DSP M-Registers
@DrWatson
Published in
atari
· 1 year ago
... "twiddle factors" with FFTs. Interestingly(?), if we consider a setting where Nn = 1024, using reverse carry repeatedly with the following code: move #Output_buffer,r1 move #0,r0 move #0,m0 ; select reverse-carry move #512,n0 ; our reverse carry "increment" do #100,rc_loop move r0,x:(r1)+ lua (r0)+n0,r0 nop ; wait for pipeline rc_loop: ... produces the following sequence: 0, 512, 256, 768, 128, 640 ... or in binary: 000000000 100000000 010000000 110000000 001000000 101000000 011000000 This may look strange, but when an FFT is produced the data is "scrambled". In the produced table, value 0 is at 0, value 1 is at 512, value 2 at 256, and so on... Ste ...