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097fc347ec
This is in prep for the migration of all unwrappers to SequenceNumberUnwrapper as a standard implementation. This moves the SeqNumUnwapper to its own header and adds 2 methods to SeqNumUnwrapper which are defined by other unwrappers: * PeekUnwrap * Reset It also adds two implementations for RtpTimestamps and RtpSequenceNumbers. Bug: webrtc:13982 Change-Id: I5baefb2de1db92fe1bb600760bd63b71e9310eb5 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/288742 Commit-Queue: Evan Shrubsole <eshr@webrtc.org> Reviewed-by: Harald Alvestrand <hta@webrtc.org> Auto-Submit: Evan Shrubsole <eshr@webrtc.org> Cr-Commit-Position: refs/heads/main@{#39030}
85 lines
2.8 KiB
C++
85 lines
2.8 KiB
C++
/*
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* Copyright (c) 2016 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 RTC_BASE_NUMERICS_SEQUENCE_NUMBER_UTIL_H_
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#define RTC_BASE_NUMERICS_SEQUENCE_NUMBER_UTIL_H_
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#include <stdint.h>
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#include <limits>
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#include <type_traits>
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#include "rtc_base/numerics/mod_ops.h"
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namespace webrtc {
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// Test if the sequence number `a` is ahead or at sequence number `b`.
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//
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// If `M` is an even number and the two sequence numbers are at max distance
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// from each other, then the sequence number with the highest value is
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// considered to be ahead.
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template <typename T, T M>
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inline typename std::enable_if<(M > 0), bool>::type AheadOrAt(T a, T b) {
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static_assert(std::is_unsigned<T>::value,
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"Type must be an unsigned integer.");
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const T maxDist = M / 2;
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if (!(M & 1) && MinDiff<T, M>(a, b) == maxDist)
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return b < a;
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return ForwardDiff<T, M>(b, a) <= maxDist;
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}
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template <typename T, T M>
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inline typename std::enable_if<(M == 0), bool>::type AheadOrAt(T a, T b) {
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static_assert(std::is_unsigned<T>::value,
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"Type must be an unsigned integer.");
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const T maxDist = std::numeric_limits<T>::max() / 2 + T(1);
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if (a - b == maxDist)
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return b < a;
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return ForwardDiff(b, a) < maxDist;
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}
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template <typename T>
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inline bool AheadOrAt(T a, T b) {
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return AheadOrAt<T, 0>(a, b);
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}
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// Test if the sequence number `a` is ahead of sequence number `b`.
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//
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// If `M` is an even number and the two sequence numbers are at max distance
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// from each other, then the sequence number with the highest value is
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// considered to be ahead.
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template <typename T, T M = 0>
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inline bool AheadOf(T a, T b) {
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static_assert(std::is_unsigned<T>::value,
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"Type must be an unsigned integer.");
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return a != b && AheadOrAt<T, M>(a, b);
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}
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// Comparator used to compare sequence numbers in a continuous fashion.
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//
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// WARNING! If used to sort sequence numbers of length M then the interval
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// covered by the sequence numbers may not be larger than floor(M/2).
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template <typename T, T M = 0>
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struct AscendingSeqNumComp {
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bool operator()(T a, T b) const { return AheadOf<T, M>(a, b); }
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};
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// Comparator used to compare sequence numbers in a continuous fashion.
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//
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// WARNING! If used to sort sequence numbers of length M then the interval
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// covered by the sequence numbers may not be larger than floor(M/2).
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template <typename T, T M = 0>
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struct DescendingSeqNumComp {
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bool operator()(T a, T b) const { return AheadOf<T, M>(b, a); }
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};
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} // namespace webrtc
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#endif // RTC_BASE_NUMERICS_SEQUENCE_NUMBER_UTIL_H_
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