| Re: FFT routines Kategorie: Programmierung Assembler (von PeterS - 28.02.2013 14:46) | |
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Als Antwort auf FFT routines von PepeV - 26.02.2013 21:50
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> Hi all, > > Attached are some FFT routines in assembler, adapted from the work of ChaN. > Any suggestions for improvement are welcome. > > The routines: > 1. perform a wave capturing (a series of AD conversions in Free Running Mode) > 2. execute 'butterfly operations' > 3. calculate the frequency spectrum > > I have tested them on my Pro-Bot128 and plan to use them for sound control, > in stead of the much slower routines in cc I used until now. > Some figures with results are included in the attached zip file too. > > Torsten, you were right twice: > - I needed access to flash in assembler for the sin/cos and other tables. Since > this is not possible directly, I now copy these to ram before use. (For this > reason I cannot process more than 256 samples, helas!) > - I need to disable the global interrupt. But to my great surprise, not only in the > ADC capture but in all routines. If I do not do that, I end up with garbage results. > > Peter: can you explain why interrupts mess up my routines? Is it that interrupts > trigger actions that change registers while my routines are running? Is it the Y- > register? Hello Pepe, you are right. I just had forgotten that the Y-Register should better not be changed, because it is normally used as Data Stackpointer. The interrupt routines are using it to save the contents of registers. Regards, Peter > > Regards, > Pepe | |
Antwort schreiben Antworten:  Re: FFT routines (von PepeV - 28.02.2013 15:41)Re: FFT routines (von PeterS - 28.02.2013 17:28)Re: FFT routines (von PepeV - 28.02.2013 21:26) | |
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