yfft

Simple FFT library written purely in Rust. Requires a Nightly Rust compiler for x86 intrinsics.

Features

• Features moderately optimized FFT kernels for small, power-of-two, single precision transforms.
• Supports real-to-complex and complex-to-real transforms.
• Clients can opt in to a swizzled input/output data order when they don't need naturally-ordered data.

Limitations

This library was written in 2017 for internal use (specifically, real-time game audio processing) and is not actively maintained anymore. For this reason, this library has the following important limitations:

• It's only optimized for small, power-of-two, single precision transforms. It may work for other sizes, but it will use extremely slow code paths.
• It only supports 1D transforms.
• It does not support detecting processor features at runtime.
• The implementation relies on a plenty of unsafe Rust code. Use at your own risk!

Notes Regarding Compilation

As of the version 1.19.0 cargo doesn't support passing codegen flags to rustc. Because of this, you need to pass the following flags via the RUSTFLAGS environment variable to enable AVX kernel:

export RUSTFLAGS='-Ctarget-feature=+avx,+sse3'

Note: this causes codegen to generate VEX prefixes to all SSE instructions and makes the binary incompatible with processors without AVX support.

Example: Round-trip Conversion

use yfft::{Setup, Options, DataOrder, DataFormat, Env};

let size = 128;

let setup1: Setup<f32> = Setup::new(&Options {
    input_data_order: DataOrder::Natural,
    output_data_order: DataOrder::Swizzled,
    input_data_format: DataFormat::Complex,
    output_data_format: DataFormat::Complex,
    len: size,
    inverse: false,
})
.unwrap();
let setup2: Setup<f32> = Setup::new(&Options {
    input_data_order: DataOrder::Swizzled,
    output_data_order: DataOrder::Natural,
    input_data_format: DataFormat::Complex,
    output_data_format: DataFormat::Complex,
    len: size,
    inverse: true,
})
.unwrap();

// Allocate temporary buffers
let mut env1 = Env::new(&setup1);
let mut env2 = Env::new(&setup2);

// Input data (interleaved complex format)
let mut pat = vec![0.0f32; size * 2];
pat[42] = 100.0;
pat[82] = 200.0;

let mut result = vec![0.0f32; size * 2];
result.copy_from_slice(&pat);

// Round-trip transform
env1.transform(&mut result);
env2.transform(&mut result);

for e in &mut result {
    *e = *e / size as f32;
}

assert_num_slice_approx_eq(
    &result,
    &pat,
    1.0e-3f32
);

License: MIT/Apache-2.0