125 lines
4.4 KiB
C++
125 lines
4.4 KiB
C++
/*
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* Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#ifndef SYSTEM_WRAPPERS_INCLUDE_NTP_TIME_H_
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#define SYSTEM_WRAPPERS_INCLUDE_NTP_TIME_H_
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#include <cmath>
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#include <cstdint>
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#include <limits>
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#include "rtc_base/numerics/safe_conversions.h"
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namespace webrtc {
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class NtpTime {
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public:
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static constexpr uint64_t kFractionsPerSecond = 0x100000000;
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NtpTime() : value_(0) {}
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explicit NtpTime(uint64_t value) : value_(value) {}
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NtpTime(uint32_t seconds, uint32_t fractions)
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: value_(seconds * kFractionsPerSecond + fractions) {}
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NtpTime(const NtpTime&) = default;
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NtpTime& operator=(const NtpTime&) = default;
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explicit operator uint64_t() const { return value_; }
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void Set(uint32_t seconds, uint32_t fractions) {
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value_ = seconds * kFractionsPerSecond + fractions;
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}
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void Reset() { value_ = 0; }
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int64_t ToMs() const {
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static constexpr double kNtpFracPerMs = 4.294967296E6; // 2^32 / 1000.
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const double frac_ms = static_cast<double>(fractions()) / kNtpFracPerMs;
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return 1000 * static_cast<int64_t>(seconds()) +
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static_cast<int64_t>(frac_ms + 0.5);
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}
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// NTP standard (RFC1305, section 3.1) explicitly state value 0 is invalid.
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bool Valid() const { return value_ != 0; }
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uint32_t seconds() const {
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return rtc::dchecked_cast<uint32_t>(value_ / kFractionsPerSecond);
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}
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uint32_t fractions() const {
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return rtc::dchecked_cast<uint32_t>(value_ % kFractionsPerSecond);
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}
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private:
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uint64_t value_;
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};
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inline bool operator==(const NtpTime& n1, const NtpTime& n2) {
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return static_cast<uint64_t>(n1) == static_cast<uint64_t>(n2);
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}
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inline bool operator!=(const NtpTime& n1, const NtpTime& n2) {
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return !(n1 == n2);
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}
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// Converts |int64_t| milliseconds to Q32.32-formatted fixed-point seconds.
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// Performs clamping if the result overflows or underflows.
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inline int64_t Int64MsToQ32x32(int64_t milliseconds) {
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// TODO(bugs.webrtc.org/10893): Change to use |rtc::saturated_cast| once the
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// bug has been fixed.
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double result =
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std::round(milliseconds * (NtpTime::kFractionsPerSecond / 1000.0));
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// Explicitly cast values to double to avoid implicit conversion warnings
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// The conversion of the std::numeric_limits<int64_t>::max() triggers
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// -Wimplicit-int-float-conversion warning in clang 10.0.0 without explicit
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// cast
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if (result <= static_cast<double>(std::numeric_limits<int64_t>::min())) {
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return std::numeric_limits<int64_t>::min();
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}
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if (result >= static_cast<double>(std::numeric_limits<int64_t>::max())) {
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return std::numeric_limits<int64_t>::max();
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}
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return rtc::dchecked_cast<int64_t>(result);
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}
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// Converts |int64_t| milliseconds to UQ32.32-formatted fixed-point seconds.
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// Performs clamping if the result overflows or underflows.
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inline uint64_t Int64MsToUQ32x32(int64_t milliseconds) {
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// TODO(bugs.webrtc.org/10893): Change to use |rtc::saturated_cast| once the
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// bug has been fixed.
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double result =
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std::round(milliseconds * (NtpTime::kFractionsPerSecond / 1000.0));
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// Explicitly cast values to double to avoid implicit conversion warnings
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// The conversion of the std::numeric_limits<int64_t>::max() triggers
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// -Wimplicit-int-float-conversion warning in clang 10.0.0 without explicit
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// cast
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if (result <= static_cast<double>(std::numeric_limits<uint64_t>::min())) {
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return std::numeric_limits<uint64_t>::min();
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}
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if (result >= static_cast<double>(std::numeric_limits<uint64_t>::max())) {
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return std::numeric_limits<uint64_t>::max();
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}
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return rtc::dchecked_cast<uint64_t>(result);
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}
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// Converts Q32.32-formatted fixed-point seconds to |int64_t| milliseconds.
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inline int64_t Q32x32ToInt64Ms(int64_t q32x32) {
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return rtc::dchecked_cast<int64_t>(
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std::round(q32x32 * (1000.0 / NtpTime::kFractionsPerSecond)));
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}
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// Converts UQ32.32-formatted fixed-point seconds to |int64_t| milliseconds.
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inline int64_t UQ32x32ToInt64Ms(uint64_t q32x32) {
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return rtc::dchecked_cast<int64_t>(
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std::round(q32x32 * (1000.0 / NtpTime::kFractionsPerSecond)));
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}
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} // namespace webrtc
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#endif // SYSTEM_WRAPPERS_INCLUDE_NTP_TIME_H_
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