mandelbrot Rust #8 program

// The Computer Language Benchmarks Game
// https://salsa.debian.org/benchmarksgame-team/benchmarksgame/
//
// contributed by Matt Watson
// contributed by TeXitoi
// contributed by Volodymyr M. Lisivka
// contributed by Michael Cicotti

extern crate generic_array;
extern crate num_traits;
extern crate numeric_array;
extern crate rayon;

use generic_array::typenum::consts::U8;
use numeric_array::NumericArray as Arr;
use rayon::prelude::*;
use std::io::Write;

// [f64;8]
type Vecf64 = Arr<f64, U8>;
type Constf64 = numeric_array::NumericConstant<f64>;

const MAX_ITER: usize = 50;
const VLEN: usize = 8;

#[inline(always)]
pub fn mbrot8(out: &mut u8, cr: Vecf64, ci: Constf64) {
    let mut zr = Arr::splat(0f64);
    let mut zi = Arr::splat(0f64);
    let mut tr = Arr::splat(0f64);
    let mut ti = Arr::splat(0f64);
    let mut absz = Arr::splat(0f64);

    for _ in 0..MAX_ITER / 5 {
        for _ in 0..5 {
            zi = (zr + zr) * zi + ci;
            zr = tr - ti + cr;
            tr = zr * zr;
            ti = zi * zi;
        }

        absz = tr + ti;
        if absz.iter().all(|&t| t > 4.) {
            return;
        }
    }

    *out = absz.iter().enumerate().fold(0, |accu, (i, &t)| {
        accu | if t <= 4. { 0x80 >> i } else { 0 }
    });
}

fn main() {
    let size = std::env::args()
        .nth(1)
        .and_then(|n| n.parse().ok())
        .unwrap_or(200);
    // Round size to multiple of 8
    let size = size / VLEN * VLEN;

    let inv = 2. / size as f64;

    let mut xloc = vec![Arr::splat(0f64); size / VLEN];
    for i in 0..size {
        xloc[i / VLEN][i % VLEN] = i as f64 * inv - 1.5;
    }

    let stdout_unlocked = std::io::stdout();
    // Main thread only can print to stdout
    let mut stdout = stdout_unlocked.lock();

    println!("P4\n{} {}", size, size);

    let mut rows = vec![0; size * size / VLEN];
    rows.par_chunks_mut(size / VLEN)
        .enumerate()
        .for_each(|(y, out)| {
            let ci = numeric_array::NumericConstant(y as f64 * inv - 1.);
            out.iter_mut()
                .enumerate()
                .for_each(|(i, inner_out)| mbrot8(inner_out, xloc[i], ci));
        });

    let _ = stdout.write_all(&rows);
}
    

NOTES:
64-bit Ubuntu quad core
1.80.1
(3f5fd8dd4
2024-08-06)
LLVM version: 18.1.7


 Thu, 05 Sep 2024 22:44:10 GMT

MAKE:
/opt/src/rust-1.80.1/bin/rustc -C opt-level=3 -C target-cpu=ivybridge -C codegen-units=1 -L /opt/src/rust-libs --extern num_traits=/opt/src/rust-libs/libnum_traits-a9cd27d969f03796.rlib mandelbrot.rs -o mandelbrot.rust-8.rust_run

9.94s to complete and log all make actions

COMMAND LINE:
 ./mandelbrot.rust-8.rust_run 16000

(BINARY) PROGRAM OUTPUT NOT SHOWN