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libcxx_old/test/std/utilities/time/time.cal/euclidian.h

39 lines
1.2 KiB
C++

//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// Assumption: minValue < maxValue
// Assumption: minValue <= rhs <= maxValue
// Assumption: minValue <= lhs <= maxValue
// Assumption: minValue >= 0
template <typename T, T minValue, T maxValue>
T euclidian_addition(T rhs, T lhs)
{
const T modulus = maxValue - minValue + 1;
T ret = rhs + lhs;
if (ret > maxValue)
ret -= modulus;
return ret;
}
// Assumption: minValue < maxValue
// Assumption: minValue <= rhs <= maxValue
// Assumption: minValue <= lhs <= maxValue
// Assumption: minValue >= 0
template <typename T, T minValue, T maxValue>
T euclidian_subtraction(T lhs, T rhs)
{
const T modulus = maxValue - minValue + 1;
T ret = lhs - rhs;
if (ret < minValue)
ret += modulus;
if (ret > maxValue) // this can happen if T is unsigned
ret += modulus;
return ret;
}