mirror of
https://github.com/jart/cosmopolitan.git
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61 lines
3 KiB
C
61 lines
3 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2023 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/calls/calls.h"
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#include "libc/calls/struct/itimerval.h"
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#include "libc/calls/struct/sigaction.h"
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#include "libc/calls/struct/timespec.h"
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#include "libc/calls/struct/timeval.h"
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#include "libc/fmt/itoa.h"
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#include "libc/sysv/consts/itimer.h"
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#include "libc/sysv/consts/sig.h"
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#define HZ 120
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struct timeval start;
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struct timeval expect;
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struct timeval interval = {0, 1e6 / HZ};
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void OnTick(int sig) {
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char ibuf[27];
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struct timeval now = timeval_real();
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switch (timeval_cmp(now, expect)) {
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case 0:
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tinyprint(1, "100% precise\n", NULL);
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break;
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case -1:
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FormatInt64Thousands(ibuf, timeval_tomicros(timeval_sub(expect, now)));
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tinyprint(1, ibuf, " µs early\n", NULL);
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break;
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case +1:
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FormatInt64Thousands(ibuf, timeval_tomicros(timeval_sub(now, expect)));
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tinyprint(1, ibuf, " µs late\n", NULL);
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break;
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default:
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__builtin_unreachable();
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}
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expect = timeval_add(expect, interval);
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}
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int main(int argc, char *argv[]) {
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start = timeval_real();
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expect = timeval_add(start, interval);
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signal(SIGALRM, OnTick);
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setitimer(ITIMER_REAL, &(struct itimerval){interval, interval}, 0);
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for (;;) pause();
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}
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