Actual source code: nt_time.c

petsc-3.4.2 2013-07-02
  2: #include <petscsys.h>
  3: #include <Windows.h>
  4: #define FACTOR   4294967296.0 /* pow(2,32) */

  8: PETSC_EXTERN PetscLogDouble PetscMicrosoftTime(void)
  9: {
 10:   static PetscBool flag = PETSC_TRUE;
 11:   PetscErrorCode   ierr;

 13:   static LARGE_INTEGER  StartTime,PerfFreq,CurTime;
 14:   static PetscLogDouble SecInTick=0.0;

 16:   DWORD          dwStartHigh,dwCurHigh;
 17:   PetscLogDouble dTime,dHigh;
 18:   PetscLogDouble ptime;


 22:   if (flag) {
 23:     QueryPerformanceCounter(&StartTime);CHKERRQ(!ierr);
 24:     QueryPerformanceFrequency(&PerfFreq);CHKERRQ(!ierr);
 25:     /* Explicitly convert the higher 32 bits, and add the lower 32 bits from the counter */
 26:     /* works on non-pentium CPUs ? */
 27: #if defined(PETSC_HAVE_LARGE_INTEGER_U)
 28:     SecInTick = 1.0/((double)PerfFreq.u.HighPart*FACTOR+(double)PerfFreq.u.LowPart);
 29: #else
 30:     SecInTick = 1.0/((double)PerfFreq.HighPart*FACTOR+(double)PerfFreq.LowPart);
 31: #endif
 32:     flag = PETSC_FALSE;
 33:   }

 35:   QueryPerformanceCounter(&CurTime);CHKERRQ(!ierr);
 36: #if defined(PETSC_HAVE_LARGE_INTEGER_U)
 37:   dwCurHigh   = (DWORD)CurTime.u.HighPart;
 38:   dwStartHigh = (DWORD)StartTime.u.HighPart;
 39: #else
 40:   dwCurHigh   = (DWORD)CurTime.HighPart;
 41:   dwStartHigh = (DWORD)StartTime.HighPart;
 42: #endif
 43:   dHigh       = (signed)(dwCurHigh - dwStartHigh);

 45: #if defined(PETSC_HAVE_LARGE_INTEGER_U)
 46:   dTime = dHigh*(double)FACTOR + (double)CurTime.u.LowPart - (double)StartTime.u.LowPart;
 47: #else
 48:   dTime = dHigh*(double)FACTOR + (double)CurTime.LowPart - (double)StartTime.LowPart;
 49: #endif
 50:   /* Use the following with older versions of the Borland compiler
 51:   dTime = dHigh*(double)FACTOR + (double)CurTime.u.LowPart - (double)StartTime.u.LowPart;
 52:   */
 53:   ptime = (double)SecInTick*dTime;
 54:   PetscFunctionReturn(ptime);
 55: }