scfx_ieee.h

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

  scfx_ieee.h - 

  Original Author: Martin Janssen, Synopsys, Inc.

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

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// $Log: scfx_ieee.h,v $
// Revision 1.3  2011/08/24 22:05:43  acg
//  Torsten Maehne: initialization changes to remove warnings.
//
// Revision 1.2  2011/08/07 18:55:24  acg
//  Philipp A. Hartmann: added guard for __clang__ to get the clang platform
//  working.
//
// Revision 1.1.1.1  2006/12/15 20:20:04  acg
// SystemC 2.3
//
// Revision 1.3  2006/01/13 18:53:58  acg
// Andy Goodrich: added $Log command so that CVS comments are reproduced in
// the source.
//

#ifndef SCFX_IEEE_H
#define SCFX_IEEE_H


#include "sysc/datatypes/fx/sc_fxdefs.h"


namespace sc_dt
{

// classes defined in this module
union ieee_double;
class scfx_ieee_double;
union ieee_float;
class scfx_ieee_float;

#define SCFX_MASK_(Size) \
   ((1u << (Size))-1u)

// ----------------------------------------------------------------------------
//  UNION : ieee_double
//
//  IEEE 754 double-precision format.
// ----------------------------------------------------------------------------

union ieee_double
{

    double d;

    struct
    {
#if defined( SC_BIG_ENDIAN )
        unsigned negative:1;
        unsigned exponent:11;
        unsigned mantissa0:20;
        unsigned mantissa1:32;
#elif defined( SC_LITTLE_ENDIAN )
        unsigned mantissa1:32;
        unsigned mantissa0:20;
        unsigned exponent:11;
        unsigned negative:1;
#endif
    } s;

};


const unsigned int SCFX_IEEE_DOUBLE_BIAS   =  1023U;

const int          SCFX_IEEE_DOUBLE_E_MAX  =  1023;
const int          SCFX_IEEE_DOUBLE_E_MIN  = -1022;

const unsigned int SCFX_IEEE_DOUBLE_M_SIZE  =    52;
const unsigned int SCFX_IEEE_DOUBLE_M0_SIZE =    20;
const unsigned int SCFX_IEEE_DOUBLE_M1_SIZE =    32;
const unsigned int SCFX_IEEE_DOUBLE_E_SIZE  =    11;



// ----------------------------------------------------------------------------
//  CLASS : scfx_ieee_double
//
//  Convenient interface to union ieee_double.
// ----------------------------------------------------------------------------

class scfx_ieee_double
{

    ieee_double m_id;

public:
    
    scfx_ieee_double();
    scfx_ieee_double( double );
    scfx_ieee_double( const scfx_ieee_double& );
    
    scfx_ieee_double& operator = ( double );
    scfx_ieee_double& operator = ( const scfx_ieee_double& );
    
    operator double() const;

    unsigned int negative() const;
    void negative( unsigned int );
    int exponent() const;
    void exponent( int );
    unsigned int mantissa0() const;
    void mantissa0( unsigned int );
    unsigned int mantissa1() const;
    void mantissa1( unsigned int );

    bool is_zero() const;
    bool is_subnormal() const;
    bool is_normal() const;
    bool is_inf() const;
    bool is_nan() const;

    void set_inf();
    void set_nan();

    int msb() const;            // most significant non-zero bit
    int lsb() const;            // least significant non-zero bit

    static const scfx_ieee_double nan();
    static const scfx_ieee_double inf( int );

};


// IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII
    
inline
scfx_ieee_double::scfx_ieee_double() : m_id()
{
    m_id.d = 0.0;
}

inline
scfx_ieee_double::scfx_ieee_double( double d ) : m_id()
{
    m_id.d = d;
}

inline
scfx_ieee_double::scfx_ieee_double( const scfx_ieee_double& a ) : m_id(a.m_id)
{
    // m_id.d = a.m_id.d;
}
    

inline
scfx_ieee_double&
scfx_ieee_double::operator = ( double d )
{
    m_id.d = d;
    return *this;
}

inline
scfx_ieee_double&
scfx_ieee_double::operator = ( const scfx_ieee_double& a )
{
    m_id.d = a.m_id.d;
    return *this;
}
    

inline
scfx_ieee_double::operator double() const
{
    return m_id.d;
}


inline
unsigned int
scfx_ieee_double::negative() const
{
    return m_id.s.negative;
}

inline
void
scfx_ieee_double::negative( unsigned int a )
{
    m_id.s.negative = a & SCFX_MASK_(1);
}

inline
int
scfx_ieee_double::exponent() const
{
    return m_id.s.exponent - SCFX_IEEE_DOUBLE_BIAS;
}

inline
void
scfx_ieee_double::exponent( int a )
{
    m_id.s.exponent = (SCFX_IEEE_DOUBLE_BIAS + a)
                      & SCFX_MASK_(SCFX_IEEE_DOUBLE_E_SIZE);
}

inline
unsigned int
scfx_ieee_double::mantissa0() const
{
    return m_id.s.mantissa0;
}

inline
void
scfx_ieee_double::mantissa0( unsigned int a )
{
    m_id.s.mantissa0 = a & SCFX_MASK_(SCFX_IEEE_DOUBLE_M0_SIZE);
}

inline
unsigned int
scfx_ieee_double::mantissa1() const
{
    return m_id.s.mantissa1;
}

inline
void
scfx_ieee_double::mantissa1( unsigned int a )
{
    m_id.s.mantissa1 = a; // & SCFX_MASK_(SCFX_IEEE_DOUBLE_M1_SIZE);
}


inline
bool
scfx_ieee_double::is_zero() const
{
    return ( exponent() == SCFX_IEEE_DOUBLE_E_MIN - 1 &&
             mantissa0() == 0U && mantissa1() == 0U );
}

inline
bool
scfx_ieee_double::is_subnormal() const
{
    return ( exponent() == SCFX_IEEE_DOUBLE_E_MIN - 1 &&
             ( mantissa0() != 0U || mantissa1() != 0U ) );
}

inline
bool
scfx_ieee_double::is_normal() const
{
    return ( exponent() >= SCFX_IEEE_DOUBLE_E_MIN &&
             exponent() <= SCFX_IEEE_DOUBLE_E_MAX );
}

inline
bool
scfx_ieee_double::is_inf() const
{
    return ( exponent() == SCFX_IEEE_DOUBLE_E_MAX + 1 &&
             mantissa0() == 0U && mantissa1() == 0U );
}

inline
bool
scfx_ieee_double::is_nan() const
{
    return ( exponent() == SCFX_IEEE_DOUBLE_E_MAX + 1 &&
             ( mantissa0() != 0U || mantissa1() != 0U ) );
}


inline
void
scfx_ieee_double::set_inf()
{
    exponent( SCFX_IEEE_DOUBLE_E_MAX + 1 );
    mantissa0( 0U );
    mantissa1( 0U );
}

inline
void
scfx_ieee_double::set_nan()
{
    exponent( SCFX_IEEE_DOUBLE_E_MAX + 1 );
    mantissa0( (unsigned int) -1 );
    mantissa1( (unsigned int) -1 );
}


#define MSB_STATEMENT(x,n) if( x >> n ) { x >>= n; i += n; }

inline
int
scfx_ieee_double::msb() const
{
    unsigned int m0 = mantissa0();
    unsigned int m1 = mantissa1();
    if( m0 != 0 )
    {
        int i = 0;
        MSB_STATEMENT(m0,16);
        MSB_STATEMENT(m0,8);
        MSB_STATEMENT(m0,4);
        MSB_STATEMENT(m0,2);
        MSB_STATEMENT(m0,1);
        return ( i - 20 );
    }
    else if( m1 != 0 )
    {
        int i = 0;
        MSB_STATEMENT(m1,16);
        MSB_STATEMENT(m1,8);
        MSB_STATEMENT(m1,4);
        MSB_STATEMENT(m1,2);
        MSB_STATEMENT(m1,1);
        return ( i - 52 );
    }
    else
    {
        return 0;
    }
}

