Well i set myself a challenge to have an FFT function using nothing but ksh93 and awk.
It took some serious jiggery pokery and concentration with all the brackets and '$' characters but here is the result. It is RADIX 2 only, but hey, show me another UNIX shell script that does it. It IS SLOW but is ideal for my needs.
It uses ksh's floating point arithmetic and awk to obtain the SINE and COSINE requirements although even awk is not needed for this as typical Taylor series for these could have been created.
This was a learning curve primarily because ksh has a few minor differences to bash; however this is the result.
(For those that know the AMIGA, I am now thinking of porting this to ARexx although it has no SINE, COSINE or SQRT. I have already done SINE and SQRT for ARexx so COSINE is just a simple SINE change.)
This is in the Public Domain, CC0, here and hopefully there will be some interest from outside our community.
The results of the code below:
The script:
Enjoy all.
Snippets like these are what keep me from going insane.
------ Post updated at 07:31 PM ------
Hi bakunin...
Quote:
Quote:
Originally Posted by wisecracker
I am an AMIGA fanatic still and was searching for a basic FFT routine for Python 1.4.0 for the AMIGA.
My suggestion is to first do it in Assembler. Doing it in Python (or any other interpreted language, except probably FORTH) is like trying to build a race car - out of Lego. And, second, to do it on a DSP. I am not up to date with the latest DSPs any more, but i suggest to take a look at the C66x series from Texas Instruments or the ADSP-SC57x series from Analog Devices. Both are RT-capable floating-point DSPs and from my personal experience (TI32C80 from TI, i can't remember the name of the AD machine) both manufacturers made great procs. You might also try the still available 56k-series by Motorola. I used these (especially the 56001) a lot back in the days.
Thank you for the info but......
I do bizarre things like this to expand my knowledge on the limits of languages, not the limits of HW.
I even got my USB Arduino Diecimila board to talk to my AMIGA with minor HW mods, uploaded to AMINET, using BWBasic purely as a challenge, that's right BWBasic. It has had hundreds of DLs which shows people ARE interested in esoteric stuff like mine.
Real time applications are of no interest at the moment as AudioScope.sh is by definition slow as is its builtin Spec-An using Python 2.7.x with module imports of scipy and scipy.IO. As these ARE dependencies then I have written FFT code that works from Python 2.0.1 to the current 3.7.0. I now have since modified code to work from Python 1.4.0, the only version to work on a stock AMIGA A1200, also up to 3.7.0. Boy how, Python has changed. These mods can be seriously difficult to work around but now I have my building blocks to work with to adapt into AudioScope.sh for AudioScope.sh's Spec-An section without the need for dependencies.
ATM FFT on ksh was a new baby to see how easy it would be, difficult? YES; impossible? NO. I really do get enjoyment out of stretching languages to strange esoteric limits.
Can I do it in AWK? Dunno, I am not good with AWK but ARexx for the AMIGA WILL be serious fun as it does have basic floating point arithmetic but NO SINE, COSINE, SQRT, etc...
Last edited by wisecracker; 09-14-2018 at 07:49 AM..
Reason: (Attached itself to this post.) Now title changed.
This User Gave Thanks to wisecracker For This Post:
I just love trying near impossible stuff like this. I watch with awe when I see some of you guys code in the shell on things I know little or nothing about so the code above is the way I can get to learn strange subtleties in languages and apply it to things I do know something about.
so two reasons why I haven't tried awk yet.
1) I wanted to see if it was possible to do it in a shell script.
And 2) I don't know enough awk yet and would love to do it, so it IS on the books...
The code is slow but there is no other at all so it might come onto Google's search list bringing people here.
Well guys, it took a while because of the serious limitations of ARexx for a stock AMIGA A1200 but here is a working FFT for it. ARexx has no ARRAY facility but there is a workaround. ;o)
Boy oh boy, ARexx's arithmetic is so convoluted and floating point precision is not the best.
This was a challenge. I could have generated SIN, COS and SQRT in pure ARexx but decided to use an external ARexx math(s) library instead...
It would be just as easy to create SIN, COS and SQRT in ksh too eliminating awk entirely but awk just made it easier...
Just for the record the AMIGA shell/terminal has a large subset of xterm's escape codes.
An exercise in futility? Maybe but serious fun nevertheless...
This is through FS-UAE AMIGA emulation and my real A1200 setup for easy transfer from this Macbook Pro.
ARexx code:
I just knew you would create a translation and get it working on awk. ;o)
You could remove the SIN_ANGLE and COS_ANGLE and put sin(ANGLE) and cos(ANGLE) directly into the two lines below them, eliminating two lines...
Thanks for the translation, I will see if I can eliminate the Python version in AudioScope.sh and attach your name to it...
Another thing is that there is no need to issue the imaginary values for this basic FFT. As long as the real values are actually, cropped or padded to power(s) of 2 then the imaginary values of 0.0 can be internally generated to the same array length as the real values, eliminating the IMAGSTR initialisation on the command line call.
But nice to see an awk version that I can steal... <wink>
Last edited by wisecracker; 09-14-2018 at 07:45 AM..
Reason: Add title...
Hi guys...
This is code that was originally designed to work on an upgraded AMIGA A1200 using Python 2.0.x.
Unfortunately it broke inside much later versions, NOT because of the print statement/function but other minor subtleties. So this is the final result tested on various machines including... (0 Replies)
Hi everyone !
Im trying to know from wich version of AIX KSH93 is available ?
Internet tell me 6.x and 7.x AIX are available, bue what about 5.x ?
Is KSH93 available on AIX 5.x ?
Is it the same way to manipulate variables as KSH93 on 7.x ?
Thanks for your support and have a nice day ! (2 Replies)
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