Motorola DSP96002 - Manual (Page 529)

B-10 DSP96002 USER’S MANUAL MOTOROLA
B.1.14 N Cascaded Real Biquad IIR Filters
w(n) = x(n) - a1 * w(n-1) - a2 * w(n-2)
y(n) = w(n) + b1 * w(n-1) + b2 * w(n-2)
X Memory Organization Y Memory Organization
b1N Coef. + 4N-1
b2N
a1N
a2N
wN(n-1) Data + 2N-1 .
wN(n-2) .
. b11
. b21
w1(n-1) a11
R1,R0
→
w1(n-2) Data R4
→
a21 Coef.
DSP56000 IMPLEMENTATION
Program ICycles
Words
move #$ffffffff,m0 2 2
move m0,m4 1 1
move #data,r0 2 2
move #coef,r4 2 2
movep x:input,a 1 2
move x:(r0)+,x0 y:(r4)+,y0 1 1
do #n,end 2 3
mac -x0,y0,a x:(r0)-,x1 y:(r4)+,y0 1 1
macr -x1,y0,a x1,x:(r0)+ y:(r4)+,y0 1 1
mac x0,y0,a a,x:(r0)+ y:(r4)+,y0 1 1
mac x1,y0,a x:(r0)+,x0 y:(r4)+,y0 1 1
end
rnd a 1 1
movep a,x:output 1 2
-------------------
Totals 17 4N+16