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/*
* Copyright (c) 2017 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#ifndef MODULES_INCLUDE_MODULE_COMMON_TYPES_PUBLIC_H_
#define MODULES_INCLUDE_MODULE_COMMON_TYPES_PUBLIC_H_
#include <limits>
#include "absl/types/optional.h"
namespace webrtc {
template <typename U>
inline bool IsNewer(U value, U prev_value) {
static_assert(!std::numeric_limits<U>::is_signed, "U must be unsigned");
// kBreakpoint is the half-way mark for the type U. For instance, for a
// uint16_t it will be 0x8000, and for a uint32_t, it will be 0x8000000.
constexpr U kBreakpoint = (std::numeric_limits<U>::max() >> 1) + 1;
// Distinguish between elements that are exactly kBreakpoint apart.
// If t1>t2 and |t1-t2| = kBreakpoint: IsNewer(t1,t2)=true,
// IsNewer(t2,t1)=false
// rather than having IsNewer(t1,t2) = IsNewer(t2,t1) = false.
if (value - prev_value == kBreakpoint) {
return value > prev_value;
}
return value != prev_value &&
static_cast<U>(value - prev_value) < kBreakpoint;
}
// NB: Doesn't fulfill strict weak ordering requirements.
// Mustn't be used as std::map Compare function.
inline bool IsNewerSequenceNumber(uint16_t sequence_number,
uint16_t prev_sequence_number) {
return IsNewer(sequence_number, prev_sequence_number);
}
// NB: Doesn't fulfill strict weak ordering requirements.
// Mustn't be used as std::map Compare function.
inline bool IsNewerTimestamp(uint32_t timestamp, uint32_t prev_timestamp) {
return IsNewer(timestamp, prev_timestamp);
}
inline uint16_t LatestSequenceNumber(uint16_t sequence_number1,
uint16_t sequence_number2) {
return IsNewerSequenceNumber(sequence_number1, sequence_number2)
? sequence_number1
: sequence_number2;
}
inline uint32_t LatestTimestamp(uint32_t timestamp1, uint32_t timestamp2) {
return IsNewerTimestamp(timestamp1, timestamp2) ? timestamp1 : timestamp2;
}
} // namespace webrtc
#endif // MODULES_INCLUDE_MODULE_COMMON_TYPES_PUBLIC_H_
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