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Add rust n-body version for comparison (#88)
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‎.gitignore‎

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@@ -3,3 +3,4 @@ docs/
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node_modules/
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out/
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raw/
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examples/n-body/rust/target/

‎examples/n-body/assembly/index.js‎

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const fs = require("fs");
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const path = require("path");
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const compiled = new WebAssembly.Module(
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fs.readFileSync(path.resolve(__dirname, "..", "build", "optimized.wasm"))
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);
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const imports = {
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env: {
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abort: (filename, line, column) => {
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throw Error("abort called at " + line + ":" + colum);
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}
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}
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};
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Object.defineProperty(module, "exports", {
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get: () => new WebAssembly.Instance(compiled, imports).exports
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});

‎examples/n-body/index.js‎

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This file was deleted.

‎examples/n-body/rust/Cargo.lock‎

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‎examples/n-body/rust/Cargo.toml‎

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[package]
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name = "rust_nbody"
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version = "0.1.0"
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authors = ["MaxGraey <maxgraey@gmail.com>"]
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[lib]
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path = "src/lib.rs"
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crate-type = ["cdylib"]

‎examples/n-body/rust/README.md‎

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### Build
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```bash
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cargo build --release --target=wasm32-unknown-unknown
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```
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***Next step optimize target wasm via wasm-opt.***

‎examples/n-body/rust/index.js‎

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const fs = require("fs");
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const path = require("path");
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const compiled = new WebAssembly.Module(
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fs.readFileSync(path.resolve(__dirname, "..", "build", "rust.optimized.wasm"))
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);
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const imports = {
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env: {
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abort: (filename, line, column) => {
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throw Error("abort called at " + line + ":" + colum);
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}
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}
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};
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Object.defineProperty(module, "exports", {
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get: () => new WebAssembly.Instance(compiled, imports).exports
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});

