Struct FftPlannerNeon

pub struct FftPlannerNeon<T: FftNum> { /* private fields */ }

The Neon FFT planner creates new FFT algorithm instances using a mix of scalar and Neon accelerated algorithms. It is supported when using the 64-bit AArch64 instruction set.

RustFFT has several FFT algorithms available. For a given FFT size, the FftPlannerNeon decides which of the available FFT algorithms to use and then initializes them.

// Perform a forward Fft of size 1234
use std::sync::Arc;
use rustfft::{FftPlannerNeon, num_complex::Complex};

if let Ok(mut planner) = FftPlannerNeon::new() {
  let fft = planner.plan_fft_forward(1234);

  let mut buffer = vec![Complex{ re: 0.0f32, im: 0.0f32 }; 1234];
  fft.process(&mut buffer);

  // The FFT instance returned by the planner has the type `Arc<dyn Fft<T>>`,
  // where T is the numeric type, ie f32 or f64, so it's cheap to clone
  let fft_clone = Arc::clone(&fft);
}

If you plan on creating multiple FFT instances, it is recommended to reuse the same planner for all of them. This is because the planner re-uses internal data across FFT instances wherever possible, saving memory and reducing setup time. (FFT instances created with one planner will never re-use data and buffers with FFT instances created by a different planner)

Each FFT instance owns Arcs to its internal data, rather than borrowing it from the planner, so it’s perfectly safe to drop the planner after creating Fft instances.

Implementations

impl<T: FftNum> FftPlannerNeon<T>

pub fn new() -> Result<Self, ()>

Creates a new FftPlannerNeon instance.

Returns Ok(planner_instance) if this machine has the required instruction sets. Returns Err(()) if some instruction sets are missing.

pub fn plan_fft( &mut self, _len: usize, _direction: FftDirection, ) -> Arc<dyn Fft<T>>

Returns a Fft instance which uses Neon instructions to compute FFTs of size len.

If the provided direction is FftDirection::Forward, the returned instance will compute forward FFTs. If it’s FftDirection::Inverse, it will compute inverse FFTs.

If this is called multiple times, the planner will attempt to re-use internal data between calls, reducing memory usage and FFT initialization time.

pub fn plan_fft_forward(&mut self, _len: usize) -> Arc<dyn Fft<T>>

Returns a Fft instance which uses Neon instructions to compute forward FFTs of size len.

If this is called multiple times, the planner will attempt to re-use internal data between calls, reducing memory usage and FFT initialization time.

pub fn plan_fft_inverse(&mut self, _len: usize) -> Arc<dyn Fft<T>>

Returns a Fft instance which uses Neon instructions to compute inverse FFTs of size `len.

If this is called multiple times, the planner will attempt to re-use internal data between calls, reducing memory usage and FFT initialization time.