gem5/src/base/bitunion.test.cc

/*
 * Copyright 2014 Google, Inc.
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#include <gtest/gtest.h>

#include <cassert>
#include <iostream>
#include <type_traits>

#include "base/bitunion.hh"
#include "base/cprintf.hh"

using namespace gem5;

namespace {

BitUnion64(SixtyFour)
    Bitfield<39, 32> byte5;
    Bitfield<2> bit2;
    BitfieldRO<39, 32> byte5RO;
    BitfieldWO<39, 32> byte5WO;
    SubBitUnion(byte6, 47, 40)
        Bitfield<43, 42> bits43To42;
        Bitfield<41> bit41;
        SignedBitfield<41> bit41Signed;
    EndSubBitUnion(byte6)
    SignedBitfield<47, 40> byte6Signed;
    SignedBitfieldRO<47, 40> byte6SignedRO;
    SignedBitfieldWO<47, 40> byte6SignedWO;
EndBitUnion(SixtyFour)

BitUnion64(EmptySixtyFour)
EndBitUnion(EmptySixtyFour)

BitUnion32(EmptyThirtyTwo)
EndBitUnion(EmptyThirtyTwo)

BitUnion16(EmptySixteen)
EndBitUnion(EmptySixteen)

BitUnion8(EmptyEight)
EndBitUnion(EmptyEight)

class SplitField
{
  protected:
    BitUnion64(In)
        Bitfield<15, 12> high;
        Bitfield<7, 4> low;
    EndBitUnion(In)

    BitUnion64(Out)
        Bitfield<7, 4> high;
        Bitfield<3, 0> low;
    EndBitUnion(Out)
  public:
    uint64_t
    getter(const uint64_t &storage) const
    {
        Out out = 0;
        In in = storage;
        out.high = in.high;
        out.low = in.low;
        return out;
    }

    void
    setter(uint64_t &storage, uint64_t val)
    {
        Out out = val;
        In in = 0;
        in.high = out.high;
        in.low = out.low;
        storage = in;
    }
};

BitUnion64(Split)
    BitfieldType<SplitField> split;
EndBitUnion(Split)

struct ContainingStruct
{
    BitUnion64(Contained)
        Bitfield<63, 60> topNibble;
    EndBitUnion(Contained)

    Contained contained;
};

uint64_t
containingFunc(uint64_t init_val, uint64_t fieldVal)
{
    BitUnion32(Contained)
        Bitfield<16, 15> field;
    EndBitUnion(Contained)

    Contained contained = init_val;
    contained.field = fieldVal;
    return contained;
}

} // anonymous namespace

// Declare these as global so g++ doesn't ignore them. Initialize them in
// various ways.
EmptySixtyFour emptySixtyFour = 0;
EmptyThirtyTwo emptyThirtyTwo{};
[[maybe_unused]] EmptySixteen emptySixteen;
EmptyEight emptyEight(0);

class BitUnionData : public testing::Test
{
  protected:
    SixtyFour sixtyFour;
    Split split;

    void SetUp() override { sixtyFour = 0; split = 0; }

    template <typename T>
    uint64_t templatedFunction(T) { return 0; }

    template <typename T>
    uint64_t
    templatedFunction(BitUnionType<T> u)
    {
        BitUnionBaseType<T> b = u;
        return b;
    }
};

TEST_F(BitUnionData, NormalBitfield)
{
    EXPECT_EQ(sixtyFour.byte5, 0);
    sixtyFour.byte5 = 0xff;
    EXPECT_EQ(sixtyFour, 0xff00000000);
    sixtyFour.byte5 = 0xfff;
    EXPECT_EQ(sixtyFour, 0xff00000000);
    EXPECT_EQ(sixtyFour.byte5, 0xff);
}

TEST_F(BitUnionData, SingleBitfield)
{
    EXPECT_EQ(sixtyFour.bit2, 0);
    sixtyFour.bit2 = 0x1;
    EXPECT_EQ(sixtyFour, 0x4);
    EXPECT_EQ(sixtyFour.bit2, 0x1);
}

TEST_F(BitUnionData, ReadOnlyBitfield)
{
    EXPECT_EQ(sixtyFour.byte5RO, 0);
    sixtyFour.byte5 = 0xff;
    EXPECT_EQ(sixtyFour.byte5RO, 0xff);
}

