/*******************************************************************************
*
* Name : FIR Filter
* Purpose : Benchmark an FIR filter. The input values for the filter
* is an array of 51 16-bit values. The order of the filter is
* 17.
*
*******************************************************************************/
#ifdef MSP430
#include "msp430x14x.h"
#endif
#include <math.h>
#define FIR_LENGTH 17
const float COEFF[FIR_LENGTH] =
{
-0.000091552734, 0.000305175781, 0.004608154297, 0.003356933594, -0.025939941406,
-0.044006347656, 0.063079833984, 0.290313720703, 0.416748046875, 0.290313720703,
0.063079833984, -0.044006347656, -0.025939941406, 0.003356933594, 0.004608154297,
0.000305175781, -0.000091552734};
/* The following array simulates input A/D converted values */
const unsigned int INPUT[] =
{
0x0000, 0x0000, 0x0000, 0x0000,0x0000, 0x0000, 0x0000, 0x0000,
0x0000, 0x0000, 0x0000, 0x0000,0x0000, 0x0000, 0x0000, 0x0000,
0x0400, 0x0800, 0x0C00, 0x1000, 0x1400, 0x1800, 0x1C00, 0x2000,
0x2400, 0x2000, 0x1C00, 0x1800, 0x1400, 0x1000, 0x0C00, 0x0800,
0x0400, 0x0400, 0x0800, 0x0C00, 0x1000, 0x1400, 0x1800, 0x1C00,
0x2000, 0x2400, 0x2000, 0x1C00, 0x1800, 0x1400, 0x1000, 0x0C00,
0x0800, 0x0400, 0x0400, 0x0800, 0x0C00, 0x1000, 0x1400, 0x1800,
0x1C00, 0x2000, 0x2400, 0x2000, 0x1C00, 0x1800, 0x1400, 0x1000,
0x0C00, 0x0800, 0x0400};
void main(void)
{
int i, y; /* Loop counters */
volatile float OUTPUT[36],sum;
for(y = 0; y < 36; y++)
{
sum=0;
for(i = 0; i < FIR_LENGTH/2; i++)
{
sum = sum+COEFF[i] * ( INPUT[y + 16 - i] + INPUT[y + i] );
}
OUTPUT[y] = sum + (INPUT[y + FIR_LENGTH/2] * COEFF[FIR_LENGTH/2] );
}
return;
}