sc_fxval.cpp

system C源码 一种替代verilog的语言

        int value = 0;
        for( int j = step - 1; j >= 0; -- j )
	{
            value += static_cast<int>( a.get_bit( i ) ) << j;
            -- i;
        }
        if( value < 10 )
            s += static_cast<char>( value + '0' );
	else
            s += static_cast<char>( value + 'a' - 10 );
	if( i == -1 )
	    s += '.';
    }

    if( lsb > 0 && fmt == SC_F )
    {
	for( int i = lsb / step; i > 0; i -- )
	    s += '0';
    }

    if( s[s.length() - 1] == '.' )
	s.discard( 1 );

    if( fmt != SC_F )
    {
	if( msb < 0 )
	    scfx_print_exp( s, ( msb + 1 ) / step );
	else if( lsb > 0 )
	    scfx_print_exp( s, lsb / step );
    }

    if( numrep == SC_CSD )
	scfx_tc2csd( s, w_prefix );
}


const char*
to_string( const scfx_ieee_double& id, sc_numrep numrep, int w_prefix,
	   sc_fmt fmt, const scfx_params* params = 0 )
{
    static scfx_string s;

    s.clear();

    if( id.is_nan() )
        scfx_print_nan( s );
    else if( id.is_inf() )
        scfx_print_inf( s, static_cast<bool>( id.negative() ) );
    else if( id.negative() && ! id.is_zero() &&
	     ( numrep == SC_BIN_US ||
	       numrep == SC_OCT_US ||
	       numrep == SC_HEX_US ) )
        s += "negative";
    else if( numrep == SC_DEC )
        sc_dt::print_dec( s, id, w_prefix, fmt );
    else
        sc_dt::print_other( s, id, numrep, w_prefix, fmt, params );

    return s;
}


// explicit conversion to character string

const std::string
sc_fxval_fast::to_string() const
{
    return std::string( sc_dt::to_string( m_val, SC_DEC, -1, SC_E ) );
}

const std::string
sc_fxval_fast::to_string( sc_numrep numrep ) const
{
    return std::string( sc_dt::to_string( m_val, numrep, -1, SC_E ) );
}

const std::string
sc_fxval_fast::to_string( sc_numrep numrep, bool w_prefix ) const
{
    return std::string( sc_dt::to_string( m_val, numrep, (w_prefix ? 1 : 0),
					SC_E ) );
}

const std::string
sc_fxval_fast::to_string( sc_fmt fmt ) const
{
    return std::string( sc_dt::to_string( m_val, SC_DEC, -1, fmt ) );
}

const std::string
sc_fxval_fast::to_string( sc_numrep numrep, sc_fmt fmt ) const
{
    return std::string( sc_dt::to_string( m_val, numrep, -1, fmt ) );
}

const std::string
sc_fxval_fast::to_string( sc_numrep numrep, bool w_prefix, sc_fmt fmt ) const
{
    return std::string( sc_dt::to_string( m_val, numrep, (w_prefix ? 1 : 0),
					fmt ) );
}


const std::string
sc_fxval_fast::to_dec() const
{
    return std::string( sc_dt::to_string( m_val, SC_DEC, -1, SC_E ) );
}

const std::string
sc_fxval_fast::to_bin() const
{
    return std::string( sc_dt::to_string( m_val, SC_BIN, -1, SC_E ) );
}

const std::string
sc_fxval_fast::to_oct() const
{
    return std::string( sc_dt::to_string( m_val, SC_OCT, -1, SC_E ) );
}

const std::string
sc_fxval_fast::to_hex() const
{
    return std::string( sc_dt::to_string( m_val, SC_HEX, -1, SC_E ) );
}


// print or dump content

void
sc_fxval_fast::print( ::std::ostream& os ) const
{
    os << sc_dt::to_string( m_val, SC_DEC, -1, SC_E );
}

void
sc_fxval_fast::scan( ::std::istream& is )
{
    std::string s;
    is >> s;
    *this = s.c_str();
}

void
sc_fxval_fast::dump( ::std::ostream& os ) const
{
    os << "sc_fxval_fast" << ::std::endl;
    os << "(" << ::std::endl;
    os << "val = " << m_val << ::std::endl;
    // TO BE COMPLETED
    // os << "r_flag   = " << m_r_flag << ::std::endl;
    // os << "observer = ";
    // if( m_observer != 0 )
    //     m_observer->dump( os );
    // else
    //     os << "0" << ::std::endl;
    os << ")" << ::std::endl;
}


// internal use only;
bool
sc_fxval_fast::get_bit( int i ) const
{
    scfx_ieee_double id( m_val );
    if( id.is_zero() || id.is_nan() || id.is_inf() )
        return false;

    // convert to two's complement

    unsigned int m0 = id.mantissa0();
    unsigned int m1 = id.mantissa1();

    if( id.is_normal() )
        m0 += 1U << 20;

    if( id.negative() != 0 )
    {
	m0 = ~ m0;
	m1 = ~ m1;
	unsigned int tmp = m1;
	m1 += 1U;
	if( m1 <= tmp )
	    m0 += 1U;
    }

    // get the right bit

    int j = i - id.exponent();
    if( ( j += 20 ) >= 32 )
        return ( ( m0 & 1U << 31 ) != 0 );
    else if( j >= 0 )
        return ( ( m0 & 1U << j ) != 0 );
    else if( ( j += 32 ) >= 0 )
        return ( ( m1 & 1U << j ) != 0 );
    else
        return false;
}


