vec_reg.hh

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 * property including but not limited to intellectual property relating
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#ifndef __ARCH_GENERIC_VEC_REG_HH__
#define __ARCH_GENERIC_VEC_REG_HH__

#include <array>
#include <cassert>
#include <iostream>
#include <string>
#include <type_traits>
#include <vector>

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

constexpr unsigned MaxVecRegLenInBytes = 4096;

template <size_t Sz>
class VecRegContainer;

template <typename VecElem, size_t NumElems, bool Const>
class VecRegT
{
    static constexpr inline size_t
    size()
    {
        return sizeof(VecElem) * NumElems;
    }
  public:
    using Container = typename std::conditional<Const,
                                              const VecRegContainer<size()>,
                                              VecRegContainer<size()>>::type;
  private:
    using MyClass = VecRegT<VecElem, NumElems, Const>;
    Container& container;

  public:
    VecRegT(Container& cnt) : container(cnt) {};

    template<bool Condition = !Const>
    typename std::enable_if<Condition, void>::type
    zero() { container.zero(); }

    template<bool Condition = !Const>
    typename std::enable_if<Condition, MyClass&>::type
    operator=(const MyClass& that)
    {
        container = that.container;
        return *this;
    }

    const VecElem& operator[](size_t idx) const
    {
        return container.template raw_ptr<VecElem>()[idx];
    }

    template<bool Condition = !Const>
    typename std::enable_if<Condition, VecElem&>::type
    operator[](size_t idx)
    {
        return container.template raw_ptr<VecElem>()[idx];
    }

    template<typename VE2, size_t NE2, bool C2>
    bool
    operator==(const VecRegT<VE2, NE2, C2>& that) const
    {
        return container == that.container;
    }
    template<typename VE2, size_t NE2, bool C2>
    bool
    operator!=(const VecRegT<VE2, NE2, C2>& that) const
    {
        return !operator==(that);
    }

    friend std::ostream&
    operator<<(std::ostream& os, const MyClass& vr)
    {
        /* 0-sized is not allowed */
        os << "[" << std::hex << (uint32_t)vr[0];
        for (uint32_t e = 1; e < vr.size(); e++)
            os << " " << std::hex << (uint32_t)vr[e];
        os << ']';
        return os;
    }

    const std::string print() const { return csprintf("%s", *this); }
    operator Container&() { return container; }
};

/* Forward declaration. */
template <typename VecElem, bool Const>
class VecLaneT;

template <size_t SIZE>
class VecRegContainer
{
  static_assert(SIZE > 0,
          "Cannot create Vector Register Container of zero size");
  static_assert(SIZE <= MaxVecRegLenInBytes,
          "Vector Register size limit exceeded");
  public:
    static constexpr inline size_t size() { return SIZE; };
    using Container = std::array<uint8_t, SIZE>;
  private:
    // 16-byte aligned to support 128bit element view
    alignas(16) Container container;
    using MyClass = VecRegContainer<SIZE>;

  public:
    VecRegContainer() {}
    VecRegContainer(const VecRegContainer &) = default;
    /* This is required for de-serialisation. */
    VecRegContainer(const std::vector<uint8_t>& that)
    {
        assert(that.size() >= SIZE);
        std::memcpy(container.data(), &that[0], SIZE);
    }

    void zero() { memset(container.data(), 0, SIZE); }

    MyClass& operator=(const MyClass& that)
    {
        if (&that == this)
            return *this;
        memcpy(container.data(), that.container.data(), SIZE);
        return *this;
    }

    MyClass& operator=(const Container& that)
    {
        std::memcpy(container.data(), that.data(), SIZE);
        return *this;
    }

