Humble Framework for SkyOS

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HRandom.h

Go to the documentation of this file.

/****************************************************************************
**
**  $Header: /SkyOS.root/pig/Humble/HRandom.h 3     12/10/04 3:57p Neusel $
**
****************************************************************************/
#ifndef HRANDOM_H
    #define HRANDOM_H

class HRandom : public HObjNoCopy
    {
    typedef HObjNoCopy  base_class;
    static StringPtr    ClassName(void) { return "HRandom"; }

    enum    {
            kPeriod = 397,
            kLength = 624
            } bogus;
/*  -----------------------------------------------------------------------
    VARIABLES
    ----------------------------------------------------------------------- */
protected:
    int32               m_nLeft;        
    uint32              m_uSeed;        
    uint32 *            m_puNext;       
    uint32              m_uState[kLength+1];    
/*  -----------------------------------------------------------------------
    CTOR / DTOR
    ----------------------------------------------------------------------- */
public:
    HRandom(uint32 uSeed = 0) : m_nLeft(-1), m_uSeed(0), m_puNext(NULL)
        { if (uSeed) SetSeed(uSeed); }

    ~HRandom(void)
        { /* EMPTY DTOR */ }
/*  -----------------------------------------------------------------------
    METHODS
    ----------------------------------------------------------------------- */
protected:
    uint32
    reload(void)
        {
        int32       ndx;
        uint32      uS0, 
                    uS1;
        uint32 *    pu0 = m_uState;
        uint32 *    pu2 = &m_uState[2];
        uint32 *    puM = &m_uState[kPeriod];

        if (m_nLeft < -1)
            HError::Throw(ERR_NOT_INITIALIZED, __FILE__, __LINE__);

#define hiBit(u)        ((u) & 0x80000000U)     // mask all but highest   bit of u
#define loBit(u)        ((u) & 0x00000001U)     // mask all but lowest    bit of u
#define loBits(u)       ((u) & 0x7FFFFFFFU)     // mask     the highest   bit of u
#define mixBits(u,v)    (hiBit(u) | loBits(v))  // move hi bit of u to hi bit of v

        m_nLeft = kLength - 1;
        m_puNext = m_uState + 1;

        uS0 = m_uState[0];
        uS1 = m_uState[1];
        for (ndx = (kLength - kPeriod) + 1; --ndx; uS0 = uS1, uS1 = *pu2++)
            *pu0++ = *puM++ ^ (mixBits(uS0, uS1) >> 1) ^ (loBit(uS1) ? 0x9908B0DFU : 0U);

        for (puM = m_uState, ndx = kPeriod; --ndx; uS0 = uS1, uS1 = *pu2++)
            *pu0++ = *puM++ ^ (mixBits(uS0, uS1) >> 1) ^ (loBit(uS1) ? 0x9908B0DFU : 0U);

        uS1 = m_uState[0];
        *pu0 = *puM ^ (mixBits(uS0, uS1) >> 1) ^ (loBit(uS1) ? 0x9908B0DFU : 0U);
        uS1 ^= (uS1 >> 11);
        uS1 ^= (uS1 <<  7) & 0x9D2C5680U;
        uS1 ^= (uS1 << 15) & 0xEFC60000U;

        return uS1 ^ (uS1 >> 18);
        }
/*  -----------------------------------------------------------------------
    GETTERS & SETTERS
    ----------------------------------------------------------------------- */
public: 
    uint32              Get(void)
                            {
                            uint32  uiRnd;

                            if (--m_nLeft >= 0)
                                {
                                uiRnd  = *m_puNext++;
                                uiRnd ^= (uiRnd >> 11);
                                uiRnd ^= (uiRnd <<  7) & 0x9D2C5680U;
                                uiRnd ^= (uiRnd << 15) & 0xEFC60000U;
                                uiRnd ^= (uiRnd >> 18);
                                }
                            else
                                uiRnd = reload();

                            return uiRnd;
                            }
    uint32              Get(uint32 uMax)
                            {
                            uint32  uRnd = Get();

                            if (uMax == 1)  // special case is a 0/1 coin flip
                                uRnd &= 0x01;
                            else if (uMax < uint32(INT32_MAX))
                                uRnd %= uMax;

                            return uRnd;
                            }
    int32               Get(uint32 uCount, uint32 uDieSize, int32 nBonus = 0)
                            {
                            int32   nRnd = nBonus * uCount;
                        
                            if (uCount > 0 && uDieSize > 0)
                                {
                                ASSERT(uCount < uint32(INT32_MAX));
                                ASSERT(uDieSize < uint32(INT32_MAX));
                            
                                while (uCount-- > 0)
                                    nRnd += Get(uDieSize) + 1;
                                }
                            
                            return nRnd;
                            }
    uint32              GetSeed(void) const
                            { return m_uSeed; }
    ErrCode             SetSeed(uint32 uSeed)
                            {
                            uint32 *    puState = m_uState;

                            DEBUG_LOG("HRandom::SetSeed() => seed value is %lu\n", uSeed);

                            m_uSeed = uSeed;
                            uSeed |= 1U;
                            for (int32 ndx = 0; ndx < kLength; ++ndx)
                                {
                                *puState++ = uSeed;
                                uSeed *= 69069U;
                                }
/*                              
                            *puState++ = uSeed;
                            for (int32 ndx = kLength; --ndx > 0; *puState++ = uSeed)
                                uSeed *= 69069U;
*/
                            m_nLeft = 0;
                            return HError::NoError();
                            }
    };

#endif  // HRANDOM_H
/****************************************************************************
**
**  $History: HRandom.h $
 * 
 * *****************  Version 3  *****************
 * User: Neusel       Date: 12/10/04   Time: 3:57p
 * Updated in $/SkyOS.root/pig/Humble
 * 20041210
 * 
 * *****************  Version 2  *****************
 * User: Neusel       Date: 11/30/04   Time: 1:01p
 * Updated in $/SkyOS.root/pig/Humble
 * Released as HUMBLE_VER 20041130.
 * 
 * *****************  Version 1  *****************
 * User: Neusel       Date: 11/23/04   Time: 8:24a
 * Created in $/SkyOS.root/pig/Humble
**
**  -------------------------------------------------------------------------
**
**  End of HRandom.h
**
****************************************************************************/

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