sysmacros.h 2.9 KB

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  1. /* Definitions of macros to access `dev_t' values.
  2. Copyright (C) 1996-2021 Free Software Foundation, Inc.
  3. This file is part of the GNU C Library.
  4. The GNU C Library is free software; you can redistribute it and/or
  5. modify it under the terms of the GNU Lesser General Public
  6. License as published by the Free Software Foundation; either
  7. version 2.1 of the License, or (at your option) any later version.
  8. The GNU C Library is distributed in the hope that it will be useful,
  9. but WITHOUT ANY WARRANTY; without even the implied warranty of
  10. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  11. Lesser General Public License for more details.
  12. You should have received a copy of the GNU Lesser General Public
  13. License along with the GNU C Library; if not, see
  14. <https://www.gnu.org/licenses/>. */
  15. #ifndef _BITS_SYSMACROS_H
  16. #define _BITS_SYSMACROS_H 1
  17. #ifndef _SYS_SYSMACROS_H
  18. # error "Never include <bits/sysmacros.h> directly; use <sys/sysmacros.h> instead."
  19. #endif
  20. /* dev_t in glibc is a 64-bit quantity, with 32-bit major and minor numbers.
  21. Our default encoding is MMMM Mmmm mmmM MMmm, where M is a hex digit of
  22. the major number and m is a hex digit of the minor number. This is
  23. downward compatible with legacy systems where dev_t is 16 bits wide,
  24. encoded as MMmm. It is also downward compatible with the Linux kernel,
  25. which (as of 2016) uses 32-bit dev_t, encoded as mmmM MMmm.
  26. Systems that use an incompatible encoding for dev_t should override this
  27. file in the appropriate sysdeps subdirectory. */
  28. #define __SYSMACROS_DECLARE_MAJOR(DECL_TEMPL) \
  29. DECL_TEMPL(unsigned int, major, (__dev_t __dev))
  30. #define __SYSMACROS_DEFINE_MAJOR(DECL_TEMPL) \
  31. __SYSMACROS_DECLARE_MAJOR (DECL_TEMPL) \
  32. { \
  33. unsigned int __major; \
  34. __major = ((__dev & (__dev_t) 0x00000000000fff00u) >> 8); \
  35. __major |= ((__dev & (__dev_t) 0xfffff00000000000u) >> 32); \
  36. return __major; \
  37. }
  38. #define __SYSMACROS_DECLARE_MINOR(DECL_TEMPL) \
  39. DECL_TEMPL(unsigned int, minor, (__dev_t __dev))
  40. #define __SYSMACROS_DEFINE_MINOR(DECL_TEMPL) \
  41. __SYSMACROS_DECLARE_MINOR (DECL_TEMPL) \
  42. { \
  43. unsigned int __minor; \
  44. __minor = ((__dev & (__dev_t) 0x00000000000000ffu) >> 0); \
  45. __minor |= ((__dev & (__dev_t) 0x00000ffffff00000u) >> 12); \
  46. return __minor; \
  47. }
  48. #define __SYSMACROS_DECLARE_MAKEDEV(DECL_TEMPL) \
  49. DECL_TEMPL(__dev_t, makedev, (unsigned int __major, unsigned int __minor))
  50. #define __SYSMACROS_DEFINE_MAKEDEV(DECL_TEMPL) \
  51. __SYSMACROS_DECLARE_MAKEDEV (DECL_TEMPL) \
  52. { \
  53. __dev_t __dev; \
  54. __dev = (((__dev_t) (__major & 0x00000fffu)) << 8); \
  55. __dev |= (((__dev_t) (__major & 0xfffff000u)) << 32); \
  56. __dev |= (((__dev_t) (__minor & 0x000000ffu)) << 0); \
  57. __dev |= (((__dev_t) (__minor & 0xffffff00u)) << 12); \
  58. return __dev; \
  59. }
  60. #endif /* bits/sysmacros.h */