2: #include <petscsys.h>
  3: #include <Windows.h>
  4: #define FACTOR   4294967296.0 /* pow(2,32) */

  6: EXTERN_C_BEGIN

 10: PetscLogDouble  nt_time(void)
 11: {
 12:   static PetscBool      flag = PETSC_TRUE;

 15:   static LARGE_INTEGER  StartTime,PerfFreq,CurTime;
 16:   static PetscLogDouble SecInTick=0.0;
 17: 
 18:   DWORD                 dwStartHigh,dwCurHigh;
 19:   PetscLogDouble        dTime,dHigh;
 20:   PetscLogDouble        ptime;
 21: 
 22: 
 24:   if (flag) {
 25:     QueryPerformanceCounter(&StartTime);CHKERRQ(!ierr);
 26:     QueryPerformanceFrequency(&PerfFreq);CHKERRQ(!ierr);
 27:     /* Explicitly convert the higher 32 bits, and add the lower 32 bits from the counter */
 28:     /* works on non-pentium CPUs ? */
 29: #if defined(PETSC_HAVE_LARGE_INTEGER_U)
 30:     SecInTick = 1.0/((double)PerfFreq.u.HighPart*FACTOR+(double)PerfFreq.u.LowPart);
 31: #else
 32:     SecInTick = 1.0/((double)PerfFreq.HighPart*FACTOR+(double)PerfFreq.LowPart);
 33: #endif
 34:     flag = PETSC_FALSE;
 35:   }
 36: 
 37:   QueryPerformanceCounter(&CurTime);CHKERRQ(!ierr);
 38: #if defined(PETSC_HAVE_LARGE_INTEGER_U)
 39:   dwCurHigh   = (DWORD)CurTime.u.HighPart;
 40:   dwStartHigh = (DWORD)StartTime.u.HighPart;
 41: #else
 42:   dwCurHigh   = (DWORD)CurTime.HighPart;
 43:   dwStartHigh = (DWORD)StartTime.HighPart;
 44: #endif
 45:   dHigh       = (signed)(dwCurHigh - dwStartHigh);

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

 57:   PetscFunctionReturn(ptime);
 58: }

 60: EXTERN_C_END