‎examples/n-body/rust/src/lib.rs‎

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// Code adopted from https://benchmarksgame-team.pages.debian.net/benchmarksgame/program/nbody-rust-1.html
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#![feature(core_intrinsics, lang_items)]
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#![no_std]
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#[lang = "panic_fmt"]
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extern "C" fn panic_fmt(_args: ::core::fmt::Arguments, _file: &'static str, _line: u32) -> ! {
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use core::intrinsics;
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unsafe {
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intrinsics::abort();
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}
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}
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#[inline(always)]
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fn sqrt(x: f64) -> f64 {
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use core::intrinsics;
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unsafe {
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intrinsics::sqrtf64(x)
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}
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}
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const PI: f64 = 3.141592653589793;
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const SOLAR_MASS: f64 = 4.0 * PI * PI;
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const YEAR: f64 = 365.24;
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const N_BODIES: usize = 5;
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static mut BODIES: [Planet; N_BODIES] = [
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// Sun
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Planet {
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x: 0.0,
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y: 0.0,
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z: 0.0,
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vx: 0.0,
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vy: 0.0,
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vz: 0.0,
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mass: SOLAR_MASS,
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},
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// Jupiter
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Planet {
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x: 4.84143144246472090e+00,
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y: -1.16032004402742839e+00,
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z: -1.03622044471123109e-01,
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vx: 1.66007664274403694e-03 * YEAR,
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vy: 7.69901118419740425e-03 * YEAR,
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vz: -6.90460016972063023e-05 * YEAR,
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mass: 9.54791938424326609e-04 * SOLAR_MASS,
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},
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// Saturn
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Planet {
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x: 8.34336671824457987e+00,
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y: 4.12479856412430479e+00,
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z: -4.03523417114321381e-01,
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vx: -2.76742510726862411e-03 * YEAR,
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vy: 4.99852801234917238e-03 * YEAR,
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vz: 2.30417297573763929e-05 * YEAR,
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mass: 2.85885980666130812e-04 * SOLAR_MASS,
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},
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// Uranus
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Planet {
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x: 1.28943695621391310e+01,
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y: -1.51111514016986312e+01,
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z: -2.23307578892655734e-01,
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vx: 2.96460137564761618e-03 * YEAR,
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vy: 2.37847173959480950e-03 * YEAR,
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vz: -2.96589568540237556e-05 * YEAR,
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mass: 4.36624404335156298e-05 * SOLAR_MASS,
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},
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// Neptune
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Planet {
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x: 1.53796971148509165e+01,
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y: -2.59193146099879641e+01,
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z: 1.79258772950371181e-01,
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vx: 2.68067772490389322e-03 * YEAR,
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vy: 1.62824170038242295e-03 * YEAR,
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vz: -9.51592254519715870e-05 * YEAR,
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mass: 5.15138902046611451e-05 * SOLAR_MASS,
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},
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];
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#[derive(Clone, Copy)]
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struct Planet {
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x: f64,
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y: f64,
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z: f64,
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vx: f64,
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vy: f64,
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vz: f64,
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mass: f64,
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}
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fn advance(bodies: &mut [Planet; N_BODIES], dt: f64) {
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let mut b_slice: &mut [_] = bodies;
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loop {
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let bi = match shift_mut_ref(&mut b_slice) {
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Some(bi) => bi,
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None => break,
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};
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for bj in b_slice.iter_mut() {
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let dx = bi.x - bj.x;
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let dy = bi.y - bj.y;
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let dz = bi.z - bj.z;
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let d2 = dx * dx + dy * dy + dz * dz;
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let mag = dt / (d2 * sqrt(d2));
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let massj_mag = bj.mass * mag;
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bi.vx -= dx * massj_mag;
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bi.vy -= dy * massj_mag;
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bi.vz -= dz * massj_mag;
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let massi_mag = bi.mass * mag;
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bj.vx += dx * massi_mag;
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bj.vy += dy * massi_mag;
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bj.vz += dz * massi_mag;
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}
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bi.x += dt * bi.vx;
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bi.y += dt * bi.vy;
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bi.z += dt * bi.vz;
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}
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}
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fn energy(bodies: &[Planet; N_BODIES]) -> f64 {
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let mut e = 0.0;
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let mut bodies = bodies.iter();
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loop {
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let bi = match bodies.next() {
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Some(bi) => bi,
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None => break,
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};
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e += (bi.vx * bi.vx + bi.vy * bi.vy + bi.vz * bi.vz) * bi.mass / 2.0;
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for bj in bodies.clone() {
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let dx = bi.x - bj.x;
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let dy = bi.y - bj.y;
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let dz = bi.z - bj.z;
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let dist = sqrt(dx * dx + dy * dy + dz * dz);
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e -= bi.mass * bj.mass / dist;
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}
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}
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e
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}
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fn offset_momentum(bodies: &mut [Planet; N_BODIES]) {
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let mut px = 0.0;
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let mut py = 0.0;
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let mut pz = 0.0;
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for bi in bodies.iter() {
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px += bi.vx * bi.mass;
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py += bi.vy * bi.mass;
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pz += bi.vz * bi.mass;
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}
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let sun = &mut bodies[0];
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sun.vx = -px / SOLAR_MASS;
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sun.vy = -py / SOLAR_MASS;
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sun.vz = -pz / SOLAR_MASS;
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}
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#[no_mangle]
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pub unsafe extern "C" fn init() {
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offset_momentum(&mut BODIES);
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}
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#[no_mangle]
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pub unsafe extern "C" fn step() -> f64 {
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advance(&mut BODIES, 0.01);
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energy(&BODIES)
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}
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#[no_mangle]
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pub unsafe extern "C" fn bench(steps: i32) {
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for _ in 0..steps {
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advance(&mut BODIES, 0.01);
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}
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}
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/// Pop a mutable reference off the head of a slice, mutating the slice to no
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/// longer contain the mutable reference.
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fn shift_mut_ref<'a, T>(r: &mut &'a mut [T]) -> Option<&'a mut T> {
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if r.len() == 0 {
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return None;
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}
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let tmp = core::mem::replace(r, &mut []);
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let (h, t) = tmp.split_at_mut(1);
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*r = t;
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Some(&mut h[0])
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}

