/****************************************************************************** * $Id: dgnfloat.cpp,v 1.5 2003/05/21 03:42:01 warmerda Exp $ * * Project:  Microstation DGN Access Library * Purpose:  Functions for translating DGN floats into IEEE floats. * Author:   Frank Warmerdam, warmerdam@pobox.com * ****************************************************************************** * Copyright (c) 2000, Avenza Systems Inc, http://www.avenza.com/ * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the "Software"), * to deal in the Software without restriction, including without limitation * the rights to use, copy, modify, merge, publish, distribute, sublicense, * and/or sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included * in all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER * DEALINGS IN THE SOFTWARE. ****************************************************************************** * * $Log: dgnfloat.cpp,v $ * Revision 1.5  2003/05/21 03:42:01  warmerda * Expanded tabs * * Revision 1.4  2002/11/11 20:35:42  warmerda * added support for converting to vax floating point * * Revision 1.3  2001/07/18 04:55:16  warmerda * added CPL_CSVID * * Revision 1.2  2001/03/07 13:56:44  warmerda * updated copyright to be held by Avenza Systems * * Revision 1.1  2000/12/14 17:11:05  warmerda * New * */#include "dgnlibp.h"CPL_CVSID("$Id: dgnfloat.cpp,v 1.5 2003/05/21 03:42:01 warmerda Exp $");typedef struct dbl {    GUInt32 hi;    GUInt32 lo;} double64_t;/************************************************************************//*                           DGN2IEEEDouble()                           *//************************************************************************/void    DGN2IEEEDouble(void * dbl){    double64_t  dt;    GUInt32     sign;    GUInt32     exponent;    GUInt32     rndbits;    unsigned char       *src;    unsigned char       *dest;/* -------------------------------------------------------------------- *//*      Arrange the VAX double so that it may be accessed by a          *//*      double64_t structure, (two GUInt32s).                           *//* -------------------------------------------------------------------- */    src =  (unsigned char *) dbl;    dest = (unsigned char *) &dt;#ifdef CPL_LSB    dest[2] = src[0];    dest[3] = src[1];    dest[0] = src[2];    dest[1] = src[3];    dest[6] = src[4];    dest[7] = src[5];    dest[4] = src[6];    dest[5] = src[7];#else    dest[1] = src[0];    dest[0] = src[1];    dest[3] = src[2];    dest[2] = src[3];    dest[5] = src[4];    dest[4] = src[5];    dest[7] = src[6];    dest[6] = src[7];#endif/* -------------------------------------------------------------------- *//*      Save the sign of the double                                     *//* -------------------------------------------------------------------- */    sign         = dt.hi & 0x80000000;/* -------------------------------------------------------------------- *//*      Adjust the exponent so that we may work with it                 */      /* -------------------------------------------------------------------- */    exponent = dt.hi >> 23;    exponent = exponent & 0x000000ff;    if (exponent)        exponent = exponent -129 + 1023;/* -------------------------------------------------------------------- *//*      Save the bits that we are discarding so we can round properly   *//* -------------------------------------------------------------------- */    rndbits = dt.lo & 0x00000007;            dt.lo = dt.lo >> 3;    dt.lo = (dt.lo & 0x1fffffff) | (dt.hi << 29);    if (rndbits)        dt.lo = dt.lo | 0x00000001;/* -------------------------------------------------------------------- *//*      Shift the hi-order int over 3 and insert the exponent and sign  *//* -------------------------------------------------------------------- */    dt.hi = dt.hi >> 3;    dt.hi = dt.hi & 0x000fffff;    dt.hi = dt.hi | (exponent << 20) | sign;#ifdef CPL_LSB/* -------------------------------------------------------------------- *//*      Change the number to a byte swapped format                      *//* -------------------------------------------------------------------- */    src = (unsigned char *) &dt;    dest = (unsigned char *) dbl;    dest[0] = src[4];    dest[1] = src[5];    dest[2] = src[6];    dest[3] = src[7];    dest[4] = src[0];    dest[5] = src[1];    dest[6] = src[2];    dest[7] = src[3];#else    memcpy( dbl, &dt, 8 );#endif}/************************************************************************//*                           IEEE2DGNDouble()                           *//************************************************************************/void    IEEE2DGNDouble(void * dbl){    double64_t  dt;    GInt32      exponent;    GInt32      sign;    GByte       *src,*dest;        #ifdef CPL_LSB    src  = (GByte *) dbl;    dest = (GByte *) &dt;    dest[0] = src[4];    dest[1] = src[5];    dest[2] = src[6];    dest[3] = src[7];    dest[4] = src[0];    dest[5] = src[1];    dest[6] = src[2];    dest[7] = src[3];#else    memcpy( &dt, dbl, 8 );#endif    sign         = dt.hi & 0x80000000;    exponent = dt.hi >> 20;    exponent = exponent & 0x000007ff;/* -------------------------------------------------------------------- *//*      An exponent of zero means a zero value.                         *//* -------------------------------------------------------------------- */    if (exponent)        exponent = exponent -1023+129;/* -------------------------------------------------------------------- *//*      In the case of overflow, return the largest number we can       *//* -------------------------------------------------------------------- */    if (exponent > 255)    {        dest = (GByte *) dbl;        if (sign)             dest[1] = 0xff;        else            dest[1] = 0x7f;        dest[0] = 0xff;        dest[2] = 0xff;        dest[3] = 0xff;        dest[4] = 0xff;        dest[5] = 0xff;        dest[6] = 0xff;        dest[7] = 0xff;        return;    }   /* -------------------------------------------------------------------- *//*      In the case of of underflow return zero                         *//* -------------------------------------------------------------------- */    else if ((exponent < 0 ) ||             (exponent == 0 && sign == 0))    {        dest = (GByte *) dbl;        dest[0] = 0x00;        dest[1] = 0x00;        dest[2] = 0x00;        dest[3] = 0x00;        dest[4] = 0x00;        dest[5] = 0x00;        dest[6] = 0x00;        dest[7] = 0x00;        return;    }    else    {/* -------------------------------------------------------------------- *//*          Shift the fraction 3 bits left and set the exponent and sign*//* -------------------------------------------------------------------- */        dt.hi = dt.hi << 3;        dt.hi = dt.hi | (dt.lo >> 29);        dt.hi = dt.hi & 0x007fffff;        dt.hi = dt.hi | (exponent << 23) | sign;                    dt.lo = dt.lo << 3;    }/* -------------------------------------------------------------------- *//*      Convert the double back to VAX format                           *//* -------------------------------------------------------------------- */    src = (GByte *) &dt;    dest = (GByte *) dbl;#ifdef CPL_LSB    dest[2] = src[0];    dest[3] = src[1];    dest[0] = src[2];    dest[1] = src[3];    dest[6] = src[4];    dest[7] = src[5];    dest[4] = src[6];    dest[5] = src[7];#else    dest[1] = src[0];    dest[0] = src[1];    dest[3] = src[2];    dest[2] = src[3];    dest[5] = src[4];    dest[4] = src[5];    dest[7] = src[6];    dest[6] = src[7];#endif}