src/systemc/dt/fx/scfx_utils.cc

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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 20:20:04  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.
//

#include "systemc/ext/dt/fx/scfx_utils.hh"

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 {
                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