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Caleb Zulawski 2022-10-16 20:11:39 -04:00 • committed by GitHub
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@ -24,20 +24,10 @@ or by setting up `rustup default nightly` or else with `cargo +nightly {build,te
```bash
cargo new hellosimd
```
to create a new crate. Edit `hellosimd/Cargo.toml` to be
```toml
[package]
name = "hellosimd"
version = "0.1.0"
edition = "2018"
[dependencies]
core_simd = { git = "https://github.com/rust-lang/portable-simd" }
```
and finally write this in `src/main.rs`:
to create a new crate. Finally write this in `src/main.rs`:
```rust
#![feature(portable_simd)]
use core_simd::*;
use std::simd::f32x4;
fn main() {
let a = f32x4::splat(10.0);
let b = f32x4::from_array([1.0, 2.0, 3.0, 4.0]);
@ -45,24 +35,22 @@ fn main() {
}
```
Explanation: We import all the bindings from the crate with the first line. Then, we construct our SIMD vectors with methods like `splat` or `from_array`. Finally, we can use operators on them like `+` and the appropriate SIMD instructions will be carried out. When we run `cargo run` you should get `[11.0, 12.0, 13.0, 14.0]`.
Explanation: We construct our SIMD vectors with methods like `splat` or `from_array`. Next, we can use operators like `+` on them, and the appropriate SIMD instructions will be carried out. When we run `cargo run` you should get `[11.0, 12.0, 13.0, 14.0]`.
## Code Organization
## Supported vectors
Currently the crate is organized so that each element type is a file, and then the 64-bit, 128-bit, 256-bit, and 512-bit vectors using those types are contained in said file.
All types are then exported as a single, flat module.
Currently, vectors may have up to 64 elements, but aliases are provided only up to 512-bit vectors.
Depending on the size of the primitive type, the number of lanes the vector will have varies. For example, 128-bit vectors have four `f32` lanes and two `f64` lanes.
The supported element types are as follows:
* **Floating Point:** `f32`, `f64`
* **Signed Integers:** `i8`, `i16`, `i32`, `i64`, `i128`, `isize`
* **Unsigned Integers:** `u8`, `u16`, `u32`, `u64`, `u128`, `usize`
* **Masks:** `mask8`, `mask16`, `mask32`, `mask64`, `mask128`, `masksize`
* **Signed Integers:** `i8`, `i16`, `i32`, `i64`, `isize` (`i128` excluded)
* **Unsigned Integers:** `u8`, `u16`, `u32`, `u64`, `usize` (`u128` excluded)
* **Masks:** 8-bit, 16-bit, 32-bit, 64-bit, and `usize`-sized masks
Floating point, signed integers, and unsigned integers are the [primitive types](https://doc.rust-lang.org/core/primitive/index.html) you're already used to.
The `mask` types are "truthy" values, but they use the number of bits in their name instead of just 1 bit like a normal `bool` uses.
The mask types have elements that are "truthy" values, like `bool`, but have an unspecified layout because different architectures prefer different layouts for mask types.
[simd-guide]: ./beginners-guide.md
[zulip-project-portable-simd]: https://rust-lang.zulipchat.com/#narrow/stream/257879-project-portable-simd