1  /* Definitions of macros to access `dev_t' values.
       2     Copyright (C) 1996-2023 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 */