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      1 /*
      2  * libjingle
      3  * Copyright 2005 Google Inc.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions are met:
      7  *
      8  *  1. Redistributions of source code must retain the above copyright notice,
      9  *     this list of conditions and the following disclaimer.
     10  *  2. Redistributions in binary form must reproduce the above copyright notice,
     11  *     this list of conditions and the following disclaimer in the documentation
     12  *     and/or other materials provided with the distribution.
     13  *  3. The name of the author may not be used to endorse or promote products
     14  *     derived from this software without specific prior written permission.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
     17  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
     18  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
     19  * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     20  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     21  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
     22  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
     23  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
     24  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
     25  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     26  */
     27 
     28 #ifndef TALK_BASE_TIMEUTILS_H_
     29 #define TALK_BASE_TIMEUTILS_H_
     30 
     31 #include <time.h>
     32 
     33 #include "talk/base/basictypes.h"
     34 
     35 namespace talk_base {
     36 
     37 static const int64 kNumMillisecsPerSec = INT64_C(1000);
     38 static const int64 kNumMicrosecsPerSec = INT64_C(1000000);
     39 static const int64 kNumNanosecsPerSec = INT64_C(1000000000);
     40 
     41 static const int64 kNumMicrosecsPerMillisec = kNumMicrosecsPerSec /
     42     kNumMillisecsPerSec;
     43 static const int64 kNumNanosecsPerMillisec =  kNumNanosecsPerSec /
     44     kNumMillisecsPerSec;
     45 static const int64 kNumNanosecsPerMicrosec =  kNumNanosecsPerSec /
     46     kNumMicrosecsPerSec;
     47 
     48 // January 1970, in NTP milliseconds.
     49 static const int64 kJan1970AsNtpMillisecs = INT64_C(2208988800000);
     50 
     51 typedef uint32 TimeStamp;
     52 
     53 // Returns the current time in milliseconds.
     54 uint32 Time();
     55 // Returns the current time in microseconds.
     56 uint64 TimeMicros();
     57 // Returns the current time in nanoseconds.
     58 uint64 TimeNanos();
     59 
     60 // Stores current time in *tm and microseconds in *microseconds.
     61 void CurrentTmTime(struct tm *tm, int *microseconds);
     62 
     63 // Returns a future timestamp, 'elapsed' milliseconds from now.
     64 uint32 TimeAfter(int32 elapsed);
     65 
     66 // Comparisons between time values, which can wrap around.
     67 bool TimeIsBetween(uint32 earlier, uint32 middle, uint32 later);  // Inclusive
     68 bool TimeIsLaterOrEqual(uint32 earlier, uint32 later);  // Inclusive
     69 bool TimeIsLater(uint32 earlier, uint32 later);  // Exclusive
     70 
     71 // Returns the later of two timestamps.
     72 inline uint32 TimeMax(uint32 ts1, uint32 ts2) {
     73   return TimeIsLaterOrEqual(ts1, ts2) ? ts2 : ts1;
     74 }
     75 
     76 // Returns the earlier of two timestamps.
     77 inline uint32 TimeMin(uint32 ts1, uint32 ts2) {
     78   return TimeIsLaterOrEqual(ts1, ts2) ? ts1 : ts2;
     79 }
     80 
     81 // Number of milliseconds that would elapse between 'earlier' and 'later'
     82 // timestamps.  The value is negative if 'later' occurs before 'earlier'.
     83 int32 TimeDiff(uint32 later, uint32 earlier);
     84 
     85 // The number of milliseconds that have elapsed since 'earlier'.
     86 inline int32 TimeSince(uint32 earlier) {
     87   return TimeDiff(Time(), earlier);
     88 }
     89 
     90 // The number of milliseconds that will elapse between now and 'later'.
     91 inline int32 TimeUntil(uint32 later) {
     92   return TimeDiff(later, Time());
     93 }
     94 
     95 // Converts a unix timestamp in nanoseconds to an NTP timestamp in ms.
     96 inline int64 UnixTimestampNanosecsToNtpMillisecs(int64 unix_ts_ns) {
     97   return unix_ts_ns / kNumNanosecsPerMillisec + kJan1970AsNtpMillisecs;
     98 }
     99 
    100 }  // namespace talk_base
    101 
    102 #endif  // TALK_BASE_TIMEUTILS_H_
    103