This crate implements a half-precision floating point f16
type for Rust implementing the IEEE
754-2008 standard binary16
a.k.a "half" format, as well as a bf16
type implementing the
bfloat16
format.
The f16
and bf16
types attempt to match existing Rust floating point type functionality where possible, and provides both conversion operations (such as to/from f32
and f64
) and basic
arithmetic operations. Hardware support for these operations will be used whenever hardware support
is available—either through instrinsics or targeted assembly—although a nightly Rust toolchain may
be required for some hardware.
This crate provides no_std
support by
default so can easily be used in embedded code where a smaller float format is most useful.
Requires Rust 1.61 or greater. If you need support for older versions of Rust, use 1.x versions of this crate.
See the crate documentation for more details.
-
serde
- ImplementSerialize
andDeserialize
traits forf16
andbf16
. This adds a dependency on theserde
crate. -
use-intrinsics
— Use unstable hardware intrinsics forf16
andbf16
conversions if available on the compiler target. By default, only hardware support compatible with the Rust stable toolchain will be used, or software emulation otherwise. Available only on Rust nightly channel. -
alloc
— Enable use of thealloc
crate when not using thestd
library.This enables the
vec
module, which contains zero-copy conversions for theVec
type. This allows fast conversion between rawVec<u16>
bits andVec<f16>
orVec<bf16>
arrays, and vice versa. -
std
— Enable features that depend on the Ruststd
library, including everything in thealloc
feature.Enabling the
std
feature enables runtime CPU feature detection of hardware support. Without this feature detection, harware is only used when compiler target supports them. -
num-traits
— EnableToPrimitive
,FromPrimitive
,Num
,Float
,FloatCore
andBounded
trait implementations from thenum-traits
crate. -
bytemuck
— EnableZeroable
andPod
trait implementations from thebytemuck
crate. -
zerocopy
— EnableAsBytes
andFromBytes
trait implementations from thezerocopy
crate. -
rand_distr
— Enable sampling from distributions likeUniform
andNormal
from therand_distr
crate.
The following list details hardware support for floating point types in this crate. When using std
library, runtime CPU target detection will be used. To get the most performance benefits, compile
for specific CPU features which avoids the runtime overhead and works in a no_std
environment.
Architecture | CPU Target Feature | Notes |
---|---|---|
x86 /x86_64 |
f16c |
Only on nightly Rust toolchain with use-intrinsics cargo feature. This supports conversion to/from f16 only (including vector SIMD) and does not support any bf16 or arithmetic operations. |
aarch64 |
fp16 |
This supports all operations on f16 only. |
This library is distributed under the terms of either of:
- MIT License (https://opensource.org/licenses/MIT)
- Apache License, Version 2.0 (https://www.apache.org/licenses/LICENSE-2.0)
at your option.
This project is REUSE-compliant. Copyrights are retained by their contributors. Some files may include explicit copyright notices and/or license SPDX identifiers. For full authorship information, see the version control history.
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.