KeFindFirstSetRightAffinityEx

NTSTATUS __fastcall KeFindFirstSetRightAffinityEx(WORD *a1){
  __int16 v1; 
  unsigned __int64 v2; 
  unsigned __int64 v4; 

  v1 = 0;
  if( !*a1 )
    return -1;
  while( 1 )
  {
    v2 = *(_QWORD *)&a1[4 * v1 + 4];
    if( v2 )
      break;
    if( ++v1 >= (int)*a1 )
      return -1;
  }
  _BitScanForward64(&v4, v2);
  return KiProcessorNumberToIndexMappingTable[(unsigned int)(v4 + (v1 << 6))];
}

Referenced by:

KeResumeClockTimerFromIdle
PpmCheckContinueExecution
PpmParkSteerInterrupts