f7e7cb349b
Original-commit: flang-compiler/f18@aa7f55e15f Reviewed-on: https://github.com/flang-compiler/f18/pull/217
59 lines
2 KiB
C++
59 lines
2 KiB
C++
// Copyright (c) 2018, NVIDIA CORPORATION. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef FORTRAN_EVALUATE_INT_POWER_H_
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#define FORTRAN_EVALUATE_INT_POWER_H_
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// Computes an integer power of a real or complex value.
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#include "common.h"
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namespace Fortran::evaluate {
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template<typename REAL, typename INT>
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ValueWithRealFlags<REAL> IntPower(
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const REAL &base, const INT &power, Rounding rounding = defaultRounding) {
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REAL one{REAL::FromInteger(INT{1}).value};
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ValueWithRealFlags<REAL> result;
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result.value = one;
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if (base.IsNotANumber()) {
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result.value = REAL::NotANumber();
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if (base.IsSignalingNaN()) {
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result.flags.set(RealFlag::InvalidArgument);
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}
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} else if (power.IsZero()) {
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if (base.IsZero() || base.IsInfinite()) {
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result.flags.set(RealFlag::InvalidArgument);
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}
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} else {
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bool negativePower{power.IsNegative()};
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INT absPower{power.ABS().value};
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REAL shifted{base};
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int nbits{INT::bits - absPower.LEADZ()};
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for (int j{0}; j + 1 < nbits; ++j) {
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if (absPower.BTEST(j)) {
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result.value =
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result.value.Multiply(shifted).AccumulateFlags(result.flags);
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}
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shifted = shifted.Add(shifted).AccumulateFlags(result.flags);
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}
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result.value = result.value.Multiply(shifted).AccumulateFlags(result.flags);
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if (negativePower) {
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result.value = one.Divide(result.value).AccumulateFlags(result.flags);
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}
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}
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return result;
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}
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}
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#endif // FORTRAN_EVALUATE_INT_POWER_H_
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