// protected methods and friend functions

sc_fxval_fast_observer*
sc_fxval_fast::lock_observer() const
{
    SC_ASSERT_( m_observer != 0, "lock observer failed" );
    sc_fxval_fast_observer* tmp = m_observer;
    m_observer = 0;
    return tmp;
}

void
sc_fxval_fast::unlock_observer( sc_fxval_fast_observer* observer_ ) const
{
    SC_ASSERT_( observer_ != 0, "unlock observer failed" );
    m_observer = observer_;
}


#define SCFX_FAIL_IF_(cnd)                                                    \
{                                                                             \
    if( ( cnd ) )                                                             \
        return static_cast<double>( scfx_ieee_double::nan() );                \
}

double
sc_fxval_fast::from_string( const char* s )
{
    SCFX_FAIL_IF_( s == 0 || *s == 0 );

    scfx_string s2;
    s2 += s;
    s2 += '\0';

    bool sign_char;
    int sign = scfx_parse_sign( s, sign_char );

    sc_numrep numrep = scfx_parse_prefix( s );

    int base = 0;

    switch( numrep )
    {
	case SC_DEC:
	{
	    base = 10;
	    if( scfx_is_nan( s ) )  // special case: NaN
		return static_cast<double>( scfx_ieee_double::nan() );
	    if( scfx_is_inf( s ) )  // special case: Infinity
		return static_cast<double>( scfx_ieee_double::inf( sign ) );
	    break;
	}
	case SC_BIN:
	case SC_BIN_US:
	{
	    SCFX_FAIL_IF_( sign_char );
	    base = 2;
	    break;
	}
	
	case SC_BIN_SM:
	{
	    base = 2;
	    break;
	}
	case SC_OCT:
	case SC_OCT_US:
	{
	    SCFX_FAIL_IF_( sign_char );
	    base = 8;
	    break;
	}
	case SC_OCT_SM:
	{
	    base = 8;
	    break;
	}
	case SC_HEX:
	case SC_HEX_US:
	{
	    SCFX_FAIL_IF_( sign_char );
	    base = 16;
	    break;
	}
	case SC_HEX_SM:
	{
	    base = 16;
	    break;
	}
	case SC_CSD:
	{
	    SCFX_FAIL_IF_( sign_char );
	    base = 2;
	    scfx_csd2tc( s2 );
	    s = (const char*) s2 + 4;
	    numrep = SC_BIN;
	    break;
	}
       default:;// Martin, what is default???
    }

    //
    // find end of mantissa and count the digits and points
    //

    const char *end = s;
    bool based_point = false;
    int int_digits = 0;
    int frac_digits = 0;

    while( *end )
    {
	if( scfx_exp_start( end ) )
	    break;
	
	if( *end == '.' )
	{
	    SCFX_FAIL_IF_( based_point );
	    based_point = true;
	}
	else
	{
	    SCFX_FAIL_IF_( ! scfx_is_digit( *end, numrep ) );
	    if( based_point )
		frac_digits ++;
	    else
		int_digits ++;
	}

	end ++;
    }

    SCFX_FAIL_IF_( int_digits == 0 && frac_digits == 0 );

    // [ exponent ]
    
    int exponent = 0;

    if( *end )
    {
	for( const char *e = end + 2; *e; e ++ )
	    SCFX_FAIL_IF_( ! scfx_is_digit( *e, SC_DEC ) );
	exponent = atoi( end + 1 );
    }

    //
    // convert the mantissa
    //

    double integer = 0.0;

    if( int_digits != 0 )
    {

	bool first_digit = true;

	for( ; s < end; s ++ )
	{
	    if( *s == '.' )
		break;
	    
	    if( first_digit )
	    {
		integer = scfx_to_digit( *s, numrep );
		switch( numrep )
		{
		    case SC_BIN:
		    case SC_OCT:
		    case SC_HEX:
		    {
			if( integer >= ( base >> 1 ) )
			    integer -= base;  // two's complement
			break;
		    }
		    default:
			;
		}
		first_digit = false;
	    }
            else
	    {
		integer *= base;
		integer += scfx_to_digit( *s, numrep );
	    }
	}
    }

    // [ . fraction ]

    double fraction = 0.0;
    
    if( frac_digits != 0 )
    {
	s ++;  // skip '.'

	bool first_digit = ( int_digits == 0 );

	double scale = 1.0;

	for( ; s < end; s ++ )
	{
	    scale /= base;
	    
	    if( first_digit )
	    {
		fraction = scfx_to_digit( *s, numrep );
		switch( numrep )
		{
		    case SC_BIN:
		    case SC_OCT:
		    case SC_HEX:
		    {
			if( fraction >= ( base >> 1 ) )
			    fraction -= base;  // two's complement
			break;
		    }
		    default:
			;
		}
		fraction *= scale;
		first_digit = false;
	    }
	    else
		fraction += scfx_to_digit( *s, numrep ) * scale;
	}
    }

    double exp = ( exponent != 0 ) ? pow( (double) base, (double) exponent )
	                           : 1;

    return ( sign * ( integer + fraction ) * exp );
}

#undef SCFX_FAIL_IF_

} // namespace sc_dt


// Taf!