// Copyright (c) 2000-2011 by Digital Mars
// All Rights Reserved
// written by Walter Bright
// http://www.digitalmars.com
// License for redistribution is by either the Artistic License
// in artistic.txt, or the GNU General Public License in gnu.txt.
// See the included readme.txt for details.

#include <string.h>

#if __DMC__
// Inline bit operations
#include <bitops.h>
#endif

#ifdef linux
#include "gccbitops.h"
#endif

#if _MSC_VER
    // Disable useless warnings about unreferenced functions
    #pragma warning (disable : 4514)
#endif // _MSC_VER


#define BITS_PER_WORD   32
#define BITS_SHIFT      5
#define BITS_MASK       31

struct Mem;

struct GCBits
{
    unsigned *data;
    unsigned nwords;    // allocated words in data[] excluding sentinals
    unsigned nbits;     // number of bits in data[] excluding sentinals

    GCBits();
    ~GCBits();
    void invariant();

    void alloc(unsigned nbits);

#if __DMC__
    unsigned test(unsigned i) { return _inline_bt(data + 1, i); }
    void set(unsigned i)      { _inline_bts(data + 1, i); }
    void clear(unsigned i)    { _inline_btr(data + 1, i); }
    unsigned testClear(unsigned i) { return _inline_btr(data + 1, i); }
    unsigned testSet(unsigned i) { return _inline_bts(data + 1, i); }
#elif 0 //defined linux
    // for unknown reasons, GCC does badly with this
    unsigned test(unsigned i) { return _inline_bt(data + 1, i); }
    void set(unsigned i)      { _inline_bts(data + 1, i); }
    void clear(unsigned i)    { _inline_btr(data + 1, i); }
    unsigned testClear(unsigned i) { return _inline_btr(data + 1, i); }
    unsigned testSet(unsigned i) { return _inline_bts(data + 1, i); }
#else
    unsigned test(unsigned i) { return data[1 + (i >> BITS_SHIFT)] & (1 << (i & BITS_MASK)); }
    void set(unsigned i)      { data[1 + (i >> BITS_SHIFT)] |= (1 << (i & BITS_MASK)); }
    void clear(unsigned i)    { data[1 + (i >> BITS_SHIFT)] &= ~(1 << (i & BITS_MASK)); }
    unsigned testClear(unsigned i)
    {
        unsigned *p = &data[1 + (i >> BITS_SHIFT)];
        unsigned mask = (1 << (i & BITS_MASK));
        unsigned result = *p & mask;
        *p &= ~mask;
        return result;
    }
    unsigned testSet(unsigned i)
    {
        unsigned *p = &data[1 + (i >> BITS_SHIFT)];
        unsigned mask = (1 << (i & BITS_MASK));
        unsigned result = *p & mask;
        *p |= mask;
        return result;
    }
#endif

    void zero() { memset(data + 1, 0, nwords * sizeof(unsigned)); }
    void copy(GCBits *f) { memcpy(data + 1, f->data + 1, nwords * sizeof(unsigned)); }

    unsigned *base() { return data + 1; }
};