bitfield.h

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#pragma once
//------------------------------------------------------------------------------
#include "core/types.h"
 
//------------------------------------------------------------------------------
namespace Util
{
template <unsigned int NUMBITS> class BitField
{
    static_assert(NUMBITS > 0);
 
public:
    BitField();
    constexpr BitField(std::initializer_list<unsigned int> list);
    BitField(const BitField<NUMBITS>& rhs) = default;
 
    constexpr bool operator==(const BitField<NUMBITS>& rhs) const;
    constexpr bool operator!=(const BitField<NUMBITS>& rhs) const;
 
    constexpr bool IsSet(const uint64_t bitIndex) const;
    template <uint64_t bitIndex> constexpr bool IsSet() const;
    void Clear();
    bool IsNull() const;
    constexpr void SetBit(const uint64_t bitIndex);
    constexpr void SetBitIf(const uint64_t bitIndex, uint64_t cond);
    template <uint64_t bitIndex> constexpr void SetBit();
    void ClearBit(const uint64_t bitIndex);
    
    bool SectionIsNull(uint64_t section) const;
 
    static constexpr BitField<NUMBITS> Or(const BitField<NUMBITS>& b0, const BitField<NUMBITS>& b1);
    static constexpr BitField<NUMBITS> And(const BitField<NUMBITS>& b0, const BitField<NUMBITS>& b1);
 
private:
    static constexpr uint64_t BASE = NUMBITS > 32 ? 64 : NUMBITS > 16 ? 32 : NUMBITS > 8 ? 16 : 8;
    static const int size = ((NUMBITS + BASE - 1) / BASE);
 
    // Template magic to automatically use the smallest type possible
    template <size_t S> struct BitType
    {
        using T = uint8_t;
    };
    template <> struct BitType<16>
    {
        using T = uint16_t;
    };
    template <> struct BitType<32>
    {
        using T = uint32_t;
    };
    template <> struct BitType<64>
    {
        using T = uint64_t;
    };
 
    using TYPE = typename BitType<BASE>::T;
 
    TYPE bits[size];
};
 
//------------------------------------------------------------------------------
template <unsigned int NUMBITS> BitField<NUMBITS>::BitField()
{
    IndexT i;
    for (i = 0; i < size; i++)
    {
        this->bits[i] = 0;
    }
}
 
//------------------------------------------------------------------------------
template <unsigned int NUMBITS> constexpr BitField<NUMBITS>::BitField(std::initializer_list<unsigned int> list)
{
    for (IndexT i = 0; i < size; i++)
    {
        this->bits[i] = 0;
    }
 
    for (auto bit : list)
    {
        this->SetBit(bit);
    }
}
 
//------------------------------------------------------------------------------
template <unsigned int NUMBITS>
constexpr bool
BitField<NUMBITS>::operator==(const BitField<NUMBITS>& rhs) const
{
    for (IndexT i = 0; i < size; i++)
    {
        if (this->bits[i] != rhs.bits[i])
        {
            return false;
        }
    }
    return true;
}
 
//------------------------------------------------------------------------------
template <unsigned int NUMBITS>
constexpr bool
BitField<NUMBITS>::operator!=(const BitField<NUMBITS>& rhs) const
{
    return !(*this == rhs);
}
 
//------------------------------------------------------------------------------
template <unsigned int NUMBITS>
constexpr bool
BitField<NUMBITS>::IsSet(const uint64_t bitIndex) const
{
    n_assert(bitIndex < NUMBITS);
    const TYPE i = (1ull << (bitIndex % BASE));
    const TYPE index = bitIndex / BASE;
    return (this->bits[index] & i) == i;
}
 
//------------------------------------------------------------------------------
template <unsigned int NUMBITS>
template <uint64_t bitIndex>
constexpr bool
BitField<NUMBITS>::IsSet() const
{
    static_assert(bitIndex < NUMBITS);
    constexpr TYPE i = (1ull << (bitIndex % BASE));
    constexpr TYPE index = bitIndex / BASE;
    return (this->bits[index] & i) == i;
}
 
//------------------------------------------------------------------------------
template <unsigned int NUMBITS>
void
BitField<NUMBITS>::Clear()
{
    IndexT i;
    for (i = 0; i < size; i++)
    {
        this->bits[i] = 0;
    }
}
 
//------------------------------------------------------------------------------
template <unsigned int NUMBITS>
bool
BitField<NUMBITS>::IsNull() const
{
    IndexT i;
    for (i = 0; i < size; i++)
    {
        if (this->bits[i] != 0)
        {
            return false;
        }
    }
    return true;
}
 
//------------------------------------------------------------------------------
template <unsigned int NUMBITS>
constexpr void
BitField<NUMBITS>::SetBit(const uint64_t i)
{
    n_assert(i < NUMBITS);
    const TYPE index = i / BASE;
    const TYPE bit = (1ull << (i % BASE));
    this->bits[index] |= bit;
}
 
//------------------------------------------------------------------------------
template <unsigned int NUMBITS>
constexpr void
BitField<NUMBITS>::SetBitIf(const uint64_t i, uint64_t cond)
{
    n_assert(i < NUMBITS);
    const TYPE index = i / BASE;
    const TYPE bit = (1ull << (i % BASE));
    this->bits[index] |= bit * cond;
}
 
//------------------------------------------------------------------------------
template <unsigned int NUMBITS>
template <uint64_t i>
constexpr void
BitField<NUMBITS>::SetBit()
{
    static_assert(i < NUMBITS);
    constexpr TYPE index = i / BASE;
    constexpr TYPE bit = (1ull << (i % BASE));
    this->bits[index] |= bit;
}
 
//------------------------------------------------------------------------------
template <unsigned int NUMBITS>
void
BitField<NUMBITS>::ClearBit(const uint64_t i)
{
    n_assert(i < NUMBITS);
    const TYPE index = i / BASE;
    const TYPE bit = ~(1ull << (i % BASE));
    this->bits[index] &= bit;
}
 
//------------------------------------------------------------------------------
template <unsigned int NUMBITS>
bool
BitField<NUMBITS>::SectionIsNull(uint64_t section) const
{
    n_assert(section < this->size);
    return this->bits[section] == 0;
}
 
//------------------------------------------------------------------------------
template <unsigned int NUMBITS>
constexpr BitField<NUMBITS>
BitField<NUMBITS>::Or(const BitField<NUMBITS>& b0, const BitField<NUMBITS>& b1)
{
    BitField<NUMBITS> res;
    for (IndexT i = 0; i < size; i++)
    {
        res.bits[i] = b0.bits[i] | b1.bits[i];
    }
    return res;
}
 
//------------------------------------------------------------------------------
template <unsigned int NUMBITS>
constexpr BitField<NUMBITS>
BitField<NUMBITS>::And(const BitField<NUMBITS>& b0, const BitField<NUMBITS>& b1)
{
    BitField<NUMBITS> res;
    for (IndexT i = 0; i < size; i++)
    {
        res.bits[i] = b0.bits[i] & b1.bits[i];
    }
    return res;
}
 
} // namespace Util
//------------------------------------------------------------------------------