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sysmacros.h 3.5 KB

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  1. //
  2. // Copyright 2026 Aarav Ravindra Kharade
  3. //
  4. // Licensed under the Apache License, Version 2.0 (the "License");
  5. // you may not use this file except in compliance with the License.
  6. // You may obtain a copy of the License at
  7. //
  8. // http://www.apache.org/licenses/LICENSE-2.0
  9. //
  10. // Unless required by applicable law or agreed to in writing, software
  11. // distributed under the License is distributed on an "AS IS" BASIS,
  12. // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13. // See the License for the specific language governing permissions and
  14. // limitations under the License.
  15. //
  16. /* Definitions of macros to access `dev_t' values.
  17. Copyright (C) 1996-2026 Free Software Foundation, Inc.
  18. This file is part of the GNU C Library.
  19. The GNU C Library is free software; you can redistribute it and/or
  20. modify it under the terms of the GNU Lesser General Public
  21. License as published by the Free Software Foundation; either
  22. version 2.1 of the License, or (at your option) any later version.
  23. The GNU C Library is distributed in the hope that it will be useful,
  24. but WITHOUT ANY WARRANTY; without even the implied warranty of
  25. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  26. Lesser General Public License for more details.
  27. You should have received a copy of the GNU Lesser General Public
  28. License along with the GNU C Library; if not, see
  29. <https://www.gnu.org/licenses/>. */
  30. #ifndef _BITS_SYSMACROS_H
  31. #define _BITS_SYSMACROS_H 1
  32. #ifndef _SYS_SYSMACROS_H
  33. # error "Never include <bits/sysmacros.h> directly; use <sys/sysmacros.h> instead."
  34. #endif
  35. /* dev_t in glibc is a 64-bit quantity, with 32-bit major and minor numbers.
  36. Our default encoding is MMMM Mmmm mmmM MMmm, where M is a hex digit of
  37. the major number and m is a hex digit of the minor number. This is
  38. downward compatible with legacy systems where dev_t is 16 bits wide,
  39. encoded as MMmm. It is also downward compatible with the Linux kernel,
  40. which (as of 2016) uses 32-bit dev_t, encoded as mmmM MMmm.
  41. Systems that use an incompatible encoding for dev_t should override this
  42. file in the appropriate sysdeps subdirectory. */
  43. #define __SYSMACROS_DECLARE_MAJOR(DECL_TEMPL) \
  44. DECL_TEMPL(unsigned int, major, (__dev_t __dev))
  45. #define __SYSMACROS_DEFINE_MAJOR(DECL_TEMPL) \
  46. __SYSMACROS_DECLARE_MAJOR (DECL_TEMPL) \
  47. { \
  48. unsigned int __major; \
  49. __major = ((__dev & (__dev_t) 0x00000000000fff00u) >> 8); \
  50. __major |= ((__dev & (__dev_t) 0xfffff00000000000u) >> 32); \
  51. return __major; \
  52. }
  53. #define __SYSMACROS_DECLARE_MINOR(DECL_TEMPL) \
  54. DECL_TEMPL(unsigned int, minor, (__dev_t __dev))
  55. #define __SYSMACROS_DEFINE_MINOR(DECL_TEMPL) \
  56. __SYSMACROS_DECLARE_MINOR (DECL_TEMPL) \
  57. { \
  58. unsigned int __minor; \
  59. __minor = ((__dev & (__dev_t) 0x00000000000000ffu) >> 0); \
  60. __minor |= ((__dev & (__dev_t) 0x00000ffffff00000u) >> 12); \
  61. return __minor; \
  62. }
  63. #define __SYSMACROS_DECLARE_MAKEDEV(DECL_TEMPL) \
  64. DECL_TEMPL(__dev_t, makedev, (unsigned int __major, unsigned int __minor))
  65. #define __SYSMACROS_DEFINE_MAKEDEV(DECL_TEMPL) \
  66. __SYSMACROS_DECLARE_MAKEDEV (DECL_TEMPL) \
  67. { \
  68. __dev_t __dev; \
  69. __dev = (((__dev_t) (__major & 0x00000fffu)) << 8); \
  70. __dev |= (((__dev_t) (__major & 0xfffff000u)) << 32); \
  71. __dev |= (((__dev_t) (__minor & 0x000000ffu)) << 0); \
  72. __dev |= (((__dev_t) (__minor & 0xffffff00u)) << 12); \
  73. return __dev; \
  74. }
  75. #endif /* bits/sysmacros.h */