    MyClass& operator=(const std::vector<uint8_t>& that)
    {
        assert(that.size() >= SIZE);
        std::memcpy(container.data(), that.data(), SIZE);
        return *this;
    }
    void copyTo(Container& dst) const
    {
        std::memcpy(dst.data(), container.data(), SIZE);
    }

    void copyTo(std::vector<uint8_t>& dst) const
    {
        dst.resize(SIZE);
        std::memcpy(dst.data(), container.data(), SIZE);
    }
    template<size_t S2>
    inline bool
    operator==(const VecRegContainer<S2>& that) const
    {
        return SIZE == S2 &&
               !memcmp(container.data(), that.container.data(), SIZE);
    }
    template<size_t S2>
    bool
    operator!=(const VecRegContainer<S2>& that) const
    {
        return !operator==(that);
    }

    const std::string print() const { return csprintf("%s", *this); }
    template <typename Ret>
    const Ret* raw_ptr() const { return (const Ret*)container.data(); }

    template <typename Ret>
    Ret* raw_ptr() { return (Ret*)container.data(); }

    template <typename VecElem, size_t NumElems=(SIZE / sizeof(VecElem))>
    VecRegT<VecElem, NumElems, true> as() const
    {
        static_assert(SIZE % sizeof(VecElem) == 0,
                "VecElem does not evenly divide the register size");
        static_assert(sizeof(VecElem) * NumElems <= SIZE,
                "Viewing VecReg as something bigger than it is");
        return VecRegT<VecElem, NumElems, true>(*this);
    }

    template <typename VecElem, size_t NumElems=(SIZE / sizeof(VecElem))>
    VecRegT<VecElem, NumElems, false> as()
    {
        static_assert(SIZE % sizeof(VecElem) == 0,
                "VecElem does not evenly divide the register size");
        static_assert(sizeof(VecElem) * NumElems <= SIZE,
                "Viewing VecReg as something bigger than it is");
        return VecRegT<VecElem, NumElems, false>(*this);
    }

    template <typename VecElem, int LaneIdx>
    VecLaneT<VecElem, false> laneView();
    template <typename VecElem, int LaneIdx>
    VecLaneT<VecElem, true> laneView() const;
    template <typename VecElem>
    VecLaneT<VecElem, false> laneView(int laneIdx);
    template <typename VecElem>
    VecLaneT<VecElem, true> laneView(int laneIdx) const;
    friend std::ostream& operator<<(std::ostream& os, const MyClass& v)
    {
        for (auto& b: v.container) {
            os << csprintf("%02x", b);
        }
        return os;
    }
};

enum class LaneSize
{
    Empty = 0,
    Byte,
    TwoByte,
    FourByte,
    EightByte,
};

template <LaneSize LS>
class LaneData
{
  public:
    using UnderlyingType =
        typename std::conditional<LS == LaneSize::EightByte, uint64_t,
            typename std::conditional<LS == LaneSize::FourByte, uint32_t,
                typename std::conditional<LS == LaneSize::TwoByte, uint16_t,
                    typename std::conditional<LS == LaneSize::Byte, uint8_t,
                    void>::type
                >::type
            >::type
        >::type;
  private:
    static constexpr auto ByteSz = sizeof(UnderlyingType);
    UnderlyingType _val;
    using MyClass = LaneData<LS>;

  public:
    template <typename T> explicit
    LaneData(typename std::enable_if<sizeof(T) == ByteSz, const T&>::type t)
                : _val(t) {}

    template <typename T>
    typename std::enable_if<sizeof(T) == ByteSz, MyClass&>::type
    operator=(const T& that)
    {
        _val = that;
        return *this;
    }
    template<typename T,
             typename std::enable_if<sizeof(T) == ByteSz, int>::type I = 0>
    operator T() const {
        return *static_cast<const T*>(&_val);
    }
};

template <LaneSize LS>
inline std::ostream&
operator<<(std::ostream& os, const LaneData<LS>& d)
{
    return os << static_cast<typename LaneData<LS>::UnderlyingType>(d);
}

/* General */
template <typename VecElem, bool Const>
class VecLaneT
{
  public:
    friend VecLaneT<VecElem, !Const>;

    /*template <size_t Sz>
    friend class VecRegContainer;*/
    friend class VecRegContainer<8>;
    friend class VecRegContainer<16>;
    friend class VecRegContainer<32>;
    friend class VecRegContainer<64>;
    friend class VecRegContainer<128>;
    friend class VecRegContainer<256>;
    friend class VecRegContainer<MaxVecRegLenInBytes>;

    using MyClass = VecLaneT<VecElem, Const>;

  private:
    using Cont = typename std::conditional<Const,
                                              const VecElem,
                                              VecElem>::type;
    static_assert(!std::is_const<VecElem>::value || Const,
            "Asked for non-const lane of const type!");
    static_assert(std::is_integral<VecElem>::value,
            "VecElem type is not integral!");
    Cont& container;

