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Fast Fourier Transforms on Motorola's Digital Signal Processors

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move #(data+pg128),r1<br />

move #64,n7 ; still 64 r2 groups to calculate<br />

move #(pg128-3),r7 ; pg128 r2 butterflies in a group<br />

move #(pg128+1),n0 ; step to next group<br />

jsr _nr2<br />

;****************************************************************************<br />

; ------------ 8. STAGE AS RADIX-2 BUTTERFLY ------------------------------ *<br />

;****************************************************************************<br />

move #5,n0<br />

move #(data+4),r1<br />

move #tab4,r6<br />

move #data,r0<br />

move r1,r5<br />

mover 0,r4<br />

move n0,n1<br />

move n0,n4<br />

move n0,n5<br />

move x:(r6),d9.s y:,d8.s<br />

move x:(r1)+,d0.s y:,d1.s<br />

move x:(r0),d4.s y:(r6),d2.s<br />

move y:(r1),d7.s<br />

faddsub.s d4,d0 x:(r1)+,d6.s y:(r6)+n6,d3.s<br />

do #pg8,_end3 ; loop of groups<br />

fmpy d9,d6,d0 fsub.s d1,d2 d0.s,x:(r4) y:(r0)+,d5.s<br />

fmpy d9,d7,d1 faddsub.s d5,d2 d4.s,x:(r5) y:(r1),d7.s<br />

fmpy d8,d6,d2 fadd.s d3,d0 x:(r0),d4.s d2.s,y:(r5)+<br />

fmpy d8,d7,d3 faddsub.s d4,d0 x:(r1)+,d6.s d5.s,y:(r4)+<br />

fmpy d9,d6,d0 fsub.s d1,d2 d0.s,x:(r4) y:(r0)+,d5.s<br />

fmpy d9,d7,d1 faddsub.s d5,d2 d4.s,x:(r5) y:(r1),d7.s<br />

fmpy d8,d6,d2 fadd.s d3,d0 x:(r0),d4.s d2.s,y:(r5)+<br />

fmpy d8,d7,d3 faddsub.s d4,d0 x:(r1)+n1,d6.s d5.s,y:(r4)+<br />

fmpy d9,d6,d0 fsub.s d1,d2 d0.s,x:(r4) y:(r0)+,d5.s<br />

fmpy d9,d7,d1 faddsub.s d5,d2 d4.s,x:(r5) y:(r1),d7.s<br />

fmpy d8,d6,d2 fadd.s d3,d0 x:(r0),d4.s d2.s,y:(r5)+<br />

move x:(r6)+n6,d9.s y:,d8.s<br />

fmpy d8,d7,d3 faddsub.s d4,d0 x:(r1)+,d6.s d5.s,y:(r4)+<br />

fmpy d9,d6,d0 fsub.s d1,d2 d0.s,x:(r4) y:(r0)+n0,d5.s<br />

fmpy d9,d7,d1 faddsub.s d5,d2 d4.s,x:(r5) y:(r1),d7.s<br />

fmpy d8,d6,d2 fadd.s d3,d0 x:(r0),d4.s d2.s,y:(r5)+n5<br />

fmpy d8,d7,d3 faddsub.s d4,d0 x:(r1)+,d6.s d5.s,y:(r4)+n4<br />

_end3<br />

;****************************************************************************<br />

; ------------ LAST TWO STAGES AS RADIX-4 BUTTERFLY ----------------------- *<br />

;****************************************************************************<br />

move #$0,m2<br />

move m2,m3<br />

Figure A-1 Optimized Complex FFT for the DSP96002 (sheet 6 of 20)<br />

A-6 MOTOROLA

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