1 /********************************************************************************
2 *                                                                               *
3 *                                 N T P - T i m e                               *
4 *                                                                               *
5 *********************************************************************************
6 * Copyright (C) 2019,2021 by Jeroen van der Zijp.   All Rights Reserved.        *
7 *********************************************************************************
8 * This library is free software; you can redistribute it and/or modify          *
9 * it under the terms of the GNU Lesser General Public License as published by   *
10 * the Free Software Foundation; either version 3 of the License, or             *
11 * (at your option) any later version.                                           *
12 *                                                                               *
13 * This library is distributed in the hope that it will be useful,               *
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of                *
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the                 *
16 * GNU Lesser General Public License for more details.                           *
17 *                                                                               *
18 * You should have received a copy of the GNU Lesser General Public License      *
19 * along with this program.  If not, see <http://www.gnu.org/licenses/>          *
20 ********************************************************************************/
21 #include "xincs.h"
22 #include "fxver.h"
23 #include "fxdefs.h"
24 #include "fxmath.h"
25 #include "fxascii.h"
26 #include "FXString.h"
27 #include "FXSystem.h"
28 
29 
30 /*
31   Notes:
32 
33   - Conversions between Network Time Protocol (NTP) time and Unix Epoch Time.
34 */
35 
36 
37 using namespace FX;
38 
39 /*******************************************************************************/
40 
41 namespace FX {
42 
43 // Offset from Epoch to 1-Jan-1900 @ 00:00:00 UTC
44 const FXTime JANUARY1900=-FXLONG(2208988800000000000);
45 
46 // Offset from Epoch to 7-Feb-2036 @ 06:28:16 UTC
47 const FXTime FEBRUARY2036=+FXLONG(2085978496000000000);
48 
49 
50 // Convert NTP format (ssss:ffff) to nanoseconds since Unix Epoch
timeFromNTPTime(FXulong ntptime)51 FXTime FXSystem::timeFromNTPTime(FXulong ntptime){
52   FXTime secs=(ntptime>>32)&0xFFFFFFFF;
53   FXTime frac=ntptime-(secs<<32);
54   FXTime nano=(frac*1000000000+2147483647)>>32;
55   return (secs&0x80000000) ? (secs*1000000000+nano+JANUARY1900) : (secs*1000000000+nano+FEBRUARY2036);
56   }
57 
58 
59 // Convert utc in nanoseconds since Unix Epoch to NTP (ssss:ffff)
ntpTimeFromTime(FXTime utc)60 FXulong FXSystem::ntpTimeFromTime(FXTime utc){
61   FXlong base=utc-FEBRUARY2036;
62   FXlong secs=(0<=base ? base : base-999999999)/1000000000;
63   FXlong nano=base-secs*1000000000;
64   FXlong frac=((nano<<32)+500000000)/1000000000;
65   return (secs<<32)+frac;
66   }
67 
68 }
69 
70