cosmopolitan/libc/time/dsleep.c

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 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/calls/struct/timespec.h"
#include "libc/math.h"
#include "libc/nexgen32e/nexgen32e.h"
#include "libc/time/time.h"

/**
 * Sleeps w/ higher precision.
 */
long double dsleep(long double secs) {
  struct timespec dur, rem;
  dur.tv_sec = secs;
  dur.tv_nsec = secs * 1e9;
  dur.tv_nsec = rem1000000000int64(dur.tv_nsec);
  if (secs > 1e-6) {
    nanosleep(&dur, &rem);
    secs = rem.tv_nsec;
    secs *= 1 / 1e9;
    secs += rem.tv_sec;
    return secs;
  } else {
    return 0;
  }
}