diff options
Diffstat (limited to 'sys/sys/time.h')
| -rw-r--r-- | sys/sys/time.h | 62 |
1 files changed, 38 insertions, 24 deletions
diff --git a/sys/sys/time.h b/sys/sys/time.h index b3ec8b726217..e06ea2647189 100644 --- a/sys/sys/time.h +++ b/sys/sys/time.h @@ -31,7 +31,7 @@ * SUCH DAMAGE. * * @(#)time.h 8.5 (Berkeley) 5/4/95 - * $Id: time.h,v 1.19 1998/02/25 02:14:14 bde Exp $ + * $Id: time.h,v 1.20 1998/03/04 10:26:44 dufault Exp $ */ #ifndef _SYS_TIME_H_ @@ -78,20 +78,22 @@ struct timezone { #define DST_CAN 6 /* Canada */ /* - * Structure used to interface to the machine dependent hardware - * support for timekeeping. + * Structure used to interface to the machine dependent hardware support + * for timekeeping. * - * A timecounter is a binary counter which has two simple properties: - * * it runs at a fixed frequency. - * * must not roll over in less than (1+epsilon)/HZ + * A timecounter is a (hard or soft) binary counter which has two properties: + * * it runs at a fixed, known frequency. + * * it must not roll over in less than (1 + delta)/HZ seconds. "delta" + * is expected to be less than 20 msec, but no hard data has been + * collected on this. 16 bit at 5 MHz (31 msec) is known to work. * - * get_timecount reads the counter. + * get_timedelta() returns difference between the counter now and offset_count. * - * get_timedelta returns difference between the counter now and offset_count + * get_timecount() reads the counter. * - * counter_mask removes unimplemented bits from the count value + * counter_mask removes unimplemented bits from the count value. * - * frequency should be obvious + * frequency is the counter frequency in hz. * * name is a short mnemonic name for this counter. * @@ -100,34 +102,44 @@ struct timezone { * adjustment [PPM << 16] which means that the smallest unit of correction * you can apply amounts to 481.5 usec/year. * - * scale_micro [2^32 * usec/tick] - * - * scale_nano_i [ns/tick] - * - * scale_nano_f [(ns/2^32)/tick] + * scale_micro [2^32 * usec/tick]. + * scale_nano_i [ns/tick]. + * scale_nano_f [(ns/2^32)/tick]. * * offset_count is the contents of the counter which corresponds to the - * rest of the offset_* values + * rest of the offset_* values. * - * offset_sec [s] - * offset_micro [usec] + * offset_sec [s]. + * offset_micro [usec]. * offset_nano [ns/2^32] is misnamed, the real unit is .23283064365... * attoseconds (10E-18) and before you ask: yes, they are in fact * called attoseconds, it comes from "atten" for 18 in Danish/Swedish. + * + * Each timecounter must supply an array of three timecounters, this is needed + * to guarantee atomicity in the code. Index zero is used to transport + * modifications, for instance done with sysctl, into the timecounter being + * used in a safe way. Such changes may be adopted with a delay of up to 1/HZ, + * index one & two are used alternately for the actual timekeeping. + * + * `other' points to the opposite "work" timecounter, ie, in index one it + * points to index two and vice versa + * + * `tweak' points to index zero. + * */ struct timecounter; -typedef u_int timecounter_get_t __P((struct timecounter *)); +typedef unsigned timecounter_get_t __P((struct timecounter *)); typedef u_int64_t timecounter_delta_t __P((void)); struct timecounter { - /* These fields must be initialized by the driver */ + /* These fields must be initialized by the driver. */ timecounter_get_t *get_timedelta; timecounter_delta_t *get_timecount; u_int64_t counter_mask; u_int32_t frequency; char *name; - /* These fields will be managed by the generic code */ + /* These fields will be managed by the generic code. */ int cost; int32_t adjustment; u_int32_t scale_micro; @@ -211,14 +223,16 @@ struct clockinfo { extern struct timecounter *timecounter; void forward_timecounter __P((void)); -void gettime __P((struct timeval *tv)); -void init_timecounter __P((struct timecounter *)); +void getmicrotime __P((struct timeval *tv)); +void getnanotime __P((struct timespec *tv)); +#define gettime(xxx) getmicrotime(xxx) /* XXX be compatible */ +void init_timecounter __P((struct timecounter *tc)); int itimerfix __P((struct timeval *tv)); int itimerdecr __P((struct itimerval *itp, int usec)); void microtime __P((struct timeval *tv)); void nanotime __P((struct timespec *ts)); void second_overflow __P((u_int32_t *psec)); -void set_timecounter __P((struct timespec *)); +void set_timecounter __P((struct timespec *ts)); void timevaladd __P((struct timeval *, struct timeval *)); void timevalsub __P((struct timeval *, struct timeval *)); #else /* !KERNEL */ |