#undef MSB_STATEMENT

#define LSB_STATEMENT(x,n) if( x << n ) { x <<= n; i -= n; }

inline
int
scfx_ieee_double::lsb() const
{
    unsigned int m0 = mantissa0();
    unsigned int m1 = mantissa1();
    if( m1 != 0 )
    {
        int i = 31;
        LSB_STATEMENT(m1,16);
        LSB_STATEMENT(m1,8);
        LSB_STATEMENT(m1,4);
        LSB_STATEMENT(m1,2);
        LSB_STATEMENT(m1,1);
        return ( i - 52 );
    }
    else if( m0 != 0 )
    {
        int i = 31;
        LSB_STATEMENT(m0,16);
        LSB_STATEMENT(m0,8);
        LSB_STATEMENT(m0,4);
        LSB_STATEMENT(m0,2);
        LSB_STATEMENT(m0,1);
        return ( i - 20 );
    }
    else
    {
        return 0;
    }
}

#undef LSB_STATEMENT


inline
const scfx_ieee_double
scfx_ieee_double::nan()
{
    scfx_ieee_double id;
    id.set_nan();
    return id;
}

inline
const scfx_ieee_double
scfx_ieee_double::inf( int sign )
{
    scfx_ieee_double id( sign );
    id.set_inf();
    return id;
}


// ----------------------------------------------------------------------------
//  UNION : ieee_float
//
//  IEEE 754 single-precision format.
// ----------------------------------------------------------------------------
    
union ieee_float
{

    float f;

    struct
    {
#if defined( SC_BIG_ENDIAN )
        unsigned negative:1;
        unsigned exponent:8;
        unsigned mantissa:23;
#elif defined( SC_LITTLE_ENDIAN )
        unsigned mantissa:23;
        unsigned exponent:8;
        unsigned negative:1;
#endif
    } s;

};


const unsigned int SCFX_IEEE_FLOAT_BIAS   =  127U;

const int          SCFX_IEEE_FLOAT_E_MAX  =  127;
const int          SCFX_IEEE_FLOAT_E_MIN  = -126;

const unsigned int SCFX_IEEE_FLOAT_M_SIZE =   23;
const unsigned int SCFX_IEEE_FLOAT_E_SIZE =    8;


// ----------------------------------------------------------------------------
//  CLASS : scfx_ieee_float
//
// Convenient wrapper to union ieee_float.
// ----------------------------------------------------------------------------

class scfx_ieee_float
{

    ieee_float m_if;

public:

    scfx_ieee_float();
    scfx_ieee_float( float );
    scfx_ieee_float( const scfx_ieee_float& );

    scfx_ieee_float& operator = ( float );
    scfx_ieee_float& operator = ( const scfx_ieee_float& );

    operator float() const;

    unsigned int negative() const;
    void negative( unsigned int );
    int exponent() const;
    void exponent( int );
    unsigned int mantissa() const;
    void mantissa( unsigned int );

    bool is_zero() const;
    bool is_subnormal() const;
    bool is_normal() const;
    bool is_inf() const;
    bool is_nan() const;

    void set_inf();
    void set_nan();

};


// IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII
    
inline
scfx_ieee_float::scfx_ieee_float() : m_if()
{
    m_if.f = 0.0;
}

inline
scfx_ieee_float::scfx_ieee_float( float f ) : m_if()
{
    m_if.f = f;
}

inline
scfx_ieee_float::scfx_ieee_float( const scfx_ieee_float& a ) : m_if(a.m_if)
{
    // m_if.f = a.m_if.f;
}


inline
scfx_ieee_float&
scfx_ieee_float::operator = ( float f )
{
    m_if.f = f;
    return *this;
}

inline
scfx_ieee_float&
scfx_ieee_float::operator = ( const scfx_ieee_float& a )
{
    m_if.f = a.m_if.f;
    return *this;
}
    

