TRandom.cpp

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#include "ToshiPCH.h"
#include "TRandom.h"
 
#ifdef USE_PORTABLE
#  define cut( a ) ( (a)&0xffffffff ) /* Cut the integer down to 32bits */
#else
#  define cut( a ) ( a ) /* A no-op */
#endif
 
#define ind( mm, x ) ( ( mm )[ ( x >> 2 ) & ( RANDSIZ - 1 ) ] )
/* the call to cut() is a macro defined in standard.h */
#define rngstep( mix, a, b, mm, m, m2, r, x )               \
    {                                                       \
        x        = *m;                                      \
        a        = cut( ( a ^ ( mix ) ) + *( m2++ ) );      \
        *( m++ ) = y = cut( ind( mm, x ) + a + b );         \
        *( r++ ) = b = cut( ind( mm, y >> RANDSIZL ) + x ); \
    }
 
#define mix( a, b, c, d, e, f, g, h ) \
    {                                 \
        a ^= b << 11;                 \
        d += a;                       \
        b += c;                       \
        b ^= c >> 2;                  \
        e += b;                       \
        c += d;                       \
        c ^= d << 8;                  \
        f += c;                       \
        d += e;                       \
        d ^= e >> 16;                 \
        g += d;                       \
        e += f;                       \
        e ^= f << 10;                 \
        h += e;                       \
        f += g;                       \
        f ^= g >> 4;                  \
        a += f;                       \
        g += h;                       \
        g ^= h << 8;                  \
        b += g;                       \
        h += a;                       \
        h ^= a >> 9;                  \
        c += h;                       \
        a += b;                       \
    }
 
#define shuffle( a, b, mm, m, m2, r, x )           \
    {                                              \
        rngstep( a << 13, a, b, mm, m, m2, r, x ); \
        rngstep( a >> 6, a, b, mm, m, m2, r, x );  \
        rngstep( a << 2, a, b, mm, m, m2, r, x );  \
        rngstep( a >> 16, a, b, mm, m, m2, r, x ); \
    }
 
TOSHI_NAMESPACE_START
 
// $Barnyard: FUNCTION 006b5ca0
TRandom::TRandom()
{
    THPTimer timer = THPTimer();
    SetSeed( timer.GetRaw32() );
}
 
// $Barnyard: FUNCTION 006b5850
void TRandom::Isaac()
{
    TUINT a, b, x, y, *m, *mm, *m2, *r, *mend;
    mm = m_pRandmem;
    r  = m_pRandrsl;
    a  = m_uiRandA;
    b  = cut( m_uiRandB + ( ++m_uiRandC ) );
 
    m    = mm;
    mend = m2 = m + ( RANDSIZ / 2 );
    while ( m < mend )
    {
        shuffle( a, b, mm, m, m2, r, x );
    }
 
    m2 = mm;
    while ( m2 < mend )
    {
        shuffle( a, b, mm, m, m2, r, x );
    }
 
    m_uiRandA = a;
    m_uiRandB = b;
}
 
// $Barnyard: FUNCTION 006b5af0
void TRandom::RandInit()
{
    TUINT32 a, b, c, d, e, f, g, h;
    TINT    i;
 
    m_uiRandA = m_uiRandB = m_uiRandC = 0;
 
    /* Initialize a to h with the golden ratio and seed */
    a = b = c = d = e = f = g = h = 0x9e3779b9 + m_uiSeed;
 
    /* scramble it */
    for ( i = 0; i < RANDSIZL; i++ )
    {
        mix( a, b, c, d, e, f, g, h );
    }
 
    TUINT32* m = m_pRandmem;
    TUINT32* r = m_pRandrsl;
 
    /* initialize using the contents of r[] as the seed */
    for ( i = 0; i < RANDSIZ; i += 8 )
    {
        a += r[ i ];
        b += r[ i + 1 ];
        c += r[ i + 2 ];
        d += r[ i + 3 ];
        e += r[ i + 4 ];
        f += r[ i + 5 ];
        g += r[ i + 6 ];
        h += r[ i + 7 ];
 
        mix( a, b, c, d, e, f, g, h );
 
        m[ i ]     = a;
        m[ i + 1 ] = b;
        m[ i + 2 ] = c;
        m[ i + 3 ] = d;
        m[ i + 4 ] = e;
        m[ i + 5 ] = f;
        m[ i + 6 ] = g;
        m[ i + 7 ] = h;
    }
 
    /* do a second pass to make all of the seed affect all of m */
    for ( i = 0; i < RANDSIZ; i += 8 )
    {
        a += m[ i ];
        b += m[ i + 1 ];
        c += m[ i + 2 ];
        d += m[ i + 3 ];
        e += m[ i + 4 ];
        f += m[ i + 5 ];
        g += m[ i + 6 ];
        h += m[ i + 7 ];
 
        mix( a, b, c, d, e, f, g, h );
 
        m[ i ]     = a;
        m[ i + 1 ] = b;
        m[ i + 2 ] = c;
        m[ i + 3 ] = d;
        m[ i + 4 ] = e;
        m[ i + 5 ] = f;
        m[ i + 6 ] = g;
        m[ i + 7 ] = h;
    }
 
    Isaac();
    m_uiRndCnt = RANDSIZ;
}
 
TINT TRandom::GetInt( TUINT32 a_iLower, TUINT32 a_iUpper )
{
    TASSERT( a_iUpper > a_iLower, "a_iLower can't be higher than a_iUpper" );
 
    unsigned long long rand  = RandRaw();
    unsigned long long range = a_iUpper - a_iLower;
    return a_iLower + ( range * rand >> 32 );
}
 
// $Barnyard: FUNCTION 006b5ce0
TINT TRandom::GetInt( TUINT32 a_iUpper )
{
    return GetInt( 0, a_iUpper );
}
 
TINT TRandom::GetInt()
{
    return RandRaw();
}
 
TFLOAT TRandom::GetFloat()
{
    return ( RandRaw() >> 1 ) * 4.6566129E-10f;
}
 
// $Barnyard: FUNCTION 00401080
TFLOAT TRandom::GetFloatMinMax( TFLOAT a_fLower, TFLOAT a_fUpper )
{
    return (TFLOAT)( RandRaw() >> 1 ) * 4.6566129E-10f * ( a_fUpper - a_fLower ) + a_fLower;
}
 
TFLOAT TRandom::GetFloat2()
{
    return ( RandRaw() >> 1 ) * 9.3132257E-10f * -1.0f;
}
 
void TRandom::SetSeed( TUINT a_uiSeed )
{
    m_uiSeed = a_uiSeed;
    RandInit();
}
 
TUINT32 TRandom::RandRaw()
{
    if ( ( m_uiRndCnt-- ) != 0 )
    {
        return m_pRandrsl[ m_uiRndCnt ];
    }
 
    Isaac();
    m_uiRndCnt = RANDSIZ - 1;
    return m_pRandrsl[ RANDSIZ - 1 ];
}
 
TOSHI_NAMESPACE_END