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// Copyright 2019 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "cast/streaming/ntp_time.h"
#include "util/logging.h"
using openscreen::platform::Clock;
using std::chrono::duration_cast;
namespace cast {
namespace streaming {
namespace {
// The number of seconds between 1 January 1900 and 1 January 1970.
constexpr NtpSeconds kTimeBetweenNtpEpochAndUnixEpoch{INT64_C(2208988800)};
} // namespace
NtpTimeConverter::NtpTimeConverter(Clock::time_point now,
std::chrono::seconds since_unix_epoch)
: start_time_(now),
since_ntp_epoch_(duration_cast<NtpSeconds>(since_unix_epoch) +
kTimeBetweenNtpEpochAndUnixEpoch) {}
NtpTimeConverter::~NtpTimeConverter() = default;
NtpTimestamp NtpTimeConverter::ToNtpTimestamp(
Clock::time_point time_point) const {
const Clock::duration time_since_start = time_point - start_time_;
const auto whole_seconds = duration_cast<NtpSeconds>(time_since_start);
const auto remainder =
duration_cast<NtpFraction>(time_since_start - whole_seconds);
return AssembleNtpTimestamp(since_ntp_epoch_ + whole_seconds, remainder);
}
Clock::time_point NtpTimeConverter::ToLocalTime(NtpTimestamp timestamp) const {
auto ntp_seconds = NtpSecondsPart(timestamp);
// Year 2036 wrap-around check: If the NTP timestamp appears to be a
// point-in-time before 1970, assume the 2036 wrap-around has occurred, and
// adjust to compensate.
if (ntp_seconds <= kTimeBetweenNtpEpochAndUnixEpoch) {
constexpr NtpSeconds kNtpSecondsPerEra{INT64_C(1) << 32};
ntp_seconds += kNtpSecondsPerEra;
}
const auto whole_seconds = ntp_seconds - since_ntp_epoch_;
const auto seconds_since_start =
duration_cast<Clock::duration>(whole_seconds) + start_time_;
const auto remainder =
duration_cast<Clock::duration>(NtpFractionPart(timestamp));
return seconds_since_start + remainder;
}
} // namespace streaming
} // namespace cast
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