scfx_utils.cpp

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  The following code is derived, directly or indirectly, from the SystemC
  source code Copyright (c) 1996-2006 by all Contributors.
  All Rights reserved.

  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");
  You may not use this file except in compliance with such restrictions and
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  License at http://www.systemc.org/. Software distributed by Contributors
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  ANY KIND, either express or implied. See the License for the specific
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/*****************************************************************************

  scfx_utils.cpp - 

  Original Author: Martin Janssen, Synopsys, Inc.

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

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

  MODIFICATION LOG - modifiers, enter your name, affiliation, date and
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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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