zephyr/lib/posix/clock.c

109 lines
2.2 KiB
C

/*
* Copyright (c) 2018 Intel Corporation
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <kernel.h>
#include <errno.h>
#include <posix/time.h>
#include <posix/sys/time.h>
/*
* `k_uptime_get` returns a timestamp based on an always increasing
* value from the system start. To support the `CLOCK_REALTIME`
* clock, this `rt_clock_base` records the time that the system was
* started. This can either be set via 'clock_settime', or could be
* set from a real time clock, if such hardware is present.
*/
static struct timespec rt_clock_base;
/**
* @brief Get clock time specified by clock_id.
*
* See IEEE 1003.1
*/
int clock_gettime(clockid_t clock_id, struct timespec *ts)
{
u64_t elapsed_msecs;
struct timespec base;
switch (clock_id) {
case CLOCK_MONOTONIC:
base.tv_sec = 0;
base.tv_nsec = 0;
break;
case CLOCK_REALTIME:
base = rt_clock_base;
break;
default:
errno = EINVAL;
return -1;
}
elapsed_msecs = k_uptime_get();
ts->tv_sec = (s32_t) (elapsed_msecs / MSEC_PER_SEC);
ts->tv_nsec = (s32_t) ((elapsed_msecs % MSEC_PER_SEC) *
USEC_PER_MSEC * NSEC_PER_USEC);
ts->tv_sec += base.tv_sec;
ts->tv_nsec += base.tv_nsec;
if (ts->tv_nsec > NSEC_PER_SEC) {
ts->tv_sec++;
ts->tv_nsec -= NSEC_PER_SEC;
}
return 0;
}
/**
* @brief Set the time of the specified clock.
*
* See IEEE 1003.1.
*
* Note that only the `CLOCK_REALTIME` clock can be set using this
* call.
*/
int clock_settime(clockid_t clock_id, const struct timespec *tp)
{
struct timespec base;
if (clock_id != CLOCK_REALTIME) {
errno = EINVAL;
return -1;
}
u64_t elapsed_msecs = k_uptime_get();
s64_t delta = (s64_t)NSEC_PER_SEC * tp->tv_sec + tp->tv_nsec
- elapsed_msecs * USEC_PER_MSEC * NSEC_PER_USEC;
base.tv_sec = delta / NSEC_PER_SEC;
base.tv_nsec = delta % NSEC_PER_SEC;
rt_clock_base = base;
return 0;
}
/**
* @brief Get current real time.
*
* See IEEE 1003.1
*/
int gettimeofday(struct timeval *tv, const void *tz)
{
struct timespec ts;
int res;
/* As per POSIX, "if tzp is not a null pointer, the behavior
* is unspecified." "tzp" is the "tz" parameter above. */
ARG_UNUSED(tv);
res = clock_gettime(CLOCK_REALTIME, &ts);
tv->tv_sec = ts.tv_sec;
tv->tv_usec = ts.tv_nsec / NSEC_PER_USEC;
return res;
}