    VecLaneT(Cont& cont) : container(cont) { }

  public:
    template <bool Assignable = !Const>
    typename std::enable_if<Assignable, MyClass&>::type
    operator=(const VecElem& that) {
        container = that;
        return *this;
    }
    template <bool Assignable = !Const, typename T>
    typename std::enable_if<Assignable, MyClass&>::type
    operator=(const T& that) {
        static_assert(sizeof(T) >= sizeof(VecElem),
                "Attempt to perform widening bitwise copy.");
        static_assert(sizeof(T) <= sizeof(VecElem),
                "Attempt to perform narrowing bitwise copy.");
        container = static_cast<VecElem>(that);
        return *this;
    }
    operator VecElem() const { return container; }

    template <bool Cond = !Const, typename std::enable_if<Cond, int>::type = 0>
    operator VecLaneT<typename std::enable_if<Cond, VecElem>::type, true>()
    {
        return VecLaneT<VecElem, true>(container);
    }
};

namespace std {
    template<typename T, bool Const>
    struct add_const<VecLaneT<T, Const>> { typedef VecLaneT<T, true> type; };
}

template <size_t Sz>
template <typename VecElem, int LaneIdx>
VecLaneT<VecElem, false>
VecRegContainer<Sz>::laneView()
{
    return VecLaneT<VecElem, false>(as<VecElem>()[LaneIdx]);
}

template <size_t Sz>
template <typename VecElem, int LaneIdx>
VecLaneT<VecElem, true>
VecRegContainer<Sz>::laneView() const
{
    return VecLaneT<VecElem, true>(as<VecElem>()[LaneIdx]);
}

template <size_t Sz>
template <typename VecElem>
VecLaneT<VecElem, false>
VecRegContainer<Sz>::laneView(int laneIdx)
{
    return VecLaneT<VecElem, false>(as<VecElem>()[laneIdx]);
}

template <size_t Sz>
template <typename VecElem>
VecLaneT<VecElem, true>
VecRegContainer<Sz>::laneView(int laneIdx) const
{
    return VecLaneT<VecElem, true>(as<VecElem>()[laneIdx]);
}

using VecLane8 = VecLaneT<uint8_t, false>;
using VecLane16 = VecLaneT<uint16_t, false>;
using VecLane32 = VecLaneT<uint32_t, false>;
using VecLane64 = VecLaneT<uint64_t, false>;

using ConstVecLane8 = VecLaneT<uint8_t, true>;
using ConstVecLane16 = VecLaneT<uint16_t, true>;
using ConstVecLane32 = VecLaneT<uint32_t, true>;
using ConstVecLane64 = VecLaneT<uint64_t, true>;

template <size_t Sz>
inline bool
to_number(const std::string& value, VecRegContainer<Sz>& v)
{
    fatal_if(value.size() > 2 * VecRegContainer<Sz>::size(),
             "Vector register value overflow at unserialize");

    for (int i = 0; i < VecRegContainer<Sz>::size(); i++) {
        uint8_t b = 0;
        if (2 * i < value.size())
            b = stoul(value.substr(i * 2, 2), nullptr, 16);
        v.template raw_ptr<uint8_t>()[i] = b;
    }
    return true;
}
using DummyVecElem = uint32_t;
constexpr unsigned DummyNumVecElemPerVecReg = 2;
using DummyVecReg = VecRegT<DummyVecElem, DummyNumVecElemPerVecReg, false>;
using DummyConstVecReg = VecRegT<DummyVecElem, DummyNumVecElemPerVecReg, true>;
using DummyVecRegContainer = DummyVecReg::Container;
constexpr size_t DummyVecRegSizeBytes = DummyNumVecElemPerVecReg *
    sizeof(DummyVecElem);
#endif /* __ARCH_GENERIC_VEC_REG_HH__ */