major = ((__dev & (__dev_t) 0x00000000000fff00u) >> 8); \ 44 __major |= ((__dev & (__dev_t) 0xfffff00000000000u) >> 32); \ 45 return __major; \ 46 } 47 48 #define __SYSMACROS_DECLARE_MINOR(DECL_TEMPL) \ 49 DECL_TEMPL(unsigned int, minor, (__dev_t __dev)) 50 51 #define __SYSMACROS_DEFINE_MINOR(DECL_TEMPL) \ 52 __SYSMACROS_DECLARE_MINOR (DECL_TEMPL) \ 53 { \ 54 unsigned int __minor; \ 55 __minor = ((__dev & (__dev_t) 0x00000000000000ffu) >> 0); \ 56 __minor |= ((__dev & (__dev_t) 0x00000ffffff00000u) >> 12); \ 57 return __minor; \ 58 } 59 60 #define __SYSMACROS_DECLARE_MAKEDEV(DECL_TEMPL) \ 61 DECL_TEMPL(__dev_t, makedev, (unsigned int __major, unsigned int __minor)) 62 63 #define __SYSMACROS_DEFINE_MAKEDEV(DECL_TEMPL) \ 64 __SYSMACROS_DECLARE_MAKEDEV (DECL_TEMPL) \ 65 { \ 66 __dev_t __dev; \ 67 __dev = (((__dev_t) (__major & 0x00000fffu)) << 8); \ 68 __dev |= (((__dev_t) (__major & 0xfffff000u)) << 32); \ 69 __dev |= (((__dev_t) (__minor & 0x000000ffu)) << 0); \ 70 __dev |= (((__dev_t) (__minor & 0xffffff00u)) << 12); \ 71 return __dev; \ 72 } 73 74 #endif /* bits/sysmacros.h */ 75