‎examples/n-body/tests/index.js‎

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const fs = require("fs");
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// Load WASM version
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const nbodyWASM = require("../index.js");
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const nbodyAS = require("../assembly/index.js");
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const nbodyRS = require("../rust/index.js");
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// Load ASMJS version
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src = fs.readFileSync(__dirname + "/../build/index.asm.js", "utf8");
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var src = fs.readFileSync(__dirname + "/../build/index.asm.js", "utf8");
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if (src.indexOf("var Math_sqrt =") < 0) { // currently missing in asm.js output
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let p = src.indexOf(" var abort = env.abort;");
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src = src.substring(0, p) + " var Math_sqrt = global.Math.sqrt;\n " + src.substring(p);
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}
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var nbodyASMJS = eval("0," + src)({
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const nbodyAsmJS = eval("0," + src)({
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Int8Array,
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Int16Array,
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Int32Array,
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Float64Array,
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Math
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}, {
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abort: function() { throw Error(); }
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abort: () => { throw Error(); }
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}, new ArrayBuffer(0x10000));
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// Load JS version
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var src = fs.readFileSync(__dirname + "/../build/index.js", "utf8");
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var scopeJS = {
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require: function() {},
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exports: {},
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unchecked: function(expr) { return expr }
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src = fs.readFileSync(__dirname + "/../build/index.js", "utf8");
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const scopeJS = {
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require: () => {},
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exports: {},
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unchecked: expr => expr
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};
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var nbodyJS = new Function(...Object.keys(scopeJS).concat(src + "\nreturn exports"))(...Object.values(scopeJS));
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const nbodyJS = new Function(
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...Object.keys(scopeJS).concat(src + "\nreturn exports"))(...Object.values(scopeJS)
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);
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function test(nbody, steps) {
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nbody.init();
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var steps = process.argv.length > 2 ? parseInt(process.argv[2], 10) : 20000000;
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var time;
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console.log("Performing " + steps + " steps (WASM) ...");
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time = test(nbodyWASM, steps);
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console.log("Performing " + steps + " steps (AssemblyScript WASM) ...");
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time = test(nbodyAS, steps);
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console.log("Took " + (time[0] * 1e3 + time[1] / 1e6) + "ms");
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console.log("Performing " + steps + " steps (ASMJS) ...");
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time = test(nbodyASMJS, steps);
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console.log("Performing " + steps + " steps (AssemblyScript ASMJS) ...");
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time = test(nbodyAsmJS, steps);
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console.log("Took " + (time[0] * 1e3 + time[1] / 1e6) + "ms");
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console.log("Performing " + steps + " steps (JS) ...");
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time = test(nbodyJS, steps);
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console.log("Took " + (time[0] * 1e3 + time[1] / 1e6) + "ms");
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console.log("Performing " + steps + " steps (Rust WASM) ...");
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time = test(nbodyRS, steps);
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console.log("Took " + (time[0] * 1e3 + time[1] / 1e6) + "ms");
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console.log("\nWARMED UP:\n");
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console.log("Performing " + steps + " steps (WASM) ...");
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time = test(nbodyWASM, steps);
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console.log("Performing " + steps + " steps (AssemblyScript WASM) ...");
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time = test(nbodyAS, steps);
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console.log("Took " + (time[0] * 1e3 + time[1] / 1e6) + "ms");
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console.log("Performing " + steps + " steps (ASMJS) ...");
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time = test(nbodyASMJS, steps);
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console.log("Performing " + steps + " steps (AssemblyScript ASMJS) ...");
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time = test(nbodyAsmJS, steps);
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console.log("Took " + (time[0] * 1e3 + time[1] / 1e6) + "ms");
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console.log("Performing " + steps + " steps (JS) ...");
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time = test(nbodyJS, steps);
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console.log("Took " + (time[0] * 1e3 + time[1] / 1e6) + "ms");
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console.log("Performing " + steps + " steps (Rust WASM) ...");
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time = test(nbodyRS, steps);
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console.log("Took " + (time[0] * 1e3 + time[1] / 1e6) + "ms");

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