Fast Fourier Transforms on Motorola's Digital Signal Processors

; ------------ NORMAL RADIX-2 BUTTERFLY ----------------------------------- *
;**************************************************************************
**
_nr2
move r0,r4
move r1,r5
move n0,n1
move n0,n4
move n0,n5
move x:(r6)+n6,d9.s y:,d8.s
move y:(r1),d7.s
fmpy.s d8,d7,d3 x:(r1)+,d6.s
fmpy.s d9,d6,d0
fmpy.s d9,d7,d1 y:(r1),d7.s
fmpy d8,d6,d2 fadd.s d3,d0 x:(r0),d4.s
fmpy d8,d7,d3 faddsub.s d4,d0 x:(r1)+,d6.s
do n7,_endgrp ; loop of groups
do r7,_bfly ; butterflyloop
fmpy d9,d6,d0 fsub.s d1,d2 d0.s,x:(r4) y:(r0)+,d5.s
fmpy d9,d7,d1 faddsub.s d5,d2 d4.s,x:(r5) y:(r1),d7.s
fmpy d8,d6,d2 fadd.s d3,d0 x:(r0),d4.s d2.s,y:(r5)+
fmpy d8,d7,d3 faddsub.s d4,d0 x:(r1)+,d6.s d5.s,y:(r4)+
_bfly
fmpy d9,d6,d0 fsub.s d1,d2 d0.s,x:(r4) y:(r0)+,d5.s
fmpy d9,d7,d1 faddsub.s d5,d2 d4.s,x:(r5) y:(r1),d7.s
fmpy d8,d6,d2 fadd.s d3,d0 x:(r0),d4.s d2.s,y:(r5)+
fmpy d8,d7,d3 faddsub.s d4,d0 x:(r1)+n1,d6.s d5.s,y:(r4)+
fmpy d9,d6,d0 fsub.s d1,d2 d0.s,x:(r4) y:(r0)+,d5.s
fmpy d9,d7,d1 faddsub.s d5,d2 d4.s,x:(r5) y:(r1),d7.s
fmpy d8,d6,d2 fadd.s d3,d0 x:(r0),d4.s d2.s,y:(r5)+
move x:(r6)+n6,d9.s y:,d8.s
fmpy d8,d7,d3 faddsub.s d4,d0 x:(r1)+,d6.s d5.s,y:(r4)+
fmpy d9,d6,d0 fsub.s d1,d2 d0.s,x:(r4) y:(r0)+n0,d5.s
fmpy d9,d7,d1 faddsub.s d5,d2 d4.s,x:(r5) y:(r1),d7.s
fmpy d8,d6,d2 fadd.s d3,d0 x:(r0),d4.s d2.s,y:(r5)+n5
fmpy d8,d7,d3 faddsub.s d4,d0 x:(r1)+,d6.s d5.s,y:(r4)+n4
_endgrp
rts
endm
% MATLAB-File to generate the radix-4 twiddle factor table for the
% fast FFT-program RMIX1.ASM .
% By increasing the variable fftlength you can make tables for higher
% FFT-lengths than 1024.
%
% Karl Schwarz, Raimund Meyer 17.10.1989
% Lehrstuhl fuer Nachrichtentechnik
% Universitaet Erlangen-Nuernberg
Figure A-1 Optimized Complex FFT for the DSP96002 (sheet 9 of 20)
MOTOROLA A-9