1 /*
2 * Copyright 2004 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 #include <stdint.h>
12
13 #if defined(WEBRTC_POSIX)
14 #include <sys/time.h>
15 #if defined(WEBRTC_MAC)
16 #include <mach/mach_time.h>
17 #endif
18 #endif
19
20 #if defined(WEBRTC_WIN)
21 #ifndef WIN32_LEAN_AND_MEAN
22 #define WIN32_LEAN_AND_MEAN
23 #endif
24 #include <windows.h>
25 #include <mmsystem.h>
26 #endif
27
28 #include "webrtc/base/checks.h"
29 #include "webrtc/base/timeutils.h"
30
31 #define EFFICIENT_IMPLEMENTATION 1
32
33 namespace rtc {
34
35 const uint32_t HALF = 0x80000000;
36
TimeNanos()37 uint64_t TimeNanos() {
38 int64_t ticks = 0;
39 #if defined(WEBRTC_MAC)
40 static mach_timebase_info_data_t timebase;
41 if (timebase.denom == 0) {
42 // Get the timebase if this is the first time we run.
43 // Recommended by Apple's QA1398.
44 if (mach_timebase_info(&timebase) != KERN_SUCCESS) {
45 RTC_DCHECK(false);
46 }
47 }
48 // Use timebase to convert absolute time tick units into nanoseconds.
49 ticks = mach_absolute_time() * timebase.numer / timebase.denom;
50 #elif defined(WEBRTC_POSIX)
51 struct timespec ts;
52 // TODO: Do we need to handle the case when CLOCK_MONOTONIC
53 // is not supported?
54 clock_gettime(CLOCK_MONOTONIC, &ts);
55 ticks = kNumNanosecsPerSec * static_cast<int64_t>(ts.tv_sec) +
56 static_cast<int64_t>(ts.tv_nsec);
57 #elif defined(WEBRTC_WIN)
58 static volatile LONG last_timegettime = 0;
59 static volatile int64_t num_wrap_timegettime = 0;
60 volatile LONG* last_timegettime_ptr = &last_timegettime;
61 DWORD now = timeGetTime();
62 // Atomically update the last gotten time
63 DWORD old = InterlockedExchange(last_timegettime_ptr, now);
64 if (now < old) {
65 // If now is earlier than old, there may have been a race between
66 // threads.
67 // 0x0fffffff ~3.1 days, the code will not take that long to execute
68 // so it must have been a wrap around.
69 if (old > 0xf0000000 && now < 0x0fffffff) {
70 num_wrap_timegettime++;
71 }
72 }
73 ticks = now + (num_wrap_timegettime << 32);
74 // TODO: Calculate with nanosecond precision. Otherwise, we're just
75 // wasting a multiply and divide when doing Time() on Windows.
76 ticks = ticks * kNumNanosecsPerMillisec;
77 #endif
78 return ticks;
79 }
80
Time()81 uint32_t Time() {
82 return static_cast<uint32_t>(TimeNanos() / kNumNanosecsPerMillisec);
83 }
84
TimeMicros()85 uint64_t TimeMicros() {
86 return static_cast<uint64_t>(TimeNanos() / kNumNanosecsPerMicrosec);
87 }
88
89 #if defined(WEBRTC_WIN)
90 static const uint64_t kFileTimeToUnixTimeEpochOffset = 116444736000000000ULL;
91
92 struct timeval {
93 long tv_sec, tv_usec; // NOLINT
94 };
95
96 // Emulate POSIX gettimeofday().
97 // Based on breakpad/src/third_party/glog/src/utilities.cc
gettimeofday(struct timeval * tv,void * tz)98 static int gettimeofday(struct timeval *tv, void *tz) {
99 // FILETIME is measured in tens of microseconds since 1601-01-01 UTC.
100 FILETIME ft;
101 GetSystemTimeAsFileTime(&ft);
102
103 LARGE_INTEGER li;
104 li.LowPart = ft.dwLowDateTime;
105 li.HighPart = ft.dwHighDateTime;
106
107 // Convert to seconds and microseconds since Unix time Epoch.
108 int64_t micros = (li.QuadPart - kFileTimeToUnixTimeEpochOffset) / 10;
109 tv->tv_sec = static_cast<long>(micros / kNumMicrosecsPerSec); // NOLINT
110 tv->tv_usec = static_cast<long>(micros % kNumMicrosecsPerSec); // NOLINT
111
112 return 0;
113 }
114
115 // Emulate POSIX gmtime_r().
gmtime_r(const time_t * timep,struct tm * result)116 static struct tm *gmtime_r(const time_t *timep, struct tm *result) {
117 // On Windows, gmtime is thread safe.
118 struct tm *tm = gmtime(timep); // NOLINT
119 if (tm == NULL) {
120 return NULL;
121 }
122 *result = *tm;
123 return result;
124 }
125 #endif // WEBRTC_WIN
126
CurrentTmTime(struct tm * tm,int * microseconds)127 void CurrentTmTime(struct tm *tm, int *microseconds) {
128 struct timeval timeval;
129 if (gettimeofday(&timeval, NULL) < 0) {
130 // Incredibly unlikely code path.
