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Linux/include/linux/kdev_t.h

  1 #ifndef _LINUX_KDEV_T_H
  2 #define _LINUX_KDEV_T_H
  3 
  4 #include <uapi/linux/kdev_t.h>
  5 
  6 #define MINORBITS       20
  7 #define MINORMASK       ((1U << MINORBITS) - 1)
  8 
  9 #define MAJOR(dev)      ((unsigned int) ((dev) >> MINORBITS))
 10 #define MINOR(dev)      ((unsigned int) ((dev) & MINORMASK))
 11 #define MKDEV(ma,mi)    (((ma) << MINORBITS) | (mi))
 12 
 13 #define print_dev_t(buffer, dev)                                        \
 14         sprintf((buffer), "%u:%u\n", MAJOR(dev), MINOR(dev))
 15 
 16 #define format_dev_t(buffer, dev)                                       \
 17         ({                                                              \
 18                 sprintf(buffer, "%u:%u", MAJOR(dev), MINOR(dev));       \
 19                 buffer;                                                 \
 20         })
 21 
 22 /* acceptable for old filesystems */
 23 static inline int old_valid_dev(dev_t dev)
 24 {
 25         return MAJOR(dev) < 256 && MINOR(dev) < 256;
 26 }
 27 
 28 static inline u16 old_encode_dev(dev_t dev)
 29 {
 30         return (MAJOR(dev) << 8) | MINOR(dev);
 31 }
 32 
 33 static inline dev_t old_decode_dev(u16 val)
 34 {
 35         return MKDEV((val >> 8) & 255, val & 255);
 36 }
 37 
 38 static inline int new_valid_dev(dev_t dev)
 39 {
 40         return 1;
 41 }
 42 
 43 static inline u32 new_encode_dev(dev_t dev)
 44 {
 45         unsigned major = MAJOR(dev);
 46         unsigned minor = MINOR(dev);
 47         return (minor & 0xff) | (major << 8) | ((minor & ~0xff) << 12);
 48 }
 49 
 50 static inline dev_t new_decode_dev(u32 dev)
 51 {
 52         unsigned major = (dev & 0xfff00) >> 8;
 53         unsigned minor = (dev & 0xff) | ((dev >> 12) & 0xfff00);
 54         return MKDEV(major, minor);
 55 }
 56 
 57 static inline int huge_valid_dev(dev_t dev)
 58 {
 59         return 1;
 60 }
 61 
 62 static inline u64 huge_encode_dev(dev_t dev)
 63 {
 64         return new_encode_dev(dev);
 65 }
 66 
 67 static inline dev_t huge_decode_dev(u64 dev)
 68 {
 69         return new_decode_dev(dev);
 70 }
 71 
 72 static inline int sysv_valid_dev(dev_t dev)
 73 {
 74         return MAJOR(dev) < (1<<14) && MINOR(dev) < (1<<18);
 75 }
 76 
 77 static inline u32 sysv_encode_dev(dev_t dev)
 78 {
 79         return MINOR(dev) | (MAJOR(dev) << 18);
 80 }
 81 
 82 static inline unsigned sysv_major(u32 dev)
 83 {
 84         return (dev >> 18) & 0x3fff;
 85 }
 86 
 87 static inline unsigned sysv_minor(u32 dev)
 88 {
 89         return dev & 0x3ffff;
 90 }
 91 
 92 #endif
 93 

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