C:/systemc-2.2.0/systemc-2.2.0/src/sysc/datatypes/fx/scfx_utils.cpp

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  The contents of this file are subject to the restrictions and limitations
  set forth in the SystemC Open Source License Version 2.4 (the "License");
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/*****************************************************************************

  scfx_utils.cpp - 

  Original Author: Martin Janssen, Synopsys, Inc.

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

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

  MODIFICATION LOG - modifiers, enter your name, affiliation, date and
  changes you are making here.

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// $Log: scfx_utils.cpp,v $
// Revision 1.1.1.1  2006/12/15 20:31:36  acg
// SystemC 2.2
//
// Revision 1.3  2006/01/13 18:53:58  acg
// Andy Goodrich: added $Log command so that CVS comments are reproduced in
// the source.
//

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


namespace sc_dt
{

void
scfx_tc2csd( scfx_string& s, int w_prefix )
{
    if( w_prefix != 0 ) {
        SC_ASSERT_( s[0] == '0' && s[1] == 'c' &&
                    s[2] == 's' && s[3] == 'd', "invalid prefix" );
    }

    scfx_string csd;

    // copy bits from 's' into 'csd'; skip prefix, point, and exponent
    int i = 0;
    int j = (w_prefix != 0 ? 4 : 0);
    while( s[j] )
    {
        if( s[j] == '0' || s[j] == '1' )
            csd[i ++] = s[j];
        else if( s[j] != '.' )
            break;
        ++ j;
    }
    csd[i] = '\0';

    // convert 'csd' from two's complement to csd
    -- i;
    while( i >= 0 )
    {
        if( csd[i] == '0' )
            -- i;
        else
        {
            if( i > 0 && csd[i - 1] == '0' )
                -- i;
            else if( i == 0 )
                csd[i --] = '-';
            else
            {   // i > 0 && csd[i - 1] == '1'
                csd[i --] = '-';
                while( i >= 0 && csd[i] == '1' )
                    csd[i --] = '0';
                if( i > 0 )
                    csd[i] = '1';
                else if( i == 0 )
                    csd[i --] = '1';
            }
        }
    }

    // copy bits from 'csd' back into 's'
    i = 0;
    j = (w_prefix != 0 ? 4 : 0);
    while( csd[i] )
    {
        if( s[j] == '.' )
            ++ j;
        s[j ++] = csd[i ++];
    }
}


void
scfx_csd2tc( scfx_string& csd )
{
    SC_ASSERT_( csd[0] == '0' && csd[1] == 'c' &&
                csd[2] == 's' && csd[3] == 'd', "invalid prefix" );

    scfx_string s;

    // copy bits from 'csd' into 's'; skip prefix, point, and exponent
    int i = 0;
    s[i ++] = '0';
    int j = 4;
    while( csd[j] )
    {
        if( csd[j] == '-' || csd[j] == '0' || csd[j] == '1' )
            s[i ++] = csd[j];
        else if( csd[j] != '.' )
            break;
        ++ j;
    }
    s[i] = '\0';

    // convert 's' from csd to two's complement
    int len = i;
    i = 1;
    while( i < len )
    {
        while( i < len && s[i] != '-' )
            i ++;
        if( i < len )
        {
            j = i ++;
            s[j --] = '1';
            while( j >= 0 && s[j] == '0' )
                s[j --] = '1';
            if( j >= 0 )
                s[j] = '0';
        }
    }

    // copy bits from 's' back into 'csd'
    j = csd.length();
    csd[j + 1] = '\0';
    while( j > 4 )
    {
        csd[j] = csd[j - 1];
        -- j;
    }
        
    i = 0;
    j = 4;
    while( s[i] )
    {
        if( csd[j] == '.' )
            ++ j;
        csd[j ++] = s[i ++];
    }
}

} // namespace sc_dt


// Taf!

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