o3de/Code/Editor/Util/bitarray.h

/*
 * Copyright (c) Contributors to the Open 3D Engine Project.
 * For complete copyright and license terms please see the LICENSE at the root of this distribution.
 *
 * SPDX-License-Identifier: Apache-2.0 OR MIT
 *
 */


// Description : Array of m_bits.


#ifndef CRYINCLUDE_EDITOR_UTIL_BITARRAY_H
#define CRYINCLUDE_EDITOR_UTIL_BITARRAY_H
#pragma once


//////////////////////////////////////////////////////////////////////////
//
// CBitArray is similar to std::vector but faster to clear.
//
//////////////////////////////////////////////////////////////////////////
class CBitArray
{
public:
    struct BitReference
    {
        uint32* p;
        uint32 mask;
        BitReference(uint32* __x, uint32 __y)
            : p(__x)
            , mask(__y) {}


    public:
        BitReference()
            : p(0)
            , mask(0) {}

        operator bool() const {
            return !(!(*p & mask));
        }
        BitReference& operator=(bool __x)
        {
            if (__x)
            {
                * p |= mask;
            }
            else
            {
                * p &= ~mask;
            }
            return *this;
        }
        BitReference& operator=(const BitReference& __x) { return *this = bool(__x);  }
        bool operator==(const BitReference& __x) const { return bool(*this) == bool(__x); }
        bool operator<(const BitReference& __x) const { return !bool(*this) && bool(__x);   }
        BitReference& operator |= (bool __x)
        {
            if (__x)
            {
                * p |= mask;
            }
            return *this;
        }
        BitReference& operator &= (bool __x)
        {
            if (!__x)
            {
                * p &= ~mask;
            }
            return *this;
        }
        void flip() {* p ^= mask; }
    };

    CBitArray() { m_base = nullptr; m_bits = nullptr; m_size = 0; m_numBits = 0; };
    CBitArray(int numBits)    { resize(numBits); };
    ~CBitArray()
    {
        if (m_base)
        {
            free(m_base);
        }
    };

    void    resize(int c)
    {
        m_numBits = c;
        int newSize = ((c + 63) & (~63)) >> 5;
        if (newSize > m_size)
        {
            Alloc(newSize);
        }
    }
    int size() const { return m_numBits; };
    bool empty() const { return m_numBits == 0; };

    //////////////////////////////////////////////////////////////////////////
    void set()
    {
        memset(m_bits, 0xFFFFFFFF, m_size * sizeof(uint32));  // Set all bits.
    }
    //////////////////////////////////////////////////////////////////////////
    void set(int numBits)
    {
        int num = (numBits >> 3) + 1;
        if (num > (m_size * sizeof(uint32)))
        {
            num = m_size * sizeof(uint32);
        }
        memset(m_bits, 0xFFFFFFFF, num);    // Reset num bits.
    }

    //////////////////////////////////////////////////////////////////////////
    void clear()
    {
        memset(m_bits, 0, m_size * sizeof(uint32));   // Reset all bits.
    }

    //////////////////////////////////////////////////////////////////////////
    void    clear(int numBits)
    {
        int num = (numBits >> 3) + 1;
        if (num > (m_size * sizeof(uint32)))
        {
            num = m_size * sizeof(uint32);
        }
        memset(m_bits, 0, num); // Reset num bits.
    }

    //////////////////////////////////////////////////////////////////////////
    // Check if all bits are 0.
    bool is_zero() const
    {
        for (int i = 0; i < m_size; i++)
        {
            if (m_bits[i] != 0)
            {
                return false;
            }
        }
        return true;
    }

    // Count number of set bits.
    int count_bits()    const
    {
        int c = 0;
        for (int i = 0; i < m_size; i++)
        {
            uint32 v = m_bits[i];
            for (int j = 0; j < 32; j++)
            {
                if (v & (1 << (j & 0x1F)))
                {
                    c++;                        // if bit set increase bit count.
                }
            }
        }
        return c;
    }

    BitReference operator[](int pos) { return BitReference(&m_bits[index(pos)], shift(pos)); }
    const BitReference operator[](int pos) const { return BitReference(&m_bits[index(pos)], shift(pos)); }