TEST_F(BitUnionData, WriteOnlyBitfield)
{
    sixtyFour.byte5WO = 0xff;
    EXPECT_EQ(sixtyFour, 0xff00000000);
}

TEST_F(BitUnionData, SubBitUnions)
{
    EXPECT_EQ(sixtyFour.byte6.bit41, 0);
    sixtyFour.byte6 = 0x2;
    EXPECT_EQ(sixtyFour.byte6.bit41, 1);
    sixtyFour.byte6.bits43To42 = 0x3;
    EXPECT_EQ(sixtyFour.byte6, 0xe);
    sixtyFour.byte6 = 0xff;
    sixtyFour.byte6.bit41 = 0;
    EXPECT_EQ(sixtyFour, 0xfd0000000000);
}

TEST_F(BitUnionData, SignedBitfields)
{
    sixtyFour.byte6 = 0xff;
    EXPECT_EQ(sixtyFour.byte6Signed, -1);
    EXPECT_EQ(sixtyFour.byte6SignedRO, -1);
    sixtyFour.byte6SignedWO = 0;
    EXPECT_EQ(sixtyFour.byte6Signed, 0);
    EXPECT_EQ(sixtyFour.byte6SignedRO, 0);
    EXPECT_EQ(sixtyFour.byte6, 0);
}

TEST_F(BitUnionData, InsideStruct)
{
    ContainingStruct containing;
    containing.contained = 0;
    containing.contained.topNibble = 0xd;
    EXPECT_EQ(containing.contained, 0xd000000000000000);
}

TEST_F(BitUnionData, InsideFunction)
{
    EXPECT_EQ(containingFunc(0xfffff, 0), 0xe7fff);
}

TEST_F(BitUnionData, BitfieldToBitfieldAssignment)
{
    SixtyFour otherSixtyFour = 0;
    sixtyFour.bit2 = 1;
    otherSixtyFour.byte6.bit41 = sixtyFour.bit2;
    EXPECT_EQ(otherSixtyFour, 0x20000000000);
    otherSixtyFour.bit2 = sixtyFour.bit2;
    EXPECT_EQ(otherSixtyFour, 0x20000000004);
}

TEST_F(BitUnionData, Operators)
{
    SixtyFour otherSixtyFour = 0x4;
    sixtyFour = otherSixtyFour;
    EXPECT_EQ(sixtyFour, 0x4);
    sixtyFour = 0;
    EXPECT_TRUE(sixtyFour < otherSixtyFour);
    EXPECT_TRUE(otherSixtyFour > sixtyFour);
    EXPECT_TRUE(sixtyFour != otherSixtyFour);
    sixtyFour = otherSixtyFour;
    EXPECT_TRUE(sixtyFour == otherSixtyFour);
}

TEST_F(BitUnionData, Custom)
{
    EXPECT_EQ(split, 0);
    split.split = 0xfff;
    EXPECT_EQ(split, 0xf0f0);
    EXPECT_EQ((uint64_t)split.split, 0xff);
}

TEST_F(BitUnionData, Templating)
{
    sixtyFour = 0xff;
    EXPECT_EQ(templatedFunction(sixtyFour), 0xff);
    EXPECT_EQ(templatedFunction((uint64_t)sixtyFour), 0);

    BitUnion(uint64_t, Dummy64)
    EndBitUnion(Dummy64);

    BitUnion(uint32_t, Dummy32)
    EndBitUnion(Dummy32);

    bool is64;
    is64 = std::is_same_v<BitUnionBaseType<Dummy64>, uint64_t>;
    EXPECT_TRUE(is64);
    is64 = std::is_same_v<BitUnionBaseType<Dummy32>, uint64_t>;
    EXPECT_FALSE(is64);
}

TEST_F(BitUnionData, Output)
{
    sixtyFour = 1234567812345678;
    std::stringstream ss;
    ss << sixtyFour;
    EXPECT_EQ(ss.str(), "1234567812345678");
    ss.str("");

    EmptyEight eight = 65;
    ss << eight;
    EXPECT_EQ(ss.str(), "65");
    ss.str("");
}