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      1 /*
      2  *  Copyright 2005 The WebRTC Project Authors. All rights reserved.
      3  *
      4  *  Use of this source code is governed by a BSD-style license
      5  *  that can be found in the LICENSE file in the root of the source
      6  *  tree. An additional intellectual property rights grant can be found
      7  *  in the file PATENTS.  All contributing project authors may
      8  *  be found in the AUTHORS file in the root of the source tree.
      9  */
     10 
     11 #ifndef WEBRTC_BASE_TIMEUTILS_H_
     12 #define WEBRTC_BASE_TIMEUTILS_H_
     13 
     14 #include <time.h>
     15 
     16 #include "webrtc/base/basictypes.h"
     17 
     18 namespace rtc {
     19 
     20 static const int64 kNumMillisecsPerSec = INT64_C(1000);
     21 static const int64 kNumMicrosecsPerSec = INT64_C(1000000);
     22 static const int64 kNumNanosecsPerSec = INT64_C(1000000000);
     23 
     24 static const int64 kNumMicrosecsPerMillisec = kNumMicrosecsPerSec /
     25     kNumMillisecsPerSec;
     26 static const int64 kNumNanosecsPerMillisec =  kNumNanosecsPerSec /
     27     kNumMillisecsPerSec;
     28 static const int64 kNumNanosecsPerMicrosec =  kNumNanosecsPerSec /
     29     kNumMicrosecsPerSec;
     30 
     31 // January 1970, in NTP milliseconds.
     32 static const int64 kJan1970AsNtpMillisecs = INT64_C(2208988800000);
     33 
     34 typedef uint32 TimeStamp;
     35 
     36 // Returns the current time in milliseconds.
     37 uint32 Time();
     38 // Returns the current time in microseconds.
     39 uint64 TimeMicros();
     40 // Returns the current time in nanoseconds.
     41 uint64 TimeNanos();
     42 
     43 // Stores current time in *tm and microseconds in *microseconds.
     44 void CurrentTmTime(struct tm *tm, int *microseconds);
     45 
     46 // Returns a future timestamp, 'elapsed' milliseconds from now.
     47 uint32 TimeAfter(int32 elapsed);
     48 
     49 // Comparisons between time values, which can wrap around.
     50 bool TimeIsBetween(uint32 earlier, uint32 middle, uint32 later);  // Inclusive
     51 bool TimeIsLaterOrEqual(uint32 earlier, uint32 later);  // Inclusive
     52 bool TimeIsLater(uint32 earlier, uint32 later);  // Exclusive
     53 
     54 // Returns the later of two timestamps.
     55 inline uint32 TimeMax(uint32 ts1, uint32 ts2) {
     56   return TimeIsLaterOrEqual(ts1, ts2) ? ts2 : ts1;
     57 }
     58 
     59 // Returns the earlier of two timestamps.
     60 inline uint32 TimeMin(uint32 ts1, uint32 ts2) {
     61   return TimeIsLaterOrEqual(ts1, ts2) ? ts1 : ts2;
     62 }
     63 
     64 // Number of milliseconds that would elapse between 'earlier' and 'later'
     65 // timestamps.  The value is negative if 'later' occurs before 'earlier'.
     66 int32 TimeDiff(uint32 later, uint32 earlier);
     67 
     68 // The number of milliseconds that have elapsed since 'earlier'.
     69 inline int32 TimeSince(uint32 earlier) {
     70   return TimeDiff(Time(), earlier);
     71 }
     72 
     73 // The number of milliseconds that will elapse between now and 'later'.
     74 inline int32 TimeUntil(uint32 later) {
     75   return TimeDiff(later, Time());
     76 }
     77 
     78 // Converts a unix timestamp in nanoseconds to an NTP timestamp in ms.
     79 inline int64 UnixTimestampNanosecsToNtpMillisecs(int64 unix_ts_ns) {
     80   return unix_ts_ns / kNumNanosecsPerMillisec + kJan1970AsNtpMillisecs;
     81 }
     82 
     83 class TimestampWrapAroundHandler {
     84  public:
     85   TimestampWrapAroundHandler();
     86 
     87   int64 Unwrap(uint32 ts);
     88 
     89  private:
     90   uint32 last_ts_;
     91   int64 num_wrap_;
     92 };
     93 
     94 }  // namespace rtc
     95 
     96 #endif  // WEBRTC_BASE_TIMEUTILS_H_
     97