Category : Assembly Language Source Code
Archive   : FP16.ZIP
Filename : FP16.C

//**************************************************************************
//
// Date: 10/22/92
// Name: Fp16.c
// Author: Michael J. Steiner
// CompuServe: [ 70304,3452 ]
//
// Description: Demonstrats the advantage in time, of using fixed point
// mathematics in place of floating point matematics. And
// the disadvantage of loss of precision.
//
// Note: Storage: Fraction
// Integer ³
// Sign ³ ³
// ³ ³ ³
// 0 ³ ³
// 000000000000000 ³
// 0000000000000000
//
//**************************************************************************

#include
#include

#define BITSHIFT 16 //significant to 4 places
#define BITS ( 1L << BITSHIFT ) //could use a constant here for
//greater speed

#define LONG2DBL( a ) (double)a / BITS //these two macros are the heart of
#define DBL2LONG( a ) (long)( a * BITS ) //the conversion double => integer

#define ADD( a, b ) LONG2DBL( ( DBL2LONG( a ) + DBL2LONG( b ) ) )
#define SUB( a, b ) LONG2DBL( ( DBL2LONG( a ) - DBL2LONG( b ) ) )
#define MUL( a, b ) LONG2DBL( ( ( DBL2LONG( a ) * \
DBL2LONG( b ) ) >> BITSHIFT ) )

#define DIV( a, b ) LONG2DBL( ( ( DBL2LONG( a ) / \
DBL2LONG( b ) ) << BITSHIFT ) )

extern long Add( long, long );
extern long Sub( long, long );

void main( void )
{
clock_t End, Start;
double AddTime1, AddTime2;
int x;
double inc;
double Value;
double Result0, Result1, Result2;
long INC,VALUE;

printf( "\n" );
printf( " Using the Macros\n" );
printf( " ----------------\n" );
printf( " (long) .11: %ld\n", DBL2LONG( .11 ) );
printf( " (long) .22: %ld\n", DBL2LONG( .22 ) );
printf( " .22 + .11: %2.4lf\n", ADD( .22, .11 ) );
printf( " .22 - .11: %2.4lf\n", SUB( .22, .11 ) );
printf( " .22 * .11: %2.4lf\n", MUL( .22, .11 ) );
printf( " .22 / .11: %2.4lf\n", DIV( .22, .11 ) );

inc = 1.11;
Value = 0.22;

INC = DBL2LONG( 1.11 );
VALUE = DBL2LONG( 0.22 );

Start = clock();

for( x=0; x<20000; x++ )
{
inc += Value;
inc -= Value;
}

End = clock();
AddTime1 = (double)( End - Start ) / CLK_TCK;

Start = clock();

for( x=0; x<20000; x++ )
{
INC += VALUE;
INC -= VALUE;
}

End = clock();
AddTime2 = (double)( End - Start ) / CLK_TCK;

printf( "\n" );
printf( " Timed Addition/Subtraction Test\n" );
printf( "ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ\n" );
printf( " FLOATING POINT ³ FIXED 16 POINT\n" );
printf( " ³\n" );
printf( " Total: %4.4lf ³ Total: %4.4lf\n", inc, LONG2DBL( INC ) );
printf( " Time: %-2.2f ³ Time: %-2.2f\n", AddTime1, AddTime2 );
printf( "Speed increase: %2.2f [%]\n", ( AddTime1 / AddTime2 ) * 100 );

}