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https://github.com/jart/cosmopolitan.git
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12d9e1e128
It now works most excellently across all supported operating sytsems (earlier it didn't work on NT and XNU). Demo code is available in examples/clock.c and this change also adds some of the newer ANSI C time functions like timespec_get(), plus timespec_getres() which hasn't even come out yet as it's C23
104 lines
4.4 KiB
C
104 lines
4.4 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=8 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 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/assert.h"
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#include "libc/calls/asan.internal.h"
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#include "libc/calls/clock_gettime.internal.h"
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#include "libc/calls/state.internal.h"
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#include "libc/calls/strace.internal.h"
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#include "libc/calls/struct/timespec.internal.h"
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#include "libc/calls/struct/timeval.h"
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#include "libc/calls/syscall_support-sysv.internal.h"
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#include "libc/dce.h"
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#include "libc/fmt/conv.h"
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#include "libc/intrin/asan.internal.h"
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#include "libc/intrin/asmflag.h"
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#include "libc/intrin/bits.h"
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#include "libc/intrin/describeflags.internal.h"
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#include "libc/mem/alloca.h"
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#include "libc/nt/synchronization.h"
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#include "libc/sysv/errfuns.h"
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/**
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* Returns nanosecond time.
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*
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* This is a high-precision timer that supports multiple definitions of
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* time. Among the more popular is CLOCK_MONOTONIC. This function has a
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* zero syscall implementation of that on modern x86.
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*
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* nowl l: 45𝑐 15𝑛𝑠
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* rdtsc l: 13𝑐 4𝑛𝑠
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* gettimeofday l: 44𝑐 14𝑛𝑠
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* clock_gettime l: 40𝑐 13𝑛𝑠
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* __clock_gettime l: 35𝑐 11𝑛𝑠
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* sys_clock_gettime l: 220𝑐 71𝑛𝑠
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*
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* @param clock can be CLOCK_REALTIME, CLOCK_MONOTONIC, etc.
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* @param ts is where the result is stored
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* @return 0 on success, or -1 w/ errno
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* @error EINVAL if clock isn't supported on this system
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* @see strftime(), gettimeofday()
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* @asyncsignalsafe
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*/
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int clock_gettime(int clock, struct timespec *ts) {
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int rc;
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if (clock == 127) {
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rc = einval(); // 127 is used by consts.sh to mean unsupported
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} else if (!ts || (IsAsan() && !__asan_is_valid_timespec(ts))) {
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rc = efault();
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} else {
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rc = __clock_gettime(clock, ts);
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}
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#if SYSDEBUG
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if (!__time_critical) {
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STRACE("clock_gettime(%s, [%s]) → %d% m", DescribeClockName(clock),
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DescribeTimespec(rc, ts), rc);
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}
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#endif
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return rc;
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}
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/**
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* Returns pointer to fastest clock_gettime().
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*/
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clock_gettime_f *__clock_gettime_get(bool *opt_out_isfast) {
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bool isfast;
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clock_gettime_f *res;
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if (IsLinux() && (res = __vdsosym("LINUX_2.6", "__vdso_clock_gettime"))) {
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isfast = true;
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} else if (IsXnu()) {
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isfast = false;
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res = sys_clock_gettime_xnu;
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} else if (IsWindows()) {
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isfast = true;
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res = sys_clock_gettime_nt;
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} else {
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isfast = false;
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res = sys_clock_gettime;
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}
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if (opt_out_isfast) {
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*opt_out_isfast = isfast;
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}
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return res;
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}
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hidden int __clock_gettime_init(int clockid, struct timespec *ts) {
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clock_gettime_f *gettime;
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__clock_gettime = gettime = __clock_gettime_get(0);
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return gettime(clockid, ts);
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}
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