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Motorola DSP96002 User Manual

Page 546

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MOTOROLA

DSP96002 USER’S MANUAL

B-27

FIR LATTICE FILTER

z

-1

move x:(r0)+,d6.s y:(r4)+,d7.s

fmpy.s d7,d6,d1 x:(r0)+,d4.s y:(r4)+,d5.s

fmpy.s d9,d4,d2

fmpy d5,d4,d0 fadd.s d7,d2 x:(r0)+,d6.s

do #4,_lms_loop

fmpy d9,d6,d3 fadd.s d0,d1 y:(r4)+,d7.s

fmpy d7,d6,d0 fadd.s d5,d3 x:(r0)+,d4.s d2.s,y:(r5)+

fmpy d9,d4,d2 fadd.s d0,d1 y:(r4)+,d5.s

fmpy d5,d4,d0 fadd.s d7,d2 x:(r0)+,d6.s d3.s,y:(r5)+

_lms_loop

fmpy d9,d6,d3 fadd.s d0,d1 d2.s,y:(r5)+

fadd.s d5,d3 (r0)-

move d3.s,y:(r5)+

move y:dsig,d2.s

fsub.s d1,d2

move d2.s,y:e

lms

nop

nop

end

The inner loop updates the coefficients and performs the FIR filtering for a speed of 2N per coefficient.

B.1.17 FIR Lattice Filter

N refers to the number of ’k’ coefficients in the lattice filter. Some filters may have other coefficients other

than the ’k’ coefficients but their number may be determined from k.

K1

K2

K3

z

-1

z

-1

K1

K2

K3

B

(in)

B

(out)

Sx