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/*
* Copyright (c) 2018 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 API_UNITS_DATA_RATE_H_
#define API_UNITS_DATA_RATE_H_
#ifdef UNIT_TEST
#include <ostream> // no-presubmit-check TODO(webrtc:8982)
#endif // UNIT_TEST
#include <limits>
#include <string>
#include <type_traits>
#include "api/units/data_size.h"
#include "api/units/frequency.h"
#include "api/units/time_delta.h"
#include "rtc_base/checks.h"
#include "rtc_base/units/unit_base.h"
namespace webrtc {
// DataRate is a class that represents a given data rate. This can be used to
// represent bandwidth, encoding bitrate, etc. The internal storage is bits per
// second (bps).
class DataRate final : public rtc_units_impl::RelativeUnit<DataRate> {
public:
template <typename T>
static constexpr DataRate BitsPerSec(T value) {
static_assert(std::is_arithmetic<T>::value, "");
return FromValue(value);
}
template <typename T>
static constexpr DataRate BytesPerSec(T value) {
static_assert(std::is_arithmetic<T>::value, "");
return FromFraction(8, value);
}
template <typename T>
static constexpr DataRate KilobitsPerSec(T value) {
static_assert(std::is_arithmetic<T>::value, "");
return FromFraction(1000, value);
}
static constexpr DataRate Infinity() { return PlusInfinity(); }
DataRate() = delete;
template <typename T = int64_t>
constexpr T bps() const {
return ToValue<T>();
}
template <typename T = int64_t>
constexpr T bytes_per_sec() const {
return ToFraction<8, T>();
}
template <typename T = int64_t>
constexpr T kbps() const {
return ToFraction<1000, T>();
}
constexpr int64_t bps_or(int64_t fallback_value) const {
return ToValueOr(fallback_value);
}
constexpr int64_t kbps_or(int64_t fallback_value) const {
return ToFractionOr<1000>(fallback_value);
}
private:
// Bits per second used internally to simplify debugging by making the value
// more recognizable.
friend class rtc_units_impl::UnitBase<DataRate>;
using RelativeUnit::RelativeUnit;
static constexpr bool one_sided = true;
};
namespace data_rate_impl {
inline constexpr int64_t Microbits(const DataSize& size) {
constexpr int64_t kMaxBeforeConversion =
std::numeric_limits<int64_t>::max() / 8000000;
RTC_DCHECK_LE(size.bytes(), kMaxBeforeConversion)
<< "size is too large to be expressed in microbits";
return size.bytes() * 8000000;
}
inline constexpr int64_t MillibytePerSec(const DataRate& size) {
constexpr int64_t kMaxBeforeConversion =
std::numeric_limits<int64_t>::max() / (1000 / 8);
RTC_DCHECK_LE(size.bps(), kMaxBeforeConversion)
<< "rate is too large to be expressed in microbytes per second";
return size.bps() * (1000 / 8);
}
} // namespace data_rate_impl
inline constexpr DataRate operator/(const DataSize size,
const TimeDelta duration) {
return DataRate::BitsPerSec(data_rate_impl::Microbits(size) / duration.us());
}
inline constexpr TimeDelta operator/(const DataSize size, const DataRate rate) {
return TimeDelta::Micros(data_rate_impl::Microbits(size) / rate.bps());
}
inline constexpr DataSize operator*(const DataRate rate,
const TimeDelta duration) {
int64_t microbits = rate.bps() * duration.us();
return DataSize::Bytes((microbits + 4000000) / 8000000);
}
inline constexpr DataSize operator*(const TimeDelta duration,
const DataRate rate) {
return rate * duration;
}
inline constexpr DataSize operator/(const DataRate rate,
const Frequency frequency) {
int64_t millihertz = frequency.millihertz<int64_t>();
// Note that the value is truncated here reather than rounded, potentially
// introducing an error of .5 bytes if rounding were expected.
return DataSize::Bytes(data_rate_impl::MillibytePerSec(rate) / millihertz);
}
inline constexpr Frequency operator/(const DataRate rate, const DataSize size) {
return Frequency::MilliHertz(data_rate_impl::MillibytePerSec(rate) /
size.bytes());
}
inline constexpr DataRate operator*(const DataSize size,
const Frequency frequency) {
RTC_DCHECK(frequency.IsZero() ||
size.bytes() <= std::numeric_limits<int64_t>::max() / 8 /
frequency.millihertz<int64_t>());
int64_t millibits_per_second =
size.bytes() * 8 * frequency.millihertz<int64_t>();
return DataRate::BitsPerSec((millibits_per_second + 500) / 1000);
}
inline constexpr DataRate operator*(const Frequency frequency,
const DataSize size) {
return size * frequency;
}
std::string ToString(DataRate value);
inline std::string ToLogString(DataRate value) {
return ToString(value);
}
#ifdef UNIT_TEST
inline std::ostream& operator<<( // no-presubmit-check TODO(webrtc:8982)
std::ostream& stream, // no-presubmit-check TODO(webrtc:8982)
DataRate value) {
return stream << ToString(value);
}
#endif // UNIT_TEST
} // namespace webrtc
#endif // API_UNITS_DATA_RATE_H_
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