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Improve time/sleep accuracy on Windows

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It's now almost as good as Linux thanks to a Windows 8+ API.
This commit is contained in:
Justine Tunney 2023-11-18 01:57:44 -08:00
parent 72ac5f18d9
commit 8caf1b48a9
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GPG key ID: BE714B4575D6E328
9 changed files with 76 additions and 31 deletions
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65
libc/calls/clock_gettime-nt.c
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@ -18,26 +18,61 @@
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/struct/timespec.h"
#include "libc/calls/struct/timespec.internal.h"
#include "libc/dce.h"
#include "libc/errno.h"
#include "libc/fmt/wintime.internal.h"
#include "libc/nt/struct/filetime.h"
#include "libc/nt/synchronization.h"
#include "libc/sysv/consts/clock.h"
#define _CLOCK_REALTIME 0
#define _CLOCK_MONOTONIC 1
#define _CLOCK_REALTIME_COARSE 2
#define _CLOCK_BOOTTIME 3
static struct {
uint64_t base;
uint64_t freq;
} g_winclock;
textwindows int sys_clock_gettime_nt(int clock, struct timespec *ts) {
uint64_t t;
struct NtFileTime ft;
if (clock == CLOCK_REALTIME) {
if (!ts) return 0;
GetSystemTimeAsFileTime(&ft);
*ts = FileTimeToTimeSpec(ft);
return 0;
} else if (clock == CLOCK_MONOTONIC) {
if (!ts) return 0;
return sys_clock_gettime_mono(ts);
} else if (clock == CLOCK_BOOTTIME) {
if (ts) *ts = timespec_frommillis(GetTickCount64());
return 0;
} else {
return -EINVAL;
switch (clock) {
case _CLOCK_REALTIME:
if (ts) {
GetSystemTimePreciseAsFileTime(&ft);
*ts = FileTimeToTimeSpec(ft);
}
return 0;
case _CLOCK_REALTIME_COARSE:
if (ts) {
GetSystemTimeAsFileTime(&ft);
*ts = FileTimeToTimeSpec(ft);
}
return 0;
case _CLOCK_MONOTONIC:
if (ts) {
QueryPerformanceCounter(&t);
t = ((t - g_winclock.base) * 1000000000) / g_winclock.freq;
*ts = timespec_fromnanos(t);
}
return 0;
case _CLOCK_BOOTTIME:
if (ts) {
*ts = timespec_frommillis(GetTickCount64());
}
return 0;
default:
return -EINVAL;
}
}
static textstartup void winclock_init() {
if (IsWindows()) {
QueryPerformanceCounter(&g_winclock.base);
QueryPerformanceFrequency(&g_winclock.freq);
}
}
const void *const winclock_ctor[] initarray = {
winclock_init,
};