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