src/filters/BaseClasses/reftime.h

   1 //------------------------------------------------------------------------------
   2 // File: RefTime.h
   3 //
   4 // Desc: DirectShow base classes - defines CRefTime, a class that manages
   5 //       reference times.
   6 //
   7 // Copyright (c) 1992-2002 Microsoft Corporation. All rights reserved.
   8 //------------------------------------------------------------------------------
   9
  10
  11 //
  12 // CRefTime
  13 //
  14 // Manage reference times.
  15 // Shares same data layout as REFERENCE_TIME, but adds some (nonvirtual)
  16 // functions providing simple comparison, conversion and arithmetic.
  17 //
  18 // A reference time (at the moment) is a unit of seconds represented in
  19 // 100ns units as is used in the Win32 FILETIME structure. BUT the time
  20 // a REFERENCE_TIME represents is NOT the time elapsed since 1/1/1601 it
  21 // will either be stream time or reference time depending upon context
  22 //
  23 // This class provides simple arithmetic operations on reference times
  24 //
  25 // keep non-virtual otherwise the data layout will not be the same as
  26 // REFERENCE_TIME
  27
  28
  29 // -----
  30 // note that you are safe to cast a CRefTime* to a REFERENCE_TIME*, but
  31 // you will need to do so explicitly
  32 // -----
  33
  34
  35 #ifndef __REFTIME__
  36 #define __REFTIME__
  37
  38
  39 const LONGLONG MILLISECONDS = (1000);            // 10 ^ 3
  40 const LONGLONG NANOSECONDS = (1000000000);       // 10 ^ 9
  41 const LONGLONG UNITS = (NANOSECONDS / 100);      // 10 ^ 7
  42
  43 /*  Unfortunately an inline function here generates a call to __allmul
  44     - even for constants!
  45 */
  46 #define MILLISECONDS_TO_100NS_UNITS(lMs) \
  47     Int32x32To64((lMs), (UNITS / MILLISECONDS))
  48
  49 class CRefTime
  50 {
  51 public:
  52
  53     // *MUST* be the only data member so that this class is exactly
  54     // equivalent to a REFERENCE_TIME.
  55     // Also, must be *no virtual functions*
  56
  57     REFERENCE_TIME m_time;
  58
  59     inline CRefTime()
  60     {
  61         // default to 0 time
  62         m_time = 0;
  63     };
  64
  65     inline CRefTime(LONG msecs)
  66     {
  67         m_time = MILLISECONDS_TO_100NS_UNITS(msecs);
  68     };
  69
  70     inline CRefTime(REFERENCE_TIME rt)
  71     {
  72         m_time = rt;
  73     };
  74
  75     inline operator REFERENCE_TIME() const
  76     {
  77         return m_time;
  78     };
  79
  80     inline CRefTime& operator=(const CRefTime& rt)
  81     {
  82         m_time = rt.m_time;
  83         return *this;
  84     };
  85
  86     inline CRefTime& operator=(const LONGLONG ll)
  87     {
  88         m_time = ll;
  89         return *this;
  90     };
  91
  92     inline CRefTime& operator+=(const CRefTime& rt)
  93     {
  94         return (*this = *this + rt);
  95     };
  96
  97     inline CRefTime& operator-=(const CRefTime& rt)
  98     {
  99         return (*this = *this - rt);
 100     };
 101
 102     inline LONG Millisecs(void)
 103     {
 104         return (LONG)(m_time / (UNITS / MILLISECONDS));
 105     };
 106
 107     inline LONGLONG GetUnits(void)
 108     {
 109         return m_time;
 110     };
 111 };
 112
 113 const LONGLONG TimeZero = 0;
 114
 115 #endif /* __REFTIME__ */
 116