rustfft

AArch64 Targets

RustFFT supports the NEON instruction set in 64-bit Arm, AArch64. As with AVX and SSE, no special code is needed to activate NEON-accelerated code paths: Simply plan a FFT using the FftPlanner on an AArch64 target, and RustFFT will automatically switch to faster NEON-accelerated algorithms.

WebAssembly Targets

RustFFT supports the fixed-width SIMD extension for WebAssembly. Just like AVX, SSE, and NEON, no special code is needed to take advantage of this code path: All you need to do is plan a FFT using the FftPlanner.

Note: There is an important caveat when compiling WASM SIMD accelerated code: Unlike AVX, SSE, and NEON, WASM does not allow dynamic feature detection. Because of this limitation, RustFFT cannot detect CPU features and automatically switch to WASM SIMD accelerated algorithms. Instead, it unconditionally uses the SIMD code path if the wasm_simd crate feature is enabled. Read more about this limitation in the official Rust docs.

Feature Flags

x86_64 Targets

The features avx and sse are enabled by default. On x86_64, these features enable compilation of AVX and SSE accelerated code.

Disabling them reduces compile time and binary size.

On other platforms than x86_64, these features do nothing and RustFFT will behave like they are not set.

AArch64 Targets

The neon is enabled by default. On AArch64, this feature enables compilation of Neon-accelerated code.

Disabling it reduces compile time and binary size.

On other platforms than AArch64, this feature does nothing and RustFFT will behave like it is not set.

WebAssembly Targets

The feature wasm_simd is disabled by default. On the WASM platform, this feature enables compilation of WASM SIMD accelerated code.

To execute binaries compiled with wasm_simd, you need a target browser or runtime which supports fixed-width SIMD. If you run your SIMD accelerated code on an unsupported platform, WebAssembly will specify a trap leading to immediate execution cancelation.

On other platforms than WASM, this feature does nothing and RustFFT will behave like it is not set.

Stability/Future Breaking Changes

The latest version is 6.2 - Version 5.0 was released at the beginning of 2022 and contains several breaking API changes from previous versions. For users on very old version of RustFFT, check out the Upgrade Guide for a walkthrough of the changes RustFFT 5.0 requires to upgrade. In the interest of stability, we're committing to making no more breaking changes for 3 years, aka until 2024.

This policy has one exception: We currently re-export pre-1.0 versions of the num-complex and num-traits crates. In the interest of avoiding ecosystem fragmentation, we will keep up with these crates even if it requires major version bumps. When those crates release new major versions, we will upgrade as soon as possible, which will require a major version change of our own. In these situations, the version increase of num-complex/num-traits will be the only breaking change in the release.

Supported Rust Version

RustFFT requires rustc 1.88 or newer. Minor releases of RustFFT may upgrade the MSRV(minimum supported Rust version) to a newer version of rustc. However, if we need to increase the MSRV, the new Rust version must have been released at least six months ago.

License

Licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

Before submitting a PR, please make sure to run cargo fmt.