Motorola DSP96002 User Manual

Page 546

MOTOROLA

DSP96002 USER’S MANUAL

B-27

FIR LATTICE FILTER

-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

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.

∑

-1

(in)

(out)