Texas Instruments TMS320C64X Manual do Utilizador descarregar pdf (Página 30)

DSP_firlms2

4-2

4.1 Adaptive Filtering

LMS FIR

DSP_firlms2

Function long DSP_firlms2(short * restrict h, const short * restrict x, short b, int nh)

Arguments h[nh] Coefficient Array

x[nh+1] Input Array

b Error from previous FIR

nh Number of coefficients. Must be multiple of 4.

return long Return value

Description The Least Mean Square Adaptive Filter computes an update of all nh

coefficients by adding the weighted error times the inputs to the original

coefficients. The input array includes the last nh inputs followed by a new

single sample input. The coefficient array includes nh coefficients.

Algorithm This is the C equivalent of the assembly code without restrictions. Note that

the assembly code is hand optimized and restrictions may apply.

long DSP_firlms2(short h[ ],short x[ ], short b,

int nh)

{

int i;

long r = 0;

for (i = 0; i < nh; i++) {

h[i] += (x[i] * b) >> 15;

r += x[i + 1] * h[i];

}

return r;

}

Special Requirements

- This routine assumes 16-bit input and output.

- The number of coefficients nh must be a multiple of 4.

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