forked from OSchip/llvm-project
116 lines
3.5 KiB
C++
116 lines
3.5 KiB
C++
//===- FixedPoint.cpp - Fixed point constant handling -----------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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/// \file
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/// Defines the implementation for the fixed point number interface.
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//
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//===----------------------------------------------------------------------===//
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#include "clang/Basic/FixedPoint.h"
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namespace clang {
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APFixedPoint APFixedPoint::convert(const FixedPointSemantics &DstSema) const {
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llvm::APSInt NewVal = Val;
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unsigned DstWidth = DstSema.getWidth();
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unsigned DstScale = DstSema.getScale();
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bool Upscaling = DstScale > getScale();
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if (Upscaling) {
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NewVal = NewVal.extend(NewVal.getBitWidth() + DstScale - getScale());
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NewVal <<= (DstScale - getScale());
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} else {
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NewVal >>= (getScale() - DstScale);
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}
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if (DstSema.isSaturated()) {
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auto Mask = llvm::APInt::getBitsSetFrom(
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NewVal.getBitWidth(),
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std::min(DstScale + DstSema.getIntegralBits(), NewVal.getBitWidth()));
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llvm::APInt Masked(NewVal & Mask);
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// Change in the bits above the sign
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if (!(Masked == Mask || Masked == 0))
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NewVal = NewVal.isNegative() ? Mask : ~Mask;
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if (!DstSema.isSigned() && NewVal.isNegative())
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NewVal = 0;
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}
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NewVal = NewVal.extOrTrunc(DstWidth);
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NewVal.setIsSigned(DstSema.isSigned());
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return APFixedPoint(NewVal, DstSema);
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}
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int APFixedPoint::compare(const APFixedPoint &Other) const {
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llvm::APSInt ThisVal = getValue();
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llvm::APSInt OtherVal = Other.getValue();
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bool ThisSigned = Val.isSigned();
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bool OtherSigned = OtherVal.isSigned();
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unsigned OtherScale = Other.getScale();
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unsigned OtherWidth = OtherVal.getBitWidth();
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unsigned CommonWidth = std::max(Val.getBitWidth(), OtherWidth);
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// Prevent overflow in the event the widths are the same but the scales differ
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CommonWidth += getScale() >= OtherScale ? getScale() - OtherScale
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: OtherScale - getScale();
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ThisVal = ThisVal.extOrTrunc(CommonWidth);
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OtherVal = OtherVal.extOrTrunc(CommonWidth);
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unsigned CommonScale = std::max(getScale(), OtherScale);
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ThisVal = ThisVal.shl(CommonScale - getScale());
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OtherVal = OtherVal.shl(CommonScale - OtherScale);
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if (ThisSigned && OtherSigned) {
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if (ThisVal.sgt(OtherVal))
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return 1;
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else if (ThisVal.slt(OtherVal))
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return -1;
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} else if (!ThisSigned && !OtherSigned) {
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if (ThisVal.ugt(OtherVal))
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return 1;
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else if (ThisVal.ult(OtherVal))
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return -1;
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} else if (ThisSigned && !OtherSigned) {
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if (ThisVal.isSignBitSet())
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return -1;
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else if (ThisVal.ugt(OtherVal))
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return 1;
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else if (ThisVal.ult(OtherVal))
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return -1;
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} else {
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// !ThisSigned && OtherSigned
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if (OtherVal.isSignBitSet())
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return 1;
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else if (ThisVal.ugt(OtherVal))
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return 1;
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else if (ThisVal.ult(OtherVal))
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return -1;
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}
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return 0;
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}
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APFixedPoint APFixedPoint::getMax(const FixedPointSemantics &Sema) {
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bool IsUnsigned = !Sema.isSigned();
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auto Val = llvm::APSInt::getMaxValue(Sema.getWidth(), IsUnsigned);
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if (IsUnsigned && Sema.hasUnsignedPadding())
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Val = Val.lshr(1);
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return APFixedPoint(Val, Sema);
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}
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APFixedPoint APFixedPoint::getMin(const FixedPointSemantics &Sema) {
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auto Val = llvm::APSInt::getMinValue(Sema.getWidth(), !Sema.isSigned());
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return APFixedPoint(Val, Sema);
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}
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} // namespace clang
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