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The C and C++ Include Header Files

cat -n /usr/include/x86_64-linux-gnu/bits/sysmacros.h

     1	/* Definitions of macros to access `dev_t' values.
     2	   Copyright (C) 1996-2026 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 */