inline
scfx_ieee_float::operator float() const
{
    return m_if.f;
}


inline
unsigned int
scfx_ieee_float::negative() const
{
    return m_if.s.negative;
}

inline
void
scfx_ieee_float::negative( unsigned int a )
{
    m_if.s.negative = a & SCFX_MASK_(1);
}

inline
int
scfx_ieee_float::exponent() const
{
    return m_if.s.exponent - SCFX_IEEE_FLOAT_BIAS;
}

inline
void
scfx_ieee_float::exponent( int a )
{
    m_if.s.exponent = (SCFX_IEEE_FLOAT_BIAS + a)
                      & SCFX_MASK_(SCFX_IEEE_FLOAT_E_SIZE);
}

inline
unsigned int
scfx_ieee_float::mantissa() const
{
    return m_if.s.mantissa;
}

inline
void
scfx_ieee_float::mantissa( unsigned int a )
{
    m_if.s.mantissa = a & SCFX_MASK_(SCFX_IEEE_FLOAT_M_SIZE);
}


inline
bool
scfx_ieee_float::is_zero() const
{
    return ( exponent() == SCFX_IEEE_FLOAT_E_MIN - 1 && mantissa() == 0U );
}

inline
bool
scfx_ieee_float::is_subnormal() const
{
    return ( exponent() == SCFX_IEEE_FLOAT_E_MIN - 1 && mantissa() != 0U );
}

inline
bool
scfx_ieee_float::is_normal() const
{
    return ( exponent() >= SCFX_IEEE_FLOAT_E_MIN &&
             exponent() <= SCFX_IEEE_FLOAT_E_MAX );
}

inline
bool
scfx_ieee_float::is_inf() const
{
    return ( exponent() == SCFX_IEEE_FLOAT_E_MAX + 1 && mantissa() == 0U );
}

inline
bool
scfx_ieee_float::is_nan() const
{
    return ( exponent() == SCFX_IEEE_FLOAT_E_MAX + 1 && mantissa() != 0U );
}


inline
void
scfx_ieee_float::set_inf()
{
    exponent( SCFX_IEEE_FLOAT_E_MAX + 1 );
    mantissa( 0U );
}

inline
void
scfx_ieee_float::set_nan()
{
    exponent( SCFX_IEEE_FLOAT_E_MAX + 1 );
    mantissa( (unsigned int) -1 );
}


// ----------------------------------------------------------------------------
//  FUNCTION : scfx_pow2
//
//  Computes 2.0**exp in double-precision.
// ----------------------------------------------------------------------------

inline
double scfx_pow2( int exp )
{
    scfx_ieee_double r;
    if( exp < SCFX_IEEE_DOUBLE_E_MIN )
    {
        r = 0.0;
        // handle subnormal case
        exp -= SCFX_IEEE_DOUBLE_E_MIN;
        if( ( exp += 20 ) >= 0 )
        {
            r.mantissa0( 1U << exp );
        }
        else if( ( exp += 32 ) >= 0 )
        {
            r.mantissa1( 1U << exp );
        }
    }
    else if( exp > SCFX_IEEE_DOUBLE_E_MAX )
    {
        r.set_inf();
    }
    else
    {
        r = 1.0;
        r.exponent( exp );
    }
    return r;
}


// ----------------------------------------------------------------------------
//  FUNCTION : uint64_to_double
//
//  Platform independent conversion from double uint64 to double.
//  Needed because VC++6 doesn't support this conversion.
// ----------------------------------------------------------------------------

inline
double
uint64_to_double( uint64 a )
{
#if defined( _MSC_VER ) || defined( __clang__ )
    // conversion from uint64 to double not implemented; use int64
    double tmp = static_cast<double>( static_cast<int64>( a ) );
    return ( tmp >= 0 ) ? tmp : tmp + sc_dt::scfx_pow2( 64 );
#else
    return static_cast<double>( a );
#endif
}

} // namespace sc_dt

#undef SCFX_MASK_

#endif

// Taf!