include/linux/time.h

   1 #ifndef _LINUX_TIME_H
   2 #define _LINUX_TIME_H
   3
   4 #include <asm/param.h>
   5 #include <linux/types.h>
   6
   7 #ifndef _STRUCT_TIMESPEC
   8 #define _STRUCT_TIMESPEC
   9 struct timespec {
  10         time_t  tv_sec;         /* seconds */
  11         long    tv_nsec;        /* nanoseconds */
  12 };
  13 #endif /* _STRUCT_TIMESPEC */
  14
  15 #ifdef __KERNEL__
  16
  17 /*
  18  * Change timeval to jiffies, trying to avoid the
  19  * most obvious overflows..
  20  *
  21  * And some not so obvious.
  22  *
  23  * Note that we don't want to return MAX_LONG, because
  24  * for various timeout reasons we often end up having
  25  * to wait "jiffies+1" in order to guarantee that we wait
  26  * at _least_ "jiffies" - so "jiffies+1" had better still
  27  * be positive.
  28  */
  29 #define MAX_JIFFY_OFFSET ((~0UL >> 1)-1)
  30
  31 static __inline__ unsigned long
  32 timespec_to_jiffies(struct timespec *value)
  33 {
  34         unsigned long sec = value->tv_sec;
  35         long nsec = value->tv_nsec;
  36
  37         if (sec >= (MAX_JIFFY_OFFSET / HZ))
  38                 return MAX_JIFFY_OFFSET;
  39         nsec += 1000000000L / HZ - 1;
  40         nsec /= 1000000000L / HZ;
  41         return HZ * sec + nsec;
  42 }
  43
  44 static __inline__ void
  45 jiffies_to_timespec(unsigned long jiffies, struct timespec *value)
  46 {
  47         value->tv_nsec = (jiffies % HZ) * (1000000000L / HZ);
  48         value->tv_sec = jiffies / HZ;
  49 }
  50
  51
  52 /* Converts Gregorian date to seconds since 1970-01-01 00:00:00.
  53  * Assumes input in normal date format, i.e. 1980-12-31 23:59:59
  54  * => year=1980, mon=12, day=31, hour=23, min=59, sec=59.
  55  *
  56  * [For the Julian calendar (which was used in Russia before 1917,
  57  * Britain & colonies before 1752, anywhere else before 1582,
  58  * and is still in use by some communities) leave out the
  59  * -year/100+year/400 terms, and add 10.]
  60  *
  61  * This algorithm was first published by Gauss (I think).
  62  *
  63  * WARNING: this function will overflow on 2106-02-07 06:28:16 on
  64  * machines were long is 32-bit! (However, as time_t is signed, we
  65  * will already get problems at other places on 2038-01-19 03:14:08)
  66  */
  67 static inline unsigned long
  68 mktime (unsigned int year, unsigned int mon,
  69         unsigned int day, unsigned int hour,
  70         unsigned int min, unsigned int sec)
  71 {
  72         if (0 >= (int) (mon -= 2)) {    /* 1..12 -> 11,12,1..10 */
  73                 mon += 12;              /* Puts Feb last since it has leap day */
  74                 year -= 1;
  75         }
  76
  77         return (((
  78                 (unsigned long) (year/4 - year/100 + year/400 + 367*mon/12 + day) +
  79                         year*365 - 719499
  80             )*24 + hour /* now have hours */
  81           )*60 + min /* now have minutes */
  82         )*60 + sec; /* finally seconds */
  83 }
  84
  85 #endif /* __KERNEL__ */
  86
  87
  88 struct timeval {
  89         time_t          tv_sec;         /* seconds */
  90         suseconds_t     tv_usec;        /* microseconds */
  91 };
  92
  93 struct timezone {
  94         int     tz_minuteswest; /* minutes west of Greenwich */
  95         int     tz_dsttime;     /* type of dst correction */
  96 };
  97
  98 #define NFDBITS                 __NFDBITS
  99
 100 #ifdef __KERNEL__
 101 extern void do_gettimeofday(struct timeval *tv);
 102 extern void do_settimeofday(struct timeval *tv);
 103 extern void get_fast_time(struct timeval *tv);
 104 extern void (*do_get_fast_time)(struct timeval *);
 105 #endif
 106
 107 #define FD_SETSIZE              __FD_SETSIZE
 108 #define FD_SET(fd,fdsetp)       __FD_SET(fd,fdsetp)
 109 #define FD_CLR(fd,fdsetp)       __FD_CLR(fd,fdsetp)
 110 #define FD_ISSET(fd,fdsetp)     __FD_ISSET(fd,fdsetp)
 111 #define FD_ZERO(fdsetp)         __FD_ZERO(fdsetp)
 112
 113 /*
 114  * Names of the interval timers, and structure
 115  * defining a timer setting.
 116  */
 117 #define ITIMER_REAL     0
 118 #define ITIMER_VIRTUAL  1
 119 #define ITIMER_PROF     2
 120
 121 struct  itimerspec {
 122         struct  timespec it_interval;    /* timer period */
 123         struct  timespec it_value;       /* timer expiration */
 124 };
 125
 126 struct  itimerval {
 127         struct  timeval it_interval;    /* timer interval */
 128         struct  timeval it_value;       /* current value */
 129 };
 130
 131 #endif