wmemchr.rs

use criterion::{criterion_group, criterion_main, Criterion};
use rand::Rng;
use wmemchr_benches::unrolled_find_u16s;

const SMALL: usize = 256;
const MEDIUM: usize = 66536;

const fn middle(n: usize) -> usize {
    n * 3 / 4
}

fn bench_small_no_null(c: &mut Criterion) {
    let mut rng = rand::thread_rng();

    // exclude NUL byte from 1..256 range
    let buf: Vec<u16> = (0..SMALL).map(|_| rng.gen_range(1, 256) as u16).collect();

    let mut group = c.benchmark_group("small slice      [no null in slice]");
    group.bench_function("iter::position", |b| {
        b.iter(|| buf.iter().position(|&c| c == 0))
    });
    group.bench_function("unrolled_find_u16s", |b| {
        b.iter(|| unrolled_find_u16s(0, &buf))
    });
    group.finish();
}

fn bench_small_null_middle(c: &mut Criterion) {
    let mut rng = rand::thread_rng();

    // exclude NUL byte from 1..256 range
    let mut buf: Vec<u16> = (0..SMALL).map(|_| rng.gen_range(1, 256) as u16).collect();
    buf[middle(SMALL)] = 0;

    let mut group = c.benchmark_group("small slice      [null in the middle of slice]");
    group.bench_function("iter::position", |b| {
        b.iter(|| buf.iter().position(|&c| c == 0))
    });
    group.bench_function("unrolled_find_u16s", |b| {
        b.iter(|| unrolled_find_u16s(0, &buf))
    });
    group.finish();
}

fn bench_small_null_end(c: &mut Criterion) {
    let mut rng = rand::thread_rng();

    // exclude NUL byte from 1..256 range
    let mut buf: Vec<u16> = (0..SMALL).map(|_| rng.gen_range(1, 256) as u16).collect();
    buf[SMALL - 1] = 0;

    let mut group = c.benchmark_group("small slice      [null at the end of slice]");
    group.bench_function("iter::position", |b| {
        b.iter(|| buf.iter().position(|&c| c == 0))
    });
    group.bench_function("unrolled_find_u16s", |b| {
        b.iter(|| unrolled_find_u16s(0, &buf))
    });
    group.finish();
}

fn bench_medium_no_null(c: &mut Criterion) {
    let mut rng = rand::thread_rng();

    // exclude NUL byte from 1..256 range
    let buf: Vec<u16> = (0..MEDIUM).map(|_| rng.gen_range(1, 256) as u16).collect();

    let mut group = c.benchmark_group("[medium slice    [no null in slice]");
    group.bench_function("iter::position", |b| {
        b.iter(|| buf.iter().position(|&c| c == 0))
    });
    group.bench_function("unrolled_find_u16s", |b| {
        b.iter(|| unrolled_find_u16s(0, &buf))
    });
    group.finish();
}

fn bench_medium_null_middle(c: &mut Criterion) {
    let mut rng = rand::thread_rng();

    // exclude NUL byte from 1..256 range
    let mut buf: Vec<u16> = (0..MEDIUM).map(|_| rng.gen_range(1, 256) as u16).collect();
    buf[middle(MEDIUM)] = 0;

    let mut group = c.benchmark_group("medium slice     [null in the middle of slice]");
    group.bench_function("iter::position", |b| {
        b.iter(|| buf.iter().position(|&c| c == 0))
    });
    group.bench_function("unrolled_find_u16s", |b| {
        b.iter(|| unrolled_find_u16s(0, &buf))
    });
    group.finish();
}

fn bench_medium_null_end(c: &mut Criterion) {
    let mut rng = rand::thread_rng();

    // exclude NUL byte from 1..256 range
    let mut buf: Vec<u16> = (0..MEDIUM).map(|_| rng.gen_range(1, 256) as u16).collect();
    buf[MEDIUM - 1] = 0;

    let mut group = c.benchmark_group("medium slice     [null at the end of slice]");
    group.bench_function("iter::position", |b| {
        b.iter(|| buf.iter().position(|&c| c == 0))
    });
    group.bench_function("unrolled_find_u16s", |b| {
        b.iter(|| unrolled_find_u16s(0, &buf))
    });
    group.finish();
}

criterion_group!(
    benches,
    bench_small_no_null,
    bench_small_null_middle,
    bench_small_null_end,
    bench_medium_no_null,
    bench_medium_null_middle,
    bench_medium_null_end,
);
criterion_main!(benches);