1/* Definitions of macros to access `dev_t' values.
 2   Copyright (C) 1996-2025 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 */