Add IPP (Intel performance primitives) implementations

[dgrahelj]

• adds a cargo feature ipp (for use on Intel processors) which requires the IPP framework to be locally installed and the environment variable IPPROOT set (normally done using a script in the Intel OneApi framework - see readme)
• Uses IPP functions in FFT, FFTConvolver, TwoStageConvolver and CrossfadeConvolver
• Exposes the head_size and tail_size parameters of the TwoStageConvolver to enable optimal performance tweaking on different platforms

Note: currently points to a fork of the rust ipp-sys crate with the rust bindings, since the original crate does not include the latest bindings. Hopefully this gets merged upstream soon it seems like the upstream crate repository is not maintained anymore. I made a fork on holoplot and am pointing to it

[wiccy46]

As this is open source, does it have implication to user without such framework ?

[dgrahelj]

As this is open source, does it have implication to user without such framework ?

The ipp feature is optional. By default the old implementations that rely only on rustfft are used. The ipp implementations are used only if the user specifically enables the feature (eg. cargo build --features ipp).

[holopeat]

Great stuff! The preferred way would be to use generics or traits to inject the right FFT implementation and reuse as much code as possible. This generalization would also include functions to allocate data and complex number multiplications, as far as I can see.

[dgrahelj]

Great stuff! The preferred way would be to use generics or traits to inject the right FFT implementation and reuse as much code as possible. This generalization would also include functions to allocate data and complex number multiplications, as far as I can see.

Good point! I now unified the code with two extra traits - FftBackend and ComplexOps. Please take another look @holopeat