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roken: gettimeofday using GetSystemTimePreciseAsFileTime

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GetSystemTimeAsFileTime() has 16ms precision.

GetSystemTimePreciseAsFileTime() has <1ns precision but is only available
on Windows 8 or later.

This change dynamically loads GetSystemTimePreciseAsFileTime() if it is
available.

Change-Id: Ib9c616c01948384e6b256ac9b6023f1e39673613
This commit is contained in:
Jeffrey Altman
2018-09-18 22:06:23 -04:00
committed by Jeffrey Altman
parent 07b3e6fd74
commit 1feff82129
1 changed files with 18 additions and 2 deletions

20
lib/roken/gettimeofday.c

@ -37,6 +37,10 @@
#ifdef _WIN32
typedef BOOL (WINAPI *LPFN_GETSYSTEMTIME) (LPFILETIME);
static LPFN_GETSYSTEMTIME lpGetSystemTime = NULL;
ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL
gettimeofday (struct timeval *tp, void *ignore)
{
@ -44,7 +48,20 @@ gettimeofday (struct timeval *tp, void *ignore)
ULARGE_INTEGER li;
ULONGLONG ull;
GetSystemTimeAsFileTime(&ft);
if (lpGetSystemTime == NULL) {
HANDLE h1;
LPFN_GETSYSTEMTIME fn;
h1 = GetModuleHandle(TEXT("kernel32.dll")); /* no refcount increase */
fn = (LPFN_GETSYSTEMTIME)GetProcAddress(h1,
"GetSystemTimePreciseAsFileTime");
if (fn == NULL)
fn = (LPFN_GETSYSTEMTIME)GetProcAddress(h1,
"GetSystemTimeAsFileTime");
lpGetSystemTime = fn;
}
lpGetSystemTime(&ft);
li.LowPart = ft.dwLowDateTime;
li.HighPart = ft.dwHighDateTime;
ull = li.QuadPart;
@ -57,7 +74,6 @@ gettimeofday (struct timeval *tp, void *ignore)
return 0;
}
#else
/*