epics/epics-base
0
0
Fork 0
Code Issues Pull Requests Projects Wiki Activity

Make returned value relative to IOC boot time to improve accuracy

Browse Source
This commit is contained in:
Freddie Akeroyd
2020-10-04 00:20:11 +01:00
parent bbdd9392fe
commit 8a90688880
1 changed files with 9 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files
modules/libcom/src/osi/os/WIN32/osdMonotonic.c
+9 -6
View File
@@ -14,8 +14,10 @@
#include "epicsTime.h"
#include "generalTimeSup.h"
static epicsUInt64 osdMonotonicResolution; /* timer resolution in nanoseconds */
static double perfCounterScale; /* convert performance counter tics to nanoseconds */
static epicsUInt64 osdMonotonicResolution; /* timer resolution in nanoseconds */
static epicsUInt64 perfCounterFrequency; /* performance counter tics per second */
static epicsUInt64 perfCounterOffset; /* performance counter value at initialisation */
static const epicsUInt64 sec2nsec = 1000000000; /* number of nanoseconds in a second */
void osdMonotonicInit(void)
{
@@ -27,8 +29,9 @@ void osdMonotonicInit(void)
QueryPerformanceCounter(&val) &&
freq.QuadPart != 0)
{
perfCounterScale = 1e9 / freq.QuadPart;
osdMonotonicResolution = 1 + (int)perfCounterScale;
perfCounterFrequency = freq.QuadPart;
perfCounterOffset = val.QuadPart;
osdMonotonicResolution = sec2nsec / perfCounterFrequency + (sec2nsec % perfCounterFrequency != 0 ? 1 : 0);
} else {
cantProceed("osdMonotonicInit: Windows Performance Counter is not available\n");
}
@@ -45,7 +48,7 @@ epicsUInt64 epicsMonotonicGet(void)
if(!QueryPerformanceCounter(&val)) {
cantProceed("epicsMonotonicGet: Failed to read Windows Performance Counter\n");
return 0;
} else {
return (epicsUInt64)(val.QuadPart * perfCounterScale + 0.5); /* return value in nanoseconds */
} else { /* return value in nanoseconds */
return (epicsUInt64)((double)(val.QuadPart - perfCounterOffset) * sec2nsec / perfCounterFrequency + 0.5);
}
}