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harbour-core/contrib/hbct/exponent.c
vszakats 9687850865 2013-03-16 02:10 UTC+0100 Viktor Szakats (harbour syenar.net)
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2013-03-16 02:11:42 +01:00

161 lines
4.1 KiB
C

/*
* Harbour Project source code:
* CT3 Number and bit manipulation functions: - Mantissa()
* - Exponent()
*
* Copyright 2002 Walter Negro - FOEESITRA" <waltern@foeesitra.org.ar>
* www - http://harbour-project.org
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this software; see the file COPYING.txt. If not, write to
* the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
* Boston, MA 02111-1307 USA (or visit the web site http://www.gnu.org/).
*
* As a special exception, the Harbour Project gives permission for
* additional uses of the text contained in its release of Harbour.
*
* The exception is that, if you link the Harbour libraries with other
* files to produce an executable, this does not by itself cause the
* resulting executable to be covered by the GNU General Public License.
* Your use of that executable is in no way restricted on account of
* linking the Harbour library code into it.
*
* This exception does not however invalidate any other reasons why
* the executable file might be covered by the GNU General Public License.
*
* This exception applies only to the code released by the Harbour
* Project under the name Harbour. If you copy code from other
* Harbour Project or Free Software Foundation releases into a copy of
* Harbour, as the General Public License permits, the exception does
* not apply to the code that you add in this way. To avoid misleading
* anyone as to the status of such modified files, you must delete
* this exception notice from them.
*
* If you write modifications of your own for Harbour, it is your choice
* whether to permit this exception to apply to your modifications.
* If you do not wish that, delete this exception notice.
*
*/
#include "ct.h"
#include "ctmath.h"
/* undefine the following if you want to evaluate the mantissa and exponent from the doubles' bit representation */
/* #define CT_EXPONENT_MANTISSA_BIT 1 */
HB_FUNC( MANTISSA )
{
#ifdef CT_EXPONENT_MANTISSA_BIT
union
{
double value;
char string[ sizeof( double ) ];
} xConvert;
xConvert.value = hb_parnd( 1 );
if( xConvert.value != 0 )
{
xConvert.string[ 6 ] |= 0xF0;
xConvert.string[ 7 ] |= 0x3F;
xConvert.string[ 7 ] &= 0xBF;
}
hb_retnd( xConvert.value );
#else
double dValue;
dValue = hb_parnd( 1 );
if( dValue == 0.0 )
{
hb_retnd( 0.0 );
return;
}
if( fabs( dValue ) < 1.0 )
{
while( fabs( dValue ) < 1.0 )
dValue *= 2.0;
}
else if( fabs( dValue ) >= 2.0 )
{
while( fabs( dValue ) >= 2.0 )
dValue /= 2.0;
}
hb_retnd( dValue );
#endif
}
HB_FUNC( EXPONENT )
{
#ifdef CT_EXPONENT_MANTISSA_BIT
int iExponent = 0;
union
{
double value;
char string[ sizeof( double ) ];
} xConvert;
xConvert.value = hb_parnd( 1 );
if( xConvert.value != 0 )
{
iExponent = ( int ) ( xConvert.string[ 7 ] & 0x07F );
iExponent = iExponent << 4;
iExponent += ( int ) ( ( xConvert.string[ 6 ] & 0xF0 ) >> 4 );
iExponent -= 1023;
}
hb_retni( iExponent );
#else
int iExponent = 0;
double dValue;
dValue = hb_parnd( 1 );
if( dValue == 0.0 )
{
hb_retni( 0 );
return;
}
if( fabs( dValue ) < 1.0 )
{
while( fabs( dValue ) < 1.0 )
{
dValue *= 2.0;
iExponent--;
}
}
else if( fabs( dValue ) >= 2.0 )
{
while( fabs( dValue ) >= 2.0 )
{
dValue /= 2.0;
iExponent++;
}
}
hb_retni( iExponent );
#endif
}