forked from OSchip/llvm-project
59 lines
2.0 KiB
C++
59 lines
2.0 KiB
C++
//===-- lib/Evaluate/int-power.h --------------------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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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 "flang/Evaluate/common.h"
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namespace Fortran::evaluate {
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template <typename REAL, typename INT>
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ValueWithRealFlags<REAL> TimesIntPowerOf(const REAL &factor, const REAL &base,
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const INT &power, Rounding rounding = defaultRounding) {
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ValueWithRealFlags<REAL> result{factor};
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if (base.IsNotANumber()) {
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result.value = REAL::NotANumber();
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result.flags.set(RealFlag::InvalidArgument);
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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 squares{base};
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int nbits{INT::bits - absPower.LEADZ()};
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for (int j{0}; j < nbits; ++j) {
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if (absPower.BTEST(j)) {
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if (negativePower) {
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result.value = result.value.Divide(squares, rounding)
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.AccumulateFlags(result.flags);
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} else {
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result.value = result.value.Multiply(squares, rounding)
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.AccumulateFlags(result.flags);
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}
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}
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squares =
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squares.Multiply(squares, rounding).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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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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return TimesIntPowerOf(one, base, power, rounding);
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}
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} // namespace Fortran::evaluate
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#endif // FORTRAN_EVALUATE_INT_POWER_H_
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