131 timeval.tv_sec = timeval.tv_usec = 0;
132 }
133 time_t secs = timeval.tv_sec;
134 gmtime_r(&secs, tm);
135 *microseconds = timeval.tv_usec;
136 }
137
TimeAfter(int32_t elapsed)138 uint32_t TimeAfter(int32_t elapsed) {
139 RTC_DCHECK_GE(elapsed, 0);
140 RTC_DCHECK_LT(static_cast<uint32_t>(elapsed), HALF);
141 return Time() + elapsed;
142 }
143
TimeIsBetween(uint32_t earlier,uint32_t middle,uint32_t later)144 bool TimeIsBetween(uint32_t earlier, uint32_t middle, uint32_t later) {
145 if (earlier <= later) {
146 return ((earlier <= middle) && (middle <= later));
147 } else {
148 return !((later < middle) && (middle < earlier));
149 }
150 }
151
TimeIsLaterOrEqual(uint32_t earlier,uint32_t later)152 bool TimeIsLaterOrEqual(uint32_t earlier, uint32_t later) {
153 #if EFFICIENT_IMPLEMENTATION
154 int32_t diff = later - earlier;
155 return (diff >= 0 && static_cast<uint32_t>(diff) < HALF);
156 #else
157 const bool later_or_equal = TimeIsBetween(earlier, later, earlier + HALF);
158 return later_or_equal;
159 #endif
160 }
161
TimeIsLater(uint32_t earlier,uint32_t later)162 bool TimeIsLater(uint32_t earlier, uint32_t later) {
163 #if EFFICIENT_IMPLEMENTATION
164 int32_t diff = later - earlier;
165 return (diff > 0 && static_cast<uint32_t>(diff) < HALF);
166 #else
167 const bool earlier_or_equal = TimeIsBetween(later, earlier, later + HALF);
168 return !earlier_or_equal;
169 #endif
170 }
171
TimeDiff(uint32_t later,uint32_t earlier)172 int32_t TimeDiff(uint32_t later, uint32_t earlier) {
173 #if EFFICIENT_IMPLEMENTATION
174 return later - earlier;
175 #else
176 const bool later_or_equal = TimeIsBetween(earlier, later, earlier + HALF);
177 if (later_or_equal) {
178 if (earlier <= later) {
179 return static_cast<long>(later - earlier);
180 } else {
181 return static_cast<long>(later + (UINT32_MAX - earlier) + 1);
182 }
183 } else {
184 if (later <= earlier) {
185 return -static_cast<long>(earlier - later);
186 } else {
187 return -static_cast<long>(earlier + (UINT32_MAX - later) + 1);
188 }
189 }
190 #endif
191 }
192
TimestampWrapAroundHandler()193 TimestampWrapAroundHandler::TimestampWrapAroundHandler()
194 : last_ts_(0), num_wrap_(0) {}
195
Unwrap(uint32_t ts)196 int64_t TimestampWrapAroundHandler::Unwrap(uint32_t ts) {
197 if (ts < last_ts_) {
198 if (last_ts_ > 0xf0000000 && ts < 0x0fffffff) {
199 ++num_wrap_;
200 }
201 }
202 last_ts_ = ts;
203 int64_t unwrapped_ts = ts + (num_wrap_ << 32);
204 return unwrapped_ts;
205 }
206
TmToSeconds(const std::tm & tm)207 int64_t TmToSeconds(const std::tm& tm) {
208 static short int mdays[12] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
209 static short int cumul_mdays[12] = {0, 31, 59, 90, 120, 151,
210 181, 212, 243, 273, 304, 334};
211 int year = tm.tm_year + 1900;
212 int month = tm.tm_mon;
213 int day = tm.tm_mday - 1; // Make 0-based like the rest.
214 int hour = tm.tm_hour;
215 int min = tm.tm_min;
216 int sec = tm.tm_sec;
217
218 bool expiry_in_leap_year = (year % 4 == 0 &&
219 (year % 100 != 0 || year % 400 == 0));
220
221 if (year < 1970)
222 return -1;
223 if (month < 0 || month > 11)
224 return -1;
225 if (day < 0 || day >= mdays[month] + (expiry_in_leap_year && month == 2 - 1))
226 return -1;
227 if (hour < 0 || hour > 23)
228 return -1;
229 if (min < 0 || min > 59)
230 return -1;
231 if (sec < 0 || sec > 59)
232 return -1;
233
234 day += cumul_mdays[month];
235
236 // Add number of leap days between 1970 and the expiration year, inclusive.
237 day += ((year / 4 - 1970 / 4) - (year / 100 - 1970 / 100) +
238 (year / 400 - 1970 / 400));
239
240 // We will have added one day too much above if expiration is during a leap
241 // year, and expiration is in January or February.
242 if (expiry_in_leap_year && month <= 2 - 1) // |month| is zero based.
243 day -= 1;
244
245 // Combine all variables into seconds from 1970-01-01 00:00 (except |month|
246 // which was accumulated into |day| above).
247 return (((static_cast<int64_t>
248 (year - 1970) * 365 + day) * 24 + hour) * 60 + min) * 60 + sec;
249 }
250
251 } // namespace rtc
252