cosmopolitan/libc/calls/clock_gettime.c

84 lines
3.9 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=8 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ This program is free software; you can redistribute it and/or modify │
│ it under the terms of the GNU General Public License as published by │
│ the Free Software Foundation; version 2 of the License. │
│ │
│ This program is distributed in the hope that it will be useful, but │
│ WITHOUT ANY WARRANTY; without even the implied warranty of │
│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
│ General Public License for more details. │
│ │
│ You should have received a copy of the GNU General Public License │
│ along with this program; if not, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/bits/bits.h"
#include "libc/bits/safemacros.h"
#include "libc/calls/calls.h"
#include "libc/calls/internal.h"
#include "libc/calls/struct/timespec.h"
#include "libc/calls/struct/timeval.h"
#include "libc/conv/conv.h"
#include "libc/dce.h"
#include "libc/mach.h"
#include "libc/nt/struct/filetime.h"
#include "libc/nt/struct/systemtime.h"
#include "libc/nt/synchronization.h"
#include "libc/sysv/consts/clock.h"
#include "libc/sysv/consts/fileno.h"
#include "libc/sysv/errfuns.h"
#include "libc/time/time.h"
/**
* Returns nanosecond time.
*
* This is a high-precision timer that supports multiple definitions of
* time. Among the more popular is CLOCK_MONOTONIC. This function has a
* zero syscall implementation of that on modern x86.
*
* @param clockid can be CLOCK_REALTIME, CLOCK_MONOTONIC, etc. noting
* that on Linux CLOCK_MONOTONIC is redefined to use the monotonic
* clock that's actually monotonic lool
* @param out_ts is where the nanoseconds are stored if non-NULL
* @return 0 on success or -1 w/ errno on error
* @error ENOSYS if clockid isn't available; in which case this function
* guarantees an ordinary timestamp is still stored to out_ts; and
* errno isn't restored to its original value, to detect prec. loss
* @see strftime(), gettimeofday()
* @asyncsignalsafe
*/
int clock_gettime(int clockid, struct timespec *out_ts) {
/* TODO(jart): Just ignore O/S for MONOTONIC and measure RDTSC on start */
if (!IsWindows()) {
if (!IsXnu()) {
if (out_ts) {
out_ts->tv_sec = 0;
out_ts->tv_nsec = 0;
}
return clock_gettime$sysv(clockid, out_ts);
} else {
int rc;
static_assert(sizeof(struct timeval) == sizeof(struct timespec));
if (out_ts) {
out_ts->tv_sec = 0;
out_ts->tv_nsec = 0;
}
rc = gettimeofday$sysv((struct timeval *)out_ts, NULL);
if (out_ts) {
out_ts->tv_nsec *= 1000;
}
return rc;
}
} else {
struct NtFileTime ft;
GetSystemTimeAsFileTime(&ft);
*out_ts = FileTimeToTimeSpec(ft);
return 0;
}
}