CODEWITHSUNDEEP
iosxcodefft
mmr
mmr

Reputation: 14919

How can I build ffts for XCode 5?

Anthony Blake published a novel fft approach he calls the Fastest Fourier Transform in the South, and I'd like to use it in my iOS apps. He's also a user here on SO, so if he can answer this question, that would be great :) But if not, maybe another XCode/MacOS guru can point the way to solving the problem.

The issue is described in this github issue posting here. The short version, as I understand it, is that XCode is trying to build a 64 bit version of the library, but the code itself is 32 bit. I don't know if the ffts code as its posted there will work as part of a 64 bit app anyway (there's a lot of assembly there, and it's my understanding that assembly has to be hand-tuned to particular processors, and he may not have done such tuning for a 64 bit processor yet). What I want to know is:

  1. How can I compile and use this library as part of an iOS app?
  2. If I do so, can I make the app a 32 bit app on a 64 bit iOS device, so that I don't have to worry about compiling both 32 and 64 bit versions?

As a side note, I do believe that this question should be tagged 'ffts' (as 'fftw' is a tag), but meh.

Upvotes: 1

Views: 284

Answers (2)

Razvan
Razvan

Reputation: 4122

Go to your project's target build settings and and leave only armv7 as build arhitecture and armv7 & armv7s as valid architectures.

This will build your project for both 32bit & 64bit devices but the app will run in 32bit mode.

Upvotes: 0

gnasher729
gnasher729

Reputation: 52538

I'd use the Accelerate framework, unless you measure things and can prove that it isn't fast enough. Apple has some pretty clever people working on these libraries (from personal knowledge, not just an assumption), so beating them in speed, especially on all kinds of different devices, would be quite a challenge.

Upvotes: 1

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