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posix: clock: nanosecond resolution

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directly convert ticks to nsecs in the clock_* posix
functions which will provide the best resolution the
system allows

Signed-off-by: Nicholas Lowell <nlowell@lexmark.com>
This commit is contained in:
Nicholas Lowell 2020-10-21 11:03:19 -04:00 • committed by Anas Nashif
commit ce480e8577
1 changed files with 6 additions and 7 deletions
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13
lib/posix/clock.c
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@ -25,7 +25,7 @@ static struct timespec rt_clock_base;
*/ */
int z_impl_clock_gettime(clockid_t clock_id, struct timespec *ts) int z_impl_clock_gettime(clockid_t clock_id, struct timespec *ts)
{ {
uint64_t elapsed_msecs; uint64_t elapsed_nsecs;
struct timespec base; struct timespec base;
switch (clock_id) { switch (clock_id) {
@ -43,10 +43,9 @@ int z_impl_clock_gettime(clockid_t clock_id, struct timespec *ts)
return -1; return -1;
} }
elapsed_msecs = k_uptime_get(); elapsed_nsecs = k_ticks_to_ns_floor64(k_uptime_ticks());
ts->tv_sec = (int32_t) (elapsed_msecs / MSEC_PER_SEC); ts->tv_sec = (int32_t) (elapsed_nsecs / NSEC_PER_SEC);
ts->tv_nsec = (int32_t) ((elapsed_msecs % MSEC_PER_SEC) * ts->tv_nsec = (int32_t) (elapsed_nsecs % NSEC_PER_SEC);
USEC_PER_MSEC * NSEC_PER_USEC);
ts->tv_sec += base.tv_sec; ts->tv_sec += base.tv_sec;
ts->tv_nsec += base.tv_nsec; ts->tv_nsec += base.tv_nsec;
@ -84,9 +83,9 @@ int clock_settime(clockid_t clock_id, const struct timespec *tp)
return -1; return -1;
} }
uint64_t elapsed_msecs = k_uptime_get(); uint64_t elapsed_nsecs = k_ticks_to_ns_floor64(k_uptime_ticks());
int64_t delta = (int64_t)NSEC_PER_SEC * tp->tv_sec + tp->tv_nsec int64_t delta = (int64_t)NSEC_PER_SEC * tp->tv_sec + tp->tv_nsec
- elapsed_msecs * USEC_PER_MSEC * NSEC_PER_USEC; - elapsed_nsecs;
base.tv_sec = delta / NSEC_PER_SEC; base.tv_sec = delta / NSEC_PER_SEC;
base.tv_nsec = delta % NSEC_PER_SEC; base.tv_nsec = delta % NSEC_PER_SEC;