    //////////////////////////////////////////////////////////////////////////
    void swap(CBitArray& bitarr)
    {
        std::swap(m_base, bitarr.m_base);
        std::swap(m_bits, bitarr.m_bits);
        std::swap(m_size, bitarr.m_size);
    }

    CBitArray&  operator =(const CBitArray& b)
    {
        if (m_size != b.m_size)
        {
            Alloc(b.m_size);
        }
        memcpy(m_bits, b.m_bits, m_size * sizeof(uint32));
        return *this;
    }

    bool    checkByte(int pos) const {    return reinterpret_cast<char*>(m_bits)[pos] != 0; };

    //////////////////////////////////////////////////////////////////////////
    // Compresses this bit array into the specified one.
    // Uses run length encoding compression.
    void    compress(CBitArray& b) const
    {
        int i, countz, compsize, bsize;
        char* out;
        char* in;

        bsize = m_size * 4;
        compsize = 0;
        in = (char*)m_bits;
        for (i = 0; i < bsize; i++)
        {
            compsize++;
            if (in[i] == 0)
            {
                countz = 1;
                while (++i < bsize)
                {
                    if (in[i] == 0 && countz != 255)
                    {
                        countz++;
                    }
                    else
                    {
                        break;
                    }
                }
                i--;
                compsize++;
            }
        }
        b.resize((compsize + 1) << 3);
        out = (char*)b.m_bits;
        in = (char*)m_bits;
        *out++ = static_cast<char>(bsize);
        for (i = 0; i < bsize; i++)
        {
            *out++ = in[i];
            if (in[i] == 0)
            {
                countz = 1;
                while (++i < bsize)
                {
                    if (in[i] == 0 && countz != 255)
                    {
                        countz++;
                    }
                    else
                    {
                        break;
                    }
                }
                i--;
                *out++ = static_cast<char>(countz);
            }
        }
    }

    //////////////////////////////////////////////////////////////////////////
    // Decompress specified bit array in to this one.
    // Uses run length encoding compression.
    void    decompress(CBitArray& b)
    {
        int raw, decompressed, c;
        char* out, * in;

        in = (char*)m_bits;
        out = (char*)b.m_bits;
        decompressed = 0;
        raw = *in++;
        while (decompressed < raw)
        {
            if (*in != 0)
            {
                *out++ = *in++;
                decompressed++;
            }
            else
            {
                in++;
                c = *in++;
                decompressed += c;
                while (c)
                {
                    *out++ = 0;
                    c--;
                }
                ;
            }
        }
        m_numBits = decompressed;
    }

    void    CopyFromMem(const char* src, int size)
    {
        Alloc(size);
        memcpy(m_bits, src, size);
    }
    int     CopyToMem(char* trg)
    {
        memcpy(trg, m_bits, m_size);
        return m_size;
    }

private:
    void* m_base;
    uint32* m_bits;
    int     m_size;
    int     m_numBits;

    void    Alloc(int s)
    {
        if (m_base)
        {
            free(m_base);
        }
        m_size = s;
        m_base = (char*)malloc(m_size * sizeof(uint32) + 32);
        m_bits = (uint32*)(((UINT_PTR)m_base + 31) & (~31));    // align by 32.
        memset(m_bits, 0, m_size * sizeof(uint32));   // Reset all bits.
    }
    uint32  shift(int pos) const
    {
        return (1 << (pos & 0x1F));
    }
    uint32  index(int pos) const
    {
        return pos >> 5;
    }

    friend  int concatBitarray(CBitArray& b1, CBitArray& b2, CBitArray& test, CBitArray& res);
};

inline  int concatBitarray(CBitArray& b1, CBitArray& b2, CBitArray& test, CBitArray& res)
{
    unsigned int b, any;
    any = 0;
    for (int i = 0; i < b1.size(); i++)
    {
        b = b1.m_bits[i] & b2.m_bits[i];
        any |= (b & (~test.m_bits[i])); // test if any different from test(i) bit set.
        res.m_bits[i] = b;
    }
    return any;
}

#endif // CRYINCLUDE_EDITOR_UTIL_BITARRAY_H