Bitfield.h

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/*
 * Copyright (c) 2005 Palmsource, Inc.
 * 
 * This software is licensed as described in the file LICENSE, which
 * you should have received as part of this distribution. The terms
 * are also available at http://www.openbinder.org/license.html.
 * 
 * This software consists of voluntary contributions made by many
 * individuals. For the exact contribution history, see the revision
 * history and logs, available at http://www.openbinder.org
 */

#ifndef _SUPPORT_BITFIELD_H_
#define _SUPPORT_BITFIELD_H_

#include <support/SupportDefs.h>

#if _SUPPORTS_NAMESPACE
namespace palmos {
namespace support {
#endif

/**************************************************************************************/


class SBitfield
{
    struct bitfield_bit;
    friend struct bitfield_bit;

public:
                        SBitfield(size_t size = 0);             
                        SBitfield(size_t size, bool intial);    
                        SBitfield(const SBitfield& copy);
                        ~SBitfield();

            bool        operator == (const SBitfield& other);   
            status_t    Resize(size_t bits);                    
    inline  size_t      CountBits() const;                      
            status_t    InitCheck() const;                      
    
    inline  bool        Test(size_t bit) const;                 

            status_t    Set(size_t start, size_t len);
    inline  void        Set(size_t bit);                        

            bool        TestAndSet(size_t bit);                 

            status_t    Clear(size_t start, size_t len);
    inline  void        Clear(size_t bit);                      

            ssize_t     FirstSet() const;

            ssize_t     FirstClear() const;
    
    inline  bitfield_bit    operator[] (size_t bit)         { return bitfield_bit(*this, bit); }
    inline  bool            operator[] (size_t bit) const   {  return Test(bit); }

private:
    struct bitfield_bit {
        inline bitfield_bit(SBitfield& bitfield, size_t bit) : m_bitfield(bitfield), m_bit(bit) { }
        inline bitfield_bit& operator = (bool value);
        inline operator bool();
    private:
        SBitfield& m_bitfield;
        size_t m_bit;
    };

    inline size_t alloc_size(size_t size);

    struct bitfield_fill_info;
    static void compute_masks(size_t start, size_t len, bitfield_fill_info&);
    static int32_t SBitfield::word_set(uint32_t word);
    bool is_inline() const;
    union {
        uint32_t *  m_bits;
        uint32_t    m_inlineBits;
    };
    ssize_t m_numBits;
};

/*-------------------------------------------------------------*/
/*---- No user serviceable parts after this -------------------*/

#define BF_NUM_INLINE_BITS  (32)

inline size_t SBitfield::CountBits() const
{
    return m_numBits;
}

inline bool SBitfield::Test(size_t bit) const
{
    return ( ((m_numBits > BF_NUM_INLINE_BITS) ? (m_bits[bit>>5]) : (m_inlineBits)) & (0x80000000LU >> (bit & 0x1F)) ) != 0;
    //This was in the BeOS tree:
    //return (bool)( ( ((m_numBits > BF_NUM_INLINE_BITS) ? (m_bits[bit>>5]) : m_inlineBits) >> ((~bit) & 0x1F) ) & 0x1LU );
}

inline void SBitfield::Set(size_t bit)
{
    ((m_numBits > BF_NUM_INLINE_BITS) ? (m_bits[bit>>5]) : (m_inlineBits)) |= (0x80000000LU >> (bit & 0x1F));
}

inline size_t SBitfield::alloc_size(size_t size)
{
    // allocate always in multiple of 32
    // so we round up to multiple of 32 and then divide by 8
    // to return number of bytes

    return ((size+31) & ~31) >> 3; 
}

inline void SBitfield::Clear(size_t bit)
{
    ((m_numBits > BF_NUM_INLINE_BITS) ? (m_bits[bit>>5]) : (m_inlineBits)) &= ~(0x80000000LU >> (bit & 0x1F));
}

inline SBitfield::bitfield_bit& SBitfield::bitfield_bit::operator = (bool value)
{
    if (value)  m_bitfield.Set(m_bit);
    else m_bitfield.Clear(m_bit);
    return *this;
}

inline SBitfield::bitfield_bit::operator bool()
{
    return m_bitfield.Test(m_bit);
}

/**************************************************************************************/

#if _SUPPORTS_NAMESPACE
} } // namespace palmos::support
#endif

#endif  /* _SUPPORT_BITFIELD_H_ */

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