webrtc/rtc_base/numerics/divide_round.h
Danil Chapovalov 33b83fdc95 Introduce integer division helpers with non-default rounding
There are multiple places in webrtc code where alternative than
default rounding is desired. Typically this rounding is inlined.
e.g. as (<x> + <y>/2) / <y> making code more clumpsy (<y> might be long expression)
and unsafe for large values of <x>

This change introduce small helpers to address both concerns.

Bug: None
Change-Id: Icd8dcee80a697b7c50ba0b2e50295087d2be8670
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/153354
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Reviewed-by: Niels Moller <nisse@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29222}
2019-09-18 15:08:39 +00:00

48 lines
1.5 KiB
C++

/*
* Copyright 2019 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 RTC_BASE_NUMERICS_DIVIDE_ROUND_H_
#define RTC_BASE_NUMERICS_DIVIDE_ROUND_H_
#include <type_traits>
#include "rtc_base/checks.h"
#include "rtc_base/numerics/safe_compare.h"
namespace webrtc {
template <typename Dividend, typename Divisor>
inline auto constexpr DivideRoundUp(Dividend dividend, Divisor divisor) {
static_assert(std::is_integral<Dividend>(), "");
static_assert(std::is_integral<Divisor>(), "");
RTC_DCHECK_GE(dividend, 0);
RTC_DCHECK_GT(divisor, 0);
auto quotient = dividend / divisor;
auto remainder = dividend % divisor;
return quotient + (remainder > 0 ? 1 : 0);
}
template <typename Dividend, typename Divisor>
inline auto constexpr DivideRoundToNearest(Dividend dividend, Divisor divisor) {
static_assert(std::is_integral<Dividend>(), "");
static_assert(std::is_integral<Divisor>(), "");
RTC_DCHECK_GE(dividend, 0);
RTC_DCHECK_GT(divisor, 0);
auto half_of_divisor = (divisor - 1) / 2;
auto quotient = dividend / divisor;
auto remainder = dividend % divisor;
return quotient + (rtc::SafeGt(remainder, half_of_divisor) ? 1 : 0);
}
} // namespace webrtc
#endif // RTC_BASE_NUMERICS_DIVIDE_ROUND_H_