homework-jianmu/deps/MsvcLibX/src/clock_gettime.c

90 lines
2.8 KiB
C

/*****************************************************************************\
* *
* Filename: clock_gettime.c *
* *
* Description: WIN32 port of standard C library's clock_gettime(). *
* *
* Notes: *
* *
* History: *
* 2014-06-04 JFL Created this file. *
* *
* Copyright 2016 Hewlett Packard Enterprise Development LP *
* Licensed under the Apache 2.0 license - www.apache.org/licenses/LICENSE-2.0 *
\*****************************************************************************/
#include "msvclibx.h"
#include <time.h>
#include <errno.h>
#ifdef _MSDOS
/* Check for the definition of _STRUCT_TIMESPEC before using clock_gettime().
If it's not defined, use time() instead, which is supported by all OSs. */
#endif /* defined(_MSDOS) */
#ifdef _WIN32
#define WIN32_LEAN_AND_MEAN /* Avoid lots of unnecessary inclusions */
#include <windows.h>
#include "msvcTime.h"
#include "sys/msvcStat.h" /* For MsvcLibX's Filetime2Timespec */
#define MS_PER_SEC 1000ULL // MS = milliseconds
#define US_PER_MS 1000ULL // US = microseconds
#define HNS_PER_US 10ULL // HNS = hundred-nanoseconds (e.g., 1 hns = 100 ns)
#define NS_PER_US 1000ULL
#define HNS_PER_SEC (MS_PER_SEC * US_PER_MS * HNS_PER_US)
#define NS_PER_HNS (100ULL) // NS = nanoseconds
#define NS_PER_SEC (MS_PER_SEC * US_PER_MS * NS_PER_US)
int clock_gettime_monotonic(struct timespec *tv) {
static LARGE_INTEGER ticksPerSec;
LARGE_INTEGER ticks;
double seconds;
if (!ticksPerSec.QuadPart) {
QueryPerformanceFrequency(&ticksPerSec);
if (!ticksPerSec.QuadPart) {
errno = ENOTSUP;
return -1;
}
}
QueryPerformanceCounter(&ticks);
seconds = (double) ticks.QuadPart / (double) ticksPerSec.QuadPart;
tv->tv_sec = (time_t)seconds;
tv->tv_nsec = (long)((ULONGLONG)(seconds * NS_PER_SEC) % NS_PER_SEC);
return 0;
}
int clock_gettime_realtime(struct timespec *pTS) {
FILETIME ft;
GetSystemTimeAsFileTime(&ft);
Filetime2Timespec(&ft, pTS);
return 0;
}
int clock_gettime(clockid_t clock_id, struct timespec *pTS) {
if (clock_id == CLOCK_MONOTONIC) {
return clock_gettime_monotonic(pTS);
} else if (clock_id == CLOCK_REALTIME) {
return clock_gettime_realtime(pTS);
}
errno = ENOTSUP;
return -1;
}
#endif /* defined(_WIN32) */